Bias in case-crossover studies of medications due to persistent use: A simulation study

Bias Due to Within-Subject Exposure Dependency With or Without Bias Due to Lack of Pairwise Exchangeability When Exposure Is Chronic in Case-Crossover and Case-Time-Control Studies: A Simulation Study

The case-crossover study design has been proposed as a suitable design for use when a brief exposure causes a transient change in risk of an acute-onset disease. In pharmacoepidemiology, the condition of "brief exposure" is rarely satisfied because medication use is often chronic or successive, which may result in bias due to within-subject exposure dependency. Here we describe a simulation of a case-crossover study conducted within a cohort, where patients successively used a drug for 60 or more days and the rate ratio for the outcome occurrence was 4.0. Standard conditional logistic regression for the analysis produced overestimated odds ratios ranging up to 7.8. This bias due to within-subject exposure dependency from chronic use can be removed by the Mantel-Haenszel method or by our recently proposed weighting method. We also show that when some patients are censored after switching to another drug, a lack of pairwise exchangeability causes bias which is similar to bias due to an exposure time trend. This bias can be removed by using the case-time-control study design. We show that bias due to within-subject exposure dependency and lack of pairwise exchangeability occur independently and can occur separately or simultaneously, and we demonstrate how to detect and remove them.

Evaluating the use of methods to mitigate bias from non-transient medications in the case-crossover design: A systematic review

PURPOSE

The case-crossover design is a self-controlled study design used to compare exposure immediately preceding an event occurrence with exposure in earlier control periods. The design is most suitable for transient exposures in order to avoid biases that can be problematic when using the case-crossover design for non-transient (i.e., chronic) exposures. Our goal was to conduct a systematic review of case-crossover studies and its variants (case-time-control and case-case-time-control) in order to compare design and analysis choices by medication type.

METHODS

We conducted a systematic search to identify recent case-crossover, case-time-control, and case-case-time-control studies focused on medication exposures. Articles indexed in MEDLINE and EMBASE using these study designs that were published between January 2015 and December 2021 in the English language were identified. Reviews, methodological studies, commentaries, articles without medications as the exposure of interest, and articles with no available full text were excluded. Study characteristics including study design, outcome, risk window, control window, reporting of discordant pairs, and inclusion of sensitivity analyses were summarized overall and by medication type. We further evaluated the implementation of recommended methods to account for biases introduced by non-transient exposures among articles that used the case-crossover design on a non-transient exposure.

RESULTS

Of the 2036 articles initially identified, 114 articles were included. The case-crossover was the most common study design (88%), followed by the case-time-control (17%), and case-case-time-control (3%). Fifty-three percent of the articles included only transient medications, 35% included only non-transient medications, and 12% included both. Across years, the proportion of case-crossover articles evaluating a non-transient medication ranged from 30% in 2018 to 69% in 2017. We found that 41% of the articles that evaluated a non-transient medication did not apply any of the recommended methods to account for biases and more than half of which were conducted by authors with no previous publication history of case-crossover studies.

CONCLUSION

Using the case-crossover design to evaluate a non-transient medication remains common in pharmacoepidemiology. Researchers should apply appropriate design and analysis choices when opting to use a case-crossover design with non-transient medication exposures.

Medications influencing the risk of fall-related injuries in older adults: case-control and case-crossover design studies

BACKGROUND

Medications influencing the risk of fall-related injuries (FRIs) in older adults have been inconsistent in previous guidelines. This study employed case-control design to assess the association between FRIs and medications, and an additional case-crossover design was conducted to examine the consistency of the associations and the transient effects of the medications on FRIs.

METHODS

This study was conducted using a national claims database (2002-2015) in Korea. Older adults (≥ 65 years) who had their first FRI between 2007 and 2015 were matched with non-cases in 1:2 ratio. Drug exposure was examined for 60 days prior to the date of the first FRI (index date) in the case-control design. The hazard period (1-60 days) and two control periods (121-180 and 181-240 days prior to the index date) were investigated in the case-crossover design. The risk of FRIs with 32 medications was examined using conditional logistic regression after adjusting for other medications that were significant in the univariate analysis. In the case-crossover study, the same conditional model was applied.

RESULTS

In the case-control design, the five medications associated with the highest risk of FRIs were muscle relaxants (adjusted odd ratio(AOR) = 1.35, 95% confidence interval (CI) = 1.31-1.39), anti-Parkinson agents (AOR = 1.30, 95%CI = 1.19-1.40), opioids (AOR = 1.23, 95%CI = 1.19-1.27), antiepileptics (AOR = 1.19, 95%CI = 1.12-1.26), and antipsychotics (AOR = 1.16, 95%CI = 1.06-1.27). In the case-crossover design, the five medications associated with the highest risk of FRIs were angiotensin II antagonists (AOR = 1.87, 95%CI = 1.77-1.97), antipsychotics (AOR = 1.63, 95%CI = 1.42-1.83), anti-Parkinson agents (AOR = 1.58, 95%CI = 1.32-1.85), muscle relaxants (AOR = 1.42, 95%CI = 1.35-1.48), and opioids (AOR = 1.35, 95%CI = 1.30-1.39).

CONCLUSIONS

Anti-Parkinson agents, opioids, antiepileptics, antipsychotics, antidepressants, hypnotics and sedatives, anxiolytics, muscle relaxants, and NSAIDs/antirheumatic agents increased the risk of FRIs in both designs among older adults. Medications with a significant risk only in the case-crossover analysis, such as antithrombotic agents, calcium channel blockers, angiotensin II antagonists, lipid modifying agents, and benign prostatic hypertrophy agents, may have transient effects on FRIs at the time of initiation. Corticosteroids, which were only associated with risk of FRIs in the case-control analysis, had more of cumulative than transient effects on FRIs.

Methodology of the brodalumab assessment of hazards: a multicentre observational safety (BRAHMS) study

INTRODUCTION

Safe and effective pharmacological treatment is of paramount importance for treating severe psoriasis. Brodalumab, a monoclonal antibody against interleukin (IL) 17 receptor A, was granted marketing authorisation in the EU in 2017. The European Medicines Agency requested a postauthorisation safety study of brodalumab to address potential safety issues raised during drug development regarding major adverse cardiovascular events, suicidal conduct, cancer and serious infections.

METHODS AND ANALYSIS

BRodalumab Assessment of Hazards: A Multinational Safety is a multicentre observational safety study of brodalumab running from 2017 to 2029 using population-based healthcare databases from Denmark, Sweden, Norway, Netherlands, Germany and three different centres in Italy. A distributed database network approach is used, such that only aggregate data are exchanged between sites.Two types of designs are used: a case-time-control design to study acute effects of transient treatment and a variation of the new user active comparator design to study the effects of transient or chronic treatment. As comparators, inhibitors of TNF-α, inhibitors of IL-12 and IL-23, and other inhibitors of cytokine IL-17A are included.In the self-controlled case-time-control design, the risk of developing the outcome of interest during periods of brodalumab use is compared within individuals to the risk in periods without use.In the active comparator cohort design, new users of brodalumab are identified and matched to new users of active comparators. Potential baseline confounders are adjusted for by using propensity score modelling. For outcomes that potentially require large cumulative exposure, an adapted active comparator design has been developed.

ETHICS AND DISSEMINATION

The study is approved by relevant authorities in Denmark, Norway, Sweden, the Netherlands, Germany and Italy in line with the relevant legislation at each site. Data confidentiality is secured by the distributed network approach. Results will be published in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

EUPAS30280.

Recent tapering from long-term opioid therapy and odds of opioid-related hospital use

PURPOSE

The number of patients tapered from long-term opioid therapy (LTOT) has increased in recent years in the United States. Some patients tapered from LTOT report improved quality of life, while others face increased risks of opioid-related hospital use. Research has not yet established how the risk of opioid-related hospital use changes across LTOT dose and subsequent tapering. Our objective was to examine associations between recent tapering from LTOT with odds of opioid-related hospital use.

METHODS

Case-crossover design using 2014-2018 health information exchange data from Indiana. We defined opioid-related hospital use as hospitalizations, and emergency department (ED) visits for a drug overdose, opioid abuse, and dependence. We defined tapering as a 15% or greater dose reduction following at least 3 months of continuous opioid therapy of 50 morphine milligram equivalents (MME)/day or more. We used conditional logistic regression to estimate odds ratios (OR) with 95% confidence intervals (CI).

RESULTS

Recent tapering from LTOT was associated with increased odds of opioid-related hospital use (OR: 1.50, 95%CI: 1.34-1.63), ED visit (OR: 1.52; 95%CI: 1.35-1.72), and inpatient hospitalization (OR: 1.40; 95%CI: 1.20-1.65). We found no evidence of heterogeneity of the effect of tapering on opioid-related hospital use by gender, age, and race. Recent tapering among patients on a high baseline dose (>300 MME) was associated with increased odds of opioid-related hospital use (OR: 2.95, 95% CI: 2.12-4.11, p < 0.001) compared to patients on a lower baseline doses.

CONCLUSIONS

Recent tapering from LTOT is associated with increased odds of opioid-related hospital use.

Association between tramadol use and seizures: A nationwide case-case-time-control study

PURPOSE

Tramadol may lower the seizure threshold; however, there is no conclusive evidence to confirm this. This study aimed to determine whether the use of tramadol is associated with the occurrence of seizures.

METHODS

We conducted a case-case-time-control (CCTC) study by identifying patients who had received tramadol and seizure diagnosis in a nationwide healthcare database in South Korea between 2003 and 2015. Each case was matched for age and sex to one future case to adjust for time trends in exposure without selection bias from the use of an external control group. The use of tramadol was assessed during a risk period of 1-30 days, and two reference periods, 61-90 days and 91-120 days, preceding the first diagnosis of seizures. We calculated the adjusted odds ratio (aOR) by dividing the OR in cases (case-crossover) by the OR in future cases (control-crossover). We performed a dose-response analysis using the average daily dose.

RESULTS

We identified 2,523 incident cases with matched future cases (mean age, 45.4 years; 50% men). The aOR for seizure with tramadol use was 0.94 (95% confidence interval [CI], 0.98-1.43) in the CCTC analysis, with a case-crossover OR of 1.19 (0.98-1.43) and control-crossover OR of 1.27 (1.03-1.56). The dose-response analysis showed a similar trend in the main analysis: a low-dose aOR of 0.80 (0.50-1.28) and a high-dose aOR of 0.92 (0.41-2.11).

CONCLUSION

We could not identify a significant association between transient use of tramadol and incidence of seizures in clinical practice.

Effects of anticholinergic and sedative medication use on fractures: A self-controlled design study

BACKGROUND/OBJECTIVES

Unintentional falls are a leading cause of injury for older adults, and evidence is needed to understand modifiable risk factors. We evaluated 1-year fall-related fracture risk and whether dispensing of medications with anticholinergic/sedating properties is temporally associated with an increased odds of these fractures.

DESIGN

A retrospective cohort study with nested self-controlled analyses conducted between January 1, 2014, and December 31, 2016.

SETTING

Twenty percent nationwide, random sample of US Medicare beneficiaries.

PARTICIPANTS

New users of medications with anticholinergic/sedating properties who were 66+ years old and had Medicare Parts A, B, and D coverage but no claims for medications with anticholinergic/sedating properties in the year before initiation were eligible.

MEASUREMENTS

We followed new users of medications with anticholinergic/sedating properties until first non-vertebral, fall-related fracture (primary outcome), Medicare disenrollment, death, or end of study data. We estimated the 1-year risk with corresponding 95% confidence intervals (CIs) of first fracture after new use. We applied the self-controlled case-crossover and case-time-control designs to estimate odds ratios (ORs) and 95% CIs by comparing anticholinergic and/or sedating medication exposure (any vs. none) during a 14-day hazard period preceding the fracture to exposure to these medications during an earlier 14-day control period.

RESULTS

A total of 1,097,989 Medicare beneficiaries initiated medications with anticholinergic/sedating properties in the study period. The 1-year cumulative incidence of fall-related fracture, accounting for death as a competing risk, was 5.0% (95% CI: 5.0%-5.0%). Using the case-crossover design (n = 41,889), the adjusted OR for the association between anticholinergic/sedating medications and fractures was 1.03 (95% CI: 0.99, 1.08). Accounting for the noted temporal trend using the case-time-control design (n = 209,395), the adjusted OR was 1.60 (95% CI: 1.52, 1.69).

CONCLUSION

Use of anticholinergic/sedating medication was temporally associated with an increased odds of fall-related fractures. Patients and their healthcare providers should consider pharmacologic and non-pharmacologic treatments for the target condition that are safer.

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.

Proton Pump Inhibitors are Risk Factors for Viral Infections: Even for COVID-19?

During the ongoing pandemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), more attention should be paid to the balance of risks and benefits associated with proton pump inhibitors for the following reasons. One of the main functions of gastric juice is to inactivate swallowed microorganisms, thereby inhibiting infectious agents from reaching the intestine. Studies have documented that proton pump inhibitors are a risk factor for rotavirus, influenza virus, norovirus, and Middle East respiratory syndrome coronavirus infections, and are associated with an increased risk of acute gastroenteritis during periods of highest circulation of enteric viruses. In light of the evidence for gastrointestinal infection implying a fecal–oral transmission of SARS-CoV-2 and given the magnitude of the SARS-CoV-2/coronavirus disease 2019 pandemic, associated with the widespread misuse of proton pump inhibitors, this suggests that we should not rule out the hypothesis that patients treated with proton pump inhibitors may be more at risk of being infected by SARS-CoV-2.