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

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.

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

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

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).

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.

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.

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.