Association Between Body Mass Index and Age at End-Stage Renal Disease in Patients With Autosomal Dominant Polycystic Kidney Disease in the United States and Japan

Objective

To evaluate the association between body mass index (BMI) and age at initiation of renal replacement therapy (RRT) of patients with autosomal dominant polycystic kidney disease (ADPKD) in the United States and Japan, 2 populations with different dietary habits and BMIs.

Methods

We performed a cross-sectional analysis using data from the United States Renal Data System (USRDS) and the Japanese Society for Dialysis Therapy Renal Data Registry (JRDR) to compare age, BMI, and other clinical characteristics of the patients who initiated RRT in the 2 countries between January 1, 2006, and December 31, 2007.

Results

This study included 3556 patients (1877 men and 1679 women) with RRT from the USRDS (n=2491) and JRDR (n=1065). Mean ages at RRT were 56.6±13.1 years in the United States and 61.6±12.5 years in Japan (P<.001). The BMI was 28.2±7.1 kg/m² in the USRDS and 22.0±3.3 kg/m² in the JRDR (P<.001). Japanese participants were the oldest, followed in descending order by Asian Americans, White Americans, and African Americans. Japanese participants had the lowest BMI, followed in ascending order by Asian Americans, White Americans, and African Americans. Univariable and adjusted analyses found that BMI was significantly and inversely associated with age at RRT, both overall and separately in American and Japanese populations.

Conclusion

Lower BMI is significantly associated with older age at RRT in patients with ADPKD in both the United States and Japan. Japanese individuals had lower BMI and were older than US people of various ethnicities. Lower BMI in Japan is likely to be associated with a slower progression of ADPKD.