Testing for chlamydial infection: Are we meeting clinical guidelines? Evidence from a state-level laboratory data linkage analysis for 15- to 29-year-olds

Background: Clinical guidelines recommend annual chlamydia tests for all sexually active people aged 15-29 years. This study measured adherence to these guidelines and compared testing rates to the projected levels required to reduce chlamydia prevalence.

Methods: All chlamydia tests conducted in Tasmania during 2012-13, for residents aged 15-29 years, were linked. Data linkage allowed individuals who had multiple tests across different healthcare settings to be counted only once each year in analyses. Rates of testing and test positivity by age, sex, rebate status and socioeconomic indicators were measured.

Results: There were 31899 eligible tests conducted in 24830 individuals. Testing coverage was higher in females (21%, 19404/92685) than males (6%, 5426/98123). Positivity was higher in males (16%, 862/5426) than females (10%, 1854/19404). Most tests (81%, 25803/31899) were eligible for a rebate. Positivity was higher in females with non-rebatable tests (12%, 388/3116 compared with those eligible for a rebate (9%, 1466/16285). More testing occurred in areas of middle disadvantage (10%, 9688/93678) compared with least (8%, 1680/21670) and most (10%, 7284/75460) (both P<0.001) disadvantaged areas. Higher test positivity was found in areas of most-disadvantage (11%, 822/7284) compared with middle- (10%, 983/9688) and least- (8%, 139/1680) disadvantaged areas.

Conclusions: Chlamydia testing rates are lower than recommended levels. Sustaining the current testing rates in females aged 20-24 years may reduce population prevalence within 10 years. This study meets key priorities of national strategies for chlamydia control by providing a method of monitoring testing coverage and evidence to evaluate prevention programs.