Association between Schizophrenia and Urinary Calculi: A Population-Based Case-Control Study

BACKGROUND: People with schizophrenia have been demonstrated to have higher overall morbidity and all-cause mortality rates from general medical conditions. However, little attention has been given to the urinary system of people with schizophrenia. As no direct evidence has been reported demonstrating a link between schizophrenia and urinary calculi, this study utilized a population-based case-control study design to investigate the possibility of an association between schizophrenia and the occurrence of urinary calculi. METHOD: This study used data from the Taiwan Longitudinal Health Insurance Database. Cases consisted of 53,965 urinary calculi patients newly diagnosed between 2002 and 2008. In total, 269,825 controls were randomly selected and matched with the cases in terms of age and sex. Each person was traced to discern whether he had previously received a diagnosis of schizophrenia. Conditional logistic regression models were performed for the analysis. RESULTS: A total of 3,119 (1.0%) subjects had been diagnosed with schizophrenia prior to the index date. This included 0.7% of the patients with urinary calculi, and 1.0% of the controls. A prior diagnosis of schizophrenia was independently associated with a 30% decrease (95% CI = 0.62–0.76) in the occurrence of urinary calculi. The reduction was even more remarkable in males (38%, 95% CI = 0.55–0.71) and in elder individuals independent of gender (48% in those aged >69, 95% CI = 0.36–0.77). CONCLUSION: Our findings suggest that there is an inverse association between schizophrenia and urinary calculi. Future studies are needed to elucidate the mechanisms by which schizophrenia negatively associates with urinary calculi.