A methodological study was performed in 1992 to evaluate the accuracy of self-reported use of nonsteroidal antiinflammatory drugs (NSAIDs) and noncontraceptive estrogens that had been dispensed during the previous 12 years.

A sample of 560 individuals dispensed NSAIDs or estrogens, and 140 individuals without NSAID/estrogen dispensations were selected from the Group Health Cooperative pharmacy database.

Demographic, behavioral, and drug information was ascertained by telephone interview for 356 persons with and 98 persons without NSAID/estrogen dispensations.

Of those with only a single NSAID dispensation, 41% (95% confidence interval (CI) 32-50%) were able to recall any NSAID use compared with 85% (95% CI 76-94%) for those with multiple NSAID dispensations.

Thirty percent (95% CI 24-36%) recalled the NSAID name, and 15% (95% CI 10-20%) recalled both the name and dose.

For estrogens, 78% (95% CI 70-86%) recalled the name, but only 26% (95% CI 17-34%) recalled the name and dose.

Age, but not sex, appeared to influence recall accuracy : Persons 50-65 years of age recalled the NSAID name more accurately than those aged 66-80 (odds ratio (OR)=1.8,95% confidence interval (CI) 1.0-3.4).

A similar advantage was noted for 50-to 65-year-old women in recalling the estrogen name (OR=1.5,95% CI 0.6-3.9).

This study suggests significant underascertainment of self-reported prescription drug exposure but little evidence that exposures are overreported.