OBJECTIVES: To investigate risk factors for self-reported adverse drug events (ADEs) in a cohort of annually surveyed Iowa Medicare beneficiaries with mobility limitations.
DESIGN: Prospective cohort study with baseline and two annual follow-up questionnaires.
SETTING: Population-based sample of Iowa Medicare beneficiaries with mobility limitations.
PARTICIPANTS: Members of the cohort with complete follow-up questionnaires and prescription dispensing data (N=689).
MEASUREMENTS: The questionnaires asked about self-reported ADEs in the previous 12 months, sociodemographic data, smoking, alcohol use, number of mobility limitations, and history of chronic disease. Pharmacy dispensing records were the source of number and classes of prescription drug use. Linked Medicare claims provided additional comorbidity data.
RESULTS: Of the 689 subjects, 151 (21.9%) reported an ADE, 83% of which resulted in physician contact and 56% of which resulted in discontinuing the medication. Number of different medications dispensed during the prior year was an independent predictor of a self-reported ADE. Neither age, extent of mobility limitation, nor number of chronic conditions was independently associated with reporting an ADE.
CONCLUSION: Excess ADE risk observed with increasing mobility limitations is mediated through greater medication use.