Fluoroquinolone use and serious arrhythmias: A nationwide case-crossover 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.

Computational and experimental studies on the inhibitory mechanism of hydroxychloroquine on hERG

Hydroxychloroquine (HCQ) was noted to produce severe cardiac arrhythmia, an adverse effect as its use against severe acute respiratory syndrome caused by coronavirus 2 (SAES-CoV-2). HCQ is an antimalarial drug with quinoline structure. Some other quinoline compounds, such as fluoroquinolone antibiotics (FQs), also lead to arrhythmias characterized by QT prolongation. QT prolongation is usually related to the human ether-a-go-go-related gene (hERG) potassium channel inhibitory activity of most drugs. In this research, molecular docking was used to study the potential inhibitory activities of HCQ as well as other quinolines derivatives and hERG potassium channel protein. The possible causes of these QT prolongation effects were revealed. Molecular docking and patch clamp experiments showed that HCQ could bind to hERG and inhibit the efflux of potassium ion preferentially in the repolarization stage. The IC₅₀ of HCQ was 8.6 μM ± 0.8 μM. FQs, which are quinoline derivatives, could also bind to hERG molecules. The binding energies of FQs varied according to their molecular polarity. It was found that drugs with a quinoline structure, particularly with high molecular polarity, can exert a significant potential hERG inhibitory activity. The potential side effects of QT prolongation during the development and use of quinolines should be carefully considered.