Obesity as measured by body mass index (BMI) is associated with increased risk for urinary tract infection (UTI) and pyelonephritis in both sexes, according to a retrospective, cross-sectional study.
Overall, the incidences of UTI and pyelonephritis were 2.5- and 5-fold higher among obese individuals (BMI ≥ 30 kg/m2) than among nonobese individuals, report Michelle J. Semins, MD, and colleagues from the Johns Hopkins University School of Medicine in Baltimore, Maryland, in an article published in the February issue of Urology.
"Obesity has also been associated with urological conditions such as male and female sexual dysfunction, infertility, incontinence, genitourinary malignancy, and nephrolithiasis," the authors write. "A similar relationship between obesity and [UTI] may exist but it has not been as well defined."
To better characterize the potential association, the researchers examined UTI rates among 95,598 participants who were drawn from a national private insurance claims database. All participants were insured by Blue Cross and Blue Shield in 7 states during the period of 2002 to 2006 and had undergone a health risk assessment that included BMI screening.
In total, 13% of participants developed UTIs, and 0.84% developed pyelonephritis. The incidence of UTI was higher among both men and women with a BMI of from 30.0 to 34.9 kg/m2 than among those with a BMI lower than 30 kg/m2 (men: odds ratio, 1.59; 95% confidence interval [CI], 1.43 - 1.76; P < .0001; women: odds ratio, 1.22; 95% CI, 1.15 - 1.28; P < .0001). In addition, women were 4.2- and 3.6-fold more likely to develop UTIs and pyelonephritis than men, respectively.
The authors defined UTI and pyelonephritis according to International Classification of Diseases, Ninth Revision, codes. In this study, "UTI" included both UTI and cystitis, whereas "pyelonephritis" was restricted to acute and chronic pyelonephritis.
The authors mention that the association between obesity and infection could have medical and financial implications. "[T]he high incidence of infection observed in the obese population places a meaningful financial burden on health care resource use and may also lead to other medical complications," the authors write. "Further study to determine whether weight loss among the obese population translates to a reduced risk of infection should be undertaken."