Microscopic examination of Gram-stained smears for anogenital gonorrhoea in men who have sex with men is cost-effective: evidence from a modelling study.

OBJECTIVE: To assess the cost-effectiveness of three testing strategies with or without light microscopic Gram-stained smear (GSS) evaluation for the detection of anogenital gonorrhoea among men who have sex with men (MSM) at the Amsterdam STI clinic using a healthcare payer perspective.

METHODS: Three testing strategies for MSM were compared: (1) GSS in symptomatic MSM only (currently practised strategy), (2) no GSS and (3) GSS in symptomatic and asymptomatic MSM. The three testing protocols include testing with nucleic acid amplification test to verify the GSS results in (1) and (3), or as the only test in (2). A transmission model was employed to calculate the influence of the testing strategies on the prevalence of anogenital gonorrhoea over 10 years. An economic model combined cost data on medical consultations, tests and treatment and utility data to estimate the number of epididymitis cases and quality-adjusted life years (QALY) associated with gonorrhoea. Incremental cost-effectiveness ratios (ICERs) for the testing scenarios were estimated. Uncertainty and sensitivity analyses were performed.

RESULTS: No GSS testing compared with GSS in symptomatic MSM only (current strategy) resulted in nine extra epididymitis cases (95% uncertainty interval (UI): 2-22), 72 QALYs lost (95% UI: 59-187) and €7300 additional costs (95% UI: -€185 000 (i.e.cost-saving) to €407 000) over 10 years. GSS testing in both symptomatic and asymptomatic MSM compared with GSS in symptomatic MSM only resulted in one prevented epididymitis case (95% UI: 0-2), 1.1 QALY gained (95% UI: 0.1-3.3), €148 000 additional costs (95% UI: €86 000 to-€217 000) and an ICER of €177 000 (95% UI: €67 000-to €705 000) per QALY gained over 10 years. The results were robust in sensitivity analyses.

CONCLUSIONS: GSS for symptomatic MSM only is cost-effective compared with no GSS for MSM and with GSS for both symptomatic and asymptomatic MSM.