The impact of concurrency on sexually transmitted infection transmission depends on coital frequency, condom use, duration of relationship overlap, and number of partners. Previous research has identified distinct concurrency types; however, little is known about their risk characteristics.Methods
Men (n = 261) and women (n = 275) aged 18 to 30 years at increased risk for acquiring HIV were recruited from community locations in Los Angeles. Participants completed 4 in-person interviews for 12 months. Partnership data were used to characterize the prevalence of 4 types of concurrency: transitional (2 overlapping relationships in which the first relationship ended before the second), single day (a second relationship of 1 day’s duration during the course of another relationship), contained (a second relationship >1 day began and ended during the course of another), and multiple (≥3 overlapping relationships). Multilevel random intercept models were used to estimate mean coital frequency, proportion of condom-protected acts, total duration of overlap, and lifetime sex partners.Results
At baseline, 47% of male and 32% of female participants reported any type of concurrency in the previous 4 months, and 26% of men and 10% of women reported multiple concurrencies. Condom use ranged from 56% to 64%, with the highest use in transitional concurrency (61% for men, 68% for women) and the lowest in contained (52% for men, 54% for women). Coital frequency, total overlap, and lifetime sex partners also varied by concurrency type.Conclusions
Inconsistent condom use and repeated opportunities for exposure characterize common types of concurrency among high-risk young adults.