May 2024
Adverse events associated with prescribing diuretics after calcium-channel blockers

This common ‘prescribing cascade’ can lead to more emergency visits and hospitalisations.

Lower-extremity oedema is a well-known side effect of calcium-channel blockers (CCBs). Although diuretics are prescribed sometimes to manage this oedema, they are typically ineffective, as CCB-related oedema probably is caused by arteriolar vasodilation rather than excess plasma volume (NEJM JW Gen Med Apr 1 2020 and JAMA Intern Med 2020; 180: 643-651). This series of prescriptions represents a ‘prescribing cascade’: the addition of a second, often unnecessary medication to manage an adverse drug effect.

To study rates of serious adverse events associated with this specific prescribing cascade, researchers in Ontario, Canada, used local health databases to follow about 40,000 older adults (age, over 65 years; no history of heart failure or advanced renal disease) after CCB initiation. About 5% of patients were prescribed new diuretics within 90 days of CCB initiation. The authors used propensity-score matching to account for differences in baseline health status between those who received diuretics and those who did not. During 90 days of follow up, those who received diuretics were significantly more likely to have emergency department visits or hospitalisations than those who did not (hazard ratio, 1.21).

Comment: Prescribing cascades are a well-described contributor to polypharmacy. This study, although observational, suggests they might also lead to medication-related harm. The same research group has described other common prescribing cascades, including excess diuretic prescribing after initiation of gabapentinoids (which can also cause oedema; NEJM JW Gen Med Dec 1 2021 and J Am Geriatr Soc 2021; 69: 2842-2850). Both studies are reminders that many symptoms can be addressed by deprescribing – rather than adding – medications.

Molly S. Brett, MD, Assistant Professor of Medicine, University of Colorado, Boulder, USA.

Rochon PA, et al. Association of a calcium channel blocker and diuretic prescribing cascade with adverse events: a population-based cohort study. J Am Geriatr Soc 2024; 72: 467-478.

This summary is taken from the following Journal Watch titles: General Medicine, Cardiology, Ambulatory Medicine, Hospital Medicine.

J Am Geriatr Soc