Prescribing cascades among hospitalized older adults: a retrospective cohort study from the REPOSI registry.

A prescribing cascade occurs when an adverse drug reaction (ADR) generated from an index drug (Drug A) is mistaken for a new medical condition that is in turn managed with a new drug prescription (Drug B). Prescribing cascades represent a factor influencing inappropriate prescribing and unnecessary polypharmacy, especially among older adults. Using the REPOSI registry, we conduct a retrospective observational study to examine the prevalence of potential prescribing cascades, as identified in the ThinkCascades framework, among patients aged ≥ 65 years admitted to geriatric or internal medicine wards. Evaluation was made at (i) admission, (ii) discharge, and (iii) at the 3 month follow-up. At admission the prescribing cascade was defined as "not-determined" owing to the unavailability of sequential prescription information, while at discharge or 3 month follow-up the cascade was defined as "introduced" when the marker medication (Drug B) was prescribed after the index medication (Drug A). At admission, among the REPOSI population of 10,253 hospitalized patients, 13.0% of them (1,335 cases) showed at least one "not-determined" prescribing cascade, with major prevalence for calcium channel blockers (CCBs) combined with diuretics (n = 932, 65.6%). During hospitalization, a total of 305 potential prescribing cascades were introduced, but 474 not-determined cascades were deprescribed at discharge. Three months after discharge, 31 new cases of potential prescribing cascades were introduced. For four out of nine prescribing cascades, low or no cases were found in all three situations. The proportion of patients exposed to potentially inappropriate prescribing cascades was relatively low. However, these findings highlight the need for practical tools to support physicians in preventing inappropriate prescribing.