Usefulness of waist circumference as a marker of abdominal adiposity in peritoneal dialysis: a cross-sectional and prospective analysis.

BACKGROUND Waist circumference (WC) has been well recognized as a surrogate marker of abdominal adiposity. In peritoneal dialysis (PD) patients, however, aspects related to this dialysis modality, such as abdominal distension, presence of catheter and frequent hernia, raise questions regarding the reliability of WC measurements. Herein, we investigated for the first time whether WC is a reliable marker of abdominal adiposity in PD population. METHODS This study included 107 prevalent PD patients [56% male, age 52 ± 17 years, 35% diabetics, body mass index (BMI) 24.8 ± 3.9 kg/m(2)]. WC measured at umbilicus level was evaluated against the trunk fat assessed by dual-energy x-ray absorptiometry at baseline and after 6 months. All measurements were taken with the empty abdominal cavity. RESULTS At baseline, a strong correlation of WC with trunk fat (r = 0.81; P < 0.001) was observed. Adjusting for gender, age, dialysis vintage and BMI, WC was independently associated with trunk fat (β = 0.30; P < 0.001; R(2) = 0.77). The agreement between WC and trunk fat was 0.59 (kappa statistic) and the area under the curve was 0.90. In the prospective evaluation, we observed that changes in WC correlated with changes in trunk fat as well (r = 0.49; P < 0.001). The kappa statistic of 0.48 remained indicative of a moderate agreement between the methods. The receiver operating characteristic curve analysis showed that WC was sensitive to detect changes in trunk fat (area under the curve 0.76). In the logistic regression analysis adjusting for gender, age and BMI, changes in WC were independently associated with changes in trunk fat. CONCLUSION The simple anthropometric method of WC is a reliable marker of abdominal adiposity in PD patients.