OBJECTIVES:Patients with systemic lupus erythematosus (SLE) are at higher risk for osteoporosis and fragility fractures. Our study aimed to identify disease-specific factors with impact on bone mineral density (BMD) and the risk of osteoporosis, and to evaluate the effectiveness of DXA-derived 3D femur parameters versus BMD and trabecular bone score (TBS) in discriminating pre-existent fragility fractures. METHODS:We analyzed baseline data of a consecutive subcohort of patients with SLE with current or past GC treatment, fulfilling the EULAR/ACR 2019 SLE classification criteria. We used multivariable linear and logistic regression models to identify BMD- and osteoporosis-related factors. DXA-derived 3D measurements of the femur were performed with 3D-Shaper software. Discriminatory performance of BMD, TBS and 3D femoral parameters for fragility fractures was assessed by AUC values. RESULTS:Forty-one percent of 110 patients with SLE had osteoporosis. Lupus nephritis (LN) was present in 35% of cases, with 61% (23/38) of these being predominantly classified as classes IV and V. Factors significantly associated with lower BMD included LN classes III and IV, U1-RNP antibodies, higher C-reactive protein, and longer disease duration. Clinical remission, higher Siglec-1 levels, higher body mass index, and higher health assessment questionnaire (HAQ) scores correlated positively with BMD. Osteoporosis was linked to LN, higher age, HAQ, and complement factor 3 levels. Our findings suggest that 3D bone structure analysis may be helpful in discriminating past vertebral fractures. CONCLUSION:Disease severity indicated by LN, high CRP, presence of U1-RNP antibodies, and extended disease duration are detrimental to bone health. Moreover, 3D-DXA parameters can be integrated in clinical practise to assess bone health.

The role of uric acid (UA) on bone metabolism is controversially discussed. Higher UA levels have been associated with higher T-scores and a reduced incidence of fractures in postmenopausal women. However, in the context of rheumatoid arthritis (RA), the role of UA remains unclear. This pilot study aimed to investigate the association of UA levels with bone mineral density in RA female and male patients. This pilot study analyzed patients with RA to explore preliminary associations. We utilized data from the Rh-GIOP cohort, a prospective monocentric observational study focusing on bone health in chronic rheumatic diseases. To assess the association between UA levels and the lowest T-scores measured at the lumbar spine, hip, or femur, we used linear regression with adjustment for various confounders. An interaction term was included to evaluate differential associations in pre- and postmenopausal women. Data on dual X-ray absorptiometry (DXA) measurements and serum UA levels were analyzed in a total of 206 patients. Among the 167 women 16 were premenopausal (age 40 ± 8 years) and 149 postmenopausal (age 65 ± 10 years). As expected, postmenopausal had lower T-scores than premenopausal patients (-1.53 ± 1.01 versus − 0.41 ± 1.29, respectively). No association of UA levels with T-scores was found when analyzing the whole cohort (Slope β: -0.04; p = 0.45). However, a significant negative correlation of UA with T-scores in premenopausal (Slope β: -0.98; p = 0.014), but not postmenopausal (Slope β: -0.04; p > 0.05) women was found. Uric acid appears to be negatively associated with bone mineral density in premenopausal but not in postmenopausal women with RA. Thus, the impact of UA on bone health seems to depend on the hormonal status of women. Further investigations are required to validate these results in a larger cohort of patients and to investigate the underlying mechanisms.

Background: Patients with inflammatory rheumatic diseases (iRMDs) face increased incidence of osteoporosis with respectively increased fragility fracture (FFx) risk. Traditional areal bone mineral density (BMD) measurement via dual energy x-ray absorptiometry (DXA) may not fully capture fracture risk in this group. The reference-point indentation-derived bone material strength index (BMSi) shows promise in assessing the microstructural and mechanical properties of bone and has recently been shown to be positively associated with the risk of incident osteoporotic fractures [1]. Objectives: To compare the discrimination performance of BMSi at the tibia with the gold standard DXA BMD and the trabecular bone score (TBS) in patients with iRMDs for prevalent fragility fractures. Methods: Data from consecutive iRMD patients with and without previous FFx were analyzed, excluding those with prior anti-osteoporotic treatments. Participants underwent DXA (T-Score and TBS) and BMSi (through 8 repeated indentations with the handheld OsteoProbe device) assessments. Multivariable linear regression and Partial Least Squares-Discriminant Analysis (PLS-LDA) with 5-fold cross-validation were employed to determine the discriminative abilities of these measurements for prediction of prevalent vertebral (VFx), non-vertebral (NVFx) and any fragility fractures (any FFx). Anthropometric (AP) data with weight, height, body mass index was incorporated in the model. Receiver Operating Characteristic (ROC) curves were analyzed for area under the curve (AUC) values. Results: 93 iRMD patients (40 with FFx) were included with a mean age of 64 ± 10 years. Most of the patients had rheumatoid arthritis (42%), followed by spondyloarthritides (23%) and connective tissue diseases (19%). Patients with FFx were predominantly female (84% vs. 70% in non-fractured group), with no significant difference in mean BMSi in comparison to the non-FFx group. DXA T-scores alone showed limited fracture discrimination (AUC 0.62) for any FFx. Adding BMSi and TBS did not enhance discrimination (AUC 0.57), whereas anthropometric data improved prediction of prevalent vertebral fractures (AUC 0.70). Corresponding results were found when analyzing the discriminative performance specifically for vertebral and non-vertebral fractures (Figure 1). Conclusion: BMSi did not improve the discrimination performance or provide a more accurate risk assessment in this cross-sectional cohort of patients with iRMD compared to DXA and TBS. Larger studies prospectively assessing incident FFx are needed to better characterize the value of BMSi in clinical FFx prediction in iRMD patients. REFERENCES: [1] Jaiswal R, Zoulakis M, Axelsson KF, Darelid A, Rudäng R, Sundh D, Litsne H, Johansson L, Lorentzon M. Increased Bone Material Strength Index Is Positively Associated With the Risk of Incident Osteoporotic Fractures in Older Swedish Women. J Bone Miner Res. 2023 Jun;38(6):860-868. doi: 10.1002/jbmr.4816. Epub 2023 May 9. PMID: 37088885. Acknowledgements: NIL. Disclosure of Interests: Edgar Wiebe Novartis, Marc Benjamin Kuntz: None declared, Nadège Léprêtre: None declared, Zhivana Boyadzhieva: None declared, Andriko Palmowski Novartis, Sandra Hermann: None declared, Burkhard Muche: None declared, Gerhard Krönke: None declared, Angela Galindo Santos: None declared, Kay Raum: None declared, Ralf Schmidmaier: None declared, Frank Buttgereit Abbvie, Horizon Therapeutics, Pfizer, and Roche, Abbvie, Horizon Therapeutics, Pfizer, and Roche, Abbvie, Horizon Therapeutics, Pfizer, and Roche.Figure 1ROC-AUC with 5-fold cross-validation for any (left) vertebral (center) and non-vertebral (right) fragility fractures for BMSi, DXA and TBS. AP (anthropometric data: weight, height, body mass index)

Background: Axial spondyloarthritis (axSpA) is associated with osteoporosis and fragility fracture risk that may not be reflected by areal bone mineral density (aBMD) measurements alone. DXA-derived three-dimensional (3D) analysis has emerged as a promising method for assessing structural bone properties of the femur, showing good correlation with quantitative computed tomography [1]. Objectives: To investigate the discriminative performance of DXA-derived 3D parameters of the femur in comparison to aBMD and trabecular bone score (TBS) for pre-existent fragility fractures (FFx). Methods: This cross-sectional analysis is part of the Rh-GIOP prospective observational cohort study focusing on bone health in inflammatory rheumatic diseases. We analyzed baseline visits of axSpA patients fulfilling the ASAS 2009 classification criteria. Using 3D-Shaper software (v2.12, 3D-Shaper Medical, Barcelona, Spain), we derived several parameters (integral, trabecular and cortical volumetric BMD, cortical thickness and cortical surface BMD) from hip DXA scans. Logistic regression analysis was used to develop discrimination models incorporating DXA-based T-scores, TBS, and 3D-Shaper parameters to detect prevalent FFx, vertebral fractures (VFx), and non-vertebral fractures (NVFx). Area under the curve (AUC) with 95% confidence intervals were calculated. Results: Eighty patients with axSpA (64% male) were analyzed. The prevalence of FFx was 34%, and 15% had a history of VFx. DXA T-scores showed AUC values of 0.62 (0.48; 0.75), 0.54 (0.39; 0.70), and 0.64 (0.50; 0.78) for any FFx, VFx, and NVFx, respectively. DXA-derived 3D parameters showed better discrimination for fragility fractures, with AUC values of 0.75 (0.64; 0.86), 0.81 (0.69; 0.94), and 0.72 (0.59; 0.85). Incorporating these parameters in a logistic regression model with DXA and TBS further improved the discriminative ability (any FFx: AUC 0.78 (0.67; 0.89), VFx: AUC 0.86 (0.74; 0.98), NVFx: AUC 0.75 (0.63; 0.88)). TBS alone or in combination with DXA did not improve the discrimination of the model. Conclusion: Our results suggest that DXA-derived 3D hip parameters offer superior discrimination of pre-existent FFx compared to DXA or TBS alone in patients with axSpA. Future longitudinal analysis will determine whether DXA-derived 3D femoral parameters can improve fracture prediction in clinical practice. REFERENCES: [1] Humbert L, Martelli Y, Fonolla R, Steghofer M, di Gregorio S, Malouf J, Romera J, Barquero LMDR (2017) 3D-DXA: assessing the femoral shape, the trabecular macrostructure and the cortex in 3D from DXA images. IEEE Trans Med Imaging 36:27–39. https://doi.org/10.1109/TMI.2016.2593346. Acknowledgements: NIL. Disclosure of Interests: Edgar Wiebe Novartis, Elisa Celine Schilling: None declared, Dörte Huscher: None declared, Andriko Palmowski Novartis, Zhivana Boyadzhieva: None declared, Sandra Hermann: None declared, Burkhard Muche: None declared, Frank Buttgereit Abbvie, Horizon Therapeutics, Pfizer, and Roche, Abbvie, Horizon Therapeutics, Pfizer, and Roche, Horizon Therapeutics, Roche and Abbvie.

Background: Osteoporosis and systemic bone loss play a role in immune-mediated inflammatory diseases such as psoriatic disease (psoriatic arthritis (PsA) and psoriasis (PsO)). The factors contributing to this bone loss in psoriatic patients remain unclear [1]. Objectives: To identify the factors driving systemic bone loss in patients with PsA and PsO and to evaluate the utility of bone mineral density (BMD) as measured by dual energy X-ray absorptiometry (DXA), trabecular bone score (TBS), and femoral structural parameters in identifying individuals at increased risk of fractures. Methods: PsA and PsO patients (without current or previous signs of arthritis) participated in the Rh-GIOP study –a prospective observational cohort study of patients with immune-mediated inflammatory diseases undergoing DXA scans and systematic bone health assessments. We conducted a multivariable linear regression analysis based on pre-specified variables to identify clinical, serological and treatment factors associated with BMD. The discriminatory capacity of BMD, TBS, and femoral structural parameters using 3D Shaper software (v2.12, 3D-Shaper Medical, Barcelona, Spain) to detect prior fragility fractures was compared using AUC analyses. Results: Baseline data from 133 PsA patients (66% female, mean age 62 ±10 years, mean PsA duration 5 ±7 years) and 80 PsO patients (66% female, mean age 66 ±8 years, mean psoriasis duration 23 ±15 years) (Table 1a-c). In PsA, lower BMD was linked to the need for specific anti-osteoporotic therapy (regression coefficient [95% CI]: -1.61 [-2.61;-0.61], p<0.005), older age (-0.026 [-0.044;-0.008], p<0.001), increased bone-specific alkaline phosphatase levels (-0.044 [-0.070;-0.018], p<0.001), and higher glucocorticoid doses (-0.019 [-0.034;-0.004], p=0.002). Conversely, the presence of any type of diabetes (0.538 [0.081;0.995], p<0.001) and the use of conventional synthetic disease-modifying drugs (csDMARDs) had a positive effect on BMD (+0.415 [0.057;0.774], p=0.023).For PsO patients, BMD positively correlated with csDMARD (0.481 [0.011;0.950], p=0.045) and biological DMARD use (0.515 [0.055;0.976], p=0.028), C-reactive protein levels (0.026 [0.003;0.049], p=0.030), and regular physical activity (0.481 [0.000;0.817], p=0.050) Conversely, prevalent vertebral fractures (VFx) (-1.339 [-2.101;-0.577]; p<0.001) and bone turnover markers, specifically osteocalcin (-0.038 [-0.068;-0.008]; p=0.014) and desoxypyridinoline (-0.134 [-0.236;-0.033]; p=0.010), negatively impacted BMD. Disease activity, as expressed by DAS28-CRP or PASI scores, showed no correlation with BMD in either psoratic group. BMD revealed reasonable discriminatory power for VFx (AUC (95%CI) 0.72 (0.56; 0.89)), slightly improved by femoral bone structure assessment (AUC 0.74 (0.61; 0.87)). The PsO group had similar results, with DXA showing an AUC of 0.71 (0.54;0.89) for VFx, and the 3D Shaper performing slightly better with AUC 0.74 (0.57;0.91). TBS, however, demonstrated limited discriminatory value in detecting VFx and non-vertebral fractures in both groups. Conclusion: Our findings suggest that better management of psoriatic disease-related bone loss is achievable with csDMARDs and biological DMARDs. Additionally, assessing femoral bone structure could enhance fracture risk prediction, complementing conventional methods. REFERENCES: [1] Xia J, Xie SY, Liu KQ, Xu L, Zhao PP, Gai SR, Guan PL, Zhao JQ, Zhu YP, Tsoi LC, Stuart PE, Nair RP, Yang HQ, Liao YT, Mao K, Qiu MC, Ying ZM, Hu B, Yang ZH, Bai WY, Zhu XW, Cong PK, Elder JT, Ye ZM, Wang B, Zheng HF. Systemic evaluation of the relationship between psoriasis, psoriatic arthritis and osteoporosis: observational and Mendelian randomisation study. Ann Rheum Dis. 2020 Nov;79(11):1460-1467. doi: 10.1136/annrheumdis-2020-217892. Epub 2020 Jul 31. PMID: 32737104; PMCID: PMC7970448. Acknowledgements: Gabriele May and Manuela Jakstadt for their excellent data collection and entering. Disclosure of Interests: Edgar Wiebe Novartis, Elisa Celine Schilling: None declared, Dörte Huscher: None declared, Andriko Palmowski Novarits, Zhivana Boyadzhieva: None declared, Sandra Hermann: None declared, Burkhard Muche: None declared, David Simon: None declared, Gerhard Krönke: None declared, Frank Buttgereit Abbvie, Horizon Therapeutics, Pfizer, and Roche, Abbvie, Horizon Therapeutics, Pfizer, and Roche, Horizon Therapeutics, Roche and Abbvie

Background: In a previous study, we found daily proton pump inhibitor (PPI) intake to be associated with decreased bone mineral density of the femoral neck and the lumbar spine in patients with inflammatory rheumatic diseases (IRMDs) even after comprehensive adjustment for confounders [1]. The underlying pathomechanism is unclear. Similar findings in other populations in the past were repeatedly explained by decreased intestinal calcium absorption and increased levels of intact serum parathyroid hormone (PTH) [2, 3]. Objectives: To assess whether daily PPI use is associated with changes in serum calcium or PTH in patients with IRMDs. Methods: We used cross-sectional baseline data from the single-center Rh-GIOP cohort [4]. Patients with IRMDs have been prospectively enrolled since 2015. Included patients receive DXA scans, laboratory testing and complete bone-health-related questionnaires. This study excluded patients with hyperthyroidism and multiple myeloma as treatable causes of secondary osteoporosis. The exposure - daily PPI use - was ascertained by a combination of self-reporting by patients and chart review. Co-primary outcomes were serum levels of calcium and PTH. Analyses were based on general linear models, considering complete cases only. As part of a gatekeeping procedure, adjusted analyses were performed for the respective outcomes only if unadjusted analyses identified statistically significant differences between PPI users and non-users. For adjustment, we used 1) a conventional multiple regression approach and 2) inverse probability of treatment weighting. Potential confounders were based on findings from literature review and expert opinion and included age, body mass index (BMI), self-reported degree of physical activity, smoking status, presence of diabetes mellitus type I or II, chronic kidney disease stage (based on the estimated glomerular filtration rate), cumulative and current glucocorticoid (GC) dose and serum C-reactive protein. For weighting, included covariates were allowed to affect the outcome only [5], so 25-OH-vitamin D deficiency was additionally included. A sensitivity analysis excluded patients with a prior diagnosis of hyperparathyroidism. Results: 1,504 patients (75.3% women; mean age 62.6 ± 13.1 years; 49% daily PPI use) were included (Table 1). Most patients (79.6%) received vitamin D3 supplements and were within normal ranges as measured by 25-OH-vitamin D3. Missingness regarding exposure and outcome variables was as follows: PPI use: 0%; calcium: 7%; PTH: 17%. In unadjusted analyses, serum PTH was higher in PPI users (difference = 2.49pg/mL; 95% CI 0.23 to 4.74; p = 0.031). Serum calcium was similar in PPI users and non-users and omitted from further adjusted analyses. After adjustment for confounders, statistically significant differences in serum PTH between PPI users and non-users vanished with both adjustment procedures (Figure 1). In the conventional multiple regression model, age, BMI, chronic kidney disease stage and current GC intake were statistically significantly associated with serum PTH. These results were similar after excluding patients with a prior diagnosis of hyperparathyroidism. Conclusion: In our cohort of patients with IRMDs, the previously observed reduction in bone density with PPI does not seem to be mediated by changes in serum calcium or PTH. Prior studies with such findings might have been subject to confounding. REFERENCES: [1] Palmowski A "Proton pump inhibitor use and bone health in patients with rheumatic diseases: A cross-sectional study" Accepted in Mayo Clinic Proceedings. [2] Fitzpatrick D Osteoporos Int. 2023. [3] Hinson AM J Am Geriatr Soc. 2015. [4] Wiebe E Ann Rheum Dis. 2022. [5] Brookhart MA Am J Epidemiol. 2006. Acknowledgements: Rh-GIOP is or was supported by a joint funding of Abbvie, Amgen, Almirall, Biogen, BMS, Chugai, Galapagos, Generic Assays, GSK, Hexal, Horizon Therapeutics, Lilly, Medac, Mundipharma, Novartis, Pfizer, Roche, Sanofi-Genzyme, and UCB. The Parker Institute is supported by a core grant from the Oak Foundation (OCAY-18-774-OFIL). DS is supported by a 2022 GRAPPA Pilot Research Grant and the "Forschungsinitiative 2025" of the Deutsche Gesellschaft für Rheumatologie (DGRh). Disclosure of Interests: Andriko Palmowski Novartis, Zhivana Boyadzhieva: None declared, Paula Hoff UCB Pharma Germany, Sandra Hermann: None declared, Burkhard Muche UCB Pharma Germany, Amgen Germany, Stadapharm, UCB Pharma Germany, Amgen Germany, Stadapharm, David Simon: None declared, Gerhard Krönke: None declared, Edgar Wiebe Novartis, Novartis, Frank Buttgereit: None declared.

OBJECTIVE:To assess the effect of proton pump inhibitor (PPI) use on bone mineral density (BMD) and bone microarchitecture as measured by the trabecular bone score (TBS) in patients with inflammatory rheumatic and musculoskeletal diseases (iRMDs). METHODS:Cross-sectional data from a prospective single-center cohort (2015 to 2022) of patients with iRMDs were used to evaluate 3 co-primary outcomes: BMD of the left femoral neck and the lumbar spine (as T-scores) and the TBS. Inverse probability weighting adjusted for numerous confounders including age, sex, body mass index, current and cumulative glucocorticoid (GC) dose, C-reactive protein levels, disability, and others. Analyses were based on general linear models, following a prespecified statistical analysis plan. RESULTS:The study included 1495 patients (75% women; mean age, 62.6±13.1 years; 49% and 63% with regular PPI and GC use, respectively). The PPI users had lower BMD at both spine (adjusted contrast -0.25; 95% CI, -0.47 to -0.04; P=.02) and femoral neck (-0.17 [-0.35 to 0.01]; P=.07). Differences between PPI users and nonusers were statistically significant only in patients concurrently using GCs at more than 7.5 mg/d prednisone equivalent. The TBS was similar in PPI users and nonusers (adjusted contrast, 0.00 [-0.04 to 0.04]; P=.97). CONCLUSION:Our results suggest that PPIs lead to a loss of BMD rather than an impairment of bone microarchitecture in patients with iRMDs. The negative association between PPI use and BMD appears to be dependent on concurrent GC use. Clinicians should carefully review the indication for PPI use in patients with iRMDs, especially in those receiving higher dose GCs.

Background It is unclear whether sex or age modify the association of glucocorticoid (GC) use with reduced bone mineral density (BMD) in patients with rheumatoid arthritis (RA). Methods We studied cross-sectional data of RA patients with current or previous GC treatment in a single center cohort study ( Rh-GIOP cohort). Our primary outcome was the minimum T-score (measured by DXA) of either lumbar spine, total femur, or femoral neck. Current GC dose was the main exposure; cumulative GC dose and cumulative duration of GC use were also assessed. Following a predefined statistical analysis plan, linear regression analyses with adjustment for confounders assessed whether the association of GC use with BMD was modified by sex (men versus women) or age (≥ 65 versus < 65 years). Results Four hundred eighty-three patients with RA (mean age 64 ± 12 years, 80% women) were included. 33% were not currently taking GCs, 32% were treated with a dose of 5 mg/d prednisone equivalent and 11% with more than 7.5 mg/d. 23% of patients had osteoporosis by DXA (minimum T-score ≤ -2.5). The slope, i.e., the association between changes in minimum T-scores with 1 mg/d change in current GC dose, was similar in men and women (-0.07 and -0.04, respectively; difference -0.03 [-0.11 to 0.04]; p for interaction = 0.41). Slopes were also similar for elderly and non-elderly patients (-0.03 and -0.04, respectively; difference -0.01 [-0.06 to 0.05]; p for interaction = 0.77). Using cumulative dose and duration of use as exposures did not lead to substantial changes of these results. Conclusions In our sample, the association of GC use with reduced BMD in RA was not modified by sex or age.

To investigate whether methotrexate (MTX) use is associated with bone mineral density (BMD) in patients with polymyalgia rheumatica (PMR) and various forms of vasculitis. Rh-GIOP is a cohort study designed to evaluate bone health in patients with inflammatory rheumatic diseases. This cross-sectional analysis assessed the baseline visits of all patients with PMR or any kind of vasculitis. Following univariable analysis, multivariable linear regression analysis was performed. The lowest T-score of either the lumbar spine or the femur was chosen as the dependent variable to examine the relationship between MTX use and BMD. These analyses were adjusted for a variety of potential confounders, including age, sex, and glucocorticoid (GC) intake. Of 198 patients with PMR or vasculitis, 10 patients were excluded for very high GC dose (n = 6) or short disease duration (n = 4). The remaining 188 patients had the following diseases: PMR 37.2%, giant cell arteritis 25.0%, granulomatosis with polyangiitis 16.5%, followed by rarer diseases. The mean age was 68.0 ± 11.1 years, mean disease duration was 5.58 ± 6.39 years, and 19.7% had osteoporosis by dual x-ray absorptiometry (T-score ≤ −2.5). 23.4% were taking MTX at baseline with a mean dose of 13.2 mg/week (median: 15 mg/week). 38.6% of those used a subcutaneous preparation. MTX users had similar BMD compared to non-users (minimum T-scores −1.70 (± 0.86) versus −1.75 (± 0.91), respectively; p = 0.75). There was no statistically significant dose–response relationship: neither current nor cumulative dose were associated with BMD in unadjusted or adjusted models (current dose: slope −0.02; −0.14 to 0.09; p = 0.69; cumulative dose: slope −0.12; −0.28 to 0.05; p = 0.15). In the Rh-GIOP cohort, MTX is used in about a quarter of patients with PMR or vasculitis. It is not associated with BMD levels.

Einleitung Patienten mit Systemischem Lupus Erythematodes (SLE) weisen ein erhöhtes Risiko für Osteoporose (OP) und Fragilitätsfrakturen auf. Ziel dieser Arbeit war die Identifizierung von Einflussfaktoren auf die Knochendichte, um das Zusammenspiel zwischen krankheitsspezifischen und allgemeinen Risikofaktoren besser zu verstehen.

Background Patients with systemic lupus erythematosus (SLE) are at an increased risk for osteoporosis and fragility fractures.[1] This risk is mediated by a variety of factors such as chronic inflammation, treatment with glucocorticoids (GC), vitamin D deficiency, and others.[2] The role of disease-specific factors of SLE has not been fully elucidated. Objectives We aimed to identify factors associated with bone mineral density and osteoporosis including fragility fractures to better understand the interplay between disease-specific factors and general risk factors that drive bone loss in this patient population. Methods Rh-GIOP is a prospective observational cohort study investigating bone health in consecutive patients ≥18 years with inflammatory rheumatic diseases and current or prior GC treatment. This cross-sectional analysis assessed the baseline visits of all patients with SLE fulfilling the EULAR/ACR 2019 SLE classification criteria. Multivariable linear regressions models were fitted to identify factors associated with bone mineral density (BMD). As a second outcome, we investigated factors associated with clinical osteoporosis (defined by either a T-Score of ≤ -2,5, anti-osteoporotic treatment and/or fragility fractures) by multivariable logistic regression analysis. Results Baseline data from 110 patients with SLE were analyzed. The mean age was 48.1±14.5 years, mean disease duration 16.3±9.9 years, and 41% of the cohort was identified as having osteoporosis (OP). Lupus nephritis was present in 35% of the SLE patients, of whom 55% had active nephritic disease at baseline osteoporosis screening visit. Class IV and V accounted for most nephritis cases (61%). In multivariable linear regression analysis, lupus nephritis class IV and V (reg. coefficient (95%CI): -0.745 (-1.395;-0.095)), the presence of U1-RNP antibodies (-0.750 (-1.314;-0,187)) as well as C-reactive protein (CRP, -0.015 (-0.026;-0.003)) and longer disease duration (-0.037 (-0.056;-0.018)) were significantly associated with low BMD. Conversely, clinical remission (defined as SLEDAI-2K=0 and GC dosage ≤5 mg prednisone equivalent per day) was positively associated with BMD (0.447 (0.037;0.857)), as were Siglec-1 levels on monocytes as surrogate for Type-I interferon activity (0.558 (0.150;0.967)), BMI (0.045 (0.014;0.076)), and health assessment questionnaire (HAQ, 0.307 (0.078;0.536)). In multivariable logistic regression analysis, active lupus nephritis (OR (95%CI): 7.42 (1.256;43.868)) was strongly associated with OP in patients with SLE. Additionally, age (1.06 (1.020;1.100)), HAQ (0.29 (0.120;0.682)) and complement factor 3 (1.27 (1.002;1.601)) were found to be significantly related to the presence of OP. Neither current GC use, cumulative GC dose nor GC duration were significantly associated with BMD or clinical OP. Conclusion In patients with SLE, indicators of disease severity, expressed by (active) lupus nephritis, high CRP, U1-RNP antibodies, and long disease duration, are related to poor bone health in addition to commonly known risk factors such as low BMI and higher age. The knowledge of these disease-specific factors helps to identify patients with SLE at particular high risk for OP and fragility fractures. References [1]Wang X, Yan S, Liu C, Xu Y, Wan L, Wang Y, et al. Fracture risk and bone mineral density levels in patients with systemic lupus erythematosus: a systematic review and meta-analysis. Osteoporos Int. 2016;27(4):1413-23. [2]Bultink IE, Lems WF. Systemic lupus erythematosus and fractures. RMD Open. 2015;1(Suppl 1):e000069. Acknowledgements: NIL. Disclosure of Interests Edgar Wiebe Speakers bureau: Medac and Novartis, Consultant of: Medac and Novartis, Elisa Celine Schilling: None declared, Dörte Huscher: None declared, Andriko Palmowski: None declared, Zhivana Boyadzhieva: None declared, Sandra Hermann: None declared, Burkhard Muche Speakers bureau: Amgen, UCB, Galapagos Biopharma, Consultant of: Amgen, UCB, Galapagos Biopharma., Tobias Alexander Speakers bureau: Abbvie, Amgen, AstraZeneca, Bayer, Janssen, GSK, Lilly, Medac, Pfizer, Consultant of: Abbvie, Amgen, AstraZeneca, Bayer, Janssen, GSK, Lilly, Medac, Pfizer, Falk Hiepe: None declared, Frank Buttgereit Speakers bureau: Abbvie, Horizon Therapeutics, Pfizer, and Roche, Consultant of: Abbvie, Horizon Therapeutics, Pfizer, and Roche, Grant/research support from: Horizon Therapeutics, Roche and Abbvie.