Assessing incidence of clinically significantly prescribing cascades in older adults: a nationwide retrospective cohort study using the French National Health Data System.

BACKGROUND: Prescribing cascades occur when an adverse drug event is misinterpreted as a new medical condition, leading to the prescription of additional medications. They represent an important and preventable source of potentially inappropriate prescribing in older adults, yet their population-level incidence remains poorly documented in France. METHODS: We conducted a nationwide retrospective cohort study in 2022 using the French National Health Data System, including all individuals aged ≥65 years in 2022. Clinically important prescribing cascades were identified using a consensus-based list (ThinkCascades). Two complementary approaches were applied: a conservative longitudinal analysis and prescription sequence symmetry analysis. Incidence ranges were estimated, and subgroup analyses were performed to identify factors associated with cascade initiation. RESULTS: Among 16.6 million older adults, four of seven predefined potential prescribing cascades showed significant positive signals. The strongest associations were observed for benzodiazepine-antipsychotic (adjusted sequence ratio [aSR] 2.48, 99% CI 2.44-2.51) and antipsychotic-antiparkinsonian cascades (aSR 2.01, 99% CI 1.91-2.11). Incidence estimates ranged from 0.69% to 3.29%. Female sex, advanced age (≥85 years), hospital initiation of the index drug and lack of prescriber continuity were associated with higher risks for specific cascades. CONCLUSIONS: Clinically important potential prescribing cascades are common among older adults in France. These findings suggest potential prescribing cascades as a persistent and preventable contributor to medication-related harm and underscore the importance of systematic medication review, particularly during transitions of care and when new prescriptions shortly follow treatment initiation, as potential signals of prescribing cascades.