Characteristics of new users of recent antidiabetic drugs in Canada and the United Kingdom.

BACKGROUND: Characteristics of patients using newer 2nd and 3rd line antidiabetic drugs in a real-world setting are poorly understood. We described the characteristics of new users of sodium-glucose co-transporter-2 inhibitors (SGLT-2i), dipeptidyl peptidase-4 inhibitors (DPP-4i), and glucagon-like peptide-1 receptor agonists (GLP-1 RA) in Canada and the United Kingdom (UK) between 2016 and 2018. METHODS: We conducted a multi-database cohort study using administrative health databases from 7 Canadian provinces and the UK Clinical Practice Research Datalink. We assembled a base cohort of antidiabetic drug users between 2006 and 2018, from which we constructed 3 cohorts of new users of SGLT-2i, DPP-4i, and GLP-1 RA between 2016 and 2018. RESULTS: Our cohorts included 194,070 new users of DPP-4i, 166,722 new users of SGLT-2i, and 27,719 new users of GLP-1 RA. New users of GLP-1 RA were more likely to be younger (mean ± SD: 56.7 ± 12.2 years) than new users of DPP-4i (67.8 ± 12.3 years) or SGLT-2i (64.4 ± 11.1 years). In Canada, new users of DPP-4i were more likely to have a history of coronary artery disease (22%) than new users of SGLT-2i (20%) or GLP-1 RA (15%). CONCLUSION: Although SGLT-2i, DPP-4i, and GLP-1 RAs are recommended as 2nd or 3rd line therapy for type 2 diabetes, important differences exist in the characteristics of users of these drugs. Contrary to existing guidelines, new users of DPP-4i had a higher prevalence of cardiovascular disease at baseline than new users of SGLT2i or GLP-1RA.

Effectiveness and safety among direct oral anticoagulants in nonvalvular atrial fibrillation: A multi-database cohort study with meta-analysis.

AIMS: There are conflicting signals in the literature about comparative safety and effectiveness of direct oral anticoagulants (DOACs) for nonvalvular atrial fibrillation (NVAF). METHODS: We conducted multicentre matched cohort studies with secondary meta-analysis to assess safety and effectiveness of dabigatran, rivaroxaban and apixaban across 9 administrative healthcare databases. We included adults with NVAF initiating anticoagulation therapy (dabigatran, rivaroxaban or apixaban), and constructed 3 cohorts to compare DOACs pairwise. The primary outcome was pooled hazard ratio (pHR) of ischaemic stroke or systemic thromboembolism. Secondary outcomes included pHR of major bleeding, and a composite of stroke, major bleeding, or all-cause mortality. We used proportional hazard Cox regressions models, and pooled estimates were obtained with random effect meta-analyses. RESULTS: The cohorts included 73 414 new users of dabigatran, 92 881 of rivaroxaban, and 61 284 of apixaban. After matching, the pHRs (95% confidence intervals) comparing rivaroxaban initiation to dabigatran were: 1.11 (0.93, 1.32) for ischaemic stroke or systemic thromboembolism, 1.26 (1.09, 1.46) for major bleeding, and 1.17 (1.05, 1.30) for the composite endpoint. For apixaban vs dabigatran, they were: 0.91 (0.74, 1.12) for ischaemic stroke or systemic thromboembolism, 0.89 (0.75, 1.05) for major bleeding, and 0.94 (0.78 to 1.14) for the composite endpoint. For apixaban vs rivaroxaban, they were: 0.85 (0.74, 0.99) for ischaemic stroke or systemic thromboembolism, 0.61 (0.53, 0.70) for major bleeding, and 0.82 (0.76, 0.88) for the composite endpoint. CONCLUSION: We found that apixaban use is associated with lower risks of stroke and bleeding compared with rivaroxaban, and similar risks compared with dabigatran.

Validity of an algorithm to identify cardiovascular deaths from administrative health records: a multi-database population-based cohort study.

BACKGROUND: Cardiovascular death is a common outcome in population-based studies about new healthcare interventions or treatments, such as new prescription medications. Vital statistics registration systems are often the preferred source of information about cause-specific mortality because they capture verified information about the deceased, but they may not always be accessible for linkage with other sources of population-based data. We assessed the validity of an algorithm applied to administrative health records for identifying cardiovascular deaths in population-based data. METHODS: Administrative health records were from an existing multi-database cohort study about sodium-glucose cotransporter-2 (SGLT2) inhibitors, a new class of antidiabetic medications. Data were from 2013 to 2018 for five Canadian provinces (Alberta, British Columbia, Manitoba, Ontario, Quebec) and the United Kingdom (UK) Clinical Practice Research Datalink (CPRD). The cardiovascular mortality algorithm was based on in-hospital cardiovascular deaths identified from diagnosis codes and select out-of-hospital deaths. Sensitivity, specificity, and positive and negative predictive values (PPV, NPV) were calculated for the cardiovascular mortality algorithm using vital statistics registrations as the reference standard. Overall and stratified estimates and 95% confidence intervals (CIs) were computed; the latter were produced by site, location of death, sex, and age. RESULTS: The cohort included 20,607 individuals (58.3% male; 77.2% ≥70 years). When compared to vital statistics registrations, the cardiovascular mortality algorithm had overall sensitivity of 64.8% (95% CI 63.6, 66.0); site-specific estimates ranged from 54.8 to 87.3%. Overall specificity was 74.9% (95% CI 74.1, 75.6) and overall PPV was 54.5% (95% CI 53.7, 55.3), while site-specific PPV ranged from 33.9 to 72.8%. The cardiovascular mortality algorithm had sensitivity of 57.1% (95% CI 55.4, 58.8) for in-hospital deaths and 72.3% (95% CI 70.8, 73.9) for out-of-hospital deaths; specificity was 88.8% (95% CI 88.1, 89.5) for in-hospital deaths and 58.5% (95% CI 57.3, 59.7) for out-of-hospital deaths. CONCLUSIONS: A cardiovascular mortality algorithm applied to administrative health records had moderate validity when compared to vital statistics data. Substantial variation existed across study sites representing different geographic locations and two healthcare systems. These variations may reflect different diagnostic coding practices and healthcare utilization patterns.

Sodium-Glucose Cotransporter-2 Inhibitors and the Risk for Diabetic Ketoacidosis : A Multicenter Cohort Study.

BACKGROUND: Sodium-glucose cotransporter-2 (SGLT-2) inhibitors could increase the risk for diabetic ketoacidosis (DKA). OBJECTIVE: To assess whether SGLT-2 inhibitors, compared with dipeptidyl peptidase-4 (DPP-4) inhibitors, are associated with an increased risk for DKA in patients with type 2 diabetes. DESIGN: Population-based cohort study; prevalent new-user design between 2013 and 2018. (ClinicalTrials.gov: NCT04017221). SETTING: Electronic health care databases from 7 Canadian provinces and the United Kingdom. PATIENTS: 208 757 new users of SGLT-2 inhibitors were matched by using time-conditional propensity scores to 208 757 recipients of DPP-4 inhibitors. MEASUREMENTS: Cox proportional hazards models estimated site-specific hazard ratios (HRs) with 95% CIs of DKA comparing receipt of SGLT-2 inhibitors with receipt of DPP-4 inhibitors, which were pooled by using random-effects models. Secondary analyses were stratified by molecule, age, sex, and prior receipt of insulin. RESULTS: Overall, 521 patients were diagnosed with DKA during 370 454 person-years of follow-up (incidence rate per 1000 person-years, 1.40 [95% CI, 1.29 to 1.53]). Compared with DPP-4 inhibitors, SGLT-2 inhibitors were associated with an increased risk for DKA (incidence rate, 2.03 [CI, 1.83 to 2.25] versus 0.75 [CI, 0.63 to 0.89], respectively; HR, 2.85 [CI, 1.99 to 4.08]). Molecule-specific HRs were 1.86 (CI, 1.11 to 3.10) for dapagliflozin, 2.52 (CI, 1.23 to 5.14) for empagliflozin, and 3.58 (CI, 2.13 to 6.03) for canagliflozin. Age and sex did not modify the association; prior receipt of insulin appeared to decrease the risk. LIMITATIONS: There was unmeasured confounding and no laboratory data were available for the majority of patients, and molecule-specific analyses were conducted at a limited number of sites. CONCLUSION: SGLT-2 inhibitors were associated with an almost 3-fold increased risk for DKA, with molecule-specific analyses suggesting a class effect. PRIMARY FUNDING SOURCE: Canadian Institutes of Health Research.

Sodium-glucose co-transporter-2 inhibitors and the risk of urosepsis: A multi-site, prevalent new-user cohort study.

AIM: To compare urosepsis rates in patients with type 2 diabetes treated using sodium-glucose co-transporter-2 inhibitors (SGLT2i) with dipeptidyl peptidase-4 inhibitors (DPP4i) in a real-world setting. METHODS: We conducted a matched cohort study using a prevalent new-user design with time-conditional propensity scores. New users of SGLT2i from seven Canadian provinces and the UK were matched to DPP4i users. The primary outcome was hospitalization with a diagnosis of urosepsis and the secondary outcome was Fournier's gangrene. Site-specific hazard ratios for urosepsis comparing SGLT2i with DPP4i were estimated using Cox proportional hazards models and pooled using a random effects meta-analysis. RESULTS: We included 208 244 users of SGLT2i and 208 244 users of DPP4i. Among SGLT2i users, 42% initiated canagliflozin, 31% dapagliflozin and 27% empagliflozin. During a mean follow-up of 0.9 years, patients initiating SGLT2i had a lower rate of urosepsis compared with those receiving DPP4i. The pooled adjusted hazard ratio was 0.58 (95% confidence interval [CI]: 0.42-0.80). The incidence rates of Fournier's gangrene were numerically similar in SGLT2i (0.08 per 1000 person-years; 95% CI: 0.05-0.13) and DPP4i users (0.14; 95% CI: 0.09-0.21). CONCLUSIONS: In this large, multi-site study, we did not observe an increased risk for urosepsis associated with SGLT2i compared with DPP4i among patients with type 2 diabetes in a real-world setting.

A rapid monitoring plan following a shift in coverage from brand name to biosimilar drugs for rheumatoid arthritis in British Columbia.

PURPOSE: To describe a rapid monitoring plan to assess the impacts of a shift in drug coverage for biosimilar drugs in British Columbia following the introduction of a new policy on 27 May 2019. The Biosimilars Initiative requires users of originator infliximab or etanercept to switch to biosimilar versions of those drugs to maintain coverage. We propose a signal-detection method to provide near-real-time information to policymakers on the impacts of the policy change. METHODS: The exposure will be the Biosimilars Initiative, a policy affecting patients using originator infliximab (Remicade) and etanercept (Enbrel) for approved rheumatologic or dermatologic indications. Two policy cohorts and six historical control cohorts of patients using originator infliximab or etanercept will be assembled using linked and de-identified data from the British Columbia Ministry of Health. Patients will be identified during the 6-month period before the policy anniversary. Outcomes will include medication refills and switching, hospital admissions, emergency department visits, and physician visits. Summary outcome measures, such as cumulative incidence or average quantity as applicable, will be examined daily and reported monthly for 1 year. Outcomes in the policy cohorts will be compared with historical controls using likelihood ratios. RESULTS: The results of this rapid monitoring plan will be based on analyses involving approximately 9000 patients: four infliximab cohorts of approximately 430 patients and four etanercept cohorts of approximately 1800 patients. CONCLUSIONS: Rapid monitoring results will inform ongoing policy decisions related to the Biosimilars Initiative, in terms of impacts on both patient health and health services utilization.

Rapid monitoring of health services utilization following a shift in coverage from brand name to biosimilar drugs in British Columbia-An interim report.

PURPOSE: We explored changes in health services utilization associated with the Biosimilars Initiative introduced in British Columbia on May 27, 2019. To maintain drug coverage, the policy requires users of originator infliximab or etanercept to transition to biosimilar versions. We present a three-month interim analysis of this initiative. METHODS: We conducted a rapid monitoring analysis to evaluate changes in health services utilization three months after the policy was introduced compared with a three-year period before the policy's introduction. Using the administrative claims data of the British Columbia Ministry of Health, we assembled three historical cohorts and one policy cohort of users of each originator drug (8 cohorts in total). Cumulative incidences of medication refills, switching, and visits to physicians were the outcome measures used to compare policy and historical cohorts. Likelihood ratios were used to quantify statistical differences between each policy cohort and its respective historical controls. Likelihood ratios above 7.1 were considered statistically significant. RESULTS: The four infliximab cohorts included 436 patients on average, mean age 56 to 59, 53% to 55% females. The four etanercept cohorts included 1826 patients on average, mean age 57 to 58, 60% to 63% females. Three months after the policy's introduction, 21% of patients treated in the policy cohorts transitioned to the biosimilar versions. Health services utilization in the policy cohorts were consistent with the historical cohorts. CONCLUSIONS: An increase in visits to physicians was expected but not detected in the first three months of the Biosimilars Initiative. The impacts of the policy will continue to be monitored.

Policy-induced selection bias in pharmacoepidemiology: The example of coverage for Alzheimer's medications in British Columbia.

PURPOSES: To assess the impact of a government-sponsored reimbursement policy for cholinesterase inhibitors (ChEIs) on trends in physician visits with a diagnosis of Alzheimer's disease (AD). METHODS: Longitudinal population-based study using interrupted time series methods. British Columbia outpatient claims data for individuals aged 65 and older were used to compute monthly AD visit rates and examine the impact of the ChEI reimbursement policy on the coding of AD. We examined trends in the number of patients with AD visits, the number of AD visits per patient, and visits with "competing" diagnoses (mental, neurological, and cerebrovascular disorders and accidental falls). Finally, we described demographic and clinical features of diagnosed patients. RESULTS: We analyzed 1.9 million AD visits. Faster growth in recorded AD visits was observed after the policy was implemented, from monthly growth of 7.5 visits per 100 000 person-months before the policy (95% confidence interval [CI], 6.1-8.9) to monthly growth of 16.5 per 100 000 person-months after the policy (95% CI, 14.8-18.3). After the implementation of the policy, we observed increased growth in the number of patients with recorded AD visits and the number of AD visits per patient, as well as a shift in diagnoses away from mental diseases and accidental falls to AD (diagnosis substitution). CONCLUSIONS: British Columbia's reimbursement policy for ChEIs was associated with a significant acceleration in Alzheimer's visits. Evaluations of health services utilization and clinical outcomes following drug policy changes need to consider policy-induced influences on the reliability of the data used in the analysis.

Cholinesterase Inhibitor Utilization: The Impact of Provincial Drug Policy on Discontinuation.

BACKGROUND: In October 2007, British Columbia started to cover the cost of cholinesterase inhibitors (ChEIs)-donepezil, galantamine, and rivastigmine-for patients with mild to moderate dementia and prominent Alzheimer's disease. OBJECTIVES: To examine the impact of this policy on persistence with ChEIs. METHODS: A population-based cohort study was conducted using British Columbia administrative health data. We examined 45,537 new ChEI users aged 40 years and older between 2001 and 2012; 20,360 (45%) started the treatment after the coverage policy was launched. Patients were followed until treatment discontinuation, defined as a ChEI-free gap of 90 days, death, or December 2013. Persistence on ChEIs was estimated using survival analysis and competing risk approach. Hazards of discontinuation were compared using competing risk Cox regression with propensity adjustment. RESULTS: Patients who started ChEI therapy after the introduction of the coverage policy had a significantly longer persistence. Median ChEI persistence until discontinuation or death was 9.37 months (95% confidence interval [CI] 9.0-39.7) and 17.6 months (95% CI 16.9-18.3) in patients who started therapy before and after the new policy, respectively. The propensity-adjusted hazard ratio for discontinuing therapy was 0.91 (95% CI 0.88-0.94). Similar patterns were observed for persistence with the first ChEI (propensity-adjusted hazard ratio of 0.94; 95% CI 0.91-0.98). In rivastigmine users, the hazard ratio was insignificant (0.98; 95% CI 0.92-1.02). CONCLUSIONS: The British Columbia ChEI coverage policy was associated with significantly prolonged persistence with donepezil and galantamine, but not rivastigmine.

Trends in antihypertensive drug utilization in British Columbia, 2004-2019: a descriptive study.

BACKGROUND: Clinical guidelines for hypertension were updated with lower blood pressure targets following new studies in 2015; the real-world impact of these changes on antihypertensive drug use is unknown. We aimed to describe trends in antihypertensive drug utilization from 2004 to 2019 in British Columbia. METHODS: We conducted a longitudinal study to describe the annual prevalence and incidence rate of use of 5 antihypertensive drug classes (thiazides, angiotensin-converting enzyme [ACE] inhibitors, angiotensin II receptor blockers [ARBs], calcium channel blockers and ß-blockers) among BC residents aged 30-75 years. We also conducted a cohort study to compare the risk of discontinuation and switch or add-on therapy between incident users of the above drug classes. We used linkable administrative health databases from BC. We performed a Fine-Gray competing risk analysis to estimate subhazard ratios. RESULTS: Among BC residents aged 30-75 years (population: 2 376 282 [2004] to 3 014 273 [2019]), the incidence rate of antihypertensive drug use decreased from 23.7 per 1000 person-years in 2004 to 18.3 per 1000 person-years in 2014, and subsequently increased to 22.6 per 1000 person-years in 2019. The incidence rate of thiazide use decreased from 8.9 per 1000 person-years in 2004 to 3.2 per 1000 person-years in 2019, and incidence rates for the other drug classes increased. Incident users receiving thiazide monotherapy had an increased risk of discontinuing any antihypertensive treatment compared with ACE inhibitor monotherapy (subhazard ratio 0.96, 95% confidence interval [CI] 0.95-0.97), ARB monotherapy (subhazard ratio 0.84, 95% CI 0.81-0.87) and thiazide combination with ACE inhibitor or ARB (subhazard ratio 0.86, 95% CI 0.84-0.88), and had the highest risk of switching or adding on. INTERPRETATION: First-line use of thiazides continued to decrease despite a marked increase in incident antihypertensive therapy following updated guidelines; incident users receiving ARB monotherapy were least likely to discontinue, and incident users receiving thiazide monotherapy were more likely to switch or add on than users of other initial monotherapy or combination. Further research is needed on the factors influencing treatment decisions to understand the differences in trends and patterns of antihypertensive drug use.

Monitoring a Mandatory Nonmedical Switching Policy from Originator to Biosimilar Infliximab in Patients with Inflammatory Bowel Diseases: A Population-Based Cohort Study.

Background: On September 5, 2019, British Columbia announced a new policy (the Biosimilars Initiative) to switch from originator to biosimilar infliximab for patients with inflammatory bowel diseases. Objective: To monitor the impacts of the policy on the use of medications and health services during the first year of the policy. Methods: In this population-based cohort study, we used administrative health data to construct three historical cohorts and one policy cohort of patients with inflammatory bowel diseases who used the originator infliximab. We then monitored the cumulative incidence of medications and health services. Log-likelihood ratios were used to quantify differences between the policy cohort and the average of the historical cohorts. Results: The cohorts included 1839-2368 users of the originator infliximab, ages 4-90 years, mean age 43 years. During the first year of follow-up, we found: (1) a 0.9% increase in the first dispensation of infliximab, biosimilar, or originator; (2) a 16.2% increase in infliximab dose escalation; (3) a decrease of 2.4% in the dispensation of antibiotics and a 2.6% decrease in new use of prednison; (4) an anticipated increase in visits to physicians and gastroenterologists to manage switching to biosimilars (24.0%); (5) a 4.0% decrease in discharges from hospital; and (6) a 2.9% decrease in emergency admissions to hospital. Conclusion: British Columbia's Biosimilars Initiative for nonmedical switching from originator to biosimilar infliximab for inflammatory bowel diseases was not associated with harmful impacts on medications and health services use. An increase in dose escalation was accompanied by an improvement in health status proxies.

A cluster randomized trial assessing the impact of personalized prescribing feedback on antibiotic prescribing for uncomplicated acute cystitis to family physicians.

OBJECTIVE: To evaluate the impact of personalized prescribing portraits on antibiotic prescribing for treating uncomplicated acute cystitis (UAC) by Family Physicians (FPs). DESIGN: Cluster randomized control trial. SETTING: The intervention was conducted in the primary care setting in the province of BC between December 2010 and February 2012. PARTICIPANTS: We randomized 4 833 FPs by geographic location into an Early intervention arm (n = 2 417) and a Delayed control arm (n = 2 416). INTERVENTION: The Education for Quality Improvement in Patient Care (EQIP) program mailed to each FP in BC, a 'portrait' of their individual prescribing of antibiotics to women with UAC, plus therapeutic recommendations and a chart of trends in antibiotic resistance. MAIN OUTCOME MEASURES: Antibiotic prescribing preference to treat UAC. RESULTS: Implementing exclusion criteria before and after a data system change in the Ministry of Health caused the arms to be unequal in size-intervention arm (1 026 FPs, 17 637 UAC cases); control arm (1 352 FPs, 25 566 UAC cases)-but they were well balanced by age, sex and prior rates of prescribing antibiotics for UAC. In the early intervention group probability of prescribing nitrofurantoin increased from 28% in 2010 to 38% in 2011, a difference of 9.9% (95% confidence interval [CI], 9.1% to 10.7. Ciprofloxacin decreased by 6.2% (95% CI: 5.6% to 6.9%) and TMP-SMX by 3.7% (95% CI: 3.1% to 4.2%). Among 295 FPs who completed reflective surveys, 52% said they were surprized by the E. coli resistance statistics and 57% said they planned to change their treatment of UAC. CONCLUSION: The EQIP intervention demonstrated that feedback of personal data to FPs on their prescribing, plus population data on antibiotic resistance, with a simple therapeutic recommendation, can significantly improve prescribing of antibiotics. Trial registration: ISRCTN 16938907.

Nirmatrelvir-Ritonavir and COVID-19 Mortality and Hospitalization Among Patients With Vulnerability to COVID-19 Complications.

Importance: Postmarket analysis of individuals who receive nirmatrelvir and ritonavir (Paxlovid [Pfizer]) is essential because they differ substantially from individuals included in published clinical trials. Objective: To examine the association of nirmatrelvir and ritonavir with prevention of death or admission to hospital in individuals with different risks of complications from COVID-19 infection. Design, Setting, and Participants: This is a cohort study of adult patients in British Columbia, Canada, between February 1, 2022, and February 3, 2023. Patients were eligible if they belonged to 1 of 4 higher-risk groups of individuals who received priority for COVID-19 vaccination. Two groups included clinically extremely vulnerable (CEV) people who were severely (CEV1) or moderately immunocompromised (CEV2). CEV3 individuals were not immunocompromised but had medical conditions associated with a high risk for complications from COVID-19. A fourth expanded eligibility (EXEL) group was added to allow wider access to nirmatrelvir and ritonavir for certain other higher-risk individuals who were not in a CEV group, such as those older than 70 years who were unvaccinated. Exposures: Patients with COVID-19 who received nirmatrelvir and ritonavir were matched to patients in the same vulnerability group; who were of the same sex, age, and propensity score for nirmatrelvir and ritonavir treatment; and who were also infected within 1 month of the individual treated with nirmatrelvir and ritonavir. Main Outcomes and Measures: The primary outcome was death from any cause or emergency hospitalization with COVID-19 within 28 days. Results: There were 6866 individuals included in the study, of whom 3888 (56.6%) were female and whose median (IQR) age was 70 (57-80) years. Compared with unexposed controls, treatment with nirmatrelvir and ritonavir was associated with statistically significant relative reductions in the primary outcome in the CEV1 group (560 patients; risk difference [RD], -2.5%, 95% CI, -4.8% to -0.2%) and the CEV2 group (2628 patients; RD, -1.7%; 95% CI, -2.9% to -0.5%). In the CEV3 group, the RD was -1.3%, but the findings were not statistically significant (2100 patients; 95% CI, -2.8% to 0.1%). In the EXEL group, treatment was associated with higher risk of the outcome (RD, 1.0%), but the findings were not statistically significant (1578 patients; 95% CI, -0.9% to 2.9%). Conclusions and Relevance: In this cohort study of 6866 individuals in British Columbia, nirmatrelvir and ritonavir treatment was associated with reduced risk of COVID-19 hospitalization or death in CEV individuals, with the greatest benefit observed in severely immunocompromised individuals. No reduction in the primary outcome was observed in lower-risk individuals, including those aged 70 years or older without serious comorbidities.

Validity of diagnoses of SARS-CoV-2 infection in Canadian administrative health data: a multiprovince, population-based cohort study.

BACKGROUND: Accurate coding of diagnoses of SARS-CoV-2 infection in administrative data benefits population-based studies about the epidemiology, treatment and outcomes of COVID-19. We describe the validity of diagnoses of SARS-CoV-2 infection recorded in hospital discharge abstracts, emergency department records and outpatient physician service claims from 3 Canadian provinces. METHODS: In this cohort study, population-based inpatient, emergency department and outpatient records were linked to SARS-CoV-2 polymerase chain reaction (PCR; reference standard) test results from British Columbia, Manitoba and Ontario for Apr. 1, 2020, to Mar. 31, 2021. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of diagnoses of SARS-CoV-2 infection were estimated for each quarter in the study period, overall and by province, age group and sex. RESULTS: Our study encompassed more than 13 million SARS-CoV-2 PCR test results. Specificity and NPV of diagnoses of SARS-CoV-2 infection were consistently high (i.e., most estimates were > 95%). Overall sensitivity estimates were 86.2%, 60.4% and 20.3% in the first quarter for inpatient, emergency department and outpatient cohorts, and 66.2%, 47.5% and 25.0% in the last quarter, respectively. For inpatients, overall PPV estimates ranged from 50.0% to 66.4%. For emergency department patients, overall PPV estimates were 76.9% and 68.3% in the first and last quarters, respectively. For outpatients, PPV estimates were 6.8% and 29.1% in the first and last quarters, respectively. INTERPRETATION: We found variations in the validity of diagnoses for SARS-CoV-2 infection recorded in different health care settings, geographic areas and over time. Our multiprovince validation study provides evidence about the potential use of inpatient and emergency department records as an alternative to population-based laboratory data for identification of patients with SARS-CoV-2 infection, but does not support the use of outpatient claims for this purpose.

Rapid monitoring of health services use following a policy to switch patients from originator to biosimilar etanercept-a cohort study in British Columbia.

BACKGROUND: Drug coverage policies that incentivize switching patients from originator to biosimilar products may result in significant health care savings. Our study aimed to detect early impacts on health services utilization following a mandated switch from originator to biosimilar etanercept in British Columbia (BC), Canada. METHODS: We conducted a prospective, population-based cohort study using linked administrative health data from BC (2010-2020). The policy cohort consisted of patients with inflammatory arthritis who used originator etanercept in 2019, prior to BC's Biosimilars Initiative switching policy. Three historical cohorts included patients with inflammatory arthritis who used originator etanercept in the years 2016, 2017, and 2018. We compared the daily cumulative incidences of drug refills and outpatient and inpatient services between the policy and historical cohorts. A likelihood ratio sustained (≥ 31 days) at 7.1 or higher compared with the null hypothesis was chosen a priori as a threshold for a potential impact of the policy. RESULTS: Each cohort contained between 1694 and 1963 patients. We detected several potential impacts: 1) a transient increase in etanercept refills between months three and eight (cumulative incidence difference of + 3.0%); 2) an anticipated increase in visits to physicians of any specialty between months three and eight (+ 2.6%); and 3) an anticipated increase in visits to a rheumatologist from the end of month three onwards (+ 12.8%). The policy had no impact on incidences of switching to a different biologic antirheumatic drug, visits to emergency departments, or admissions to hospitals. CONCLUSIONS: Only transient and/or anticipated increases in drug refills and physician visits were observed during the study period. Additional research on clinical outcomes is recommended to strengthen the evidence that no long-term unintended negative health impacts are associated with BC's Biosimilars Initiative [switching policy].

The Impact of Mandatory Nonmedical Switching From Originator to Biosimilar Insulin Glargine.

PURPOSE: This study monitors for early changes in health services utilization after a mandatory policy to switch patients from originator to biosimilar insulin glargine in British Columbia, Canada. METHODS: We conducted a prospective cohort study of patients treated with originator insulin glargine. The policy cohort included patients treated with originator insulin glargine in the 6 months before the policy change (May 27, 2019). Three historical control cohorts included users of originator insulin glargine during the 6 months before May 27 each year in 2016, 2017, and 2018. Patients who discontinued or switched use of the originator insulin glargine and those without cost coverage by the provincial drug plan were excluded. Using likelihood ratios, we compared the daily use of medications, outpatient visits, and hospitalizations in the 12 months after the policy change with the daily use in 3 historical control cohorts. A sustained likelihood ratio above a predefined threshold of 7.1 was interpreted as an early signal of a possible policy impact. FINDINGS: Each cohort included 15,344 to 17,310 patients. In the first year of the policy, we observed increases in (1) insulin glargine use (the cumulative incidence increased by 2.5% compared with the mean of the 3 historical cohorts), (2) oral antidiabetic medication use (increased by 2.8%), and (3) outpatient visits (increased by 1.4%). Likelihood ratios greater than the threshold of 7.1 were detected for these 3 outcomes. IMPLICATIONS: We observed marginal changes in health services utilization without detecting signals of negative health impacts on patients targeted by the British Columbia policy of mandatory switching from originator to biosimilar insulin glargine.

Mandatory nonmedical switching from originator to biosimilar infliximab in patients with inflammatory arthritis and psoriasis in British Columbia: a cohort study.

BACKGROUND: In 2019, British Columbia's public drug plan, PharmaCare, was the first in Canada to implement a nonmedical switching policy from originator infliximab to its biosimilar, for patients with inflammatory arthritis or psoriasis. We aimed to detect signals of impact on health services utilization during the first year of policy implementation and to provide early data to policy-makers. METHODS: We constructed cohorts of users of originator infliximab: 3 historical cohorts (2016-2018) and 1 policy cohort (2019). We extracted data from BC Ministry of Health databases from 2015 to 2020, as we followed each cohort for 365 days from May 27 of each cohort's respective year. We excluded patients with gastrointestinal conditions and those not covered by PharmaCare. We examined the cumulative incidence of infliximab prescription refills, switching to other biologic drugs and use of additional health services. A log-likelihood ratio of 1.96 compared with the null hypothesis was used as the threshold for differences between the policy cohort and the historical cohorts. RESULTS: The study included a total of 572 unique patients: 520 in the 2016 historical cohort, 461 in the 2017 historical cohort, 423 in the 2018 historical cohort and 377 in the policy cohort (with some patients included in multiple cohorts; 335 [58.6%] were included in all 4 cohorts). During months 8 and 9 of follow-up, a transient signal was observed in infliximab refills (7.2% decrease in refilling infliximab for the fourth time for the policy cohort, log-likelihood ratio > 1.96). An anticipated increase in visits to specialists was observed from month 4 forward (15.0%, log-likelihood ratio > 1.96). No signal was observed for increased use of other health services (log-likelihood ratio < 1.96). INTERPRETATION: Early monitoring did not detect signals of negative impacts on health services use during the first year of the policy. Detailed, longer-term cohort studies and hypothesis-testing methods could provide additional assurance about the safety of the policy.

Patterns of antiemetic medication use during pregnancy: A multi-country retrospective cohort study.

OBJECTIVE: To compare patterns in use of different antiemetics during pregnancy in Canada, the United Kingdom, and the United States, between 2002 and 2014. METHODS: We constructed population-based cohorts of pregnant women using administrative healthcare data from five Canadian provinces (Alberta, British Columbia, Manitoba, Ontario, and Saskatchewan), the Clinical Practice Research Datalink from the United Kingdom, and the IBM MarketScan Research Databases from the United States. We included pregnancies ending in live births, stillbirth, spontaneous abortion, or induced abortion. We determined maternal use of antiemetics from pharmacy claims in Canada and the United States and from prescriptions in the United Kingdom. RESULTS: The most common outcome of 3 848 734 included pregnancies (started 2002-2014) was live birth (66.7% of all pregnancies) followed by spontaneous abortion (20.2%). Use of antiemetics during pregnancy increased over time in all three countries. Canada had the highest prevalence of use of prescription antiemetics during pregnancy (17.7% of pregnancies overall, 13.2% of pregnancies in 2002, and 18.9% in 2014), followed by the United States (14.0% overall, 8.9% in 2007, and 18.1% in 2014), and the United Kingdom (5.0% overall, 4.2% in 2002, and 6.5% in 2014). Besides use of antiemetic drugs being considerably lower in the United Kingdom, the increase in its use over time was more modest. The most commonly used antiemetic was combination doxylamine/pyridoxine in Canada (95.2% of pregnancies treated with antiemetics), ondansetron in the United States (72.2%), and prochlorperazine in the United Kingdom (63.5%). CONCLUSIONS: In this large cohort study, we observed an overall increase in antiemetic use during pregnancy, and patterns of use varied across jurisdictions. Continued monitoring of antiemetic use and further research are warranted to better understand the reasons for differences in use of these medications and to assess their benefit-risk profile in this population.

Tofacitinib Persistence in Patients with Rheumatoid Arthritis: A Retrospective Cohort Study.

OBJECTIVE: To compare medication persistence of tofacitinib with persistence of injectable biological disease-modifying antirheumatic drugs (bDMARD) in patients with rheumatoid arthritis (RA). METHODS: We performed a retrospective new-user cohort study of patients with RA in the IBM MarketScan Research Databases. New users of tofacitinib or bDMARD were identified between November 2012 and December 2016. Persistence, in number of years, was the time between treatment initiation and the earliest occurrence of discontinuation or switching from the medication prescribed at cohort entry. Persistence of tofacitinib was compared with bDMARD persistence using Cox proportional hazards regression with adjustment for high-dimensional propensity scores. Similar methods were used for an analysis of post first-line therapy in patients who switched to tofacitinib from a bDMARD. RESULTS: New tofacitinib users (n = 1031) were 56 years of age, on average, and 82% were women. New bDMARD users (n = 17,803) were 53 years of age, on average, and 78% were women. New tofacitinib users had shorter medication persistence (median 0.81 yrs) compared to bDMARD patients (1.02 yrs). After adjustment, the HR for discontinuation of tofacitinib compared with bDMARD was 1.14 (95% CI 1.05-1.25). Patients who switched to tofacitinib from a bDMARD had longer persistence than patients who switched to a bDMARD (adjusted HR for discontinuation 0.90, 95% CI 0.83-0.97). CONCLUSION: Further research is warranted to understand the reasons for discontinuation of tofacitinib despite its ease of administration and to understand the observed differences between switchers and new users.

Off-label postpartum use of domperidone in Canada: a multidatabase cohort study.

BACKGROUND: Trends in off-label postpartum use of domperidone and the impact of safety advisories on its use remain unknown. Our objectives were to describe postpartum use of domperidone in Canada, to evaluate the impact of Health Canada advisories on prescribing patterns, and to describe the association between domperidone use and a composite end point of sudden cardiac death or ventricular tachycardia (VT) among postpartum patients. METHODS: We conducted a multidatabase cohort study involving pregnant patients with live births between 2004 and 2017 using administrative health databases from 5 Canadian provinces (British Columbia, Alberta, Saskatchewan, Manitoba and Ontario). We excluded patients with less than 1 year of prepregnancy database history and with approved indications for domperidone. We assessed domperidone use in the 6 months postpartum and the impact of the 2012 and 2015 Health Canada advisories on prescribing via interrupted time series analysis. We estimated crude rates of VT and sudden cardiac death. RESULTS: We included 1 190 987 live births. Mean maternal age was 28.6 (standard error 0.6) years. Domperidone use increased over time, from 7% in 2003-2005 to 12% in 2009-2011, when it plateaued. The 2012 advisory was followed by a drop in use and a reduction in slope, and the 2015 advisory had a more modest impact. Crude analysis suggests that domperidone may be associated with increased VT or sudden cardiac death (0.74 v. 0.37 per 10 000 person-years; difference per 10 000 person-years: 0.37, 95% confidence interval -0.67 to 1.41). INTERPRETATION: Postpartum domperidone use increased between 2004 and 2017, with prescribing attenuated after Health Canada advisories and a very low absolute rate of VT or sudden cardiac death. These findings suggest that Health Canada advisories affected prescribing; any potential increase in VT or sudden cardiac death with use of domperidone is small and could not be confirmed in this large study STUDY REGISTRATION: ClinicalTrials.gov, no. NCT04024865.