Inappropriate medication use as a risk factor for self-reported adverse drug effects in older adults.
OBJECTIVE
To determine the association between inappropriate medication use and self-reported adverse drug effects (ADEs).


METHODS
Prospective cohort study with three annual mailed surveys.


METHODS
Population-based sample of Iowa Medicare beneficiaries.


METHODS
Cohort members (n5626) with established mobility disability and complete pharmacy dispensing records, continuous Medicare eligibility, and survey data.


METHODS
The number of unique drug ingredients dispensed and inappropriate use were assessed for the year before the ADE survey. Inappropriate medication use was defined according to published criteria: contraindicated drugs for elderly people, drug-disease interactions (constructed from linked Medicare claims), drug-drug interactions, and therapeutic duplications. An ADE was defined from the following question: "In the past 12 months, have you experienced an unwanted effect or side effect of a medication?"


RESULTS
Of respondents to the ADE survey, 22.0% reported having experienced an ADE in the past year, and 322 (51.4%) received at least one potential inappropriate medication. Factors associated univariately with ADE self-report were number of medications, number of mobility limitations, any inappropriate medication use, and each of the individual domain appropriateness indicators, as well as number of different domains of inappropriate use. The adjusted odds ratio for developing an ADE was 2.14 (95% confidence interval=1.26-3.65) for those with inappropriate use versus no inappropriate use.


CONCLUSIONS
Efforts to reduce ADEs by reducing medication inappropriateness should be encouraged as a complement to efforts focused on reducing the number of medications prescribed.
Chrischilles
Elizabeth A
EA
Department of Epidemiology, College of Public Health, The University of Iowa, 200 Hawkins Drive, C21-J-GH, Iowa City, IA 52242, USA. e-chrischilles@uiowa.edu
VanGilder
Rachel
R
Wright
Kara
K
Kelly
Michael
M
Wallace
Robert B
RB
D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D004347:Drug Interactions; D064420:Drug-Related Side Effects and Adverse Reactions; D005260:Female; D006801:Humans; D008297:Male; D008508:Medication Errors; D011177:Postal Service; D011446:Prospective Studies; D012307:Risk Factors