Trajectories of body mass index and incident kidney stone disease: a prospective cohort study in Chinese young adults.

The present study aims to explore the potential changing trajectory patterns of body mass index (BMI) for Chinese young adults and identify the relationship of BMI trajectory patterns with kidney stone disease (KSD) incidence. Latent class growth analysis was used to identify distinct trajectories of BMI during young adulthood. Cox proportion hazard models were conducted to explore the association between the BMI trajectory group memberships and incident KSD. Subgroup and sensitivity analyses were undertaken to test the robustness of the findings. In total, 2,966 young adults who attended at least three annual check-ups from 2014 to 2021 without KSD at baseline were enrolled in the cohort analysis. Three district BMI trajectories were identified for young adults, labeled as low-stable in normal BMI (28.5%), medium-rising to high BMI (67.4%), and rapid-rising to high BMI (4.1%). Compared with the low-stable in normal BMI group, Hazard ratios (HRs) of the rapid-rising and medium-rising to high BMI groups were 3.19 (95% CI: 1.54-6.63) and 1.78 (95% CI: 1.08-2.92) after adjusting the covariates. The cumulative incidence curves likewise illustrated that young adults in the rapid-rising to high BMI group had the highest risk of developing KSD compared to the other two groups. The rapid BMI growth trajectories during young adulthood were identified to be independently associated with a higher risk of KSD. The findings supplied novel insights that monitoring the BMI changing pattern may be favorable to early intervention of KSD during young adulthood.