Evaluating Provider and Pharmacy Discordance in Potential Calcium Channel Blocker-Loop Diuretic Prescribing Cascade

Abstract

Background: Prescribing cascades occur when a drug-induced adverse event is treated with a new medication. Identifying clinical scenarios in which prescribing cascades are more likely to occur may help determine ways to prevent prescribing cascades.

Objective: To understand the extent to which discordant providers and discordant pharmacies contribute to the dihydropyridine calcium channel blocker (DH CCB)-loop diuretic prescribing cascade.

Study population and design: A retrospective cohort study using Medicare Fee-For-Service data (2011-2018) of adults aged ≥ 66 years.

Exposures: Patients who initiated DH CCB with subsequent initiation of loop diuretic (DH CCB-loop diuretic dyad) within 90 days or patients who initiated angiotensin-converting enzyme inhibitor (ACEI)/angiotensin receptor blocker (ARB) with subsequent initiation of a loop diuretic (ACEI/ARB-loop diuretic dyad; control).

Main outcomes: The primary outcomes were provider and pharmacy discordance for prescribing cascades and control drug pairs. Baseline clinical and socio-demographic characteristics were balanced using inverse probability of treatment weighting with propensity scores.

Results: Overall, we identified 1987 DH CCB-loop diuretic dyads and 3148 ACEI/ARB-loop diuretic dyads. Discordant providers occurred in 64% of DH CCB-loop diuretic dyads and 55% of ACEI/ARB-loop diuretic dyads, while discordant pharmacies occurred in 19% of DH CCB-loop diuretic dyads and 16% of ACEI/ARB-loop diuretic dyads. After adjustment, the risk of having discordant providers was 20% {Relative Risk (RR) 1.20 [95% confidence interval (CI), 1.14-1.26]} higher in the DH CCB-loop diuretic dyad compared with the ACEI/ARB-loop diuretic dyad. Moreover, pharmacy discordance was 17% (RR 1.17 [95% CI 1.02-1.33]) higher.

Conclusion: Our findings suggest that discordant providers and discordant pharmacies were more commonly involved in the potential prescribing cascade when compared with a similar control dyad of medications. Opportunities for enhanced care coordination and medication reconciliation should be explored to prevent unnecessary polypharmacy.