Background Incidence and risk factors for NGU remain poorly defined. We conducted a cohort study to estimate incidence and identify associated risk factors in MSW.

Methods We enrolled cisgender male STD clinic patients age ≥16, who reported exclusively female partners. At enrollment and six monthly follow-up visits, men underwent a clinical exam, provided urethral swab and urine specimens, and completed a sexual behavior survey. We tested for chlamydia (CT) and Mycoplasma genitalium (MG) using Aptima. NGU was defined as urethral symptoms or visible discharge plus ≥5 polymorphonuclear leukocytes per high-power field on a Gram-stained slide. NGU following an NGU-negative visit was considered incident. We estimated incidence of NGU overall, pathogen-associated (MG or CT) and idiopathic NGU using Poisson regression for clustered outcomes. We performed relative risk binomial regression for clustered data to identify characteristics associated with incident NGU.

Results From 08/2014-08/2018, 254 participants had ≥1 follow-up visit, contributing 100.6 person-years at risk during follow-up. Median age was 32 (range=17–71), 53% were white and 24% black. Eighty-four (33%) had NGU at enrollment. Forty-five men had 53 cases of incident NGU (incidence=0.53 per person-year (95% confidence interval [CI]=0.39–0.71)). Incidence of pathogen-associated and idiopathic NGU was 0.06 (95% CI 0.03–0.13) and 0.47 (95%CI = 0.34–0.63), respectively. After adjustment for age, condom use and new partners during follow-up, risk of incident NGU was higher among black men (adjusted RR (ARR)=2.2; 95%CI=1.1–4.4), those with a history of NGU before enrollment (ARR=3.1; 1.5–6.5) and more sex partners during follow-up (ARR=1.2 per partner; 1.0–1.5); risk was lower among men who used lubricant at last sex (ARR=0.44; 0.20–0.96).

Conclusion Incidence of NGU was high, predominantly idiopathic, and associated with traditional socio-behavioral characteristics, but not age, condom use, or new partners. The lubricant-use association was unexpected and warrants further exploration. More precise daily diary data may yield additional insights.

Disclosure No significant relationships.