Incidence and prevalence of systemic lupus erythematosus in urban China, 2013-2017: A nationwide population-based study.

Systemic lupus erythematosus (SLE) is becoming a growing public health concern due to increasing disease and economic burdens. Epidemiological information about SLE, especially its incidence rate, is limited in developing countries. In the current study, we sought to investigate the incidence, prevalence, and economic burdens of SLE in urban China. We conducted a nationwide population-based cohort study using databases from Urban Employee Basic Medical Insurance and Urban Resident Basic Medical Insurance between 2013 and 2017, covering approximately 300 million residents in 23 provincial regions in China. Incidence rate and prevalence were standardized by age and gender to China's 2010 national census data. Additionally, we calculated the average annual costs and hospital visit rates. A total of 132,258 SLE patients were identified during the study period, with a mean age of 43.03 years (standard deviation: 15.29 years). Of these patients, 81.33% were women. In 2017, the standardized incidence rate of SLE in China was 14.09 (95% confidence interval (CI), 11.95-16.41) per 100,000 person-years, with a higher incidence in women than in men (26.41 vs. 5.92 per 100,000 person-years). Standardized prevalence in 2017 was 47.61 (41.77-53.83), 94.16 (80.67-108.69), and 17.86 (13.84-22.38) per 100,000 people in the overall, female, and male populations, respectively. The average annual rates of increase in prevalence were 21.50%, 19.72%, and 25.67% from 2013 to 2017 in the overall, female, and male populations, respectively. The age-specific incidence rates peaked at 30-49 years old in women and 40-59 years old in men. SLE incident and prevalent cases were most common in North-West China and less common in southern and eastern China. Distinct variations in incidence rates across different regions are also consistent with the varying levels of ultraviolet radiation exposure in China. Additionally, the average estimated annual per-capita cost was 1599.34 US dollars in SLE patients, with the highest costs observed in adolescent and young adult patients among different age groups. The SLE population in China is rapidly expanding, and younger at onset, especially in women, which has placed significant burdens on China's healthcare system.