BACKGROUND:Real-world data studies suggest that the vaccine effectiveness (VE) of a fourth mRNA vaccine dose against SARS-CoV2 infection related hospitalisation wanes after a few months, potentially warranting consideration of additional booster doses. METHODS:A multi-data source cohort study was conducted through the Data Analysis and Real World Interrogation Network (DARWIN EU®) using routinely collected electronic health records from the UK (CPRD GOLD), the Netherlands (IPCI), and Spain (SIDIAP) from January 2021 to June 2023. The study included individuals aged 12 and above, vaccinated with at least three doses. We matched fourth-dose to third-dose vaccinated individuals using a weekly sequential approach, defining the date of the last dose received by the exposed individual as the index date. Primary outcomes were SARS-CoV2 infection related death and hospitalisation. Hazard ratios (HR) were estimated using Cox proportional hazard models, with VE defined as the percentage of 1 minus HR. Waning of VE was assessed at monthly intervals. FINDINGS:A total number of 975,496 matched pairs were identified from the three data sources, with a median age of 63-78. The pooled VE of a fourth vaccine dose against SARS-CoV2 infection related death compared to three vaccine doses was 30% (95%CI 9 to 46, I2=0). VE against SARS-CoV2 infection related hospitalisation was 26% (19% to 33%) in Spain (SIDIAP, median follow-up 8 weeks), and 46% (15% to 66%), in the Netherlands (IPCI, median follow-up 21 weeks) respectively. VE of a fourth dose started waning at 4-8 weeks after vaccination. INTERPRETATION:A fourth dose of a mRNA COVID-19 vaccination was effective against SARS-CoV2 infection related death and hospitalisation. However, effectiveness waned over time. Periodic revaccination should be considered, with recommendations regarding booster timing taking into account circulating variants, patterns of viral transmission, and population uptake. FUNDING:European Medicines Agency.

BACKGROUND:Acetylcholinesterase inhibitors (AChEIs), are commonly prescribed for dementia and can cause adverse drug events that may lead to new prescriptions, known as prescription cascades. We aimed to identify potential AChEI-induced prescription cascades using high-throughput sequence symmetry analysis (SSA). METHODS:Patients aged ≥18 years with 365 days of prior observation initiating AChEIs (donepezil, rivastigmine, or galantamine) were identified from the Clinical Practice Research Datalink GOLD (2002-2022). We screened 510 drug classes and 1213 individual ingredients initiated within ±180 days of AChEI initiation (365 days in sensitivity analyses). Crude and adjusted sequence ratios (ASRs) were calculated, and positive signals were reviewed for clinical plausibility. RESULTS:We identified 66 155 AChEI initiators (median age 81 years [IQR 76-85]; 62.8% female). Among ATC classes and individual ingredients, 51 and 46 signals were positive with 28 (55%) and 22 (48%) classified as potential prescription cascades after review. Gastrointestinal drugs showed positive signals including antipropulsives (ASR 1.50 [99% CI 1.28-1.75]), loperamide (ASR 1.52 [1.30-1.77]) and cyclizine (ASR 2.10 [1.72-2.59]). Positive signals were also observed nervous system drugs such as benzodiazepine derivatives (ASR 1.83 [1.55-2.16]) and respiratory drugs including corticosteroids (ASR 1.66 [1.33-2.08]) and glucocorticoids (ASR 1.54 [1.30-1.83]). Most positive signals remained in sensitivity analysis. CONCLUSIONS:These findings suggest potential AChEI-related prescription cascades consistent with gastrointestinal, neuropsychiatric, dermatological and respiratory adverse effects. While findings require further validation, this study demonstrates the utility of high-throughput signal detection to support pharmacovigilance in high-risk populations.

To evaluate secular trends of incidence and prevalence of Parkinson's Disease (PD), Vascular Parkinsonism (VP), and Drug-induced Parkinsonism from 2007 to 2021 in the UK. We used primary care data, Clinical Practice Research Datalink GOLD, from the UK. Individuals were included if they were registered from January 2007 to December 2021 with at least one year of prior observation. Age-standardized and crude incidence and prevalence were calculated annually; age-standardized rates were stratified by sex, and crude rates by age and sex. From 2007 to 2019, the age-standardized incidence of PD decreased from 35.61 (95% confidence interval: 33.97-37.30) to 31.27 (29.27-33.37) per 100 000 person-years. The prevalence of PD increased from 0.21% (0.21%-0.22%) in 2007, peaking in 2016 at 0.23% (0.23%-0.24%). The number of VP diagnoses has increased since 2010, whereas the incidence and prevalence of DIP remained stable. Incidence and prevalence increased with age and were generally higher in males, except for DIP, which was slightly higher in females. Crude rates showed similar trends. Though Parkinson Disease incidence has declined, prevalence has risen, suggesting improved survival. VP rates have increased, possibly due to improvements in diagnostic screening. Drug-induced Parkinsonism rates remained stable. With an aging UK population, Parkinsonism subtypes pose a growing burden.

Purpose To develop and describe DrugUtilisation, an open-source R package that facilitates drug utilisation studies using data mapped to the OMOP Common Data Model (CDM).Methods Core functionalities include creating drug user cohorts, identifying and summarising indications, describing the duration and dose of medication/s and assessing treatment adherence. The package works with packages developed within the DARWIN EU initiative to support study-specific workflows. We show the package's workflow by analysing the use of simvastatin in three European real-world databases.Results This paper outlines the DrugUtilisation package's functions and demonstrates their application with a clinical example of simvastatin use in databases from the United Kingdom, Estonia and the Netherlands. We generated results including cohort counts, indication summaries, measures of dose and duration, as well as publication-ready tables and figures. We implemented comprehensive unit tests and standardised output format, which ensured consistency across databases and minimised coding errors.Conclusion The development of this software allows for researchers to quickly perform common drug utilisation analyses, while also providing the foundation for additional, bespoke study-specific analyses.

Abstract Patients with earlier SARS-CoV-2 variants are at increased risk of venous and arterial thromboembolic (VTE, ATE) events. Here we aimed to contextualise the incidence of thromboembolic events among patients with COVID-19 during the Omicron period. We conducted a population-based cohort study using electronic health records from the UK (CPRD GOLD), the Netherlands (IPCI), and Spain (SIDIAP) within the DARWIN EU ® network. Two cohorts were included: a pre-pandemic population (2017–2019) and individuals infected with SARS-CoV-2 during the Omicron-dominant period. We estimated incidence rates (IRs) of VTE, ATE, and other cardiovascular events at 30-, 60-, 90-, and 180-days post-infection. Crude incidence rate ratios (IRRs) and age-sex standardized incidence ratios (SIRs) were calculated relative to the pre-pandemic cohort. Analyses were stratified by prior infection, vaccination status, and immunocompromised status. In total, we included over 7.6 million individuals (CPRD GOLD: 5.28 M; IPCI: 1.59 M; SIDIAP: 0.75 M) in the general population cohort, and about 0.8 million individuals (CPRD GOLD: 248,847; IPCI: 330,200; SIDIAP: 200,563) in the COVID-19 Omicron cohort. Crude IRs varied by outcome and data source. For VTE, IRs per 100,000 person-years were 136 [95%CI 131–141] in SIDIAP, 167 [164–169] in CPRD GOLD, and 264 [259–270] in IPCI. Elevated SIRs for VTE and ATE were observed following SARS-CoV-2 infection, highest within 30 days and persisting up to 180 days. In CPRD GOLD, the VTE SIR was 3.61 [2.45–5.53] at 30 days, decreasing to 1.88 [1.52–2.34] at 180 days. Higher SIRs were observed among immunocompromised individuals and those without prior infection. Our findings indicate that among individuals diagnosed with SARS-CoV-2 infection during the Omicron-dominant period, observed rates of thromboembolic events exceeded expected background incidence, particularly in the early post-infection period.

Objectives We aimed to assess the risk of incident autoimmune and inflammatory conditions during the post-acute period of COVID-19.Design Descriptive network cohort study.Setting Electronic health records from the UK and Dutch primary care, Norwegian linked health registry, hospital records of specialist centres in Spain, France and Korea and healthcare claims from Estonia and the USA.Participants We followed individuals between September 2020 and the latest available data from day 91 after a SARS-CoV-2 negative test (comparator) or a COVID-19 record (exposed patients, ie assessing patients during the post-acute phase). We further established a reinfection cohort (any further COVID-19 record among the exposed patients). We followed patients until an outcome, end of study period, death, day 365 or an infection (comparator only) or reinfection (exposed patients only).Main outcome measures We assessed postural orthostatic tachycardia syndrome (POTS) diagnoses/symptoms, myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) diagnoses/symptoms, multi-inflammatory syndrome (MIS) and several autoimmune diseases (rheumatoid arthritis (RA), juvenile idiopathic arthritis (JIA), systemic lupus erythematosus (SLE), inflammatory bowel disease (IBD) and type 1 diabetes mellitus (T1DM)).Meta-analysed crude incidence rate ratios (IRRs) of outcomes after COVID-19 versus negative testing and after reinfection versus a previous COVID-19 record yield the ratios of respective absolute risks of each assessed outcome. We performed subgroup analyses by age, sex and predominant variant periods.Results We included 2 521 812 individuals with a first COVID-19 record, 4 233 145 with a first negative test and 135 551 with a reinfection. Age and sex were largely comparable between exposure groups with a shorter follow-up for the reinfection cohorts. After COVID-19 compared with test-negative patients and equally after reinfection compared with previous COVID-19 patients, we did not observe increased rates for all outcomes and all subgroup analyses. Counts of MIS and JIA were too small for meta-analyses.Conclusions In our descriptive meta-analyses of crude IRRs among databases from various countries and settings, we did not observe increased rates of incident POTS, ME/CFS, RA, IBD, SLE and T1DM in COVID-19 versus test-negative or reinfection versus COVID-19 during the first 9 months of the post-acute phase of COVID-19 or reinfection (>90 days postinfection until month 12). Since causal interpretation cannot be made from this study, further causal research is warranted.

Background:The opioid crisis has been a serious public health challenge in North America for decades, despite numerous efforts to mitigate its devastating consequences. As concerns grow about a similar situation developing in Europe, we evaluated the trends in opioid use and characterized prescribing indications across seven European countries. Methods:We conducted a multinational cohort study using electronic health records from various healthcare settings: primary care [Clinical Practice Research Datalink (CPRD) GOLD (United Kingdom), Sistema d'Informació per al Desenvolupament de la Investigació en Atenció Primària (SIDIAP, Spain), and Integrated Primary Care Information Project (IPCI, the Netherlands)]; primary and outpatient specialist care [IQVIA Disease Analyzer (DA) Germany and IQVIA Longitudinal Patient Database (LPD) Belgium]; hospital care [Clinical Data Warehouse of Bordeaux University Hospital (CHUBX, France)]; and the Estonian Biobank (EBB). All data were mapped to the Observational Medical Outcomes Partnership (OMOP) Common Data Model (CDM). All people registered in a contributing database for ≥365 days between 2012 and 2022 were included. Annual period prevalence and incidence rates of opioid prescriptions were estimated, and long-term trends were quantified as the percent change from 2012 to 2019. New opioid users were characterized, including potential prescribing indications. Results:Between 2012 and 2019, the incidence of opioid prescriptions in primary care decreased by -50·7% (CPRD GOLD) and -2·0% (SIDIAP), while it increased in EBB (+52·8%) and CHUBX (+25·3%) data. The incidence of codeine and tramadol use decreased in most databases. However, the prevalence of oxycodone, morphine, and fentanyl increased. Opioid use was highest among older age groups, and the majority of prescriptions were for oral formulations. Respiratory and pain-related conditions were the most common indications for new opioid users in outpatient settings. Conclusion:Despite a decrease in new opioid prescriptions in many European countries, the prevalence of opioid use remained largely stable over the last decade. More data are needed to monitor evolving opioid prescription patterns in Europe, particularly in the post-pandemic era.

IntroductionElectronic health records can be used to understand the diverse presentation of post-acute and long-term health outcomes following COVID-19 infection. In England, the UK Health Security Agency, in collaboration with the University of Oxford, has created the Evaluation of post-acute COVID-19 Health Outcomes (ECHOES) dataset to monitor how an initial SARS-CoV-2 infection episode is associated with changes in the risk of health outcomes that are recorded in routinely collected health data.MethodsThe ECHOES dataset is a national-level dataset combining national-level surveillance, administrative, and healthcare data. Entity resolution and data linkage methods are used to create a cohort of individuals who have tested positive and negative for SARS-CoV-2 in England throughout the COVID-19 pandemic, alongside information on a range of health outcomes, including diagnosed clinical conditions, mortality, and risk factor information.ResultsThe dataset contains comprehensive COVID-19 testing data and demographic, socio-economic, and health-related information for 44 million individuals who tested for SARS-CoV-2 between March 2020 and April 2022, representing 15,720,286 individuals who tested positive and 42,351,016 individuals who tested negative.DiscussionWith the application of epidemiological and statistical methods, this dataset allows a range of clinical outcomes to be investigated, including pre-specified health conditions and mortality. Furthermore, understanding potential determinants of health outcomes can be gained, including pre-existing health conditions, acute disease characteristics, SARS-CoV-2 vaccination status, and genomic variants.

Prior evidence has suggested the multisystem symptomatic manifestations of post-acute COVID-19 condition (PCC). Here we conducted a network cluster analysis of 24 WHO proposed symptoms to identify potential latent subclasses of PCC. Individuals with a positive test of or diagnosed with SARS-CoV-2 after 09/2020 and with at least one symptom within ≥ 90 to 365 days following infection were included. Sub-analyses were conducted among people with ≥ 3 different symptoms. Summary characteristics were provided for each cluster. All analyses were conducted separately in 9 databases from 7 countries, including data from primary care, hospitals, national health claims and national health registries, allowing to validate clusters across the different healthcare settings. 787,078 persons with PCC were included. Single-symptom clusters were common across all databases, particularly for joint pain, anxiety, depression and allergy. Complex clusters included anxiety-depression and abdominal-gastrointestinal symptoms. Substantial heterogeneity within and between PCC clusters was seen across healthcare settings. Current definitions of PCC should be critically reviewed to reflect this variety in clinical presentation.

BACKGROUND:Valproate-containing medicines (VPA) are first-line treatments for epilepsy; however, they pose teratogenic risks, restricting their use in women of childbearing age. We aimed to estimate the secular trends in the use of VPA and alternative treatments in young women, and to characterise dose/strength, treatment duration, and indication in new VPA users. METHODS:We conducted a multi-national population-based cohort study using primary care records from the Netherlands, Spain, and the UK (IPCI, SIDIAP, CPRD GOLD), primary and outpatient specialist care records from Germany and Belgium (IQVIA DA Germany, IQVIA LPD Belgium), and hospital records from Finland (ACI VARHA), all mapped to the OMOP Common data model. All women present in the databases aged ≥ 12 and ≤ 55 years on the 1st of January of each year in the period 2010-2022 (or latest available), with at least 365 days of prior observation, were included. RESULTS:A total of 2 948 860 (CPRD GOLD), 718 835 (IPCI), 2 494 052 (SIDIAP), 157 361 (ACI VARHA), 218 250 (IQVIA LPD Belgium); and 5 152 752 (IQVIA DA Germany) women were included. Among those, 6416, 1241, 10 398, 1447, 945, and 4002 started treatments with VPA, respectively. Incidence and prevalence of VPA use in young women decreased between 2010 and 2021, while the prevalence of the alternative treatments pregabalin and gabapentin increased, especially in CPRD (it rises from 0.5% to 1.5%). Median age of new VPA users ranged between 40 and 43 years. Anxiety and depressive disorder were frequent comorbidities, and the use of hormonal contraceptives we were able to capture was low. Average treatment duration varied substantially across databases. CONCLUSION:Incidences and prevalence of use of VPA among young women declined since 2015. Conversely, alternative antiepileptics have increased in uptake, particularly gabapentinoids. The use of standardized federated analytics allowed for a rapid assessment of VPA utilization, supporting the regulatory agencies in their decision-making and improving patient safety across Europe.

PURPOSE:We aimed to develop a standardized method to calculate daily dose (i.e., the amount of drug a patient was exposed to per day) of any drug on a global scale using only drug information of typical observational data in the Observational Medical Outcomes Partnership Common Data Model (OMOP CDM) and a single reference table from Observational Health Data Sciences And Informatics (OHDSI). MATERIALS AND METHODS:The OMOP DRUG_STRENGTH reference table contains information on the strength or concentration of drugs, whereas the OMOP DRUG_EXPOSURE table contains information on patients' drug prescriptions or dispensations/claims. Based on DRUG_EXPOSURE data from the primary care databases Clinical Practice Research Datalink GOLD (United Kingdom) and Integrated Primary Care Information (IPCI, The Netherlands) and healthcare claims from PharMetrics® Plus for Academics (USA), we developed four formulas to calculate daily dose given different DRUG_STRENGTH reference table information. We tested the dose formulas by comparing the calculated median daily dose to the World Health Organization (WHO) Defined Daily Dose (DDD) for six different ingredients in those three databases and additional four international databases representing a variety of healthcare settings: MAITT (Estonia, healthcare claims and discharge summaries), IQVIA Disease Analyzer Germany (outpatient data), IQVIA Longitudinal Patient Database Belgium (outpatient data), and IMASIS Parc Salut (Spain, hospital data). Finally, in each database, we assessed the proportion of drug records for which daily dose calculations were possible using the suggested formulas. RESULTS:Applying the dose formulas, we obtained median daily doses that generally matched the WHO DDD definitions. Our dose formulas were applicable to >85% of drug records in all but one of the assessed databases. CONCLUSION:We have established and implemented a standardized daily dose calculation in OMOP CDM providing reliable and reproducible results.

IntroductionThe COVID-19 pandemic had collateral effects on many health systems. Cancer screening and diagnostic tests were postponed, resulting in delays in diagnosis and treatment. This study assessed the impact of the pandemic on screening, diagnostics and incidence of breast, colorectal, lung, and prostate cancer; and whether rates returned to pre-pandemic levels by December, 2021.MethodsThis is a cohort study of electronic health records from the United Kingdom (UK) primary care Clinical Practice Research Datalink (CPRD) GOLD database. The study included individuals registered with CPRD GOLD between January, 2017 and December, 2021, with at least 365 days of clinical history. The study focused on screening, diagnostic tests, referrals and diagnoses of first-ever breast, colorectal, lung, and prostate cancer. Incidence rates (IR) were stratified by age, sex, and region, and incidence rate ratios (IRR) were calculated to compare rates during and after lockdown with rates before lockdown. Forecasted rates were estimated using negative binomial regression models.ResultsAmong 5,191,650 eligible participants, the first lockdown resulted in reduced screening and diagnostic tests for all cancers, which remained dramatically reduced across the whole observation period for almost all tests investigated. There were significant IRR reductions in breast (0.69 [95% CI: 0.63-0.74]), colorectal (0.74 [95% CI: 0.67-0.81]), and prostate (0.71 [95% CI: 0.66-0.78]) cancer diagnoses. IRR reductions for lung cancer were non-significant (0.92 [95% CI: 0.84-1.01]). Extrapolating to the entire UK population, an estimated 18,000 breast, 13,000 colorectal, 10,000 lung, and 21,000 prostate cancer diagnoses were missed from March, 2020 to December, 2021.DiscussionThe UK COVID-19 lockdown had a substantial impact on cancer screening, diagnostic tests, referrals, and diagnoses. Incidence rates remained significantly lower than pre-pandemic levels for breast and prostate cancers and associated tests by December, 2021. Delays in diagnosis are likely to have adverse consequences on cancer stage, treatment initiation, mortality rates, and years of life lost. Urgent strategies are needed to identify undiagnosed cases and address the long-term implications of delayed diagnoses.

Despite much research on the topic, little work has been done comparing the use of methods to control for confounding in the estimation of COVID-19 vaccine effectiveness in routinely collected medical record data. We conducted a trial emulation study to replicate the ChAdOx1 (Oxford/AstraZeneca) and BNT162b2 (BioNTech/Pfizer) COVID-19 phase 3 efficacy studies. We conducted a cohort study including individuals aged 75+ from UK CPRD AURUM (N = 916,128) in early 2021. Three different methods were assessed: Overlap weighting, inverse probability treatment weighting, and propensity score matching. All three methods successfully replicated the findings from both phase 3 trials, and overlap weighting performed best in terms of confounding, systematic error, and precision. Despite lack of trial data beyond 3 weeks, we found that even 1 dose of BNT162b2 was effective against SARS-CoV-2 infection for up to 12 weeks before a second dose was administered. These results support the UK Joint Committee on Vaccination and Immunisation modelling and related UK vaccination strategies implemented in early 2021.

Objective To assess the effect of stopping statins, antihypertensives, and bisphosphonates on the risk of cardiovascular events and fractures in older patients with complex health needs (CHN). Methods Patients aged >65 years, registered in CPRD GOLD for ≥1 year before study start (01/01/2010) and with CHN (non-elective hospitalisation/s, frailty or polypharmacy) were selected. Self-controlled case series (SCCS) analyses were subsequently conducted among people who did not use the respective preventative treatment in the year before study start. Incidence rate ratios (IRR) were calculated for myocardial infarction (MI) and stroke [antihypertensives, statins] and fractures [bisphosphonates] comparing event rates for the respective outcomes during treatment vs. post-discontinuation periods. Results 198,039 people were included to the CHN cohort. Among those, 6,245 individuals were included for the analysis of bisphosphonate discontinuation and fracture risk; 738 and 669 persons for the analysis of antihypertensive therapy discontinuation and MI/stroke risk; and 1,408 and 1,361 people for statin discontinuation and MI/stroke risk. Risk of MI was substantially increased following discontinuation of antihypertensives (IRR 2.6 [95%CI 1.56-4.33]) and statins (IRR 1.75 [1.16-2.62]). No significant association for treatment discontinuation and stroke risk was seen. Likewise, no increased fracture risk was seen after discontinuing bisphosphonates. However, discontinuation among people with >1 year history of bisphosphonate therapy pointed towards increased fracture risk. Conclusions Our study showed risks associated with discontinuing preventative medications in people with CHN, likely explained by the continued efficacy of these medications. Further research focussing on the risk-benefit of these treatments for most vulnerable older adults is needed. Key points ### Competing Interest Statement DPA 's department has received grant/s from Amgen, Chiesi-Taylor, Lilly, Janssen, Novartis, and UCB Biopharma. His research group has received consultancy fees from Astra Zeneca and UCB Biopharma. Amgen, Astellas, Janssen, Synapse Management Partners and UCB Biopharma have funded or supported training programmes organised by DPA's department. All other authors declare no conflict. ### Funding Statement The project was supported by the National Institute for Health and Care Research (NIHR) Oxford Biomedical Research Centre (BRC). DPA is funded through a NIHR Senior Research Fellowship (Grant number SRF-2018-11-ST2-004). The views expressed in this publication are those of the authors and not necessarily those of the NHS, the National Institute for Health Research or the Department of Health. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The study protocol was approved by the Independent Scientific Advisory Committee for the Clinical Practice Research Datalink, including amendments (Protocol No 19_132A2). I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes Data were obtained from CPRD under the Oxford University CPRD license. Direct data sharing is not allowed. Data access can be obtained from CPRD, conditional on approval through CPRD s Research Data Governance Process.

Background: The COVID-19 pandemic affected cancer screening, diagnosis and treatments. Many surgeries were substituted with bridging therapies during the initial lockdown, yet consideration of treatment side effects and their management was not a priority. Objectives: To examine how the changing social restrictions imposed by the pandemic affected incidence and trends of endocrine treatment prescriptions in newly diagnosed (incident) breast and prostate cancer patients and, secondarily, endocrine treatment-related outcomes (including bisphosphonate prescriptions, osteopenia and osteoporosis), in UK clinical practice from March 2020 to June 2022. Design: Population-based cohort study using UK primary care Clinical Practice Research Datalink GOLD database. Methods: There were 13,701 newly diagnosed breast cancer patients and 12,221 prostate cancer patients with ⩾1-year data availability since diagnosis between January 2017 and June 2022. Incidence rates (IR) and incidence rate ratios (IRR) were calculated across multiple time periods before and after lockdown to examine the impact of changing social restrictions on endocrine treatments and treatment-related outcomes, including osteopenia, osteoporosis and bisphosphonate prescriptions. Results: In breast cancer patients, aromatase inhibitor (AI) prescriptions increased during lockdown versus pre-pandemic [IRR: 1.22 (95% confidence interval (CI): 1.11–1.34)], followed by a decrease post-first lockdown [IRR: 0.79 (95% CI: 0.69–0.89)]. In prostate cancer patients, first-generation antiandrogen prescriptions increased versus pre-pandemic [IRR: 1.23 (95% CI: 1.08–1.4)]. For breast cancer patients on AIs, diagnoses of osteopenia, osteoporosis and bisphosphonate prescriptions were reduced across all lockdown periods versus pre-pandemic (IRR range: 0.31–0.62). Conclusion: During the first 2 years of the pandemic, newly diagnosed breast and prostate cancer patients were prescribed more endocrine treatments compared to pre-pandemic due to restrictions on hospital procedures replacing surgeries with bridging therapies. But breast cancer patients had fewer diagnoses of osteopenia and osteoporosis and bisphosphonate prescriptions. These patients should be followed up in the coming years for signs of bone thinning. Evidence of poorer management of treatment-related side effects will help assess resource allocation for patients at high risk for bone-related complications.