Summary Background Potential additive effects of polypharmacy are rarely considered in adverse events of geriatric patients living in long-term care facilities. Our aim, therefore, was to identify adverse events in this setting and to assess plausible concomitant drug causes. Methods A cross-sectional observational study was performed in three facilities as follows: (i) adverse event identification: we structurally identified adverse events using nurses’ interviews and chart review. (ii) Analysis of the concomitantly administered drugs per patient was performed in two ways: (ii.a) a review of summary of product characteristics for listed adverse drug reactions to identify possible causing drugs and (ii.b) a causality assessment according to Naranjo algorithm. Results (i) We found 424 adverse events with a median of 4 per patient (range 1–14) in 103 of the 104 enrolled patients (99%). (ii.a) We identified a median of 3 drugs (range 0–11) with actually occurring adverse events listed as an adverse drug reaction in the summary of product characteristics. (ii.b) Causality was classified in 198 (46.9%) of adverse events as “doubtful,” in 218 (51.2%) as “possible,” in 7 (1.7%) as “probable,” and in 1 (0.2%) adverse event as a “definitive” cause of the administered drugs. In 340 (80.2%) of all identified adverse events several drugs simultaneously reached the highest respective Naranjo score. Conclusion Patients in long-term facilities frequently suffer from many adverse events. Concomitantly administered drugs have to be frequently considered as plausible causes for adverse events. These additive effects of drugs should be more focused in patient care and research.

Background Medication reviews contribute to protecting long-term care (LTC) residents from drug related problems (DRPs). However, few controlled studies have examined the impact on patient-relevant outcomes so far. Objective We examined the impact of a one-time, pharmacist-led medication review on medication changes (primary endpoint) including discontinued medication, the number of chronic medications, hospital admissions, falls, and deaths (secondary endpoints). Methods A prospective, controlled intervention study was performed in three LTC facilities. In the intervention group (IG), after performing a medication review, a pharmacist gave recommendations for resolving DRPs to physicians, nurses and community pharmacists. The control group (CG) received usual care without a medication review. (i) We assessed the number of medication changes and the secondary endpoints in both groups before (t0) and after (t1, t2) the intervention. (ii) Additionally, the medication review was evaluated in the IG with regard to identified DRPs, the healthcare professional’s feedback on the forwarded pharmacist recommendations and whether DRPs were finally resolved. Results 107 (IG) and 104 (CG) residents were enrolled. (i) More medication changes were identified in the IG than in the CG at t1 (p = 0.001). However, no significant difference was identified at t2 (p = 0.680). Mainly, medication was discontinued in those medication changes. Chronic medications increased in the CG (p = 0.005) at t2 while hospital admissions, falls, and deaths showed no differences. (ii) Overall, 1252 DRPs (median: 10; minimum-maximum: 2–39) were identified. Recommendations for 82% of relevant DRPs were forwarded to healthcare professionals, of which 61% were accepted or clarified. 22% were not accepted, 12% required further review and 6% remained without feedback. 51% of forwarded DRPs were finally resolved. Conclusions We found more medication changes in the IG compared to controls. Mostly, medication was discontinued. This suggests that our intervention was successful in discontinuing unnecessary medication. Other clinical outcomes such as falls, hospitalisations, and deaths were not improved due to the one-time intervention. The medication review further identified a high prevalence of DRPs in the IG, half of which were finally resolved. Trial registration German Clinical Trials Register, DRKS00026120 (www.drks.de, retrospectively registered 07/09/2021).