Long-term trends in the incidence of urolithiasis in the United States and China: a joinpoint regression and age-period-cohort analysis based on GBD 2021

Background Urolithiasis represents a significant global health burden. Comparing incidence trends between countries with distinct socioeconomic profiles, such as the United States and China, is crucial for tailoring public health strategies. This study aimed to characterise and compare the temporal trends of urolithiasis incidence in the United States and China from 1992 to 2021, thereby providing insights for global disease management. Methods Data on urolithiasis incidence in the United States and China from 1992 to 2021 were extracted from the Global Burden of Disease (GBD) 2021 study. First, we utilised joinpoint regression analysis to quantify the magnitude and identify significant turning points in age-standardised incidence rate trends over the study period. Second, an age-period-cohort model (APC model) was applied to assess the independent influence of age, period and cohort effects on incidence. Finally, the Nordpred model was employed to project the incidence trends for the next decade. Results From 1992 to 2021, the overall incidence of urolithiasis in the United States decreased, but has recently shown an increase; in China, there was a significant reduction. According to the APC model, the highest risk was observed among middle-aged and elderly individuals in these countries. The period and cohort effects in China showed a decline. In the United States, the period effect initially declined but has recently shown an increase; cohort effect peaked around 1930, then declined and also increased in recent years. Over the next decade, the incidence of urolithiasis in both countries was expected to increase. Conclusion This study analysed the temporal trends in urolithiasis incidence over the past 30 years in the United States and China. Both countries experienced notable advancements in the burden of urolithiasis; however, the risk of an increased incidence remained higher in the United States.