Waist circumference is a better predictor of risk for frailty than BMI in the community-dwelling elderly in Beijing.

AIM: Obesity is found to be associated with frailty. Body mass index (BMI) and waist circumference (WC) are the commonly used measures for obesity, the former is more closely related to general obesity and body weight; the latter can more accurately reflect abdominal obesity and is more closely associated with metabolic disorders. In this study, we intend to study the relationship between frailty, BMI and WC among older people.

METHODS: Data were derived from the Beijing Longitudinal Study on Aging II Cohort, which included 6320 people 65 years or older from three urban districts in Beijing. A Frailty Index derived from 33 items was developed according to Rockwood's cumulative deficits method. A Frailty Index ≥ 0.25 was used as the cut-off criteria. BMI was classified as underweight, normal, overweight, or obese (< 18.5, 18.5-< 24.0, 24.0-27.9, ≥ 28.0 kg/m2 , respectively). High WC was defined as WC ≥ 85 cm in men and ≥ 80 cm in women.

RESULTS: People with a larger BMI (≥ 28.0 kg/m2 , 22.6%) or a larger WC (18.5%) were more likely to be frail. People with normal BMI and overweight people do not suffer from higher prevalence for frailty. In comparison with individuals with normal BMI (18.5-< 24.0 kg/m2 ) and normal WC (< 85 cm in men, <80 cm in women), the risk of frailty was higher among individuals who have normal BMI and large WC (odds ratio 1.68; 95% CI 1.33-2.12), have overweight and large WC (odds ratio 1.58; 95% CI 1.23-1.96), or have obesity and large WC (odds ratio 2.28; 95% CI 1.79-2.89). In people with normal WC, only those who are underweight have a higher risk for frailty (odds ratio 1.65, 95% CI 1.08-2.52). In comparison with BMI, the relation of WC with the risk for frailty was much closer.

CONCLUSIONS: Abdominal obesity is more closely associated with incidence of frailty than general obesity in the elderly. Older adults with large waist circumference are more likely to be frail. Frailty in the elderly might be more closely related to metabolic disorders. WC might be a better measurement to detect frailty than BMI, given its relationship with metabolic disorders.