Overweight and high-sensitivity C-reactive protein are weakly associated with kidney stone formation in Japanese men

To investigate longitudinal relationships between obesity/inflammation and kidney stone formation in a population where obesity is not prevalent.

Using Cox regression models, associations between kidney stone formation and body mass index, waist circumference, high-sensitivity C-reactive protein and other possible risk factors were retrospectively examined in a health screening Japanese population including 1726 men and 992 women.

During 4 years of follow up (mean 3.2 years), kidney stones were formed in 238 men (34.5 per 1000 person-years) and 82 women (20.7 per 1000 person-years). In men, when the possible risk factors were separately examined as continuous parameters, body mass index (P = 0.030) and waist circumference (P = 0.025) were significantly, and log C-reactive protein (P = 0.092) were marginally, associated with kidney stone formation. However, none of these parameters was independently associated with kidney stone formation after fully adjusted. In women, none of the aforementioned three parameters was associated with kidney stone formation. As a categorical parameter, the higher two quintiles of C-reactive protein were significantly associated with kidney stone formation compared with the lower two quintiles in men (P = 0.026).

Overweight and C-reactive protein are weakly associated with kidney stone formation in Japanese men. Inflammation might be an underlying mechanism of the association between obesity and kidney stone formation.