Individual Patient Risk Profiles for Adverse Drug Reactions: Establishing a Consecutive Research Cohort in an Interdisciplinary Polypharmacy Consultation Service of a Geriatric University Outpatient Department

Adverse drug reactions are common in older patients and can lead to severe outcomes such as falls, hospitalizations and death. They are dose-dependent and may for example be caused by inappropriate dosing due to a reduced kidney function. Also, the use of potentially inappropriate medications in older patients can result in a negative benefit-/ risk-ratio. Additionally, drug metabolism in older patients is altered due to a variety of reasons and pharmacogenetic variants of drug metabolizing enzymes can lead to a more than 10-fold interinidividual variation of drug clearance. The risk of the individual patient to experience an adverse drug reactions is determined by many reasons. Therefore, this study aims to identify patient risk profiles with regard to pharmacogenetics, drug interactions, impaired functional and cognitive status and individual drug metabolism.

Participants for this study will be consecutively recruited from patients admitted to the Interdisciplinary Polypharmacy Consultation Service of the Department of Geriatric's University Outpatient Clinic in cooperation with the Institute of Clinical Pharmacology. Regardless of their participation in this study, patients in the outpatient clinic will perform several tests and questionnaires following the comprehensive geriatric assessment. The purpose of the cohort study is to document and evaluate routine health data collected in the outpatient clinic for polypharmacy in geriatric patients (laboratory tests as well as a comprehensive medication history with therapy recommendations issued by a subsequent pharmaceutical council for both the patients and the primary care physicians).

Procedures conducted specifically for this study are a long-term capture and detailed history of all suspected adverse drug reactions, examining the fear of falling (FES-I questionnaire) and blood sampling for exploratory pharmacogenomic analyses (on cohort level, not patient diagnostics).

Aim of the long-term cohort of geriatric patients with polypharmacy is to identify risk profiles for adverse drug reactions that are specific for the population of older individuals.