Can the male-to-female ratio of gonorrhoea in one sexually transmissible infection treatment facility be solely used to judge its efficiency?

BACKGROUND: This facility has for a long time audited its efficacy in contact tracing (case finding) and found results comparable with national guidelines. In addition, we consistently measure control of the disease using three indices. A departure from the norm in one of these (the male-to-female ratio) prompted us to explore whether local case finding, and therefore control, was lacking resulting in the identification of a statistical anomaly. We have learnt a lesson, which may be of use to others who critically evaluate their work.

METHODS: Review of statutory clinic quarterly returns and manually-held contact tracer data, comparison of representative quarters (Wilcoxson sign rank test) and detailed inspection of sampled case-to-case contact tracing efficiency.

RESULTS: Evidence was found challenging our belief that male-to-female ratios are at face value an inevitably accurate surrogate for case finding or infection control. In our clinic, we identified recording anomalies giving rise to false concerns that case finding was less efficient than usual.

CONCLUSIONS: Although the heterosexual male:female ratio for gonorrhoea is one readily available and proxy measure of disease control and tracing efficiency, its sole use should be interpreted with caution. A time lag across quarters between patient and partner attendance and other recording anomalies may mislead. Ratios should therefore be interpreted in the context of partner notification outcomes, which give a more reliable measure of efficiency. The use of the ratio in critical evaluation of a unit's efficiency should be but one part of a package of measures.