title: Use of prescription and over-the-counter medications and dietary supplements among older adults in the United States.
abstract: BACKGROUND
  Despite concerns about drug safety, current information on older adults' use of prescription and over-the-counter medications and dietary supplements is limited.
  
  
  OBJECTIVE
  To estimate the prevalence and patterns of medication use among older adults (including concurrent use), and potential major drug-drug interactions.
  
  
  METHODS
  Three thousand five community-residing individuals, aged 57 through 85 years, were drawn from a cross-sectional, nationally representative probability sample of the United States. In-home interviews, including medication logs, were administered between June 2005 and March 2006. Medication use was defined as prescription, over-the-counter, and dietary supplements used "on a regular schedule, like every day or every week." Concurrent use was defined as the regular use of at least 2 medications.
  
  
  METHODS
  Population estimates of the prevalence of medication use, concurrent use, and potential major drug-drug interactions, stratified by age group and gender.
  
  
  RESULTS
  The unweighted survey response rate was 74.8% (weighted response rate, 75.5%). Eighty-one percent (95% confidence interval [CI], 79.4%-83.5%) used at least 1 prescription medication, 42% (95% CI, 39.7%-44.8%) used at least 1 over-the-counter medication, and 49% (95% CI, 46.2%-52.7%) used a dietary supplement. Twenty-nine percent (95% CI, 26.6%-30.6%) used at least 5 prescription medications concurrently; this was highest among men (37.1%; 95% CI, 31.7%-42.4%) and women (36.0%; 95% CI, 30.2%-41.9%) aged 75 to 85 years. Among prescription medication users, concurrent use of over-the-counter medications was 46% (95% CI, 43.4%-49.1%) and concurrent use of dietary supplements was 52% (95% CI, 48.8%-55.5%). Overall, 4% of individuals were potentially at risk of having a major drug-drug interaction; half of these involved the use of nonprescription medications. These regimens were most prevalent among men in the oldest age group (10%; 95% CI, 6.4%-13.7%) and nearly half involved anticoagulants. No contraindicated concurrent drug use was identified.
  
  
  CONCLUSIONS
  In this sample of community-dwelling older adults, prescription and nonprescription medications were commonly used together, with nearly 1 in 25 individuals potentially at risk for a major drug-drug interaction.
authors.affiliation: Department of Obstetrics and Gynecology, University of Chicago, Chicago, IL 60637, USA. dqato@babies.bsd.uchicago.edu
authors.forename: Dima M
authors.initials: DM
authors.lastname: Qato
authors.forename: G Caleb
authors.initials: GC
authors.lastname: Alexander
authors.forename: Rena M
authors.initials: RM
authors.lastname: Conti
authors.forename: Michael
authors.initials: M
authors.lastname: Johnson
authors.forename: Phil
authors.initials: P
authors.lastname: Schumm
authors.forename: Stacy Tessler
authors.initials: ST
authors.lastname: Lindau
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015897:Comorbidity; D019587:Dietary Supplements / Q000009:adverse effects / Q000706:statistics & numerical data*; D004347:Drug Interactions; D004363:Drug Utilization; D005260:Female; D006304:Health Status; D006306:Health Surveys; D006801:Humans; D008297:Male; D008875:Middle Aged; D004366:Nonprescription Drugs / Q000009:adverse effects; D055553:Prescription Drugs / Q000009:adverse effects; D012306:Risk; D012959:Socioeconomic Factors; D014481:United States
chemical_list: D004366:Nonprescription Drugs; D055553:Prescription Drugs