Abstract
PURPOSE: Many chlamydia infections are identified through screening, which is frequently offered to females concomitantly with cervical cancer screening. Recent cervical cancer screening guidelines recommend screening less frequently and starting later. We sought to evaluate the impact of the May 2012 Ontario, Canada, cervical cancer screening guideline change on Papanicolaou (Pap) and chlamydia trachomatis (chlamydia) testing and incidence. METHODS: We extracted population-based physician billing claims data to identify Pap and chlamydia tests and public health surveillance data to identify chlamydia cases. We used interrupted time series analysis of quarterly data spanning 2 years before and after the guideline change and fitted segmented linear regression or rational functions to the outcomes using autoregressive integrated moving average models. Outcomes were stratified by sex and age group. RESULTS: Two years after the guideline change, we observed reduced chlamydia testing in females, with the greatest relative reduction (25.5%) among those aged 15 to 19 years. We also observed decreases in reported chlamydia incidence for females aged 15 to 19 years and 20 to 24 years (relative reductions of 16.8% and 14.4%, respectively). Chlamydia incidence remained the same for males, despite increased chlamydia testing. CONCLUSIONS: Recent cervical cancer screening guideline changes in Ontario were associated with reduced chlamydia testing and reported new cases of chlamydia in females. Females aged 15 to 19 years, who are at high risk for chlamydia if sexually active, and who no longer warrant cervical cancer screening, were disproportionately affected. Females should be tested for chlamydia based on risk, regardless of need for Pap testing.