Association of a calcium channel blocker and diuretic prescribing cascade with adverse events: A population-based cohort study

• Published in: Journal of the American Geriatrics Society (JAGS) 2024-02, Vol.72 (2), p.467-478
• Main Authors: Rochon, Paula A, Austin, Peter C, Normand, Sharon-Lise, Savage, Rachel D, Read, Stephanie H, McCarthy, Lisa M, Giannakeas, Vasily, Wu, Wei, Strauss, Rachel, Wang, Xuesong, Chen, Simon, Gurwitz, Jerry H
• Format: Article
• Language: English
• Subjects: Cohort analysis; Congestive heart failure; Diuretics; Drug therapy; Emergency medical care; Hypertension; Older people; Population studies
• ISSN: 0002-8614; 1532-5415; 1532-5415
• DOI: 10.1111/jgs.18683

Prescribing cascades occur when a drug adverse event is misinterpreted as a new medical condition and a second, potentially unnecessary drug, is prescribed to treat the adverse event. The population-level consequences of prescribing cascades remain unknown. This population-based cohort study used linked health administrative databases in Ontario, Canada. The study included community-dwelling adults, 66 years of age or older with hypertension and no history of heart failure (HF) or diuretic use in the prior year, newly dispensed a calcium channel blocker (CCB). Individuals subsequently dispensed a diuretic within 90 days of incident CCB dispensing were classified as the prescribing cascade group, and compared to those not dispensed a diuretic, classified as the non-prescribing cascade group. Those with and without a prescribing cascade were matched one-to-one on the propensity score and sex. The primary outcome was a serious adverse event (SAE), which was the composite of emergency room visits and hospitalizations in the 90-day follow-up period. We estimated hazard ratios (HRs) with 95% confidence intervals (CI) for SAE using an Andersen-Gill recurrent events regression model. Among 39,347 older adults with hypertension and no history of HF who were newly dispensed a CCB, 1881 (4.8%) had a new diuretic dispensed within 90 days after CCB initiation. Compared to the non-prescribing cascade group, those in the prescribing cascade group had higher rates of SAEs (HR: 1.21, 95% CI: 1.02-1.43). The CCB-diuretic prescribing cascade was associated with an increased rate of SAEs, suggesting harm beyond prescribing a second drug therapy. Our study raises awareness of the downstream impact of the CCB-diuretic prescribing cascade at a population level and provides an opportunity for clinicians who identify this prescribing cascade to review their patients' medications to determine if they can be optimized.