Longitudinal survey of condom use across a US Navy and Marine Corps shipboard deployment

OBJECTIVES: Condoms are highly effective in preventing sexually transmitted infections (STIs) but implementation is often inconsistent with use rarely examined across travel transition periods. We examined the prevalence of condom use among ship-assigned US military personnel across an overseas deployment cycle and identified factors associated with condom non-use. METHODS: Longitudinal survey data were collected from ship-assigned US Navy/Marine Corps personnel on 11 ships before (T1), during (T2) and after (T3) an overseas deployment. The anonymous, self-completed survey included demographics, condom use at last sex, STI diagnosis, alcohol misuse and drug use with sex. Descriptive and generalised regression model analyses were conducted. RESULTS: Analysis included 1900 (T1), 549 (T2) and 1168 (T3) personnel who reported age, sex and condom use/non-use at last sex. The proportion reporting condom use was significantly higher during T2 (53%, p<0.0001) than T1 (27%) or T3 (28%), with STI prevalences of 1% (T1), 7% (T2) or 2% (T3), with fewer (29%) sexually active individuals at T2. In adjusted models, condom non-use was associated with hazardous alcohol use (OR 1.44, 95% CI 1.21 to 1.71), or drug use to enhance sex (OR 1.37, 95% CI 1.06 to 1.77), but transactional sex was negatively associated (OR 0.69, 95% CI 0.50 to 0.84). CONCLUSIONS: Condom use was highest during deployment, as was STI prevalence (among non-users), possibly reflecting concentration of high-risk sexual activities/individuals and/or sexual partners more likely to be infected. Higher condom use with transactional sex likely reflects awareness of higher STI risk. These data can be used to facilitate targeted interventions to reduce STI transmission and may extend to similarly aged cohorts travelling outside the US (eg, college students on spring break).