The Case-Crossover Design for Drug-Drug Interactions: Considerations for Implementation

A Precision Mixture Risk Model to Identify Adverse Drug Events in Subpopulations Using a Case-Crossover Design

Despite the success of pharmacovigilance studies in detecting signals of adverse drug events (ADEs) from real-world data, the risks of ADEs in subpopulations warrant increased scrutiny to prevent them in vulnerable individuals. Recently, the case-crossover design has been implemented to leverage large-scale administrative claims data for ADE detection, while controlling both observed confounding effects and short-term fixed unobserved confounding effects. Additionally, as the case-crossover design only includes cases, subpopulations can be conveniently derived. In this manuscript, we propose a precision mixture risk model (PMRM) to identify ADE signals from subpopulations under the case-crossover design. The proposed model is able to identify signals from all ADE-subpopulation-drug combinations, while controlling for false discovery rate (FDR) and confounding effects. We applied the PMRM to an administrative claims data. We identified ADE signals in subpopulations defined by demographic variables, comorbidities, and detailed diagnosis codes. Interestingly, certain drugs were associated with a higher risk of ADE only in subpopulations, while these drugs had a neutral association with ADE in the general population. Additionally, the PMRM could control FDR at a desired level and had a higher probability to detect true ADE signals than the widely used McNemar's test. In conclusion, the PMRM is able to identify subpopulation-specific ADE signals from a tremendous number of ADE-subpopulation-drug combinations, while controlling for both FDR and confounding effects.

Potential interactions between medications for rate control and direct oral anticoagulants: Population-based cohort and case-crossover study

BACKGROUND

Direct oral anticoagulants (DOACs) are commonly co-prescribed with amiodarone/diltiazem/verapamil, but whether there is a drug interaction between these drugs is unclear.

OBJECTIVE

The purpose of this study was to investigate the risk of clinical outcomes associated with concomitant use of DOACs and amiodarone/diltiazem/verapamil.

METHODS

We identified DOAC users in the Clinical Practice Research Datalink Aurum from January 1, 2011, to December 31, 2019. We used a cohort design to estimate hazard ratios for ischemic stroke, myocardial infarction, venous thromboembolism, intracranial bleeding, gastrointestinal bleeding, other bleeding, cardiovascular mortality, and all-cause mortality, comparing DOACs + amiodarone/diltiazem/verapamil users and DOACs + beta-blocker users. A case-crossover design comparing odds of exposure to different drug initiation patterns for all outcomes in hazard window vs referent window within an individual also was conducted.

RESULTS

Of 397,459 DOAC users, we included 9075 co-prescribed amiodarone, 9612 co-prescribed diltiazem, and 2907 co-prescribed verapamil. There was no difference in risk of any outcomes between DOACs + amiodarone/diltiazem/verapamil users vs DOACs + beta-blocker users in the cohort design. However, in the case-crossover design, we observed an odds ratio (OR) of 2.09 (99% confidence interval [CI] 1.37-3.18) for all-cause mortality associated with initiation of a DOAC while taking amiodarone, which was greater than that observed for DOAC monotherapy (OR 1.30; 99% CI 1.25-1.35). Similar findings were observed for cardiovascular mortality and all-cause mortality respectively with diltiazem.

CONCLUSION

Our study showed no evidence of higher bleeding or cardiovascular risk associated with co-prescribed DOACs and amiodarone, diltiazem, or verapamil. Elevated risks of cardiovascular and all-cause mortality were only observed during DOAC initiation when diltiazem/amiodarone were being taken.

Oral Janus kinase inhibitors and venous thromboembolic events in atopic dermatitis: protocols for a case-time control study and a nested case-control study based on the French national health insurance (SNDS) cohort

INTRODUCTION

Atopic dermatitis (AD) is a highly prevalent, chronic, inflammatory skin disease. Several orally administered Janus kinase inhibitors (JAKis, including baricitinib, upadacitinib and abrocitinib) have received a marketing authorisation for AD.Clinical trials in rheumatoid arthritis (RA) have flagged up a potential risk of JAKi-induced venous thromboembolic events (VTEs). Accordingly, the summary of product characteristics for a JAKi must mention VTEs as potential adverse drug reactions. In contrast to RA, AD per se is not associated with an elevated risk of VTEs. Assessing this potential risk among patients with AD would shed further light on the putative underlying relationship between JAKis and VTEs.Our research question is to investigate whether JAKi administration increases the risk of VTEs in adults with AD. Our primary objective is to assess the risk of VTEs in adults with AD exposed to JAKis compared to AD adults not exposed to JAKis, and our secondary objective is to evaluate whether JAKi initiation acts as a trigger of VTEs in adults with AD within 3 months.

METHODS AND ANALYSIS

Hence, we have designed (1) a nested case-control study and (2) a case-time control study in a cohort of adults with AD with data from the French national health insurance system (2017-2025).Here, we describe the study protocol, our methodological choices and certain novel aspects, including the combined value of the two assumptions and the use of an exhaustive national health insurance database with potentially greater statistical power for studying rare events in the population of patients with AD at a low risk of VTEs (thus limiting the influence of confounding factors).

ETHICS AND DISSEMINATION

The protocol has been approved by an independent ethics committee and registered with the French National Data Protection Commission. The study's findings will be published in peer-reviewed scientific journals and presented at international conferences.

Emergency room admissions induced by drug-drug interactions in the elderly: a cross-sectional study

The elderly people are increasingly exposed to polymedication and therefore to the risks of drug–drug interactions (DDIs). However, there are few data available on the clinical consequences of these drug combinations. We investigated the impact of the various DDIs classified as severe in terms of emergency admissions in the elderly. A cross‐sectional study was conducted using information from the emergency department admissions of Bordeaux University Hospital between September 2016 and August 2017. Events of interest were frequency of concomitant uses of interacting drugs that are contraindicated or warned against and frequency of emergency admissions due to contraindicated or warned against concomitant uses of interacting drugs. Five thousand, eight hundred sixty (5860) admissions to the emergency department were analyzed. A total of 375 (6.4%) contraindicated or warned against concomitant uses were identified, including 163 contraindicated (43.5%) and 212 warned against (56.5%). Reason for admission appeared likely related to the underlying DDI in 58 cases. Within these, 36 admissions were assessed as probably due to a DDI (0.6% of hospitalizations) and 22 as certainly (0.4% of hospitalizations). Of these, there were 24 (45%) admissions related to a long QT syndrome (LQTS), nine (16%) related to a drug overdose, and eight (14%) related to a hemorrhage. An antidepressant was involved in 22 of the 24 cases of LQTS. Seven of the eight cases of hemorrhage involved the antithrombotic agents / non‐steroidal anti‐inflammatory drugs combination. Elderly patients admitted to emergency departments are particularly exposed to high‐risk potential DDIs. These drug combinations lead mainly to LQTS and involve certain antidepressants.

Concurrent use of prescription gabapentinoids with opioids and risk for fall-related injury among older US Medicare beneficiaries with chronic noncancer pain: A population-based cohort study

BACKGROUND

Gabapentinoids are increasingly prescribed to manage chronic noncancer pain (CNCP) in older adults. When used concurrently with opioids, gabapentinoids may potentiate central nervous system (CNS) depression and increase the risks for fall. We aimed to investigate whether concurrent use of gabapentinoids with opioids compared with use of opioids alone is associated with an increased risk of fall-related injury among older adults with CNCP.

METHODS AND FINDINGS

We conducted a population-based cohort study using a 5% national sample of Medicare beneficiaries in the United States between 2011 and 2018. Study sample consisted of fee-for-service (FFS) beneficiaries aged ≥65 years with CNCP diagnosis who initiated opioids. We identified concurrent users with gabapentinoids and opioids days' supply overlapping for ≥1 day and designated first day of concurrency as the index date. We created 2 cohorts based on whether concurrent users initiated gabapentinoids on the day of opioid initiation (Cohort 1) or after opioid initiation (Cohort 2). Each concurrent user was matched to up to 4 opioid-only users on opioid initiation date and index date using risk set sampling. We followed patients from index date to first fall-related injury event ascertained using a validated claims-based algorithm, treatment discontinuation or switching, death, Medicare disenrollment, hospitalization or nursing home admission, or end of study, whichever occurred first. In each cohort, we used propensity score (PS) weighted Cox models to estimate the adjusted hazard ratios (aHRs) with 95% confidence intervals (CIs) of fall-related injury, adjusting for year of the index date, sociodemographics, types of chronic pain, comorbidities, frailty, polypharmacy, healthcare utilization, use of nonopioid medications, and opioid use on and before the index date. We identified 6,733 concurrent users and 27,092 matched opioid-only users in Cohort 1 and 5,709 concurrent users and 22,388 matched opioid-only users in Cohort 2. The incidence rate of fall-related injury was 24.5 per 100 person-years during follow-up (median, 9 days; interquartile range [IQR], 5 to 18 days) in Cohort 1 and was 18.0 per 100 person-years during follow-up (median, 9 days; IQR, 4 to 22 days) in Cohort 2. Concurrent users had similar risk of fall-related injury as opioid-only users in Cohort 1(aHR = 0.97, 95% CI 0.71 to 1.34, p = 0.874), but had higher risk for fall-related injury than opioid-only users in Cohort 2 (aHR = 1.69, 95% CI 1.17 to 2.44, p = 0.005). Limitations of this study included confounding due to unmeasured factors, unavailable information on gabapentinoids' indication, potential misclassification, and limited generalizability beyond older adults insured by Medicare FFS program.

CONCLUSIONS

In this sample of older Medicare beneficiaries with CNCP, initiating gabapentinoids and opioids simultaneously compared with initiating opioids only was not significantly associated with risk for fall-related injury. However, addition of gabapentinoids to an existing opioid regimen was associated with increased risks for fall. Mechanisms for the observed excess risk, whether pharmacological or because of channeling of combination therapy to high-risk patients, require further investigation. Clinicians should consider the risk-benefit of combination therapy when prescribing gabapentinoids concurrently with opioids.

Risk of bleeding associated with nonsteroidal anti-inflammatory drug use in patients exposed to antithrombotic therapy: a case-crossover study

Concomitant nonsteroidal anti-inflammatory drug (NSAIDs) and antithrombotic drug use is associated with an increased risk of bleeding, mainly gastrointestinal. The goal of this study was to quantify the transient increase in the risk of hospitalization for bleeding associated with NSAID use in patients treated with antiplatelet agents or anticoagulants. We performed an unidirectional case-crossover study using the EGB (Échantillon généraliste de bénéficiaires), a permanent random sample of the French nationwide health database. Patients receiving antithrombotic therapy and hospitalized for bleeding between 2009 and 2017 were included. We compared their NSAID exposure during a 15-day hazard window immediately prior to hospital admission to three earlier 15-day control windows. The risk of hospitalization for bleeding associated with the recent use of NSAIDs was estimated using conditional logistic regression to estimate odds ratios. During the study period, 33 patients treated with anticoagulants and 253 treated with antiplatelet agents received NSAIDs and were included in the case-crossover analysis. We found an increased risk of hospitalization for gastrointestinal bleeding after exposure to NSAIDs with an adjusted OR of 3.59 (95%CI, 1.58;8.17) in patients receiving anticoagulant therapy and 1.44 (95%CI, 1.07;1.94) in patients receiving antiplatelet therapy. The risk of non-gastrointestinal bleeding was also increased after exposure to NSAIDs with an adjusted OR of 2.72 (95%CI, 1.23;6.04) in patients exposed to anticoagulant therapy. The risk of gastrointestinal and non-gastrointestinal bleeding increases after NSAID use in patients treated with anticoagulants, while the risk of gastrointestinal bleeding increases, but to a lesser extent in those treated with antiplatelets. This article is protected by copyright. All rights reserved.

Risk of fall-related injury and all-cause hospitalization of select concomitant central nervous system medication prescribing in older adult persistent opioid users: A case-time-control analysis

BACKGROUND

Concomitant use of central nervous system (CNS) medications frequently occurs in older adults with persistent opioid use. The risks of adverse outcomes associated with combinations of opioids, sedative hypnotics, or skeletal muscle relaxants have not been sufficiently described in this population.

OBJECTIVE

To compare the overall and incremental risk of (1) fall-related injury and (2) all-cause hospitalization associated with sedative hypnotics and skeletal muscle relaxants among older persistent opioid users.

METHODS

A case-time-control study was conducted using administrative claims of adults ages ≥66 years with a history of persistent (≥90 days) opioid use. Cases included those with first (1) emergency department, hospital, or outpatient visit for a fall-related injury, or (2) all-cause hospitalization. Exposure to CNS medications prior to the case event versus earlier periods, and the risk associated with CNS drug class combinations and sequence of use, was estimated using conditional logistic regression, adjusted for time trends and time-varying covariates.

RESULTS

Among 140,101 older persistent opioid users, 20,723 experienced fall-related injury and 39,444 were hospitalized during follow-up. Skeletal muscle relaxant use was associated with an increased risk of fall-related injury (Odds ratio [OR] 1.28) and all-cause hospitalization (OR 1.11). Statistically significant associations were observed for the joint effects of interactions involving skeletal muscle relaxants on fall-related injury (with opioid: OR 1.25; with sedative hypnotic: OR 1.24), and interactions involving opioids on all-cause hospitalization (with sedative hypnotic: OR 1.10; with skeletal muscle relaxant: OR 1.17). The addition of a skeletal muscle relaxant to an opioid regimen was associated with a 25% increased risk of fall-related injury. Additions of other CNS medications did not have apparent incremental effects on the risk of all-cause hospitalization.

CONCLUSION

The excess risks of fall-related injury and hospitalization associated with various combinations of CNS medications among older persistent opioid users should be considered in therapeutic decision making. Further research is needed to confirm these findings.

Drug-Drug Interaction Surveillance Study: Comparing Self-Controlled Designs in Five Empirical Examples in Real-World Data

Self-controlled designs, specifically the case-crossover (CCO) and the self-controlled case series (SCCS), are increasingly utilized to generate real-world evidence (RWE) on drug-drug interactions (DDIs). Although these designs share the advantages and limitations of within-individual comparison, they also have design-specific assumptions. It is not known to what extent the differences in assumptions lead to different results in RWE DDI analyses. Using a nationwide US commercial healthcare insurance database (2006-2016), we compared the CCO and SCCS designs, as they are implemented in DDI studies, within five DDI-outcome examples: (1) simvastatin + clarithromycin and muscle-related toxicity; (2) atorvastatin + valsartan, and muscle-related toxicity; and (3-5) dabigatran + P-glycoprotein inhibitor (clarithromycin, amiodarone, and verapamil) and bleeding. Analyses were conducted within person-time exposed to the object drug (statins and dabigatran) and adjusted for bias associated with the inhibiting drugs via control groups of individuals unexposed to the object drug. The designs yielded similar estimates in most examples, with SCCS displaying better statistical efficiency. With both designs, results varied across sensitivity analyses, particularly in CCO analyses with small number of exposed individuals. Analyses in controls revealed substantial bias that may be differential across DDI-exposed and control individuals. Thus, both designs showed no association between amiodarone or verapamil and bleeding in dabigatran-exposed but revealed strong positive associations in controls. Overall, bias adjustment via a control group had a larger impact on results than the choice of a design, highlighting the importance and challenges of appropriate control group selection for adequate bias control in self-controlled analyses of DDIs.

Comparison of Self-controlled Designs for Evaluating Outcomes of Drug-Drug Interactions: Simulation Study

BACKGROUND

Self-controlled designs, both case-crossover and self-controlled case series, are well suited for evaluating outcomes of drug-drug interactions in electronic healthcare data. Their comparative performance in this context, however, is unknown.

METHODS

We simulated cohorts of patients exposed to two drugs: a chronic drug (object) and a short-term drug (precipitant) with an associated interaction of 2.0 on the odds ratio scale. We analyzed cohorts using case-crossover and self-controlled case series designs evaluating exposure to the precipitant drug within person-time exposed to the object drug. Scenarios evaluated violations of key design assumptions: (1) time-varying, within-person confounding; (2) time trend in precipitant drug exposure prevalence; (3) nontransient precipitant exposure; and (4) event-dependent object drug discontinuation.

RESULTS

Case-crossover analysis produced biased estimates when 30% of patients persisted on the precipitant drug (estimated OR 2.85) and when the use of the precipitant drug was increasing in simulated cohorts (estimated OR 2.56). Self-controlled case series produced biased estimates when patients discontinued the object drug following the occurrence of an outcome (estimated incidence ratio [IR] of 2.09 [50% of patients stopping therapy] and 2.22 [90%]). Both designs yielded similarly biased estimates in the presence of time-varying, within-person confounding.

CONCLUSION

In settings with independent or rare outcomes and no substantial event-dependent censoring (<50%), self-controlled case series may be preferable to case-crossover design for evaluating outcomes of drug-drug interactions. With frequent event-dependent drug discontinuation, a case-crossover design may be preferable provided there are no time-related trends in drug exposure.

Association between opioid analgesic plus benzodiazepine use and death: A case-crossover study

OBJECTIVE

We aimed to investigate whether concomitant use of benzodiazepines and opioids is associated with an increased risk of death in a population-based case-crossover setting.

METHODS

We conducted a case-crossover study using the National Sample Cohort database. We introduced a 30-day hazard period before the onset of death and three consecutive previous 30-day control periods with a 30-day washout period. The use of opioids and/or benzodiazepines during the hazard period was compared with that in the three control periods. We performed the conditional logistic regression analysis to estimate the adjusted odds ratios (aORs) and their 95% confidence intervals (CIs).

RESULTS

A total of 13,161 individuals who previously used benzodiazepines or opioids and died were included in the study. The risk of death was higher in patients with concomitant use of benzodiazepines and opioids (aOR, 1.86; 95% CI, 1.71-2.02) than in those who used either benzodiazepines or opioids only. In the subgroup analysis among concomitant users, the mortality risks were highest in patients aged less than 20 years (aOR, 3.85; 95% CI, 1.65-8.99), male patients (aOR, 2.20; 95% CI, 1.93-2.51), and patients with renal disease (aOR, 2.42; 95% CI, 1.57-3.74).

CONCLUSION

In this study, concomitant use of benzodiazepines and opioids was associated with a higher risk of death compared with use of a single drug. The risks and benefits of co-prescribing of benzodiazepines and opioids must be weighed carefully.