An evaluation of the performance characteristics of World Health Organization syndromic management for C. trachomatis and N. gonorrhoeae infections among female sex workers in Mombasa, Kenya

Abstract An evaluation of the performance characteristics of World Health Organization syndromic management for C. trachomatis and N. gonorrhoeae infections among female sex workers in Mombasa, Kenya Gregory Zane Chair of the Supervisory Committee: Dr. Jennifer Balkus Department of Epidemiology Objectives: To assess the performance characteristics of the World Health Organization’s (WHO) syndromic surveillance algorithms for the management of C. trachomatis (CT) and N. gonorrhoeae (GC) compared to nucleic acid amplification testing (NAAT) in a cohort of cisgender women at high risk of sexually transmitted infections (STIs) in Mombasa, Kenya. Methods: Sensitivity, specificity, negative predictive value (NPV) and positive predictive value (PPV) were calculated for syndromic criteria (self-reported vaginal discharge, vaginal discharge plus lower abdominal/adnexal pain, and vaginal discharge and/or lower abdominal/adnexal pain) versus CT/GC results from Aptima Combo II Assays for the study population overall and stratified by age (<25 years versus ≥ 25 years). We estimated the proportion of CT/GC infections that would be missed if only syndromic surveillance were implemented for routine screening (1 minus sensitivity). In addition, we assessed factors associated with self-reported vaginal discharge and lower abdominal/adnexal pain. Results: Between 2004-2017, 1,860 participants contributed 20,550 visits to this analysis. At first NAAT, median age was 31.7 years (interquartile range 26.9, 37.5). There were 353 (1.7%) cases of CT, 470 (2.3%) cases of GC, and 795 (3.9%) cases of CT and/or GC. Vaginal discharge, abdominal pain, and vaginal discharge and/or abdominal pain were reported at 1,247 (6.1%), 249 (1.5%) and 1,484 (7.3%) visits, respectively. Sensitivity, specificity, NPV, and PPV for self-reported vaginal discharge and/or abdominal pain versus NAAT for CT/GC were 15.3% 93.0%, 96.5%, and 8.1%, respectively. Limiting STI screening to syndromic management would result in 84.7% of CT/GC infections being missed due to asymptomatic presentation (95% confidence interval (CI) 82.0, 87.2). Results were similar when CT and GC were assessed as separate outcomes for all three syndromic algorithms. When stratified by age, sensitivity and PPV were higher for younger women (<25 years) than older women when CT or CT/GC NAAT results were used as a gold standard. Correlates analyses showed factors associated with reduced odds of self-reported vaginal discharge included age, parameterized as a continuous variable, (OR = 0.94 (95% CI 0.93, 0.95)) and use of highly effective, modern contraception (oral contraceptive pills (OCP), depot medroxyprogesterone acetate (DMPA), intrauterine device (IUD), and hormonal implant) compared to coitally-dependent (i.e. condoms) or no family planning method (OR = 0.75; 95% CI = 0.62, 0.89). Factors associated with an increased odds of self-reported vaginal discharge included any vaginal washing (OR = 1.28; 95% CI 1.01, 1.64) and reporting of any sexual partners in the last working week (OR = 1.03; 95% CI 1.01, 1.04), after adjustment for respective covariates. Factors associated with reduced odds of self-reported abdominal/adnexal pain were older age (OR = 0.97; 95% CI 0.95, 0.99) and any vaginal washing during the last working week (OR = 0.56; 95% CI 0.41, 0.76). Any contraception use (OR = 1.68; 95% CI 1.04, 2.71) was the only factor associated with increased odds of self-reported abdominal/adnexal pain, after adjustment for respective covariates. Conclusions: Among cisgender women with CT or GC diagnosed by NAAT, the prevalence of asymptomatic infections was extremely high, limiting the utility of syndromic approaches for routine STI screening. The development of low-cost, point-of-care STI diagnostics remains a public health priority, both to inform clinical decision making and improve STI surveillance in resource-limited settings.