Background Monitoring trends in chlamydia-related sequelae, such as epididymitis and pelvic inflammatory disease (PID), is an important aspect of the evaluation of chlamydia control initiatives such as the National Chlamydia Screening Programme (NCSP). Unlike PID, which can be difficult to diagnose, epididymitis may be a useful measure for evaluation purposes. The objective of this analysis was to examine trends in epididymitis diagnosis rates in the era of increased chlamydia testing.

Methods Diagnoses of epididymitis among 15–35 year old males were obtained from the genitourinary medicine (GUM) clinic activity dataset version 2. Diagnosis rates were calculated, per year, using the number of new-episode male clinic attendances. This accounted for changes in clinic attendance over the years. Negative binomial regression was used to derive the incidence rate ratios (IRR) and test significance of the trends.

Results Between 2009 and 2013, a total of 24,689 diagnoses of epididymitis were made among 15–35 year old males, of which 10% (2,506) were of chlamydial and 2% (473) of gonoccocal aetiology. Diagnosis rates of chlamydial epididymitis declined by an average of 12% per year (IRR = 0.88, 95% CI; 0.81–0.96, p < 0.001), while no statistically significant changes were observed in rates of gonoccocal epididymitis (IRR = 0.93, 95% CI; 0.86–1.00 p = 0.276). A small but significant decline of 2% per year (IRR 0.98: 95% CI; 0.96–0.99, p = 0.001) was observed for rates of non-specific epididymitis.

Conclusion The decreased rate of chlamydial epididymitis diagnoses in men may be associated with increased chlamydia testing, however, the influence of other contributing factors should be explored.