The association between obesity and urinary tract infection

Few studies examined the relationship between obesity and urinary tract infection (UTI), showing inconsistent results. This study aims to examine the association between obesity and UTI, and to assess whether this association is independent of diabetes mellitus and 25(OH)D level.

Using the computerized database of the largest healthcare provider in Israel, we identified a cohort of subjects ≥18years old with available BMI and serum 25(OH)D level measurements between January 2009 and December 2009. The cohort was followed for the first UTI diagnosis from January 2010 through June 2011. Cox proportional hazard model was used to test the relationship between obesity and UTI.

During follow-up, 25,145/110,736 (22.7%) females, and 4032/42,703 (9.4%) males had UTI. The crude HR for UTI in those with BMI≥50 compared to BMI<25 was 2.54 (95% CI, 1.50-4.30) in males and 1.39 (1.14-1.69) in females. After adjusting for age, 25(OH)D level, and history of diabetes mellitus, the HR for UTI in those with BMI≥50 compared to BMI<25 was 2.38 (1.40-4.03) in males and 1.25 (1.03-1.52) in females. The HR for those in the lowest quartile of serum 25(OH)D compared to the highest quartile was 1.23 (1.13-1.35) in males and 0.98 (0.95-1.02) in females. The HR for subjects with diabetes was 1.23 (1.16-1.32) in males, and 1.25 (1.20-1.28) in females.

Obesity is independently associated with UTI particularly in males. Low serum 25(OH)D levels are associated with increased risk of UTI in males.