Background Concurrent sexual partnerships can increase sexually transmissible infections (STI) transmission on a population level. However, different concurrency types may be associated with differential risks for transmission. To investigate this, we describe the prevalence and correlates of four specific concurrency types. Methods: Between 2001 and 2004, 1098 young adults attending three STI clinics were interviewed and tested for STIs. Characteristics associated with concurrency types were identified using logistic regression. Results: Approximately one-third of respondents reported reactive (34%), transitional (36%), compensatory (32%) and experimental (26%) concurrency. Among men, reactive concurrency was associated with not identifying as heterosexual, drug use and having sex the same day as meeting a partner. Among women, reactive concurrency was associated with African-American race and having >3 lifetime partners. Transitional concurrency was associated with >3 lifetime partners for men and women. Among men, compensatory concurrency was associated with African-American race; among women, there were no associations with compensatory concurrency. Among men, experimental concurrency was associated with >3 lifetime partners and having sex the same day as meeting a partner. Among women, experimental concurrency was associated with not identifying as heterosexual, drug use and having sex the same day as meeting a partner. Conclusions: All concurrency types were common in this population and each was associated with a set of demographic and risk factors. Reactive and experimental concurrency types were associated with other high-risk behaviours, such as drug use.
Risk behaviours by type of concurrency among young people in three STI clinics in the United States