Sexual partnership dates are critical to sexually transmitted infection/HIV research and control programs, although validity is limited by inaccurate recall and reporting.Methods
We examined data from 302 heterosexual adults (151 index-partner dyads) to assess reliability of reporting. Dates of first sex and last sex were collected through individual interviews and joint dyad questionnaires, which were completed together with their partners. We compared index- and partner-reported dates to estimate interpartner agreement. We used log-linear regression to model associations between interpartner differences and partnership characteristics. To assess validity, we compared individually reported dates with those from joint dyad questionnaires.Results
Most partnerships (66.2%) were 2 years or less in duration, and many (36.2%) were nonmonogamous. Interpartner agreement to within 1, 30, and 365 days was, respectively, 5.6%, 43.1%, and 81.3% for first sex, and 32.9%, 94.5%, and 100.0% for last sex. In adjusted models, longer relationship duration was associated with disagreement on first sex dates; partnership nonmonogamy was associated with disagreement on dates of first sex and last sex. Within dyads, several participant characteristics were associated with reporting dates closer to joint dyad responses (e.g., for first sex date, female sex [54.7%], having fewer sex partners [58.5%], and greater relationship commitment [57.3%]). However, percent agreement to within 30, 60, and 90 days was similar for all groups for both first and last sex dates.Conclusions
Agreement was high on date of last sex but only moderate on date of first sex. Methods to increase accuracy of reporting of dates of sex may improve STI research.