Abstract Body: Background: While occupational factors and social determinants of health (SDOH) are associated with kidney stone disease (KSD) risk in US cohorts, their role in other populations remains unexplored. We investigated the extent to which these factors are associated with KSD incidence in a Brazilian cohort.

Hypothesis: Occupational and social factors are associated with KSD risk in a Brazilian working population.

Methods: The Pro-Saude study followed employees of Universidade do Estado do Rio de Janeiro from 1999 to 2012. Baseline exposures included occupation (International Standard Classification of Occupations skill level), work hours/week, years worked, household income, education, and supplementary health insurance status. Incident KSD was defined as a first self-reported kidney stone between baseline and follow-up visits (2001, 2012). Multivariable Cox proportional hazards models estimated the risk of KSD across exposures, adjusting for known KSD risk factors.

Results: Among 2,986 participants (mean age 40.4 years; 43.3% male), 148 developed KSD over 13 years. Participants without supplementary health insurance had significantly lower reported KSD incidence than those with supplementary health insurance (adjusted HR 0.66 [95% CI 0.44-0.97]; Figure 1). Other occupational and social factors showed no statistically significant associations with KSD risk.

Conclusion: No supplementary health insurance was paradoxically associated with lower reported kidney stone incidence, a finding likely driven by detection bias rather than a protective effect. This suggests that individuals with more limited access to healthcare have lower rates of kidney stone diagnosis and reporting.