Antidepressant use during pregnancy and risk of congenital heart defects: A case-time-control study

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.

Risk of delirium associated with antimuscarinics in older adults: a case-time-control study

Background

Older adults are at an increased risk of delirium because of age, polypharmacy, multiple comorbidities and acute illness. Antimuscarinics are the backbone of the pharmacological management of overactive bladder. However, the safety profiles of antimuscarinics vary because of their dissimilarities to muscarinic receptor‐subtype affinities and are associated with differential central anticholinergic adverse effects.

Objective

This study aimed to examine delirium risk in new users of oxybutynin and solifenacin in older adults (≥ 65 years). In the secondary analyses, we examined the risk of delirium by type and dose of antimuscarinic.

Method

We applied a case‐time‐control design to investigate delirium risk in older adults who started taking oxybutynin and solifenacin. We used a nationwide inpatient hospital data (2005–2016), National Minimum Data Set, maintained by the Ministry of Health, New Zealand (NZ), to identify older adults with a new‐onset diagnosis of delirium. Eligible patients were older adults aged 65 at entry into the cohort on 1/1/2006. We used dispensing claims data to determine antimuscarinic treatment exposure. The antimuscarinic included in the study were new users of oxybutynin and solifenacin. These two antimuscarinics are subsidised by the Pharmaceutical Management Agency and are the most frequently used antimuscarinic in NZ. A conditional logistic regression model was used to compute matched odds ratios (MORs) and 95% confidence intervals (CIs). In the case‐time‐control design, we made separate analyses to evaluate the dose–response risk of delirium.

Results

We identified 4818 individuals (mean age 82.14) from 2005 to 2015 with incident delirium and were exposed to at least one of the antimuscarinic of interest. The case‐time‐control matched odds ratio (MOR) for delirium with oxybutynin was (2.06, 95% confidence interval [CI] 1.07–3.96). Solifenacin was not associated with delirium (0.89 95%CI 0.64–1.23). In the sensitivity analyses, the case‐time‐control MOR for delirium using a shorter risk period (0–3 days) did not change the results. The dose–response risk of delirium was significant for oxybutynin (0.05, 95%CI 0.02–0.08) but not for solifenacin (−0.01, 95%CI −0.03 to 0.00). In addition, in the subgroup analyses, a statistically significant association of delirium was found for oxybutynin but not for solifenacin in the non‐dementia cohort (2.11,95% CI 1.08–4.13) and the dementia cohort (1.25, 95%CI 0.05–26.9).

Conclusion

The study found that oxybutynin but not solifenacin is associated with a risk of new‐onset delirium in older adults. The higher blockade of M1 and M2 receptors by oxybutynin is likely to contribute to delirium than solifenacin, which is highly selective for the M3 receptor subtype. Therefore, the treatment choice with an M3 selective agent must be given due consideration, particularly in those with pre‐existing cognitive impairment.