Decreased body mass index as an independent risk factor for developing chronic kidney disease

Obesity and metabolic syndrome are risk factors for the development of chronic kidney disease (CKD). Few studies have examined the effect of change in body mass index (Delta BMI) on CKD incidence in a general screening setting. Subjects of this study were screenees that participated in the screening program of the Okinawa General Health Maintenance Association in 1993 and 2003 in Okinawa, Japan. Using identification number, birth date, sex, and other recorded identifiers, we identified 33,389 subjects among the 1993 screening participants (N = 143,948) who also participated in the 2003 screening. CKD was defined as estimated glomerular filtration rate < 60 ml/min/1.73 m(2), according to the modification of diet in renal disease study equation. Obesity was defined as BMI a parts per thousand yen 25 kg/m(2). CKD prevalence was 13.8% in 1993 and 22.4% in 2003. The incidence of developing CKD in 10 years was 15.5%. The effect of Delta BMI on CKD incidence was evaluated after considering other confounding factors such as age, sex, blood pressure, BMI, fasting plasma glucose, and proteinuria. Median Delta BMI was 1.0%. The adjusted odds ratio (95% CI) for the effect of Delta BMI on CKD incidence was 1.111 (1.026-1.204, P < 0.01; entire study population), 1.271 (1.116-1.448, P = 0.0030; men), and 1.030 (0.931-1.139, NS; women), when Delta BMI a parts per thousand yen 1% was taken as a reference. Delta BMI was an independent predictor of CKD incidence. The present results suggest that there was an inverse relationship between Delta BMI and CKD incidence among screened subjects. The reasons for this observation are not clear, but careful follow-up for Delta BMI is necessary, particularly in obese men with proteinuria.