Long-Term Dynamics of Pelvic Inflammatory Disease Attributable to Chlamydia trachomatis in Reproductive Aged Women: A Population-Based Study.

BACKGROUND: Pelvic inflammatory disease (PID) caused by Chlamydia trachomatis (C. trachomatis) remains a significant global reproductive health challenge. Understanding its variation across age groups, time periods, and geographic and sociodemographic contexts is essential for effective prevention strategies. METHODS: Estimates of C. trachomatis-related PID among women aged 15-49 years from 1990 to 2021 were analyzed. Temporal trends were quantified using estimated annual percent change (EAPC), and associations with the Sociodemographic Index (SDI) were examined. Future prevalence through 2050 was projected using autoregressive integrated moving average (ARIMA) models. RESULTS: Between 1990 and 2021, the global number of PID cases attributable to C. trachomatis increased from 143,258 to 232,246 (+62.1%), while prevalence remained relatively stable, rising from 10.71 to 11.92 per 100,000 (EAPC = 0.10). The highest prevalence in 2021 occurred among women aged 30-34 years (17.09 per 100,000), with women aged 25-39 years accounting for most cases. Low-SDI regions had the highest prevalence (16.83 per 100,000), whereas middle-SDI regions showed the fastest increase (EAPC = 0.76). Substantial geographic heterogeneity was observed, with particularly high prevalence in Australasia and Sub-Saharan Africa. Prevalence was nonlinearly associated with SDI (ρ = -0.464). By 2050, the burden is projected to increase most among women aged 30-39 years, reaching 34.49 per 100,000, with low-SDI regions projected to reach 38.51 per 100,000 and the future burden increasingly concentrated in Sub-Saharan Africa. CONCLUSIONS: While global prevalence has remained stable, the absolute number of cases continues to rise, particularly among women of mid-reproductive age and in specific low- and high-SDI regions. These findings highlight the need for context-specific and targeted interventions to address the growing burden of chlamydia-related PID.