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.

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.

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 β-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.

Public reporting of clinical trial findings as an ethical responsibility to participants: a qualitative study

OBJECTIVE

To understand how the experiences and views of trial participants, trial investigators and others connected to clinical trial research relate to whether researchers have a duty to participants to publicly report research findings.

DESIGN

Qualitative interview study.

SETTING

Semistructured interviews held in person or by telephone between March 2019 and April 2021 with participants in the Canadian provinces of Alberta, British Columbia and Ontario.

PARTICIPANTS

34 participants, including 10 clinical trial participants, 17 clinical trial investigators, 1 clinical research coordinator, 3 research administrators and 3 research ethics board members.

ANALYSIS

We conducted a thematic analysis, including qualitative coding of interview transcripts and identification of key themes.

MAIN OUTCOME MEASURES

Key themes identified through qualitative coding of interview data.

RESULTS

Most clinical trial participants felt that reporting clinical trial results is important. Accounts of trial participants suggest their contributions are part of a reciprocal relationship involving the expectation that research will advance medical knowledge. Similarly, comments from trial investigators suggest that reporting trial results is part of reciprocity with trial participants and is a necessary part of honouring informed consent. Accounts of trial investigators suggest that when drug trials are not reported, this may undermine informed consent in subsequent trials by withholding information on harms or efficacy relevant to informed decisions on whether to conduct or enroll in future trials of similar drugs.

CONCLUSION

The views of trial participants, trial investigators and others connected to clinical trial research in Canada suggest that researchers have an obligation to participants to publicly report clinical trial results and that reporting results is necessary for honouring informed consent.

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.

Factors relating to nonpublication and publication bias in clinical trials in Canada: A qualitative interview study

AIMS

This study aims to understand factors contributing to nonpublication and publication bias in clinical trials in Canada.

METHODS

Qualitative interviews were conducted between March 2019 and April 2021 with 34 participants from the Canadian provinces of Alberta, British Columbia and Ontario, including 17 clinical trial investigators, 1 clinical research coordinator, 3 research administrators, 3 research ethics board members and 10 clinical trial participants. We conducted a thematic analysis involving coding of interview transcripts and memo-writing to identify key themes.

RESULTS

Several factors contribute to nonpublication and publication bias in clinical trial research. A core theme was that reporting practices are shaped by incentives within the research system taht favour publication of positive over negative trials. Investigators are discouraged from reporting by experiences or perceptions of difficulty in publishing negative findings but rewarded for publishing positive findings in various ways. Trial investigators more strongly associated positive clinical trials than negative trials with opportunities for industry and nonindustry funding and with academic promotion, bonuses and recognition. Research institutions and ethics boards tended to lack well-resourced, proactive policies and practices to ensure trial findings are reported in registries or journals.

CONCLUSION

Clinical trial reporting practices in Canada are shaped by incentives favouring reporting of positive over negative trials, such as funding opportunities and academic promotion, bonuses and recognition. Research institutions could help change incentives by adopting performance metrics that emphasize full reporting of results in journals or registries.

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.

Treatment pattern trends of medications for type 2 diabetes in British Columbia, Canada

INTRODUCTION

Several new oral drug classes for type 2 diabetes (T2DM) have been introduced in the last 20 years accompanied by developments in clinical evidence and guidelines. The uptake of new therapies and contemporary use of blood glucose-lowering drugs has not been closely examined in Canada. The objective of this project was to describe these treatment patterns and relate them to changes in provincial practice guidelines.

RESEARCH DESIGN AND METHODS

We conducted a longitudinal drug utilization study among persons with T2DM aged ≥18 years from 2001 to 2020 in British Columbia (BC), Canada. We used dispensing data from community pharmacies with linkable physician billing and hospital admission records. Laboratory results were available from 2011 onwards. We identified incident users of blood glucose-lowering drugs, then determined sequence patterns of medications dispensed, with stratification by age group, and subgroup analysis for patients with a history of cardiovascular disease.

RESULTS

Among a cohort of 362 391 patients (mean age 57.7 years old, 53.5% male) treated for non-insulin-dependent diabetes, the proportion who received metformin monotherapy as first-line treatment reached a maximum of 90% in 2009, decreasing to 73% in 2020. The proportion of patients starting two-drug combinations nearly doubled from 3.3% to 6.4%. Sulfonylureas were the preferred class of second-line agents over the course of the study period. In 2020, sodium-glucose cotransporter type 2 inhibitors and glucagon-like peptide-1 receptor agonists accounted for 21% and 10% of second-line prescribing, respectively. For patients with baseline glycated hemoglobin (A1C) results prior to initiating diabetic treatment, 41% had a value ≤7.0% and 27% had a value over 8.5%.

CONCLUSIONS

Oral diabetic medication patterns have changed significantly over the last 20 years in BC, primarily in terms of medications used as second-line therapy. Over 40% of patients with available laboratory results initiated T2DM treatment with an A1C value ≤7.0%, with the average A1C value trending lower over the last decade.

How do safety warnings on medicines affect prescribing?

INTRODUCTION

Many adverse effects of medicines only become known after approval, prompting regulatory agencies to issue post-market safety advisories to inform clinicians and support safer care. Our team evaluated advisories issued by national regulators in Australia, Canada, Denmark, the United Kingdom, and the United States from 2007 to 2016 inclusive, comparing regulators' decisions to warn, effects on prescribing, doctors' awareness and responses to warnings, relevant regulatory policies, and specific case studies.

AREAS COVERED

Based mainly on our research program and a narrative review, this commentary describes how often regulators issue safety advisories and effects on clinical practice. We found extensive differences in decisions to warn, timing and content of warnings. Monitoring advice is often inadequate. The most systematic estimate suggests an average reduction in prescribing of around 6% compared with settings with no advisory. Interviews with doctors suggest limited awareness, uptake, and at times belief in these warnings.

EXPERT OPINION

Post-market safety advisories are an important intervention aiming to improve prescribing and use of medicines. However, differing warnings mean that some patients may be exposed to riskier prescribing than others. Better integration of new safety information into clinical practice is needed, as well as improved transparency, independence, and public engagement in regulatory decision-making.

Pioglitazone use in Australia and the United Kingdom following drug safety advisories on bladder cancer risk: an interrupted time series study

PURPOSE

National regulators in Australia and the United Kingdom (UK) issued safety advisories on the association between pioglitazone use and bladder cancer in July 2011. The Australian advisory noted that males were at higher risk of bladder cancer than females, while the UK advisory highlighted a new recommendation, suggest careful consideration in the elderly due to increasing risk with age. This study examined whether these differences in the advisories had different age- and sex-based impacts in each country.

METHODS

Interrupted time series analysis was used to compare pioglitazone use (prescriptions/100,000 population) in Australia and the UK for the 24 months before and 11 months after the July 2011 safety advisories (study period July 2009-June 2012). Separate models were used to compare use by sex and age group (≥65 years vs. <65 years) in each country.

RESULTS

Pioglitazone use fell in Australia (17%) and the UK (24%) following the safety advisories. Use of pioglitazone fell more for males (18%) than females (16%) in Australia, and more for females (25%) than males (23%) in the UK; however neither difference was statistically significant (Australia P=0.445, UK P=0.462). Pioglitazone use fell to a similar extent among older people than younger people in the UK (23% vs. 26%, P=0.354), and did not differ between age groups in Australia (both 18%, P=0.772).

CONCLUSIONS

The results indicate that differences in the Australian and UK safety advisories resulted in substantial reductions in pioglitazone use at the population level in both countries, however, differences by sub-groups were not observed. This article is protected by copyright. All rights reserved.

Hydroxyzine Initiation Following Drug Safety Advisories on Cardiac Arrhythmias in the UK and Canada: A Longitudinal Cohort Study

Introduction

Regulatory advisories on hydroxyzine and risk of QT prolongation and Torsade de pointes (TdP) were issued in the UK in April 2015 and Canada in June 2016. We hypothesized patients with risk factors for QT prolongation and TdP, compared with those without risk factors, would be less likely to initiate hydroxyzine in the UK and in British Columbia (BC), Canada, following advisories.

Methods

We conducted a longitudinal study with repeated measures, and evaluated hydroxyzine initiation in a UK cohort and a concurrent BC control cohort (April 2013–March 2016) as well as in a BC advisory cohort (June 2014–May 2017).

Results

This study included 247,665 patients in the UK cohort, 297,147 patients in the BC control cohort, and 303,653 patients in the BC advisory cohort. Over a 12-month post-advisory period, hydroxyzine initiation decreased by 21% in the UK (rate ratio 0.79, 95% confidence interval 0.66–0.96) relative to the expected level of initiation based on the pre-advisory trend. Hydroxyzine initiation did not change in the BC control cohort or following the Canadian advisory in the BC advisory cohort. The decrease in hydroxyzine initiation in the UK in the 12 months after the advisories was not significantly different for patients with risk factors compared with those without risk factors.

Conclusion

Hydroxyzine initiation decreased in the UK, but not in BC, in the 12 months following safety advisories. The decrease in hydroxyzine initiation in the UK was not significantly different for patients with versus without risk factors for QT prolongation and TdP.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40264-022-01175-2.

Influence of drug safety advisories on drug utilisation: an international interrupted time series and meta-analysis

Objective

To evaluate the association between regulatory drug safety advisories and changes in drug utilisation.

Design

We conducted controlled, interrupted times series analyses with administrative prescription claims data to estimate changes in drug utilisation following advisories. We used random-effects meta-analysis with inverse-variance weighting to estimate the average postadvisory change in drug utilisation across advisories.

Study population

We included advisories issued in Canada, Denmark, the UK and the USA during 2009–2015, mainly concerning drugs in common use in primary care. We excluded advisories related to over-the-counter drugs, drug-drug interactions, vaccines, drugs used primarily in hospital and advisories with co-interventions within ±6 months.

Main outcome measures

Change in drug utilisation, defined as actual versus predicted percentage change in the number of prescriptions (for advisories without dose-related advice), or in the number of defined daily doses (for dose-related advisories), per 100 000 population.

Results

Among advisories without dose-related advice (n=20), the average change in drug utilisation was −5.83% (95% CI −10.93 to –0.73; p=0.03). Advisories with dose-related advice (n=4) were not associated with a statistically significant change in drug utilisation (−1.93%; 95% CI −17.10 to 13.23; p=0.80). In a post hoc subgroup analysis of advisories without dose-related advice, we observed no statistically significant difference between the change in drug utilisation following advisories with explicit prescribing advice, such as a recommendation to consider the risk of a drug when prescribing, and the change in drug utilisation following advisories without such advice.

Conclusions

Among safety advisories issued on a wide range of drugs during 2009–2015 in 4 countries (Canada, Denmark, the UK and the USA), the association of advisories with changes in drug utilisation was variable, and the average association was modest.

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.

Industry Sponsor Influence in Clinical Trial Reporting in Canada: A Qualitative Interview Study

PURPOSE

Approximately 40% of randomized controlled trials are not published, leading to publication bias and less informed clinical decision-making. Qualitative interviews were conducted to understand whether and how industry sponsors of clinical trials of drugs and biologics in Canada influence decisions to report trial results.

METHODS

Participants eligible for an interview included clinical trial investigators and research coordinators with experience in drug research, research ethics board members with at least 1 year of experience in ethical review of trials, research administrators with knowledge of dissemination of clinical trial findings or relations with trial sponsors, and trial participants who had taken part in a drug trial as an adult in the 5 years before their interview. Semi-structured interviews were held in person or by telephone between March 2019 and April 2021 with participants in Alberta, British Columbia, and Ontario, Canada. Qualitative analysis included coding of interview transcripts and identification of key themes.

FINDINGS

Interviews were conducted with 34 participants, including 17 clinical trial investigators, 1 clinical research coordinator, 3 research administrators, 3 research ethics board members, and 10 clinical trial participants. Participants involved in the conduct, administration, or ethical review of trials represented a range of medical disciplines. Interview participant accounts indicated that in some cases, industry sponsors influence whether results are reported. A core theme was that companies have a weaker incentive to publish trials with unfavorable findings and trials for products that they have decided not to develop further. Companies may influence reporting in various ways, including stopping trials early and not reporting results of stopped trials, owning and controlling access to data, and negotiating clinical trial agreements in multicenter trials that do not fully protect the ability of investigators to publish. Internal company trials represent an additional source of unpublished trials. More broadly, the research system creates a dependency on funding from industry sponsors that may weaken the ability of researchers and research institutions to negotiate terms with industry sponsors that would fully protect publication rights.

IMPLICATIONS

Interviews with trial investigators and others connected to trial research indicate that in some cases, industry sponsors of clinical trial research in Canada influence whether results are reported. Policies aiming to bring about full reporting of trials could benefit from considering the commercial incentives of companies and the ways in which industry sponsors may influence clinical trial reporting. Future research could examine the generalizability of these findings to other jurisdictions.

Comparison of Pregnancy Outcomes of Patients Treated With Ondansetron vs Alternative Antiemetic Medications in a Multinational, Population-Based Cohort

IMPORTANCE

Ondansetron is frequently used to treat nausea and vomiting during pregnancy. Although some studies reported important safety signals, few studies have been sufficiently large to assess rare pregnancy outcomes.

OBJECTIVE

To study the association between ondansetron exposure during pregnancy and the risks of spontaneous abortion, stillbirth, and major congenital malformations.

DESIGN, SETTING, AND PARTICIPANTS

This is a cohort study conducted in 3 countries, with a meta-analysis. Participants included women and girls aged 12 to 55 years who experienced spontaneous abortion, induced abortion, stillbirth, or live birth between April 2002 and March 2016, as recorded in administrative data from 5 Canadian provinces (British Columbia, Alberta, Saskatchewan, Manitoba, and Ontario), the US IBM MarketScan Research Databases, and the UK Clinical Practice Research Datalink. The statistical analysis was completed in October 2020.

EXPOSURES

Exposure to ondansetron during pregnancy was compared with exposure to other commonly used antiemetics to minimize confounding by indication.

MAIN OUTCOMES AND MEASURES

The primary outcome was fetal death, defined as either spontaneous abortion or stillbirth. Secondary outcomes were the 2 components of the primary outcome and major congenital malformations identified during the year after a live birth. Adjusted hazard ratios were estimated using Cox proportional hazards models with time-dependent drug exposures and were adjusted using high-dimensional propensity scores. For major congenital malformations, adjusted odds ratios were estimated from logistic models. Site-level results were pooled using random-effects meta-analysis. Sensitivity analyses considered second-line antiemetic exposure and exposure specifically during 4 to 10 weeks of gestation.

RESULTS

Data from 456 963 pregnancies were included in this study of fetal death (249 787 [54.7%] in Canada, 197 913 [43.3%] in the US, and 9263 [2.0%] in the UK; maternal age, ≤24 years, 93 201 patients [20.4%]; 25-29 years, 149 117 patients [32.6%]; 30-34 years, 142 442 patients [31.2%]; and ≥35 years, 72 203 patients [15.8%]). Fetal death occurred in 12 907 (7.9%) of 163 810 pregnancies exposed to ondansetron, and 17 476 (5.7%) of 306 766 pregnancies exposed to other antiemetics. The adjusted hazard ratios were 0.91 (95% CI, 0.67-1.23) for fetal death with time-dependent ondansetron exposure during pregnancy, 0.82 (95% CI, 0.64-1.04) for spontaneous abortion, and 0.97 (95% CI, 0.79-1.20) for stillbirth. For major congenital malformations, the estimated odds ratio was 1.06 (95% CI, 0.91-1.22). Results of sensitivity analyses were generally consistent with those of the primary analyses.

CONCLUSIONS AND RELEVANCE

In this large, multicenter cohort study, there was no association between ondansetron exposure during pregnancy and increased risk of fetal death, spontaneous abortion, stillbirth, or major congenital malformations compared with exposure to other antiemetic drugs.

US Food and Drug Administration Safety Advisories and Reporting to the Adverse Event Reporting System (FAERS)

BACKGROUND

The US Food and Drug Administration (FDA) and other major regulators regularly issue safety advisories about licensed drugs with new adverse effects that have been documented through observational studies, clinical trials, and spontaneously reported adverse drug events.

OBJECTIVE

To assess the possible effects of a representative group of FDA Drug Safety Communications on the reporting of the specific adverse effect featured in the advisory on new cases reported to the FDA Adverse Event Reporting System (FAERS).

METHODS

We examined 16 FDA Drug Safety Communications issued from 2010 to 2015 that had not previously been the focus of advisories from regulators in the UK, Canada, or Australia. We compared the reports of the adverse effect in the 8 calendar quarters preceding the advisory and in the 4 quarters following. We measured change in reporting frequency by calculating the event reporting odds ratio (ROR) for the post-warning compared to the pre-warning periods. We defined a credible association of the advisory with increased reporting as a ROR ≥ 2.0 and p value of < 0.05 by Fisher's Exact Test.

RESULTS

We found statistically significant increased reporting for 4/16 advisories with RORs that ranged from 3.9 to 40.6. Three advisories had smaller but still statistically significant increases that were less than the ROR ≥ 2.0 threshold. For 7 advisories, we found no statistically significant changes in reporting.

CONCLUSIONS

No consistent pattern or effect was found on spontaneous reporting following these safety advisories. After results were available, we observed that some cases with the largest reporting increase also involved substantial numbers of legal claims. Changes in adverse event reporting following a warning need to be evaluated on a case-by-case basis.

Comparative Safety of Smoking Cessation Pharmacotherapies During a Government-Sponsored Reimbursement Program

INTRODUCTION

The British Columbia Ministry of Health launched a Smoking Cessation Program on September 30, 2011, providing financial coverage for smoking cessation pharmacotherapies. Although pharmacotherapies have been shown to have a moderate short-term benefit as a quitting aid, substantial cardiovascular and neuropsychiatric safety concerns have been identified in adverse-reporting databases, leading to prescription label warnings by Health Canada and the U.S. Food and Drug Administration. However, recent studies indicate these warnings may be without merit. This study examined the comparative safety of medications commonly used to aid smoking cessation.

AIMS AND METHODS

Population-based retrospective cohort study using B.C. administrative data to assess the relative safety between varenicline, bupropion, and nicotine replacement therapies (NRTs). The primary outcome was a composite of cardiovascular hospitalizations. Secondary outcomes included mortality, a composite of neuropsychiatric hospitalizations, and individual components of the primary outcome. Statistical analysis used propensity score-adjusted log-binomial regression models. A sensitivity analysis excluded patients with a history of cardiovascular disease.

RESULTS

The study included 116 442 participants. Compared with NRT, varenicline was associated with a 10% 1-year relative risk decrease of cardiovascular hospitalization (adjusted risk ratio [RR] = 0.90, 95% confidence interval (CI): 0.82 to 1.00), a 20% 1-year relative risk decrease of neuropsychiatric hospitalization (RR: 0.80, CI: 0.7 to 0.89), and a 19% 1-year relative risk decrease of mortality (RR: 0.81, CI: 0.71 to 0.93). We found no significant association between NRT and bupropion for cardiovascular hospitalizations, neuropsychiatric hospitalizations, or mortality.

CONCLUSIONS

Compared with NRT, varenicline is associated with fewer serious adverse events and bupropion the same number of serious adverse events.

IMPLICATIONS

This study addresses the need for comparative safety evidence in a real-world setting of varenicline and bupropion against an active comparator. Compared with NRT, varenicline was associated with a decreased risk of mortality, serious cardiovascular events, and neuropsychiatric events during the treatment, or shortly after the treatment, in the general population of adults seeking pharmacotherapy to aid smoking cessation. These results provide support for the removal of the varenicline boxed warning for neuropsychiatric events and add substantively to the cardiovascular safety findings of previous observational studies and randomized clinical trials.

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.

Sodium glucose cotransporter 2 inhibitors and risk of major adverse cardiovascular events: multi-database retrospective cohort study

OBJECTIVE

To compare the risk of cardiovascular events between sodium glucose cotransporter 2 (SGLT2) inhibitors and dipeptidyl peptidase-4 (DPP-4) inhibitors among people with type 2 diabetes in a real world context of clinical practice.

DESIGN

Multi-database retrospective cohort study using a prevalent new user design with subsequent meta-analysis.

SETTING

Canadian Network for Observational Drug Effect Studies (CNODES), with administrative healthcare databases from seven Canadian provinces and the United Kingdom, 2013-18.

POPULATION

209 867 new users of a SGLT2 inhibitor matched to 209 867 users of a DPP-4 inhibitor on time conditional propensity score and followed for a mean of 0.9 years.

MAIN OUTCOME MEASURES

The primary outcome was major adverse cardiovascular events (MACE, a composite of myocardial infarction, ischaemic stroke, or cardiovascular death). Secondary outcomes were the individual components of MACE, heart failure, and all cause mortality. Cox proportional hazards models were used to estimate site specific adjusted hazards ratios and 95% confidence intervals, comparing use of SGLT2 inhibitors with use of DPP-4 inhibitors in an as treated approach. Site specific results were pooled using random effects meta-analysis.

RESULTS

Compared with DPP-4 inhibitors, SGLT2 inhibitors were associated with decreased risks of MACE (incidence rate per 1000 person years: 11.4 v 16.5; hazard ratio 0.76, 95% confidence interval 0.69 to 0.84), myocardial infarction (5.1 v 6.4; 0.82, 0.70 to 0.96), cardiovascular death (3.9 v 7.7; 0.60, 0.54 to 0.67), heart failure (3.1 v 7.7; 0.43, 0.37 to 0.51), and all cause mortality (8.7 v 17.3; 0.60, 0.54 to 0.67). SGLT2 inhibitors had more modest benefits for ischaemic stroke (2.6 v 3.5; 0.85, 0.72 to 1.01). Similar benefits for MACE were observed with canagliflozin (0.79, 0.66 to 0.94), dapagliflozin (0.73, 0.63 to 0.85), and empagliflozin (0.77, 0.68 to 0.87).

CONCLUSIONS

In this large observational study conducted in a real world clinical practice context, the short term use of SGLT2 inhibitors was associated with a decreased risk of cardiovascular events compared with the use of DPP-4 inhibitors.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03939624.

Cardiovascular and neuropsychiatric safety of smoking cessation pharmacotherapies in non-depressed adults: a retrospective cohort study

BACKGROUND AND AIMS

Pharmacotherapies for smoking cessation are widely prescribed, despite substantial concerns being raised regarding the potential increased risk of cardiovascular (CV) and neuropsychiatric adverse events associated with these treatments. This study aimed to assess the relative CV and neuropsychiatric safety between varenicline and bupropion compared with nicotine replacement therapies (NRT) in adults without a recent history of depression.

DESIGN

Retrospective new-user cohort study.

SETTING

US administrative data from 2006 to 2016 covering more than 100 million individuals.

PARTICIPANTS

Three study cohorts of new users, aged 18 years or older, limited to patients with no diagnosis or treatment for depression in the prior 12 months.

MEASUREMENTS

Propensity score adjusted log-binomial regression models. The primary outcome was a composite of hospitalized CV events. Secondary outcomes included a composite of hospitalized neuropsychiatric events and individual components of the primary outcome.

FINDINGS

A total of 618 497 participants were included in our study cohorts. Compared with NRT (n = 32 237), varenicline (n = 454 698) was associated with a 20% lower 1-year CV risk [adjusted relative risk (RR) = 0.80, 95% confidence interval (CI) = 0.75-0.85], and bupropion (n = 131 562) was associated with a 25% lower 1-year CV risk (RR = 0.75, 95% CI = 0.69-0.81). Varenicline was associated with a 35% lower 1-year risk of neuropsychiatric hospitalization versus NRT (RR = 0.65, 95% CI = 0.59-0.72), and bupropion was associated with a 21% increase in 1-year risk of neuropsychiatric hospitalization (RR = 1.21, 95% CI = 1.09-1.35).

CONCLUSION

Varenicline compared with nicotine replacement therapy does not appear to be associated with an increased risk of cardiovascular or neuropsychiatric hospitalizations. Bupropion appears to be associated with a lower risk of cardiovascular hospitalization and a higher risk of neuropsychiatric hospitalization, compared with nicotine replacement therapy.

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.

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.

Identifying sequential episodes of pharmacotherapy as a method for assessing treatment failure in comparative effectiveness research

PURPOSE

To describe and implement a novel method of measuring comparative effectiveness using sequential episodes of pharmacotherapy as a proxy for treatment failure.

METHODS

Retrospective cohort study using linked deidentified data from the British Columbia Ministry of Health during a government-sponsored smoking cessation reimbursement program.Three study cohorts were created based on first use of varenicline, bupropion, or nicotine replacement therapy (NRT), for adults aged 18 or older, in the period September 30th, 2011 to March 31st, 2013. The study cohorts were analyzed for sequential episodes of pharmacotherapy, defined as re-initiating a smoking cessation pharmacotherapy after an initial episode of treatment and washout period. The statistical analysis used propensity score adjusted log-binomial regression models with one-year and two-year fixed follow-up after a 12-week washout period. A sensitivity analysis excluded the washout period. A secondary analysis investigated predictors of receiving a sequential episode of smoking cessation pharmacotherapy RESULTS: 116,442 participants of the B.C. Smoking Cessation Program were analyzed. Compared to NRT, varenicline users were 13% less likely, and bupropion users were 18% less likely, to re-start smoking cessation therapy within 1-year after an initial course of treatment.

CONCLUSIONS

Sequential episodes of pharmacotherapy identified treatment failures to smoking cessation therapy. Based on sequential episodes of pharmacotherapy during a drug benefit policy of smoking cessation medications, varenicline and bupropion were more effective aids to smoking cessation than NRT. The method was also used to identify patient characteristics associated with treatment effectiveness.

Comparison of cholinesterase inhibitor safety in real-world practice

Introduction

Cholinesterase inhibitors (ChEIs) are widely used to treat mild to moderate Alzheimer's disease and related dementia. Clinical trials have focused on placebo comparisons, inadequately addressing within-class comparative safety.

Methods

New users of ChEIs in British Columbia were categorized into five study cohorts: low-dose donepezil, high-dose donepezil, galantamine, rivastigmine patch, and oral rivastigmine. Comparative safety of ChEIs assessed hazard ratios using propensity score adjusted Cox regression.

Results

Compared with low-dose donepezil, galantamine use was associated with a lower risk of mortality (adjusted hazard ratio: 0.84, 95% confidence interval: 0.60–1.18), cardiovascular serious adverse events (adjusted hazard ratio: 0.78, 95% confidence interval: 0.62–0.98), and entry into a residential care facility (adjusted hazard ratio: 0.72, 95% confidence interval: 0.59–0.89).

Discussion

Given the absence of randomized trial data showing clinically meaningful benefit of ChEI therapy in Alzheimer's disease, our study suggests preferential use of galantamine may at least be associated with fewer adverse events than treatment with donepezil or rivastigmine.

•

Galantamine was associated with fewer adverse events than donepezil or rivastigmine.

•

Galantamine users experienced longer independent living.

•

The 3-year risk of cardiovascular events and mortality was lowest with galantamine.

Multiple imputation for systematically missing confounders within a distributed data drug safety network: A simulation study and real-world example

PURPOSE

In distributed data networks, some data sites may be systematically missing important confounders that are captured by other sites in the network (eg, body mass index [BMI]). Multiple imputation may help repair bias in these scenarios. However, multiple imputation has not been described for distributed data networks where data access restrictions prevent centralized analysis.

METHODS

We conducted a simulation study and a real-world analysis using the UK's Clinical Practice Research Datalink to evaluate multiple imputation for confounders that are systematically missing from a subset of data sites in mock distributed data networks. The simulation study addressed univariate missing data, while the real-world analysis addressed multivariate missing data. Both studies were designed as retrospective cohort studies of the effect of current statin use on the risk of myocardial infarction among patients with newly treated type 2 diabetes.

RESULTS

In our simulation study, multiple imputation repaired bias from missing BMI in all scenarios, with a median bias reduction of 118% in the default scenario. In our real-world study, the multiply imputed analysis (hazard ratio [HR]: 0.86; 95% confidence interval [CI], 0.69-1.08) was closer to the analysis that considered the true confounder values (HR: 0.85; 95% CI, 0.66-1.10) than the analysis that ignored them (HR: 0.93; 95% CI, 0.73-1.20).

CONCLUSIONS

Multiple imputation adapted to distributed data settings is a feasible method to reduce bias from unmeasured but measurable confounders when at least one database contains the variables of interest. Further research is needed to evaluate its validity in real distributed data networks.

A population-based analysis of antidiabetic medications in four Canadian provinces: Secular trends and prescribing patterns

PURPOSE

To use the Canadian Network for Observational Drug Effect Studies (CNODES) to describe drug utilization of antidiabetic medications in four Canadian provinces.

METHODS

With the use of data from CNODES, we constructed cohorts of patients with type 2 diabetes in four Canadian provinces (Manitoba, Ontario, Quebec, and Saskatchewan) who received their first-ever prescription for a noninsulin antidiabetic medication during the study period, defined as the earliest date of data availability in each province (range: 1993-1998) to the latest date of the data extraction in each province (range: 2013-2014). Prescriptions rates were calculated for all prescriptions by class and described over time.

RESULTS

Across provinces, we identified 650 830 patients who initiated antidiabetic medications during the study period. In most provinces, the overall prescription rate of antidiabetic medications increased during the last two decades. Metformin particularly increased in popularity, surpassing sulfonylureas in all provinces as the most widely prescribed antidiabetic medication by the early 2000s. Thiazolidinediones grew in popularity from the onset of their availability until 2006 to 2007, at which point they rapidly declined. Dipeptidyl peptidase-4 inhibitors saw substantial growth in several provinces following their addition to provincial formularies in 2008 to 2012, while glucagon-like peptide-1 agonists experienced modest growth. Insulin prescription rates remained constant or steadily increased over the last two decades.

CONCLUSIONS

CNODES can be used for cross-jurisdictional drug utilization studies. In Canada, trends in antidiabetic medication prescriptions followed changing guidelines reflecting up-to-date knowledge of drug effectiveness and safety.

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.

Influence of opioid prescribing standards on drug use among patients with long-term opioid use: a longitudinal cohort study

BACKGROUND

In mid-2016, the College of Physicians and Surgeons of British Columbia (CPSBC) issued prescribing standards and guidelines relating to opioid drugs. We evaluated the impact of these regulatory standards and guidelines on prescription drug use among patients in the province with long-term opioid use.

METHODS

We conducted a cohort study with monthly repeated measures using administrative health data in British Columbia. Patients with long-term prescription opioid use were followed for a 12-month prepolicy period and 10-month postpolicy period, and were compared with a historical control cohort. We excluded patients with a history of long-term care, palliative care or cancer. We estimated changes in use of opioids, high-dose opioids (> 90 mg of morphine equivalents/d), opioids with sedatives/hypnotics, and opioid discontinuation.

RESULTS

The study population included 68 113 patients in the policy cohort and 68 429 patients in the historical control cohort. Following the introduction of the standards and guidelines, the average monthly use of opioids declined (adjusted difference -57 mg of morphine equivalents, 95% confidence interval [CI] -74 to -39) and discontinuation of opioids increased (odds ratio [OR] 1.24, 95% CI 1.16 to 1.32). Among patients prescribed high-dose opioids, switching to lower-dose opioids increased (OR 1.88, 95% CI 1.63 to 2.17), but discontinuation did not change significantly (OR 1.21, 95% CI 0.91 to 1.59).

INTERPRETATION

The CPSBC's regulatory standards and guidelines were associated with modestly reduced opioid use and increased switching from high-dose to lower-dose opioids among patients with long-term use of prescribed opioids. Assessment of the potential impacts on health outcomes will be necessary for understanding the implications of the standards and guidelines.

Outcomes associated with hospital admissions for accidental opioid overdose in British Columbia: a retrospective cohort study

OBJECTIVES

To study the association between accidental opioid overdose and neurological, respiratory, cardiac and other serious adverse events and whether risk of these adverse events was elevated during hospital readmissions compared with initial admissions.

DESIGN

Retrospective cohort study.

SETTING

Population-based study using linked administrative data in British Columbia, Canada.

PARTICIPANTS

The primary analysis included 2433 patients with 2554 admissions for accidental opioid overdose between 2006 and 2015, including 121 readmissions within 1 year of initial admission. The secondary analysis included 538 patients discharged following a total of 552 accidental opioid overdose hospitalizations and 11 040 matched controls from a cohort of patients with ≥180 days of prescription opioid use.

OUTCOME MEASURES

The primary outcome was encephalopathy; secondary outcomes were adult respiratory distress syndrome, respiratory failure, pulmonary haemorrhage, aspiration pneumonia, cardiac arrest, ventricular arrhythmia, heart failure, rhabdomyolysis, paraplegia or tetraplegia, acute renal failure, death, a composite outcome of encephalopathy or any secondary outcome and total serious adverse events (all-cause hospitalisation or death). We analysed these outcomes using generalised linear models with a logistic link function.

RESULTS

3% of accidental opioid overdose admissions included encephalopathy and 25% included one or more adverse events (composite outcome). We found no evidence of increased risk of encephalopathy (OR 0.57; 95% CI 0.13 to 2.49) or other outcomes during readmissions versus initial admissions. In the secondary analysis, <5 patients in each cohort experienced encephalopathy. Risk of the composite outcome (OR 2.15; 95% CI 1.48 to 3.12) and all-cause mortality (OR 2.13; 95% CI 1.18 to 3.86) were higher for patients in the year following overdose relative to controls.

CONCLUSIONS

We found no evidence that risk of encephalopathy or other adverse events was higher in readmissions compared with initial admissions for accidental opioid overdose. Risk of serious morbidity and mortality may be elevated in the year following an accidental opioid overdose.

Tramadol and the risk of seizure: nested case-control study of US patients with employer-sponsored health benefits

OBJECTIVES

Tramadol is a widely prescribed analgesic that influences both opioid and monoamine neurotransmission. While seizures have been reported with its use, the risk in clinical practice has not been well characterised. We examined risk of seizure with tramadol relative to codeine, a comparable opioid analgesic.

DESIGN

Retrospective nested case-control study. For each case, we identified up to 10 controls matched on age, sex, US state of residence and date of cohort entry (±365 days). We calculated ORs to determine the association between seizure and exposure to tramadol, codeine (≥15 mg), both or neither, in the preceding 30 days.

SETTING

Cohort of patients, who had continuous health coverage and resided in the same state for≥3 years, identified from linked administrative health data in US MarketScan databases from 2009 to 2012.

PARTICIPANTS

We identified 96 753 patients with seizure and 888 540 matched controls.

PRIMARY AND SECONDARY OUTCOME MEASURES

In the primary analysis, we defined cases using a broad definition of seizure (based on either an outpatient physician claim for seizure disorder or a seizure-related emergency department visit or hospitalisation). In a secondary analysis, we used a more specific definition of seizure restricted to a hospital visit with a principal diagnosis of seizure.

RESULTS

In the primary analysis, we found no association between risk of seizure and exposure to tramadol compared with codeine (OR 1.03, 95% CI 0.93 to 1.15). However, in the secondary analysis (using a more specific definition of seizure), this association was statistically significant (OR 1.41, 95% CI 1.11 to 1.79).

CONCLUSIONS

Tramadol was not associated with an increased risk of seizure defined by inpatient and outpatient diagnoses. However, this finding was sensitive to the outcome definition used and requires further study.

Measuring the impact of pharmacoepidemiologic research using altmetrics: A case study of a CNODES drug-safety article

Purpose

To provide an overview of altmetrics, including their potential benefits and limitations, how they may be obtained, and their role in assessing pharmacoepidemiologic research impact.

Methods

Our review was informed by compiling relevant literature identified through searching multiple health research databases (PubMed, Embase, and CIHNAHL) and grey literature sources (websites, blogs, and reports). We demonstrate how pharmacoepidemiologists, in particular, may use altmetrics to understand scholarly impact and knowledge translation by providing a case study of a drug‐safety study conducted by the Canadian Network of Observational Drug Effect Studies.

Results

A common approach to measuring research impact is the use of citation‐based metrics, such as an article's citation count or a journal's impact factor. “Alternative” metrics, or altmetrics, are increasingly supported as a complementary measure of research uptake in the age of social media. Altmetrics are nontraditional indicators that capture a diverse set of traceable, online research‐related artifacts including peer‐reviewed publications and other research outputs (software, datasets, blogs, videos, posters, policy documents, presentations, social media posts, wiki entries, etc).

Conclusion

Compared with traditional citation‐based metrics, altmetrics take a more holistic view of research impact, attempting to capture the activity and engagement of both scholarly and nonscholarly communities. Despite the limited theoretical underpinnings, possible commercial influence, potential for gaming and manipulation, and numerous data quality‐related issues, altmetrics are promising as a supplement to more traditional citation‐based metrics because they can ingest and process a larger set of data points related to the flow and reach of scholarly communication from an expanded pool of stakeholders. Unlike citation‐based metrics, altmetrics are not inherently rooted in the research publication process, which includes peer review; it is unclear to what extent they should be used for research evaluation.

Comparative safety of direct oral anticoagulants and warfarin in venous thromboembolism: multicentre, population based, observational study

Objective To determine the safety of direct oral anticoagulant (DOAC) use compared with warfarin use for the treatment of venous thromboembolism.Design Retrospective matched cohort study conducted between 1 January 2009 and 31 March 2016.Setting Community based, using healthcare data from six jurisdictions in Canada and the United States.Participants 59 525 adults (12 489 DOAC users; 47 036 warfarin users) with a new diagnosis of venous thromboembolism and a prescription for a DOAC or warfarin within 30 days of diagnosis.Main outcome measures Outcomes included hospital admission or emergency department visit for major bleeding and all cause mortality within 90 days after starting treatment. Propensity score matching and shared frailty models were used to estimate adjusted hazard ratios of the outcomes comparing DOACs with warfarin. Analyses were conducted independently at each site, with meta-analytical methods used to estimate pooled hazard ratios across sites.Results Of the 59 525 participants, 1967 (3.3%) had a major bleed and 1029 (1.7%) died over a mean follow-up of 85.2 days. The risk of major bleeding was similar for DOAC compared with warfarin use (pooled hazard ratio 0.92, 95% confidence interval 0.82 to 1.03), with the overall direction of the association favouring DOAC use. No difference was found in the risk of death (pooled hazard ratio 0.99, 0.84 to 1.16) for DOACs compared with warfarin use. There was no evidence of heterogeneity across centres, between patients with and without chronic kidney disease, across age groups, or between male and female patients.Conclusions In this analysis of adults with incident venous thromboembolism, treatment with DOACs, compared with warfarin, was not associated with an increased risk of major bleeding or all cause mortality in the first 90 days of treatment.Trial registration Clinical trials NCT02833987.

Heterogeneity in Comparisons of Discontinuation of Tumor Necrosis Factor Antagonists in Rheumatoid Arthritis - A Meta-Analysis

Objective

We did a systematic review of studies comparing discontinuation of tumor necrosis factor alpha (TNF) antagonists in rheumatoid arthritis (RA) patients, pooled hazard ratios and assessed clinical and methodological heterogeneity.

Methods

We searched MEDLINE and EMBASE until June 2015 for pairwise hazard ratios for discontinuing infliximab, etanercept, and adalimumab from cohorts of RA patients. Hazard ratios were pooled using inverse variance weighting and random effects estimates of the combined hazard ratio were obtained. Clinical and methodological heterogeneity was assessed using the between-subgroup I-square statistics and meta-regression.

Results

Twenty-four unique studies were eligible and large heterogeneity (I-square statistics > 50%) was observed in all comparisons. Type of data, location, and order of treatment (first or second line) modified the magnitude and direction of discontinuation comparing infliximab with either adalimumab or etanercept; however, some heterogeneity remained. No effect modifier was identified when adalimumab and etanercept were compared.

Conclusion

Heterogeneity in studies comparing discontinuation of TNF antagonists in RA is partially explained by type of data, location, and order of treatment. Pooling hazard ratios for discontinuing TNF antagonists is inappropriate because largely unexplained heterogeneity was demonstrated when random effect estimates were calculated.

Association Between Incretin-Based Drugs and the Risk of Acute Pancreatitis

IMPORTANCE

The association between incretin-based drugs, such as dipeptidyl peptidase 4 (DPP-4) inhibitors and glucagon-like peptide 1 (GLP-1) agonists, and acute pancreatitis is controversial.

OBJECTIVE

To determine whether the use of incretin-based drugs, compared with the use of 2 or more other oral antidiabetic drugs, is associated with an increased risk of acute pancreatitis.

DESIGN, SETTING, AND PARTICIPANTS

A large, international, multicenter, population-based cohort study was conducted using combined health records from 7 participating sites in Canada, the United States, and the United Kingdom. An overall cohort of 1 532 513 patients with type 2 diabetes initiating the use of antidiabetic drugs between January 1, 2007, and June 30, 2013, was included, with follow-up until June 30, 2014.

EXPOSURES

Current use of incretin-based drugs compared with current use of at least 2 oral antidiabetic drugs.

MAIN OUTCOMES AND MEASURES

Nested case-control analyses were conducted including hospitalized patients with acute pancreatitis matched with up to 20 controls on sex, age, cohort entry date, duration of treated diabetes, and follow-up duration. Hazard ratios (HRs) and 95% CIs for hospitalized acute pancreatitis were estimated and compared current use of incretin-based drugs with current use of 2 or more oral antidiabetic drugs. Secondary analyses were performed to assess whether the risk varied by class of drug (DPP-4 inhibitors and GLP-1 agonists) or by duration of use. Site-specific HRs were pooled using random-effects models.

RESULTS

Of 1 532 513 patients included in the analysis, 781 567 (51.0%) were male; mean age was 56.6 years. During 3 464 659 person-years of follow-up, 5165 patients were hospitalized for acute pancreatitis (incidence rate, 1.49 per 1000 person-years). Compared with current use of 2 or more oral antidiabetic drugs, current use of incretin-based drugs was not associated with an increased risk of acute pancreatitis (pooled adjusted HR, 1.03; 95% CI, 0.87-1.22). Similarly, the risk did not vary by drug class (DPP-4 inhibitors: pooled adjusted HR, 1.09; 95% CI, 0.86-1.22; GLP-1 agonists: pooled adjusted HR, 1.04; 95% CI, 0.81-1.35) and there was no evidence of a duration-response association.

CONCLUSIONS AND RELEVANCE

In this large population-based study, use of incretin-based drugs was not associated with an increased risk of acute pancreatitis compared with other oral antidiabetic drugs.

Observational Studies of Drug Safety in Multi-Database Studies: Methodological Challenges and Opportunities

INTRODUCTION/OBJECTIVE

The Canadian Network for Observational Drug Effect Studies (CNODES), a network of researchers and databases, is a collaborating center of the Drug Safety and Effectiveness Network. CNODES' main mandate is to conduct observational studies of drug safety based on queries developed and submitted by Health Canada and other federal, provincial, and territorial stakeholders. Through a case study we explore several methodological opportunities and challenges that arise in distributed pharmacoepidemiology networks.

CASE STUDY

We use as a case study a study of proton pump inhibitors and hospitalization for community-acquired pneumonia. Challenges arise in the design and conduct of studies at individual sites, and then with processes and methods for combining data. On the other hand, distributed networks provide opportunities, such as the ability to detect and understand heterogeneity, in sample sizes that would typically be impossible for a single study.

CONCLUSIONS

Networks such as CNODES provide the opportunity to detect and quantify important safety signals from administrative data, and provide many challenges for methods research in pharmacoepidemiology using distributed data. As networks increase in size and scope of research questions, the need for methodological developments should continue to grow.

A Multicenter Observational Study of Incretin-based Drugs and Heart Failure

BACKGROUND

There is concern that antidiabetic incretin-based drugs, including dipeptidyl peptidase 4 (DPP-4) inhibitors and glucagon-like peptide 1 (GLP-1) analogues, can increase the risk of heart failure. Ongoing clinical trials may not have large enough samples to effectively address this issue.

METHODS

We applied a common protocol in the analysis of multiple cohorts of patients with diabetes. We used health care data from four Canadian provinces, the United States, and the United Kingdom. With the use of a nested case-control analysis, we matched each patient who was hospitalized for heart failure with up to 20 controls from the same cohort; matching was based on sex, age, cohort-entry date, duration of treated diabetes, and follow-up time. Cohort-specific hazard ratios for hospitalization due to heart failure among patients receiving incretin-based drugs, as compared with those receiving oral antidiabetic-drug combinations, were estimated by means of conditional logistic regression and pooled across cohorts with the use of random-effects models.

RESULTS

The cohorts included a total of 1,499,650 patients, with 29,741 hospitalized for heart failure (incidence rate, 9.2 events per 1000 persons per year). The rate of hospitalization for heart failure did not increase with the use of incretin-based drugs as compared with oral antidiabetic-drug combinations among patients with a history of heart failure (hazard ratio, 0.86; 95% confidence interval [CI], 0.62 to 1.19) or among those without a history of heart failure (hazard ratio, 0.82; 95% CI, 0.67 to 1.00). The results were similar for DPP-4 inhibitors and GLP-1 analogues.

CONCLUSIONS

In this analysis of data from large cohorts of patients with diabetes, incretin-based drugs were not associated with an increased risk of hospitalization for heart failure, as compared with commonly used combinations of oral antidiabetic drugs. (Funded by the Canadian Institutes of Health Research; ClinicalTrials.gov number, NCT02456428.).

Head to head comparison of the propensity score and the high-dimensional propensity score matching methods

BACKGROUND

Comparative performance of the traditional propensity score (PS) and high-dimensional propensity score (hdPS) methods in the adjustment for confounding by indication remains unclear. We aimed to identify which method provided the best adjustment for confounding by indication within the context of the risk of diabetes among patients exposed to moderate versus high potency statins.

METHOD

A cohort of diabetes-free incident statins users was identified from the Quebec's publicly funded medico-administrative database (Full Cohort). We created two matched sub-cohorts by matching one patient initiated on a lower potency to one patient initiated on a high potency either on patients' PS or hdPS. Both methods' performance were compared by means of the absolute standardized differences (ASDD) regarding relevant characteristics and by means of the obtained measures of association.

RESULTS

Eight out of the 18 examined characteristics were shown to be unbalanced within the Full Cohort. Although matching on either method achieved balance within all examined characteristic, matching on patients' hdPS created the most balanced sub-cohort. Measures of associations and confidence intervals obtained within the two matched sub-cohorts overlapped.

CONCLUSION

Although ASDD suggest better matching with hdPS than with PS, measures of association were almost identical when adjusted for either method. Use of the hdPS method in adjusting for confounding by indication within future studies should be recommended due to its ability to identify confounding variables which may be unknown to the investigators.

Incretin based drugs and the risk of pancreatic cancer: international multicentre cohort study

OBJECTIVE

To determine whether the use of incretin based drugs compared with sulfonylureas is associated with an increased risk of incident pancreatic cancer in people with type 2 diabetes.

DESIGN

Population based cohort.

SETTING

Large, international, multicentre study combining the health records from six participating sites in Canada, the United States, and the United Kingdom.

PARTICIPANTS

A cohort of 972,384 patients initiating antidiabetic drugs between 1 January 2007 and 30 June 2013, with follow-up until 30 June 2014.

MAIN OUTCOME MEASURES

Within each cohort we conducted nested case-control analyses, where incident cases of pancreatic cancer were matched with up to 20 controls on sex, age, cohort entry date, duration of treated diabetes, and duration of follow-up. Hazard ratios and 95% confidence intervals for incident pancreatic cancer were estimated, comparing use of incretin based drugs with use of sulfonylureas, with drug use lagged by one year for latency purposes. Secondary analyses assessed whether the risk varied by class (dipeptidyl peptidase-4 inhibitors and glucagon-like peptide-1 receptor agonists) or by duration of use (cumulative duration of use and time since treatment initiation). Site specific hazard ratios were pooled using random effects models.

RESULTS

During 2,024,441 person years of follow-up (median follow-up ranging from 1.3 to 2.8 years; maximum 8 years), 1221 patients were newly diagnosed as having pancreatic cancer (incidence rate 0.60 per 1000 person years). Compared with sulfonylureas, incretin based drugs were not associated with an increased risk of pancreatic cancer (pooled adjusted hazard ratio 1.02, 95% confidence interval 0.84 to 1.23). Similarly, the risk did not vary by class and evidence of a duration-response relation was lacking.

CONCLUSIONS

In this large, population based study the use of incretin based drugs was not associated with an increased risk of pancreatic cancer compared with sulfonylureas. Although this potential adverse drug reaction will need to be monitored long term owing to the latency of the cancer, these findings provide some reassurance on the safety of incretin based drugs.

Network meta-analysis incorporating randomized controlled trials and non-randomized comparative cohort studies for assessing the safety and effectiveness of medical treatments: challenges and opportunities

Network meta-analysis is increasingly used to allow comparison of multiple treatment alternatives simultaneously, some of which may not have been compared directly in primary research studies. The majority of network meta-analyses published to date have incorporated data from randomized controlled trials (RCTs) only; however, inclusion of non-randomized studies may sometimes be considered. Non-randomized studies can complement RCTs or address some of their limitations, such as short follow-up time, small sample size, highly selected population, high cost, and ethical restrictions. In this paper, we discuss the challenges and opportunities of incorporating both RCTs and non-randomized comparative cohort studies into network meta-analysis for assessing the safety and effectiveness of medical treatments. Non-randomized studies with inadequate control of biases such as confounding may threaten the validity of the entire network meta-analysis. Therefore, identification and inclusion of non-randomized studies must balance their strengths with their limitations. Inclusion of both RCTs and non-randomized studies in network meta-analysis will likely increase in the future due to the growing need to assess multiple treatments simultaneously, the availability of higher quality non-randomized data and more valid methods, and the increased use of progressive licensing and product listing agreements requiring collection of data over the life cycle of medical products. Inappropriate inclusion of non-randomized studies could perpetuate the biases that are unknown, unmeasured, or uncontrolled. However, thoughtful integration of randomized and non-randomized studies may offer opportunities to provide more timely, comprehensive, and generalizable evidence about the comparative safety and effectiveness of medical treatments.

Serotonin-Norepinephrine Reuptake Inhibitors and the Risk of AKI: A Cohort Study of Eight Administrative Databases and Meta-Analysis

BACKGROUND AND OBJECTIVES

A safety signal regarding cases of AKI after exposure to serotonin-norepinephrine reuptake inhibitors (SNRIs) was identified by Health Canada. Therefore, this study assessed whether the use of SNRIs increases the risk of AKI compared with selective serotonin reuptake inhibitors (SSRIs) and examined the risk associated with each individual SNRI.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Multiple retrospective population-based cohort studies were conducted within eight administrative databases from Canada, the United States, and the United Kingdom between January 1997 and March 2010. Within each cohort, a nested case-control analysis was performed to estimate incidence rate ratios (RRs) of AKI associated with SNRIs compared with SSRIs using conditional logistic regression, with adjustment for high-dimensional propensity scores. The overall effect across sites was estimated using meta-analytic methods.

RESULTS

There were 38,974 cases of AKI matched to 384,034 controls. Current use of SNRIs was not associated with a higher risk of AKI compared with SSRIs (fixed-effect RR, 0.97; 95% confidence interval [95% CI], 0.94 to 1.01). Current use of venlafaxine and desvenlafaxine considered together was not associated with a higher risk of AKI (RR, 0.96; 95% CI, 0.92 to 1.00). For current use of duloxetine, there was significant heterogeneity among site-specific estimates such that a random-effects meta-analysis was performed showing a 16% higher risk, although this risk was not statistically significant (RR, 1.16; 95% CI, 0.96 to 1.40). This result is compatible with residual confounding, because there was a substantial imbalance in the prevalence of diabetes between users of duloxetine and users of others SNRIs or SSRIs. After further adjustment by including diabetes as a covariate in the model along with propensity scores, the fixed-effect RR was 1.02 (95% CI, 0.95 to 1.10).

CONCLUSIONS

There is no evidence that use of SNRIs is associated with a higher risk of hospitalization for AKI compared with SSRIs.

Seasonal effects on the occurrence of nocturnal leg cramps: a prospective cohort study

BACKGROUND

It has been anecdotally reported that nocturnal leg cramps in pregnant women are worse in summer. We analyzed population-level data to determine whether the symptom burden of nocturnal leg cramps is seasonal in the general population.

METHODS

We examined time-series data for 2 independent measures of the symptom burden of leg cramps: (a) new quinine prescriptions (reflecting new or escalating treatment of leg cramps) from December 2001 to October 2007 among adults aged 50 years and older, which were obtained from linked health care databases that contain the prescribing information for the 4.2 million residents of British Columbia, Canada; and (b) the Internet search volume from February 2004 to March 2012 for the term "leg cramps" (reflecting public interest), which we obtained from Google Trends data and geographically limited to the United States and Australia. We assessed seasonality by determining how well a least-squares sinusoidal model predicted variability in the outcomes.

RESULTS

New quinine prescriptions and Internet searches related to leg cramps were both seasonal, with highs in mid-summer and lows in mid-winter, and a peak-to-peak variability that was about two-thirds of the mean. Seasonality accounted for 88% of the observed monthly variability in new quinine prescriptions (p < 0.001) and 70% of the observed variability in Internet searches related to leg cramps (p < 0.001).

INTERPRETATION

New quinine prescriptions and Internet searches related to leg cramps were seasonal and roughly doubled between the winter lows and summer highs. Why a disorder of peripheral motor neurons displays such strong seasonality warrants exploration.

Prescriber preference for a particular tumour necrosis factor antagonist drug and treatment discontinuation: population-based cohort

OBJECTIVE

To assess the effect of physician preference for a particular tumour necrosis factor α (TNF) antagonist on the risk of treatment discontinuation in rheumatoid arthritis.

DESIGN

Population-based cohort study.

SETTING

British Columbia administrative health data (inpatients, outpatients and pharmacy).

PARTICIPANTS

2742 British Columbia residents who initiated a first course of a TNF antagonist between 2001 and December 2008, had been diagnosed with rheumatoid arthritis, and were treated by 1 of 58 medium-volume to high-volume prescribers.

INDEPENDENT VARIABLE

A level of physician preference for the drug (higher or lower) was assigned based on preceding prescribing records of the care-providing physician. Higher preference was defined as at least 60% of TNF antagonist courses initiated in the preceding year. Sensitivity analysis was conducted with different thresholds for higher preference.

MAIN OUTCOME MEASURE

Drug discontinuation was defined as a drug-free interval of 180 days or switching to another TNF antagonist, anakinra, rituximab or abatacept. The risk of discontinuation was compared between different levels of physician preference using survival analysis.

RESULTS

Higher preference for the prescribed TNF antagonist was associated with improved persistence with the drug (4.28 years (95% CI 3.70 to 4.90) vs 3.27 (2.84 to 3.84), with log rank test p value of 0.017). The adjusted HR for discontinuation was significantly lower in courses of drugs with higher preference (0.85 (0.76 to 0.96)). The results were robust in a sensitivity analysis.

CONCLUSIONS

Higher physician preference was associated with decreased risk of discontinuing TNF antagonists in patients with rheumatoid arthritis. This finding suggests that physicians who strongly prefer a specific treatment help their patients to stay on treatment for a longer duration. Similar research on other treatments is warranted.