Two years and half after the first COVID-19 outbreak, we keep on learning about it. Never before in science history, so much information was quickly generated, shared and deployed. Such an amount of research and scientific development contributed to face off the challenges imposed by the pandemic that need now to be deeply dived into and not be forgotten. A growing literature is focusing on a post-COVID-19 pandemic—likely endemic—world, with a call for the next pandemic.1 Early in the forerunner countries, preventing and identifying early in-hospital COVID-19 positivity was one of the leading challenges and required a substantial step forward in hospital management and patient care.2, 3 Here, we focused on radiological assessment performed at ED admission during the first pandemic wave. Radiological imaging has indeed gained a critical role in the diagnosis of COVID-19 patients. Especially chest X-ray (CXR) has early become a useful diagnostic and monitoring tool, due to the feasibility in the emergency setting, despite its low specificity in the early stage of disease.4 Multiple CXR-based scoring systems have been proposed to stratify the risk of disease progression and mortality.5-7 Here, we investigated whether the semi-quantitative scoring of CXR Brixia may deserve a role beyond the early COVID-19 positivity such as prediction of late COVID-19 infection and serious adverse outcome (i.e. thrombotic complications and gastrointestinal [GI] bleeding). This is a sub-analysis of a previously published retrospective study carried out at the IRCCS Ospedale Policlinico San Martino in Genoa during the first wave of COVID-19 pandemic.3 Briefly, patients tested negative for COVID-19 infection during stay at ED admission were enrolled from 24 February to 24 May 2020. Brixia score was then consecutively assessed in the first 283 enrolled patients (Figure S1). Clinical and biochemical data performed at ED admission have been collected from hospital records, as previously described.3 The present study was approved by the local ethics board of IRCCS Ospedale Policlinico San Martino (200/2020 – DB id 10,515). The study was carried out in accordance with The Code of Ethics of the World Medical Association (Declaration of Helsinki) for experiments involving humans and adhered to the principles of the STROBE statement. Brixia scoring system was calculated according with previous literature4, 6 (Figure 1). Chest radiographs were performed with DRX Revolution and Kodak DirectView DR9000 (both from Carestream Health) or SEDECAL—Radiologico Mobile Digitale (ATS), or Roller 15/30 (SMAM). Image interpretation was carried out by two expert radiologists, blinded to the other clinical variables and outcome, through SuitEstensa RIS (Esaote). A case of delayed COVID-19 positivity is defined by a patient tested positive for COVID-19 infection in Internal Medicine wards after being negative during stay at ED. The primary outcome of the study is then to establish the predictive role of Brixia score towards delayed COVID-19 positivity during hospital stay. As model with binary outcome, our sample size (>125) subjects satisfy the requirements for having a power greater than 80% and a type I error lower than 5% (see AppendixS1). As secondary outcomes, we consider any COVID-19 positivity during stay in both ED and Internal Medicine ward, occurrence of adverse events (a composite of thrombotic complications and gastrointestinal [GI] bleeding) and overall mortality. The latter was tested after Brixia score categorization (< vs. ≥ 8), as previously reported.4 Analyses are performed with GraphPad Prism version 9.0.0 for Windows (GraphPad Software, San Diego, CA) and R environment for statistical computing (URL http://www. R-project. org/). Categorical data are presented as absolute and relative frequencies, whereas continuous ones as median and interquartile range [IQR] since the normality assumption is not demonstrated. Unpaired intergroup comparisons are drawn by Fisher's exact test and Mann–Whitney U-test, as appropriate. Spearman's rank coefficients are calculated to investigate the correlations between continuous/ordinal variables, whereas Cox proportional hazards models are built to test the predictive ability of Brixia scoring system towards any time and late (in-ward) COVID-19 positivity during hospitalization, and overall mortality as well. They are expressed as hazard ratio (HR) with 95% confidence interval (CI). For the latter, Brixia categorization also allows survival rate estimation through Log-rank test and Kaplan–Meier curve. Logistic regression models (presented as odds ratio [OR] with 95% CI) are further built to address the predictive role of Brixia score towards adverse thrombotic events and GI bleeding. For the adjusted models, forward stepwise regression analysis is used and non-normally variables are log-transformed to meet the linearity requirement for regression. Performances of regression analyses are also tested for (i) calibration by Hosmer–Lemeshow goodness of fit test, (ii) discrimination through receiver operator characteristic (ROC) curve and (iii) internal validation by bootstrap resampling. For all statistical analyses, a 2-sided p-Value <0.05 was considered as statistically significant. Clinical characteristics of the study cohort are summarized in Tables 1 and Tables S1,S2. As in the original cohort, patients are elderly with a median age of 80 years and equally distributed across sexes (52.1% of males). Patients with in-hospital COVID-19 positivity have more frequently fever (p = 0.03 and p = 0.099, respectively) and dyspnoea (p = 0.003 and p = 0.042, respectively) at ED admission. Since tested positive patients were immediately transferred to COVID-19 dedicated units, their median length of stay in Internal Medicine ward was lower (5 days vs. 10 days, p = 0.007), without significant differences in the overall hospitalization time. Rather, the time to delayed in-hospital positivity is correlated with advanced age (p = 0.006), comorbidity burden (p < 0.001), impaired renal function (p = 0.009 and 0.001 for creatinine and estimated glomerular filtration rate [eGFR], respectively) and inflammatory status (p = 0.037 for C-reactive protein [CRP]) (Table S3). At ED admission, Brixia score is higher in patients with delayed in-hospital positivity (p = 0.0737), history of contact with COVID-19 cases before hospitalization (p-Value for trend 0.0067) and dyspnoea (p = 0.0058) (Figure 2A–E; Tables S4,S5). Delayed in-hospital positivity occurred in 18 patients (6.4%) of total cohort and within 5 days in the half of cases (Figure 3A). Of them, 7 (38.9%) occurred at the first test just upon the admission in COVID-19-free Internal Medicine Units (Figure 1). Brixia score shows a significant predictive value towards delayed in-hospital COVID-19 positivity (HR 1.124 [1.007–1.254]) (Table S6). It also fits into a model with fever and dyspnoea (HR 1.164 [1.044–1.299]) (Figure 3B; Table S6). With a p-Value of 0.123, the Hosmer–Lemeshow test confirmed the good calibration of this model, whereas the result of ROC curve analysis indicated a significant discrimination performance of the model with an area under the curve of 0.765. As internal validation, the HR estimated from the original dataset fall within the new confidence intervals calculated with bootstrap resampling. During hospitalization, forty patients suffer gastrointestinal bleeding (n = 26) and/or thrombotic complications (n = 17), namely venous/pulmonary thromboembolism (n = 9), acute coronary syndrome (n = 4) and ischaemic stroke (n = 4) (Figure 3C). Brixia scoring system shows an independent association with serious hospital complications, fitting a model with haemoglobin and CRP towards overall adverse event (OR 1.131 [1.032–1.239]) and with D-dimer for thrombotic events (OR 1.344 [1.116–1.617]) (Figure 3D,E). Death was recorded in 81 patients (28.6%) during a median follow-up of 169 days (range 2 to 402 days). In-hospital death occurred in 27 patients with only 10 cases directly related to the COVID-19 infection (Figure 4A,B). Once categorized, Brixia values ≥8 are independent predictors of overall mortality (HR 1.948 [1.194–3.176]) and fit a model with Charlson comorbidity index, systolic blood pressure, eGFR and CRP (HR 1.708 [1.018–2.868]) (Figure 4C). Kaplan–Meier survival curve confirmed the higher mortality risk associated with a Brixia score ≥8 with a p-Value at log rank test of 0.021 (Figure 4D). During the first wave of pandemic, many diagnostic pitfalls challenged clinicians in their threshold of suspicion for COVID-19 infection. Early, reliable and feasible tools for detecting COVID-19 early at ED admission were missing and not easy to implement.8 Here, we point out the role of the semi-quantitative CXR score Brixia on COVID-19 diagnosis/prognosis4, 6 and beyond. The association with history of contact with suspicious/certain cases and the hallmark symptoms of COVID-19 infection might support the supremacy of clinical/radiological diagnosis towards molecular positivity. Nasopharyngeal swabs were routinely repeated during ED stay and this make consistent the hypothesis of a greater predictive power of Brixia, at least compared with the first-generation molecular tests for COVID-19. As additional finding we here report a predictive value of Brixia towards death and atherothrombotic adverse events during hospitalization and post-discharge. The fitting with d-dimer in logistic regression model would also suggest a pathophysiological explanation. Similar to previous coronavirus pandemics (i.e. SARS-CoV-1 and MERS-CoV-1), the association of SARS-CoV-2 infection with D-dimer and coagulation abnormalities is clearly established.9 Endothelial dysfunction and microvascular thrombosis are well-described mechanisms by which COVID-19 infection would trigger venous thromboembolism/pulmonary embolism and complement-mediated thrombotic microangiopathies/disseminated intravascular coagulation.10 Whether thrombotic complications also underlie the previous reported association between Brixia score and clinical worsening (i.e. non-invasive ventilation, intubation and/or admission in intensive care unit) cannot be ruled out.7 Even more intriguingly, we observed this association in the whole cohort that include a prevalence of COVID-19 negative patients. This should pave the way for future studies addressing clinical features associated with these radiological patterns. The independent association with mortality is another intriguing finding. Here, we confirm a greater mortality risk in elderly and frail patients with high comorbidity burden—mainly cardiovascular and renal—and inflammatory status6, 11 Whether Brixia score is ‘the pitch of the iceberg’ that reflect underlying pathological conditions remains to be elucidated. Overall, semi-quantitative scoring of CXR by Brixia would display a relevant prognostic role, not limited to COVID-19 infection. It would also have a supremacy over CT scan, a measure burdened by high radiation dose, longer examination time and less feasibility in ED12 and peripheral healthcare centres.13 The lessons from the COVID-19 pandemic may then prepare for further waves, new pandemics and open new application for the Brixia scoring systemic as well. CXR indeed meets the need to merge radiological, demographic, biochemical and clinical features in the shortest time, optimizing patient diagnosis/risk stratification and reducing the person-to-person transmission.14 Information from Brixia score might also be extended through radiomic analysis and/or artificial intelligence.15 As sub-analysis of a larger retrospective cohort, this study has an intrinsic limitation, although the sample analysed is representative of the original cohort and they both share the primary outcome. Conversely, this—and the whole cohort—may be not representative of the global pandemic, being the recruitment time limited to the first wave of pandemic in a forerunner county (i.e. Italy). As above-mentioned, the better performance of Brixia score as compared to a swab test for COVID-19 need validation with later molecular/antigenic kits. Similarly, external validations with other pandemic waves where virus variants overlapped, and vaccinated people increased would be appropriate. In conclusion, this sub-analysis of retrospective cohort points out the role of chest X-ray scoring with Brixia as predictive tool of delayed COVID-19 positivity. This would have a relevant impact in preserving COVID-19-free wards from in-hospital cluster of contagion. Results from secondary outcomes (i.e. thrombotic complication and long-term overall mortality) also suggest potential future applications of Brixia score beyond COVID-19 pandemic. This would deserve specifically designed studies so that new tool may develop from the pandemic wave. This research was funded by a grant from the Rete Cardiologica of Italian Ministry of Health (#2754291) to Prof. F. Montecucco. The research was funded by a grant from the Internal Medicine Department of the University of Genoa to Prof. Federico Carbone. The authors report no relationships that could be construed as a conflict of interest. The datasets used and/or analysedanalyzed during the current study are available from the corresponding author on reasonable request. Appendix S1: Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

SARS-CoV-2 represents a "Pandora's box" highlighting critical issues for in-hospital management of infectious patients. Over the past fifty years, the organization of hospital departments in Western countries has been driven by the need to face off noncommunicable diseases, in accordance with epidemiological data. Transmission-based precautions have been instead limited to dedicated departments. During the last year, strong efforts have been then required to improve infection prevention strategies, a process involving countless aspects of patient management. In forerunners countries (e.g., Italy), a first step was to identify different in-hospital paths for positive and nonpositive patients.1, 2 Due to the air contagiousness of disease, the identification and segregation of SARS-CoV-2-positive patients from negative ones represented a critical step. As weeks went by, it became evident that the case definition of SARS-CoV-2 infection was not straightforward. Clinical features of SARS-CoV-2 infection (different from those observed in previous SARS and MERS pandemics),3 patients overcrowding and pitfalls in molecular diagnosis4 contributed together to overwhelm the traditional pre-SARS-CoV-2 hospital organization. Clinicians had to lower the threshold of suspicion for deciding who needed to be tested/isolated and how to do that.5 When possible, separate pavilions were committed to SARS-CoV-2-positive patients and somewhere for those presenting with high clinical suspicion of disease patients but testing negative for SARS-CoV-2 infection. Our Institution–IRCCS Policlinico San Martino–in Genoa (Italy) early approached such categorization of patients, being aware of the dramatic impact that an intrahospital spread would have. Even hospital facilities were then reorganised to segregate positive/suspicious patients to prevent the dissemination of the infection among SARS-CoV-2-negative patients. By focussing on this critical point, we here retrospectively analyzed cases of late SARS-CoV-2 positivity occurring within internal medicine wards, formally not SARS-CoV-2-dedicated. Clinical and management variables were investigated, aiming at identifying potential predictors of late SARS-CoV-2 positivity and their impact on patient outcome.6, 7 Alongside, potential value of common laboratory test at hospital admission was explored. This is a retrospective analysis of patients admitted to internal medicine wards not dedicated to SARS-CoV-2 between 24 February 2020 and 24 May 2020 at IRCCS Ospedale Policlinico San Martino in Genoa (Italy). The screened population was composed of 690 patients admitted during the enrolment period. Only those admitted from the ED and tested with at least one nasal-pharyngeal swab for SARS-CoV-2 were included in the analysis (n = 668). Then, we excluded patients with positive for SARS-CoV-2 infection at ED reaching a final cohort of n = 478 (Figure S1). Clinical and biochemical data performed at ED admission have been collected from hospital records, including the provenance of patients (home, nursing home), any history of contact with SARS-CoV-2 cases and common symptoms of SARS-CoV-2 infection (i.e., fever, cough, dyspnoea, asthenia, anosmia, dysgeusia and diarrhoea). Comorbidities were then stratified according to the Charlson Comorbidity Index. Routinely, biochemical profile performed at ED admission and later during internal medicine ward hospitalization–including arterial blood gas analysis (BGA) and inflammatory biomarkers (i.e., fibrinogen, lactate dehydrogenase [LDH], ferritin and C-reactive protein [CRP])–was retrieved from hospital records performed at ED admission–and later during internal medicine ward hospitalization–was retrieved from hospital records and included arterial blood gas analysis (BGA) and inflammatory biomarkers (i.e., fibrinogen, lactate dehydrogenase [LDH], ferritin and C-reactive protein [CRP]). SARS-CoV-2 positivity of nasal-pharyngeal swabs were performed by routine real-time polymerase chain reaction. The present study was approved by the local ethics board of IRCCS Ospedale Policlinico San Martino (200/2020-DB id 10515). The study was carried out in accordance with The Code of Ethics of the World Medical Association (Declaration of Helsinki) for experiments involving humans and adhered to the principles of the transparent reporting of a multivariable prediction model for individual prognosis or diagnosis (TRIPOD), the TRIPOD statement. Cases of late positivity were defined as patients testing positive for SARS-CoV-2 in internal medicine wards, not SARS-CoV-2-dedicated, after a previous negative molecular test performed in the ED (nasopharyngeal swab). The aim of the study was then to identify whether ED length of stay may have a role as predictor of late positivity to SARS-CoV-2 infection independently of other clinical variables, as emerging in literature.7, 8 They were selected among those significantly different at descriptive analyses: contact with suspected cases, fever and dyspnoea. Alongside, the same criteria were used to identify potential biochemical biomarkers: pCO2, fibrinogen, LDH, ferritin and CRP. Sample size was calculated according to latest guidance for developing clinical prediction models.9 More specifically, by considering this study as a model with binary outcome, our sample size (n = 478) satisfied the minimum sample size required for (i) a 95% confidence interval for the overall outcome proportion of 0.5 (n ≥ 385); (ii) a mean absolute precision error (MAPE) <0.05 (n ≥ 252) and (iii) an expected uniform shrinkage factor <10% (n ≥ 340). Furthermore, we have preset a proportion of overall variance explained (R2cs) = 0.1. Analyses were performed with GraphPad Prism version 9.0.0 for Windows (GraphPad Software, San Diego, CA) and R environment for statistical computing (URL http://www. R- project. org/). Categorical data were presented as absolute and relative frequencies, whereas continuous ones as median and interquartile range [IQR] since the normality assumption was not demonstrated. Unpaired intergroup comparisons were drawn by Fisher's exact test and Mann-Whitney U-test, as appropriate. Logistic regression analyses were then used to estimate the predictive role toward a late nasal-pharyngeal swab positivity to SARS-CoV-2 infection of clinical variables and biochemical parameters separately. Results were expressed as odds ratio (OR) with 95% confidence interval (CI). Model calibration performances have been evaluated via the Hosmer-Lemeshow goodness of fit test with 10 groups. Model performance was assessed through receiver-operator characteristic (ROC) curve analysis by reporting the area under the curve, sensitivity, specificity and +/− likelihood ratio. Predictive ability toward overall and SARS-CoV-2-related mortality was tested through Cox hazard regression models presented as hazard ratio (HR) with 95% CI. Survival rate was also estimated with Kaplan-Meier curve and log-rank test. For all statistical analyses, a 2-sided p-value <0.05 was considered as statistically significant. Based on a minimum measurable difference of 1 day between the groups in our primary endpoint, a late positivity group >25 patients implies a statistical power >95%, as calculated with the two-tailed Mann-Whitney U-test. Clinical characteristics of the study cohort are reported in Table S1. Patients were almost all Caucasian (99.0%), elderly (median age of 80 years [70–86]) and equally distributed across sexes (231 males, 48.3%). When study cohort was categorised in persistent negative vs. late SARS-CoV-2-positive, the latter group was associated with history of previous contact with suspicious or ascertained cases (24.5% vs. 5.8%, p = 0.003) and clinical presentation with fever (65.0% vs. 25.6%, p < 0.001) and dyspnoea (62.5% vs. 25.3%, p < 0.001) at admission. Except for the history of ischemic stroke and peptic ulcer disease (Table S2), the impact of comorbidity burden–as assessed by Charlson Comorbidity Index–on late SARS-CoV-2 positivity was not significant. Conversely, even a slightly longer stay at ED was significantly associated with late SARS-CoV-2 positivity (3 vs. 2 days, p = 0.012). Since patients with late SARS-CoV-2 positivity were immediately transferred to dedicated units, the median length of stay in internal medicine wards, not SARS-CoV-2-dedicated, was lower in this group of patients (7 days3-13 vs. 10 days,6-17 p < 0.001), without significant differences in the overall hospitalization time (Table S1). At BGA, only pCO2 was slightly lower in late SARS-CoV-2-positive patients (33 mmHg vs. 35 mmHg, p = 0.040) (Table S3), whereas biochemical profile showed an inflamed status characterised by increased serum levels of fibrinogen (p = 0.029), LDH (p = 0.038), ferritin (p = 0.002) and CRP (p = 0.002). Out of 478 hospitalizations in internal medicine wards not SARS-CoV-2-dedicated, a total of 40 patients presented late positivity (8.3%). Positivity generally occurred within 14 days from in-ward admission (92.5%, Figure 1A) and ED admission (75.0% Figure 1B). When included in logistic regression model, fever (OR 5.406 [2.727–10.716]: p < 0.001), dyspnoea (OR 4.910 [2.499–9.647]: p < 0.001) and ED hospitalization length (OR 3.091 [1.279–7.472]: p = 0.012) emerged as clinical predictors of late SARS-CoV-2 positivity at nasal-pharyngeal swab (Figure 1C). Combining those variables allowed to improve the predictive performance–especially the sensitivity–as emerging from ROC curve analysis (Figure S2). We have then internally validated our results by performing a bootstrap resampling performance. Based on 1000 bootstrap replicates, we obtained the following estimate of the ORs (average of the 1000 ORs from the 1000 bootstrap samples) and related 95% CI. Noteworthy, the OR estimated on the original dataset falls within the new bootstrap confidence intervals (Figure S3). Conversely, no inflammatory biomarkers showed an independent association with late SARS-CoV-2 positivity (Table S4). Further emphasising the predictive role of even a slightly longer ED hospitalization, the Kaplan-Meier analysis showed that risk of late SARS-CoV-2 substantially increased according to quartiles of length of stay in ED (p-value for log-rank test 0.044, Figure 1D). Patients discharge after hospitalization in internal medicine wards formally not SARS-CoV-2-dedicated took place mostly at home (60.88%), while frailer patients were transferred to nursing homes (5.8%) (Table S5). Among late SARS-CoV-2-positive patients, 75.0% required hospitalization in SARS-CoV-2-dedicated wards, whereas only 10% was discharged at home. Overall, mortality rate during the study period was 12.6% (n = 60), whereas only 2 late SARS-CoV-2-positive patients died. Clinical variables associated with late SARS-CoV-2 positivity were then included in a Cox proportional regression model in which only ED hospitalization length was confirmed as the only predictor of overall in-hospital mortality (HR 1.029 [1.005–1.054]; p = 0.018]) (Table 1). When biochemical variables were considered, both LDH (adjusted HR 5.219 [4.251–10.125]; p = 0.022) and ferritin (adjusted HR 1.747 [1.082–2.822]; p = 0.022) were confirmed as independent predictors of overall in-hospital mortality (Table S6). The present study has been designed to address a challenging clinical problem emerged during the first wave of SARS-CoV-2 pandemic. Alongside restrictive measures instituted by the governments, hospitals had to reorganise themselves–each in its own way–according to their characteristics: location, pavilion architecture, epidemiology and available medical staff among the others.10 Here, we highlighted a critical role for length of ED stay as predictor of late positivity within internal medicine wards not SARS-CoV-2-dedicated. Although we considered a 14 days window as suggested by the WHO, the median incubation time for SARS-CoV-2 infection was six days long, in line with reported in literature.11, 12 Being the median ED hospitalization length shorter (three days), both out-hospital infection and in-hospital spreading of SARS-CoV-2 infection should be considered. Interestingly, the strongest independent predictors were fever and dyspnoea, typical presentation symptoms of SARS-CoV-2 infection. It would be then conceivable to suppose that at least a part of positive patients were initially false negatives. This hypothesis implies these cases to be more likely out-hospital rather than in-hospital infections. However, Figure S4 clearly indicates that late SARS-CoV-2-positive patients were tested several times before positivity occurred (in median 4 times) and often with different type of tests. This observation supports the role of in-hospital infection. Being this the only partially modifiable risk factor among those included in the model, it represents a clinical challenge of undoubted clinical relevance. This aspect has been widely described even in the early phase of pandemic, when positive patients attending small EDs in the North of Italy spread the infection to working personnel, other patients and relatives.10 SARS-CoV-2 infection, indeed, remained unrecognised for several weeks in Italy–and Europe as well–and no special measures were taken to reduce the spread in the early phase of contagion. This accounts for a large part of patients admitted to internal medicine wards without any molecular screening test for SARS-CoV-2 infection (and then excluded from our analysis). Most of them were admitted to ED before or in the early phase of pandemic (December 2019-February 2020). The other patients admitted without SARS-CoV-2 screening were those considered negative because of clinical presentation. Those behaviours have progressively changed as clinical pitfalls in SARS-CoV-2 infection diagnosis have been demonstrated. Furthermore, ED admittance of patients with nondeferrable disease also resumed as the weeks went by (March-April 2020), alongside with SARS-CoV-2 patients with less severe–or even atypical–disease presentation. Here, the need to identify and segregate patients at high, intermediate and low risk of carrying SARS-CoV-2 dramatically emerged.13, 14 Floor-to-ceiling partitions were built to cordon off part of the main ED. Moreover, risk of exposure for supposedly negative patients also had to be guaranteed during transport towards radiology or other facilities. As regional emergency hub, our institution then had to maintain an active surveillance of local pandemic evolution dynamically reassessing workflow processes not only in the ED but also in the whole hospital.15, 16 As a result, late SARS-CoV-2 positivity occurred in 8.3% of patients admitted in internal medicine wards not SARS-CoV-2-dedicated. Noteworthy, ED length of stay significantly impacts on overall in-hospital mortality. Keep some internal medicine wards free of SARS-CoV-2 infection should indeed represent a key achievement for preventing hospital collapse during SARS-CoV-2 pandemic. Maintaining patient outflow from ED, preserving standard of care for patients and diseases not SARS-CoV-2-related, reducing contagion risk after discharge: these main benefits are worth keeping some internal medicine wards free from SARS-CoV-2 infection. Some may argue that over 1.5 years into the pandemic, those key aspects have already been implemented. However, it should be considered that the coming fall-winter season will be likely the first where SARS-CoV-2 and seasonal influenza viruses will coexist. Vaccination campaigns have indeed significantly reduced the population at risk of SARS-CoV-2 infection, but they also resulted in a softening of containment measures. An upcoming stress for ED is then expectable due to a paradoxical increased risk of contagion and to the challenges in terms of differential diagnosis between SARS-CoV-2 and influenza viruses. Keep surveillance on what concerns patient triage, segregation and outflow will therefore represent challenges to be addressed with the lessons of pandemic. Furthermore, this experience showed how inconsistent the pandemic plans were worldwide. Any post-hoc analysis may then provide a contribution for their redesigning/implementation, although healthcare organization greatly differs at several levels between countries – and even regions, cities and hospitals within. This is a clinical study that shows a special focus on ED length of stay. On the one hand, this aspect might hinder the reproducibility of the study results in other countries especially considering potential differences in ED length of stay. Despite our attempt of internally validate our results, larger studies are warranted to perform multivariable analyses and extensive predictive modelling. Another aspect that should be considered is the diagnostic performance of the combined nasal and throat swab, which is characterised by high specificity but limited sensitivity.17 As repeated testing significantly improved diagnostic performance, this may represent a bias that should be addressed in larger studies. In conclusion, this retrospective analysis found that the duration of stay at the ED before the admission to ordinary wards represents a potential risk factor for late in-hospital positivity to SARS-CoV-2 diagnostic tests. Despite the implementation of prevention protocols, the high variability in virus incubation time might determine a failure of preventive measures. A dynamic reassessment of workflow processes throughout the hospital then represents a critical step for preventing hospital collapse during SARS-CoV-2 pandemic. Institution of quarantine sites within each clinical ward (as done at IRCCS San Martino Hospital in Genoa) might be more helpful to manage the risk of late positivity. Finally, also laboratory variables (i.e., ferritin and LDH) may help, with some limitations, in predicting late SARS-CoV-2 positivity and mortality. This study was supported by a grant from the Rete Cardiologica of Italian Ministry of Health (#2754291) to Prof. F. Montecucco. Open Access funding provided by Universita degli Studi di Genova within the CRUI-CARE Agreement. [Correction added on 19 May 2022, after first online publication: CRUI funding statement has been added.] The authors report no relationships that could be construed as a conflict of interest. Datasets are available on request by the Corresponding Author. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

In breast cancer patients undergoing neoadjuvant chemotherapy before surgery, there is an unmet need for noninvasive predictive biomarkers of response. The analysis of circulating tumor DNA (ctDNA) in particular has been the object of several reports, but few of them have studied the applicability of tagged targeted deep sequencing (tTDS) to clinical practice and its performance compared with droplet digital PCR (ddPCR). Here, we present the first results from an ongoing study involving a prospectively accrued, monocentric cohort of patients affected by invasive breast cancer, undergoing neoadjuvant chemotherapy followed by surgery with curative intent as per clinical practice. A pretreatment tumor biopsy and plasma samples were collected before and during treatment, after surgery, and every six months henceforth or until relapse, whichever came first. Pretreatment biopsies were sequenced with a 409-gene massive parallel sequencing (MPS) panel, allowing the identification of target mutations and their research in plasma by tTDS and ddPCR as a complementary approach. Using tTDS, we demonstrated the presence of at least one deleterious mutation in all the relapsed cases we studied (n = 4), with an average lead time of six months before clinical relapse. The association with ddPCR was suboptimal, and only one relapsed patient could be identified with such method. tTDS shows potential as an early noninvasive method for the detection of MRD in BC patients.

Standard treatment for locally advanced rectal adenocarcinoma (LARC) includes a combination of chemotherapy with pyrimidine analogues, such as capecitabine, and radiation therapy, followed by surgery. Currently no clinically useful genomic predictors of benefit from neoadjuvant chemoradiotherapy (nCRT) exist for LARC. In this study we assessed the expression of 8,127 long noncoding RNAs (lncRNAs), poorly studied in LARC, to infer their ability in classifying patients' pathological complete response (pCR). We collected and analyzed, using lncRNA-specific Agilent microarrays a consecutive series of 61 LARC cases undergoing nCRT. Potential lncRNA predictors in responders and non-responders to nCRT were identified with LASSO regression, and a model was optimized using k-fold cross-validation after selection of the three most informative lncRNA. 11 lncRNAs were differentially expressed with false discovery rate < 0.01 between responders and non-responders to NACT. We identified lnc-KLF7-1, lnc-MAB21L2-1, and LINC00324 as the most promising variable subset for classification building. Overall sensitivity and specificity were 0.91 and 0.94 respectively, with an AUC of our ROC curve = 0.93. Our study shows for the first time that lncRNAs can accurately predict response in LARC undergoing nCRT. Our three-lncRNA based signature must be independently validated and further analyses must be conducted to fully understand the biological role of the identified signature, but our results suggest lncRNAs may be an ideal biomarker for response prediction in the studied setting.

AIM: To compare 2-deoxy-2-(F-18) fluoro-D-glucose(F-18-FDG) and F-18-sodium (F-18-NaF) positron emission tomography/computed tomography (PET/CT) accuracy in breast cancer patients with clinically/radiologically suspected or known bone metastases.METHODS: A total of 45 consecutive patients with breast cancer and the presence or clinical/biochemical or radiological suspicion of bone metastatic disease underwent F-18-FDG and F-18-fluoride PET/CT. Imaging results were compared with histopathology when available, or clinical and radiological follow-up of at least 1 year. For each technique we calculated: Sensitivity (Se), specificity (Sp), overall accuracy, positive and negative predictive values, error rate, and Youden's index. McNemar's chi(2) test was used to test the difference in sensitivity and specificity between the two diagnostic methods. All analyses were computed on a patient basis, and then on a lesion basis, with con-sideration of the density of independent lesions on the coregistered CT (sclerotic, lytic, mixed, no-lesions) and the divergent site of disease (skull, spine, ribs, extremities, pelvis). The impact of adding F-18-NaF PET/CT to the work-up of patients was also measured in terms of change in their management due to F-18-NaF PET/CT findings.RESULTS: The two imaging methods of F-18-FDG and F-18-fluoride PET/CT were significantly different at the patient-based analysis: Accuracy was 86.7% and 84.4%, respectively (McNemar's chi(2) = 6.23, df = 1, P = 0.01). Overall, 244 bone lesions were detected in our analysis. The overall accuracy of the two methods was significantly different at lesion-based analysis (McNemar's chi(2) = 93.4, df = 1, P < 0.0001). In the lesion density-based and site-based analysis, 18F-FDG PET/CT provided more accurate results in the detection of CT-negative metastasis (P < 0.002) and vertebral localizations (P < 0.002); F-18-NaF PET/CT was more accurate in detecting sclerotic (P < 0.005) and rib lesions (P < 0.04). F-18-NaF PET/CT led to a change of management in 3 of the 45 patients (6.6%) by revealing findings that were not detected at F-18-FDG PET/CT.CONCLUSION: F-18-FDG PET/CT is a reliable imaging tool in the detection of bone metastasis in most cases, with a diagnostic accuracy that is slightly, but significantly, superior to that of F-18-NaF PET/CT in the general population of breast cancer patients. However, the extremely high sensitivity of F-18-fluoride PET/CT can exploit its diagnostic potential in specific clinical settings (i.e., small CT-evident sclerotic lesions, high clinical suspicious of relapse, and negative F-18-FDG PET and conventional imaging).

Introduction: Neoadjuvant radiochemotherapy (NCRT) reduces the risk of local recurrence in patients (pts) with locally advanced rectal cancer (LARC). The main issue is the accurate staging before and after NCRT and its predictive role for select responding pts.Methods: From January 2010 to November 2014, 71 consecutive pts with rectal cancer (stage II-III) received NCRT with capecitabine 825 mg/m2 bid concomitant with 45-50 Gy conventional fractionation external beam radiotherapy followed by radical surgery (total mesorectal excision) at 12 weeks. All patients were staged with pelvic magnetic resonance imaging (MRI); 65 of them performed also endoscopic ultrasound (EUS) before and after NCRT.Results: the mean age of patients was 64 years (range: 36-84). 51% pts had tumor in lower third of rectum (sphincter preservation was performed in 55,5% of pts). Pathological complete response (pCR) was observed in 24% of patients, partial response in 50%, no response in 21% and progression disease in 5%. Median follow-up was 22 months. At this time disease-free-survival was 81,7% and overall survival was 85,9%. Median time for restaging exams was 32 days (11-68) from the end of therapy. In the staging phase (before NCRT) there was concordance between EUS and MRI in 91,3% of cases with regard T stage and 70,9% for N stage; MRI is able to detect lymph node involvement increased by 20% compared to EUS. In the post-treatment phase pelvic MRI predicted pathological T stage in 39,0% versus 41,5% for EUS and in 53,0% versus 66,0% respectively for N stage. For the subgroup of pts with pCR MRI predicted pathological T stage in 23,5% versus 47,0% for EUS and in 50,0% versus 76,5% respectively for N stage.Conclusion: MRI and EUS showed good performances for staging rectal cancer but nodal staging remains challenging. Both techniques appear to be inadequate in predicting response and especially in predicting the pathologic complete response after NCRT. It is necessary to improve diagnostic tools and develop predictive markers of response in order to be able, in the future, to select pts that may avoid surgery or adjuvant chemotherapy. Introduction: Neoadjuvant radiochemotherapy (NCRT) reduces the risk of local recurrence in patients (pts) with locally advanced rectal cancer (LARC). The main issue is the accurate staging before and after NCRT and its predictive role for select responding pts. Methods: From January 2010 to November 2014, 71 consecutive pts with rectal cancer (stage II-III) received NCRT with capecitabine 825 mg/m2 bid concomitant with 45-50 Gy conventional fractionation external beam radiotherapy followed by radical surgery (total mesorectal excision) at 12 weeks. All patients were staged with pelvic magnetic resonance imaging (MRI); 65 of them performed also endoscopic ultrasound (EUS) before and after NCRT. Results: the mean age of patients was 64 years (range: 36-84). 51% pts had tumor in lower third of rectum (sphincter preservation was performed in 55,5% of pts). Pathological complete response (pCR) was observed in 24% of patients, partial response in 50%, no response in 21% and progression disease in 5%. Median follow-up was 22 months. At this time disease-free-survival was 81,7% and overall survival was 85,9%. Median time for restaging exams was 32 days (11-68) from the end of therapy. In the staging phase (before NCRT) there was concordance between EUS and MRI in 91,3% of cases with regard T stage and 70,9% for N stage; MRI is able to detect lymph node involvement increased by 20% compared to EUS. In the post-treatment phase pelvic MRI predicted pathological T stage in 39,0% versus 41,5% for EUS and in 53,0% versus 66,0% respectively for N stage. For the subgroup of pts with pCR MRI predicted pathological T stage in 23,5% versus 47,0% for EUS and in 50,0% versus 76,5% respectively for N stage. Conclusion: MRI and EUS showed good performances for staging rectal cancer but nodal staging remains challenging. Both techniques appear to be inadequate in predicting response and especially in predicting the pathologic complete response after NCRT. It is necessary to improve diagnostic tools and develop predictive markers of response in order to be able, in the future, to select pts that may avoid surgery or adjuvant chemotherapy.

Summary Aim: To compare 18F-FDG PET/CT and 18F-NaF PET/CT with respect to disease prognostication and outcome in patients affected by bone metastases from breast cancer (BC). Patients, methods: We retrospectively investigated 32 women with BC and documented bone metastases. Semi-quantitative parameters were applied to 18F-FDG PET/CT and 18F-Na PET/CT in order to evaluate disease extent and tumour metabolism. We used time-to-event analyses (Kaplan Meier and COX proportional hazard methods) to estimate progression-free (PFS) and overall survival (OS) in order to assess the independent prognostic value of 18F-FDG PET/CT and 18F-Na PET/CT. Results: The sensitivity of 18F-NaF PET/CT (100%) was higher (p < 0.05) than that of 18F-FDG PET/CT (72% and 72%). None of the 18F-FDG PET/CT-negative patients showed disease progression at the end of follow-up. After adjustment for age, Ki-67 levels, presence of visceral metastases, hormone therapy, duration of bone disease and response to first-line therapy, only 18F-FDG SUV mean [HR 15.7, 95% confidence interval (CI) 1.15-214.5] and 18F-FDG whole-body bone metabolic burden (WB-B-MB) (HR 16.9; 95%CI 1.87-152.2) were independently and significantly associated with OS. None of the 18F-NaF PET/CT parameters were associated with OS. None of the conventional clinical prognostic parameters remained significantly associated with OS after the inclusion of PET/ CT parameters in the model. Conclusion: 18F-FDG PET/CT is independently associated with OS in BC patients with bone metastases and its prognostic impact seems to be higher than conventional clinical and biological prognostic factors. Although 18F-NaF PET/CT has a higher diagnostic sensitivity than 18F-FDG PET/ CT, it is not independently associated with OS.

AIM:The aim of present study was to investigate the feasibility of a densified sequence of FEC75 (5-fluorouracil 600 mg/m2, epirubicin 75 mg/m2, cyclophosphamide 600 mg/m2) and docetaxel 100 mg/m2 (D100) in patients with primary operable high-risk breast cancer.METHODS:Fifty-one consecutive patients with resectable breast cancer and 4 or more positive axillary lymph nodes were enrolled. After a common regimen of 4 cycles of FEC75 given every 14 days, patients received 4 cycles of D100 every 14 days. Prophylactic granulocyte colony-stimulating factor was administered subcutaneously at 5 mg/kg daily from days 5 to 10 to each patient.RESULTS:The primary endpoint was the proportion of subjects receiving at least 85% of the relative dose intensity (rDI) both in the FEC and docetaxel parts of the regimen. In view of the high percentage of grade 3-4 skin toxicity (32%) observed in the first 25 patients (Group A) during D100 treatment, it was decided to continue the study using a docetaxel dose reduced by 15% (85 mg/m2; D85). This second group of 26 patients was defined as Group B. Of the total 51 patients, 38 (75%) received docetaxel rDI ≥85%, 23/26 patients (88.5%) and 15/25 patients (60.0%) in Group B and Group A, respectively. The observed grade 3-4 hematological and nonhematological toxicities were in line with data from the literature. The only significant difference was the higher percentage of grade 3-4 skin toxicity experienced with D100.CONCLUSION:This study failed to demonstrate the feasibility of a dose-dense FEC-D regimen with docetaxel 100 mg/m2. Docetaxel 85 mg/m2 seems to allow a higher rDI than docetaxel 100 mg/m2 but this should be confirmed in a larger cohort of patients.

To the editor: Based on the results of the PARMA and CORAL studies, high-dose chemotherapy (HDT) followed by autologous stem cell rescue has become the standard of care for patients with relapsed, chemosensitive aggressive non-Hodgkin lymphoma (NHL).[1][1],[2][2] Moreover, HDT/autologous stem cell

Abstract Background We previously demonstrated (Visani et al, Blood 2011) the safety of a new conditioning regimen with bendamustine, etoposide, cytarabine, and melphalan (BeEAM) prior to autologous stem cell transplant (ASCT) in resistant/relapsed lymphoma patients (EUDRACTnumber2008-002736-15). Furthermore, this regimen showed significant anti-lymphoma activity (80% CR). At the time of publication (2011), disease type (NHL versus HL) and disease status at transplant (chemosensitive versus chemoresistant) were the only statistically significant variables influencing PFS (p=0.01; p=0.007). However, median follow-up for surviving patients was short (18 months), therefore, it was not possible to draw final conclusions on the efficacy. Aims We evaluated the efficacy of the BeEAM regimen in terms of disease-free (DFS) and overall survival (OS) after a median follow-up of 41 months. Methods Forty-three patients (median age 47 years, range 18-70) with resistant/relapsed NHL (28) or Hodgkin lymphoma (HL, 15) were consecutively enrolled in the study. Twenty-one patients had primary refractory disease, whereas 22 had relapsed disease, 5 of whom where in second or subsequent relapse, at the time of enrolment. The study was designed according to Fleming’s method. The primary objective of the study was to determine the 36-months event free survival rate. We fixed the lowest acceptable rate as 40% and the successful rate as 60%, with a significance level a=0.05 and a power 1-b =0.80. At the time of publication, the median follow-up was 18 months, and therefore it was not possible to establish if we had met the primary end-point of the study. Results we updated the follow-up at 41 months after transplant. Thirty-one out of 43 patients are still in CR (72%), as documented by both PET and CT scan. Two patients with HL were refractory and rapidly died, whereas 10/43 patients (23%) relapsed after a median time of 7.5 months (range:3-23) from transplant. Five patients died (3 NHL, 2 HL), whereas 5 patients are still alive after relapse. Median PFS and OS were still not reached. Conversely, 3-year PFS was 75%, allowing our study to met its primary end-point. Interestingly, disease type (HL versus NHL) at transplant is no longer influencing PFS (p=0.7), and still does not influence OS (p=0.1). On the other hand, disease status at transplant (chemosensitive vs chemoresistant) is still a strong predictor of both PFS and OS (p=0.03 and p=0.009, respectively). At present, one patient developed myelodisplasia after transplant. No other late effects were observed up to now. Conclusions The new BeEAM regimen met the primary end-point of the study and confirms its safety, after 41 months of follow-up. Interestingly, NHL and HL were not statistically different in terms of both PFS and OS at 41 months of observation. These data confirm the high efficacy of this regimen in heavily pretreated non-Hodgkin, as well as Hodgkin lymphoma. Acknowledgments supported in part by AIL Pesaro Onlus. Disclosures: Ocio: Onyx: Consultancy, Research Funding; Novartis: Consultancy; Array Biopharma: Consultancy, Research Funding; Bristol Myers Squibb: Consultancy; Celgene: Consultancy, Research Funding.

The role of high-dose therapy (HDT) followed by autologous stem cell transplantation (ASCT) in the treatment armamentarium of aggressive B- and T-cell non-Hodgkin lymphoma (NHL) is still a matter of debate. In the pre-Rituximab era, the PARMA study demonstrated the superiority of HDT/ASCT over conventional salvage chemotherapy in chemosensitive, relapsed patients. Subsequently, HDT/ASCT has become a standard approach for relapsed NHL. With the advent of Rituximab in the landscape of NHL, transplantation as part of first-line therapy has been challenged. However, no benefit in terms of disease-free or overall survival of HDT/ASCT over standard therapy was shown when Rituximab was added to both arms. Moreover, the superiority of HDT/ASCT over conventional salvage therapy in patients relapsing from first-line therapy including Rituximab was not confirmed. From these disappointing results, novel strategies, which can enhance the anti-lymphoma effect, at the same time reducing toxicity have been developed, with the aim of improving the outcome of HDT/ASCT in aggressive NHL. In T-cell lymphoma, few publications demonstrated that consolidation of complete remission with HDT/ASCT is safe and feasible. However, up to one-third of patients may never receive transplant, mostly due to progressive disease, and relapse still remains a major concern even after transplant.

Treatment of Hodgkin's lymphoma (HL) is perceived to be relatively straightforward. Consequently, patients are not usually referred to hemato-oncologically specialized centres and are treated locally instead. Comprehensive findings beyond prospective controlled trials are therefore lacking. Clinical data of 209 patients who had received a HL diagnosis were collected. A total of 7 patients received radiotherapy (RT) alone (3%), 75 (35%) were treated with a combination of chemotherapy (CT) and RT and 127 patients received CT alone [mainly doxorubicin, bleomycin, vinblastine and dacarbazine (ABVD)]. Complete response (CR) following first-line treatment was achieved in 178 patients (85%) and in 195 (93%) after salvage treatment. Favorable disease (p=0.000359), limited-stage disease (p=0.0003), involvement of lymph nodes above the diaphragm (p=0.05) and absence of mediastinal bulky tumor involvement positively affected the CR rate following first-line treatment. Out of the 195 patients that achieved CR, 31 relapsed. Male gender (p=0.043) and age over 45 years (p=0.047) were significantly associated with an increased incidence of relapse. Age at diagnosis was the key factor affecting long-term outcome. The event-free survival (EFS) projected at 120 months was 80 and 57% for patients younger and older than 45 years, respectively (p=0.022). The overall survival (OS) projected at 120 months was 92 and 38% for patients younger and older than 45 years, respectively (p=0.00561). A second neoplasia was diagnosed in 8 patients. The development of a tumor in 4 cases (breast, lung and thyroid cancer) was likely RT-related. Only 1 patient not receiving RT developed acute myeloid leukemia. The EFS and OS of the 141 early-stage patients treated with CT + RT (n=62) or with CT alone (n=79) were not statistically different.

BACKGROUND: Numerous mechanisms have been proposed to explain the beneficial action of intravenous immune globulin ( IVIG) in autoimmune and systemic inflammatory disorders. Among others' data, an in vitro increase of intracellular TGF-beta expression when culturing CD4+ T lymphocytes in the presence of IVIG has been reported. As IVIG infusion involves administration of soluble contaminants likewise all hemoderivative preparations, we hypothesized that, besides several other immunomodulatory proposed mechanisms, the clinical effects of IVIG therapy might be, at least partly, due to contaminating soluble HLA Class I (sHLA-I) molecules capable to exert pleiotropic immunomodulatory effects among which TGF-beta(1) modulation.STUDY DESIGN AND METHODS: Ex vivo and in vitro transcriptional and posttranscriptional modulation of TGF-beta(1) in CD8+ T lymphocytes and neutrophils after IVIG infusion was analyzed.RESULTS: Ex vivo analysis of cells drawn from 10 enrolled IVIG recipients pointed out a significant increase of TGF-beta(1) mRNA and intracellular TGF-beta(1) molecules in both leukotypes. In vitro comparable results were obtained incubating CD8+ T lymphocytes and neutrophils from healthy donors with IVIG. The immunodepletion of sHLA-I and/or soluble Fas ligand (sFasL) abolished TGF-beta(1) modulation in both leukotypes. Coculture with human immunoglobulin (Ig) M monoclonal antibody or chimeric IgG (MabThera, Roche), whose manufacturing excludes "contamination," did not exert any mRNA modulation. Finally, IgM or MabThera plus purified sHLA-I molecules enhanced TGF-beta(1) mRNA in both white blood cells to levels comparable to those obtained with IVIG incubation.CONCLUSION: On the whole, these data lead us to speculate that the ability of IVIG administration to modulate TGF-beta(1) might be related to the immunomodulatory activities of sHLA-I and sFasL molecules on activated CD8+ T lymphocytes and neutrophils.

To evaluate the safety and efficacy of pegfilgrastim administered as haematological support after autologous peripheral blood stem cell transplantation, we compared 44 patients with solid tumours and lymphomas receiving a 6-mg single dose of pegfilgrastim on day +5 after transplantation to a historical control group of 25 patients receiving filgrastim 5 μg kg−1 day−1 starting on day +5. There were no significant differences in haematological recovery nor in the incidence and duration of neutropenic fever. Median duration of grade 4 neutropenia in the pegfilgrastim and filgrastim group was similar. The incidence of grade III–IV mucositis was lower in pegfilgrastim than in filgrastim group due to the significant difference observed among the patients with solid tumours (p = 0.00). The only adverse event considered to be cytokine related was mild to moderate bone pain occurring during haematological recovery. According to the present study design and taking into account the current prices in our institution, the cost of the two drugs was similar in both treatment groups. In conclusion, a single injection of pegfilgrastim administered at day +5 post-transplantation shows comparable safety and efficacy profiles to daily injections of filgrastim and may be cost effective.

16534 Background: Pegylated filgrastim is a new formulation of a granulocyte colony-stimulating factor that has a long circulating half-life, permitting a single dose of filgrastim per cycle of chemotherapy. Methods: To evaluate whether a single subcutaneous injection of pegfilgrastim (6 mg) is as safe and effective as daily filgrastim (5 mcg/kg/day), 40 consecutive autologous stem cell transplantations performed for breast cancer and lymphomas have been analysed. Median age was 47 yrs (20–61) and 48 yrs (30–63) in pegfilgrastim and filgrastim group, respectively. All patients had normal bone marrow biopsy. The first cohort of patients received 5 mcg/kg/day of filgrastim starting from day 5 post transplantation and the second cohort of patients received a single subcutaneous injection of 6 mg pegfilgrastim on day 5 after transplantation. Results: Median duration of grade 4 neutropenia in the pegfilgrastim and filgrastim groups was 7 (4–9) and 6 (5–9) days, respectively (P 0.29). Neutropenic fever incidence was significantly higher in filgrastim group, 9/20 vs 16/20 (P 0.048), the median duration was not significantly different, 1 (1–6) vs 3 (1–7) days. The grade 3–4 mucositis was higher in filgrastim patient group, 4/20 vs 13/20 in pegfilgrastim and filgrastim, respectively (P 0.009). The adverse events observed during post-transplant aplasia were attributable to complications arising from myelo-suppressive chemotherapy or the primary disease. The only occurring adverse event considered to be cytokine related was mild to moderate bone pain. The overall incidence of bone pain requiring non-narcotic analgesia was not statistically different, 20% (4/20) in pegfilgrastim patients and 40% (8/20) in filgrastim patients. The patients in filgrastim group received a mean of 9.8 daily injections. Conclusions: A single injection of pegfilgrastim administered at day 5 post transplant shows comparable safety and efficacy profiles to daily injections of filgrastim and may be cost-effective. No significant financial relationships to disclose.