Do clinic-based STD data reflect community patterns?

Sexually transmitted disease (STD) interventions in communities are often based on studies conducted in STD clinics. Clinic-based studies are relatively easy to conduct, but they do not include all people at risk for STDs in the community. Although it is widely believed that clinic-based data present a biased picture of the community, the differences between clinical and community perspectives seldom have been quantified. The Sexually Transmitted Epidemic Prevention (STEP) Project included in-depth standardized interviews administered in an STD clinic and the neighbourhoods of the same town. The populations could be quantitatively compared on some questions. The two samples yielded similar estimates of the proportions using condoms, the average age at first intercourse, and the proportion sexually abused as a child. Risky sexual behaviours were more common in the clinic population, however, and the community sample was more socio-economically stable. Clinic-based data may be useful for targeting high risk people in the community but less useful for reaching those at lower risk. The utility of clinic-based studies for community-based interventions may be enhanced by collecting extra information from clinic patients with lower risk profiles.