Recording sexual behavior: comparison of recall questionnaires with a coital diary.

OBJECTIVE: To compare sexual behavior data obtained using a weekly-recall questionnaire, a daily-recall questionnaire, and a coital diary.
DESIGN: Cross-sectional survey of female sex workers from KwaZulu-Natal, South Africa between August and October 1998.
METHODS: In this study, 52 weekly-recall questionnaires, 27 daily-recall questionnaires, and 79 coital diaries for dates corresponding to the questionnaires were obtained from female sex workers. Variables examined included: number of clients, number of condoms used with clients and partners, and number and type of sexual acts with clients and partners. Statistical analyses were conducted to examine the degree of agreement between the data collection methods and to assess differences between the mean values of the variables in the questionnaires versus the diary.
RESULTS: Comparison of weekly-recall questionnaires with coital diaries indicated a significantly greater mean number of clients (P < 0.001), number of condoms used (P < 0.001), vaginal acts (P < 0.001), and anal acts (P = 0.044) reported in the diary versus the questionnaire. On comparison of daily-recall questionnaire with coital diary, significant differences were revealed between the means detected for the number of clients (P = 0.027), number of days worked (0.009), and anal acts with clients (P = 0.004).
CONCLUSIONS: The use of coital diaries for the collection of sexual behavior data may be limited to cross-sectional community surveys. A recall questionnaire may provide more reliable and a better quality of data for longitudinal studies and for human immunodeficiency virus/sexually transmitted disease evaluation programs.