An interview strategy was critical for obtaining valid information on the use of hormone replacement therapy.

Objective: We compared telephone reports of hormone replacement therapy (HRT) use to claims for drugs dispensed.

Study Design And Setting: The study subjects included 106 women who were dispensed HRT and 107 who were not dispensed HRT.

Results: Recall of drug use overall was relatively good (65/79=82.3%, 95% confidence interval [CI] 73.9-90.7). Agreement between recall of drug name and the claims for dispensed drugs was lower (61/79=77.2%, 95% CI 68.0-86.5). Of 65 women reporting use of HRT in response to the indication prompt, nine (13.8%) could not identify the drug name using the drug list prompt, but all 65 women identified a drug using the photo prompt. Recall of start date of drug use was poor (29.2% agreement on month/year; 45.8% agreement within 1 month), and recall of end date of drug use was poorer yet (7.7% agreement on month/year; 21.5% agreement within 1 month).

Conclusion: Recall of drug use and drug names is far better than recall of dates of use. Recall can be enhanced with lists of drug names and color photos, but even with memory prompts, recall remains imperfect. If drug use is the primary exposure of interest in a study, considerable effort is needed to collect it correctly. If not, then perhaps drug histories should be omitted.