Claims Data Studies of Direct Oral Anticoagulants Can Achieve Balance in Important Clinical Parameters Only Observable in Electronic Health Records

Use of Linked Databases for Improved Confounding Control: Considerations for Potential Selection Bias

Pharmacoepidemiologic studies are increasingly conducted within linked databases, often to obtain richer confounder data. However, the potential for selection bias is frequently overlooked when linked data is available only for a subset of patients. We highlight the importance of accounting for potential selection bias by evaluating the association between antipsychotics and type 2 diabetes in youths within a claims database linked to a smaller laboratory database. We used inverse probability of treatment weights (IPTW) to control for confounding. In analyses restricted to the linked cohorts, we applied inverse probability of selection weights (IPSW) to create a population representative of the full cohort. We used pooled logistic regression weighted by IPTW only or IPTW and IPSW to estimate treatment effects. Metabolic conditions were more prevalent in linked cohorts compared with the full cohort. Within the full cohort, the confounding-adjusted hazard ratio was 2.26 (95% CI: 2.07, 2.49) comparing initiation of antipsychotics with initiation of control medications. Within the linked cohorts, a different magnitude of association was obtained without adjustment for selection, whereas applying IPSW resulted in point estimates similar to the full cohort's (e.g., an adjusted hazard ratio of 1.63 became 2.12). Linked database studies may generate biased estimates without proper adjustment for potential selection bias.

Risk for Recurrent Venous Thromboembolism and Bleeding With Apixaban Compared With Rivaroxaban: An Analysis of Real-World Data

BACKGROUND

Apixaban and rivaroxaban are replacing vitamin K antagonists for the treatment of venous thromboembolism (VTE) in adults; however, head-to-head comparisons remain limited.

OBJECTIVE

To assess the effectiveness and safety of apixaban compared with rivaroxaban in patients with VTE.

DESIGN

Retrospective new-user cohort study.

SETTING

U.S.-based commercial health care insurance database from 1 January 2015 to 30 June 2020.

PARTICIPANTS

Adults with VTE who were newly prescribed apixaban or rivaroxaban.

MEASUREMENTS

The primary effectiveness outcome was recurrent VTE, a composite of deep venous thrombosis and pulmonary embolism. The primary safety outcome was a composite of gastrointestinal and intracranial bleeding.

RESULTS

Of 49 900 eligible patients with VTE, 18 618 were new users of apixaban and 18 618 were new users of rivaroxaban. Median follow-up was 102 days (25th, 75th percentiles: 30, 128 days) among apixaban and 105 days (25th, 75th percentiles: 30, 140 days) among rivaroxaban users. After propensity score matching, apixaban (vs. rivaroxaban) was associated with a lower rate for recurrent VTE (hazard ratio, 0.77 [95% CI, 0.69 to 0.87]) and bleeding (hazard ratio, 0.60 [CI, 0.53 to 0.69]). The absolute reduction in the probability of recurrent VTE with apixaban versus rivaroxaban was 0.006 (CI, 0.005 to 0.011) within 2 months and 0.011 (CI, 0.011 to 0.013) within 6 months of initiation. The absolute reduction in the probability of gastrointestinal and intracranial bleeding with apixaban versus rivaroxaban was 0.011 (CI, 0.010 to 0.011) within 2 months and 0.015 (CI, 0.013 to 0.015) within 6 months of initiation.

LIMITATION

Short follow-up.

CONCLUSION

In this population-based cohort study, patients with VTE who were new users of apixaban had lower rates for recurrent VTE and bleeding than new users of rivaroxaban.

PRIMARY FUNDING SOURCE

None.

Cardiovascular and major bleeding outcomes with antiplatelet and direct oral anticoagulants in patients with acute coronary syndrome and atrial fibrillation: A population-based analysis

BACKGROUND

Direct oral anticoagulants (DOACs) are replacing warfarin for stroke prevention in patients with atrial fibrillation (AF).

OBJECTIVE

To assess the effectiveness and safety of concomitant treatment with antiplatelet-DOAC compared to antiplatelet-warfarin in patients with acute coronary syndrome (ACS) and AF.

DESIGN

Retrospective propensity score-matched cohort study using United States-based commercial healthcare database from January 2016 to June 2019.

PARTICIPANTS

New-users of antiplatelet-DOAC and antiplatelet-warfarin who initiated the combined therapy within 30 days following incident ACS diagnosis.

MEASUREMENTS

Primary study outcomes were recurrent cardiovascular diseases (CVD) (ie, a composite of stroke and myocardial infarction) and major bleeding events identified via discharge diagnoses. We controlled for potential confounders via propensity score matching (PSM). We generated marginal hazard ratios (HRs) via Cox proportional hazards regression using a robust variance estimator while adjusting for calendar time.

RESULTS

After PSM, a total of 2,472 persons were included (1,236 users of antiplatelet-DOAC and 1,236 users of antiplatelet-warfarin). The use of antiplatelet-DOAC (vs. antiplatelet-warfarin) was associated with a reduced rate of recurrent CVD (adjusted HR 0.72, 95% confidence interval [CI], 0.56-0.92) and major bleeding events (adjusted HR, 0.49, 95% CI 0.33-0.72).

LIMITATIONS

Residual confounding.

CONCLUSIONS

In real-world data of AF patients with concurrent ACS, the use of antiplatelet-DOAC following ACS diagnosis was associated with a lower rate of recurrent CVD and major bleeding events compared with antiplatelet-warfarin. These findings highlight a potential promising role for DOACs in patients with ACS and AF requiring combined antiplatelet therapy.

Effectiveness and Safety of Direct Oral Anticoagulants Versus Warfarin in Patients With Valvular Atrial Fibrillation : A Population-Based Cohort Study

BACKGROUND

Direct oral anticoagulants (DOACs) are increasingly used in place of warfarin, but evidence about their effectiveness and safety in patients with valvular atrial fibrillation (AF) remains limited.

OBJECTIVE

To assess the effectiveness and safety of DOACs compared with warfarin in patients with valvular AF.

DESIGN

New-user retrospective propensity score-matched cohort study.

SETTING

U.S.-based commercial health care database from 1 January 2010 to 30 June 2019.

PARTICIPANTS

Adults with valvular AF who were newly prescribed DOACs or warfarin.

MEASUREMENTS

The primary effectiveness outcome was a composite of ischemic stroke or systemic embolism. The primary safety outcome was a composite of intracranial or gastrointestinal bleeding.

RESULTS

Among a total of 56 336 patients with valvular AF matched on propensity score, use of DOACs (vs. warfarin) was associated with lower risk for ischemic stroke or systemic embolism (hazard ratio [HR], 0.64 [95% CI, 0.59 to 0.70]) and major bleeding events (HR, 0.67 [CI, 0.63 to 0.72]). The results for the effectiveness and safety outcomes remained consistent for apixaban (HRs, 0.54 [CI, 0.47 to 0.61] and 0.52 [CI, 0.47 to 0.57], respectively) and rivaroxaban (HRs, 0.74 [CI, 0.64 to 0.86] and 0.87 [CI, 0.79 to 0.96], respectively); with dabigatran, results were consistent for the major bleeding outcome (HR, 0.81 [CI, 0.68 to 0.97]) but not for effectiveness (HR, 1.03 [CI, 0.81 to 1.31]).

LIMITATION

Relatively short follow-up; inability to ascertain disease severity.

CONCLUSION

In this comparative effectiveness study using practice-based claims data, patients with valvular AF who were new users of DOACs had lower risks for ischemic stroke or systemic embolism and major bleeding than new users of warfarin. These data may be used to guide risk-benefit discussions regarding anticoagulant choices for patients with valvular AF.

PRIMARY FUNDING SOURCE

None.

Effectiveness and Safety of Oral Anticoagulants Among Non-Valvular Atrial FibrillationPatients with Polypharmacy

AIMS

Polypharmacy is prevalent among non-valvular atrial fibrillation (NVAF) patients and presents a potential issue for the effective management of NVAF. This study compared the risk of stroke/systemic embolism (SE) and major bleeding (MB) among NVAF patients with polypharmacy newly prescribed oral anticoagulants (OACs).

METHODS AND RESULTS

A retrospective study of NVAF patients with polypharmacy who initiated OACs from 01JAN2013-30SEP2015 was conducted using US CMS Medicare and four commercial databases. Polypharmacy was defined as ≥ 6 concomitant medications on the index date. Propensity score matching was conducted to compare non-Vitamin K antagonists OACs (NOACs) to warfarin as well as between NOACs. Cox proportional hazard models were used to evaluate the risk of stroke/SE and MB. A total of 188,893 patients with polypharmacy were included, with an average of 8 concomitant medications (IQR 6-9). Compared to warfarin, apixaban (HR: 0.59, 95% CI: 0.52-0.68) and rivaroxaban (HR: 0.75, 95% CI: 0.69-0.83) were associated with a lower risk of stroke/SE. Apixaban (HR: 0.57, 95% CI: 0.54-0.61) and dabigatran (HR: 0.76, 95% CI: 0.66-0.88) were associated with a decreased risk of MB compared with warfarin. Compared with dabigatran and rivaroxaban, apixaban was associated with a lower risk of stroke/SE and MB. Dabigatran was associated with lower risk of MB compared with rivaroxaban.

CONCLUSIONS

In this observational study of anticoagulated NVAF patients with polypharmacy, effectiveness and safety profiles are more favorable for NOACs vs warfarin. Our observations are hypothesis generating and may help inform future clinical trials regarding appropriate OAC treatment selection in polypharmacy patients.

Understanding when real world data can be used to replicate a clinical trial: A cross-sectional study of medications approved in 2011

PURPOSE

To determine how commonly pre-approval clinical trials could potentially be replicated using real-world data from insurance claims databases.

METHODS

We conducted a cross-sectional study of medications approved by the FDA in 2011. For each medication, we reviewed the drug's label and the details of the pivotal clinical trials supporting its approval. We assessed whether each clinical trial could be replicated using an insurance claims databases by determining whether the following pivotal trial features could be reliably captured in claims data: study outcome, inclusion criteria, exclusion criteria, and the presence of an appropriate active comparator.

RESULTS

In 2011, 28 new medications were approved. The most common disease areas were oncology (N = 8, 29%), infectious disease (N = 5, 18%), and neurology (N = 4, 14%). The primary outcome of pre-approval clinical trials was identifiable in claims databases for six (21%) of the medications. Two (ticagrelor and linagliptin) had at least 80% of inclusion and exclusion criteria that could be identified in claims databases and had an available active comparator. The non-identifiable primary outcomes were related to patient-reported symptoms (N = 9, 32%), imaging findings (N = 5, 18%), laboratory values (N = 5, 18%), or other measurements (eg, blood pressure) not typically available in insurance claims databases (N = 4, 14%).

CONCLUSIONS

Among drugs FDA-approved in 2011, two (7%) had a pre-approval trial that could be replicated using insurance claims databases. In such qualifying trials, replication using claims databases could be useful in assessing whether they provide concordant results.

Effectiveness and Safety of Oral Anticoagulants in Patients With Nonvalvular Atrial Fibrillation and Diabetes Mellitus

OBJECTIVE

To address gaps in the data comparing non-vitamin K antagonist oral anticoagulants (NOACs) and warfarin among patients with nonvalvular atrial fibrillation (NVAF) and diabetes.

PATIENTS AND METHODS

A retrospective study was conducted on patients with NVAF and diabetes newly initiating apixaban, dabigatran, rivaroxaban, or warfarin from January 1, 2013, through September 30, 2015, with Medicare data from the US Centers for Medicare & Medicaid Services and 4 other US commercial claims databases. One-to-one propensity score matching was completed between NOACs and warfarin and between NOACs in each database, and the results were pooled. Cox proportional hazards models were used to evaluate the risk of stroke/systemic embolism (SE) and major bleeding (MB).

RESULTS

A total of 154,324 patients were included in the 6 matched cohorts, with a mean follow-up time of 6 to 8 months. Compared with warfarin, apixaban (hazard ratio [HR], 0.67; 95% CI, 0.57-0.77) and rivaroxaban (HR, 0.79; 95% CI, 0.71-0.89) were associated with a lower risk of stroke/SE; dabigatran (HR, 0.84; 95% CI, 0.67-1.07) was associated with a similar risk of stroke/SE. Apixaban (HR, 0.60; 95% CI, 0.56-0.65) and dabigatran (HR, 0.78; 95% CI, 0.69-0.88) were associated with a lower risk of MB; rivaroxaban (HR, 1.02; 95% CI, 0.94-1.10) was associated with a similar risk of MB compared with warfarin. Compared with dabigatran and rivaroxaban, apixaban was associated with a lower risk of MB. Compared with rivaroxaban, dabigatran was associated with a lower risk of MB.

CONCLUSION

This study-the largest observational study to date of patients with NVAF and diabetes taking anticoagulants-found that NOACs were associated with variable rates of stroke/SE and MB compared with warfarin.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT03087487.