Nationwide population based epidemiological characteristics of complex regional pain syndrome in South Korea.

Complex regional pain syndrome (CRPS) is a chronic and disabling pain disorder with limited nationwide epidemiological data. We conducted a population-based, repeated cross-sectional study using Korean Health Insurance Review and Assessment Service data from 2013 to 2022. CRPS cases were identified using Korean Classification of Diseases codes. Annual incidence and prevalence per 100,000 population were calculated and stratified by subtype, sex, and age. Crude rates showed a consistent decline in CRPS type I incidence and prevalence during the study period. Temporal trends were evaluated using negative binomial regression. Model 1 estimated overall temporal trends while adjusting for age and sex. CRPS type I demonstrated significant annual declines in incidence (20.5 to 6.5; IRR = 0.91, p < 0.001) and prevalence (30.6 to 16.8; PR = 0.93, p < 0.001), whereas type II showed no significant changes. Model 2 incorporated interaction terms between calendar year and demographic variables to assess subgroup differences. Although the overall decreasing trend for type I remained significant, age–year interactions were identified, with individuals aged ≥ 80 years demonstrating stable or modestly increasing patterns. These findings reveal subtype-specific temporal patterns and demographic heterogeneity in nationwide CRPS trends, offering updated epidemiological data to support future CRPS healthcare planning.