Potentially inappropriate medications and adverse drug reactions in the elderly: a study in a PharmacoVigilance database.

Background: Lists of potentially inappropriate medications (PIM) in the elderly were developed in order to identify patients and/or drugs at risk of adverse drug reactions (ADRs) or inefficacy. However, the relationship between PIMs and ADRs remains discussed. We hypothesized that PIM use is associated with more ADRs than other prescriptions.

Methods: All ADRs registered by the Midi-Pyrénées PharmacoVigilance Center between the 1st January and the 30th June 2012 in patients ≥75 years were included. Data on patients (age, gender, Charlson comorbidity index), drugs (number, ATC classification, Laroche PIM classification) and ADRs (type, seriousness, mechanisms) were analyzed.

Results: Among the 923 ADRs recorded, 272 (29.5%) were in patients ≥75 years. Mean age was 83.5 ± 5.5 years. Most of them (59%) were females. Mean Charlson index was 5.6 ± 2.0 by ADR report. These 272 prescriptions involved 1,775 drugs [mean value, 6.5 (±3.4) drugs by ADR report] with 129 (7.3%) PIM. Main PIM classes were nervous (n = 98, 76.0%) and cardiovascular (17.8%) drugs, including 32 atropinics (23.4%). ADR-associated drugs were mainly antithrombotics, antibacterials, and analgesics for non-PIM drugs whereas PIM-associated ADRs were mainly observed with digoxine, psycholeptics, and psychoanaleptics. ADRs were mainly found with non-PIM drugs (89.3%). Associated factors were the number of drugs for PIMs and the number of PIMs for PIM-induced ADRs.

Conclusion: Out of the ADR reports registered in the Midi-Pyrénées PharmacoVigilance Database for patients ≥75 years, 1 drug out of 12 is potentially inappropriate (mainly benzodiazepines, imipraminic antidepressants, and atropinic drugs). PIM use is not associated with more ADRs' reports than other prescriptions.