Medical use of controlled medications was measured using the following question: “The following questions are about the use of prescribed medicines. We are not interested in your use of over-the-counter medicines that can be bought in drug or grocery stores without a prescription, such as aspirin, Sominex (GlaxoSmithKline, London, United Kingdom), Benadryl (McNeil Consumer Healthcare, a subsidiary of Johnson & Johnson, New Brunswick, New Jersey), Tylenol PM (McNeil Consumer Healthcare, a subsidiary of Johnson & Johnson), cough medicine, etc. On how many occasions in your lifetime has a doctor, dentist, or nurse prescribed the following types of medicine for you?” A separate question was asked for each of the following 4 controlled medication classes and examples of generic and brand names were provided to respondents: (1) prescribed sleeping medication (eg, zolpidem [Ambien; sanofi-aventis, Bridgewater, New Jersey], eszopiclone [Lunesta; Sepracor, Marlborough, Massachusetts], temazepam [Restoril; Mallinckrodt Pharmaceuticals, Hazelwood, Missouri], generic tempazepam, and generic triazolam), (2) prescribed antianxiety medication (eg, lorazepam [Ativan; Biovail Pharmaceutical, Inc, Mississauga, Ontario, Canada], alprazolam [Xanax; Pfizer, Inc, New York, New York], diazepam [Valium; Roche Laboratories, Inc, Nutley, New Jersey], clonazepam [Klonopin; Hoffmann-La Roche, Inc, Nutley, New Jersey], generic diazepam, and generic lorazepam), (3) prescribed stimulant medication (eg, methylphenidate hydrochloride [Ritalin; Novartis Pharmaceuticals Corporation, East Hanover, New Jersey], dextroamphetamine sulfate [Dexedrine; Catalent Pharma Solutions, Winchester, Kentucky], dextroamphetamine-amphetamine [Adderall; Shire US, Inc, Wayne, Pennsylvania], and methylphenidate hydrochloride [Concerta; ALZA Corporation, Mountain View, California], and generic methylphenidate), and (4) prescribed pain medication (eg, opioids, such as acetaminophen–hydrocodone bitartrate [Vicodin; Abbott Laboratories, Abbott Park, Illinois], oxycodone [OxyContin; Purdue Pharma LP, Stamford, Connecticut], acetaminophen–codeine phosphate [Tylenol 3 with codeine; Johnson & Johnson], acetaminophen–oxycodone hydrochloride [Percocet; DuPont Merck Pharmaceutical Company, Wilmington, Delaware], acetaminophen–propoxyphene napsylate [Darvocet-N; Eli Lilly and Company, Indianapolis, Indiana], generic morphine sulfate, generic hydrocodone, and generic oxycodone and morphine sulfate). Similar questions were asked about past-year use. The response scale for each question ranged from (1) 0 occasions to (7) 40 or more occasions. For analysis, a binary variable indicating medical use (yes or no) was created for each class of prescription medication, and a binary variable indicating any medical use (yes or no) was created by summing the medical use of the 4 controlled medication classes.