Association of waist circumference and body mass index with all-cause mortality in CKD: The REGARDS (Reasons for Geographic and Racial Differences in Stroke) Study

Abstract

Background: Obesity management requires understanding the mortality risks associated with different adiposity measures.

Study design: Prospective cohort.

Setting & participants: 5,805 adults with body mass index (BMI) ≥18.5 kg/m(2) and stages 1-4 chronic kidney disease, defined as a spot urine albumin-creatinine ratio ≥30 mg/g and/or estimated glomerular filtration rate <60 mL/min/1.73 m(2), enrolled in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) Study.

Predictor: BMI categorized as 18.5-24.9, 25.0-29.9, 30.0-34.9, 35.0-39.9, and ≥40 kg/m(2) and waist circumference categorized as <80, 80-87.9, 88-97.9, 98-107.9, and ≥108 cm in women and <94, 94-101.9, 102-111.9, 112-121.9, and ≥122 cm in men.

Outcomes: All-cause mortality.

Measurements: BMI and waist circumference were measured using a standardized protocol during the home visit.

Results: 686 (11.8%) deaths occurred during a median follow-up of 4 years. Compared with the referent BMI category of 25-29.9 kg/m(2), HRs for mortality were 1.27 (95% CI, 0.96-1.69) for BMI <25 kg/m(2) and 0.84 (95% CI, 0.62-1.13), 0.81 (95% CI, 0.52-1.26), and 0.95 (95% CI, 0.54-1.65) for BMI categories 30-34.9, 35-39.9, and ≥40 kg/m(2) after adjustment for covariates including waist circumference, respectively. In contrast, after adjustment for covariates including BMI, higher mortality rates were noted for all waist circumference categories compared with the referent (<80 cm in women and <94 cm in men), with HRs of 1.04 (95% CI, 0.77-1.41) for waist circumference of 80-87.9 cm in women and 94-101.9 cm in men, 1.29 (95% CI, 0.92-1.81) for waist circumference of 88-97.9 cm in women and 102-111.9 cm in men, 1.72 (95% CI, 1.12-2.62) for waist circumference of 98-107.9 cm in women and 112-121.9 cm in men, and 2.09 (95% CI, 1.26-3.46) for waist circumference ≥108 cm in women and ≥122 cm in men.

Limitations: BMI and waist circumference measured at baseline only.

Conclusions: Waist circumference should be considered in conjunction with BMI when assessing mortality risk associated with obesity in adults with chronic kidney disease.