Relationship between body mass index and different domains of disability in older persons:: the 3C study

OBJECTIVE: To study the relationships between body mass index (BMI) and different domains of disability in elderly subjects from the French 3C study. SETTING: Three cities in France: Bordeaux (South-West), Dijon (North-East) and Montpellier (South-East). DESIGN: Cross-sectional study. SUBJECTS: A sample of 8966 elderly community dwellers (age: 65-101 y). MEASUREMENTS: Main outcome measures: BMI, continence, basic and Instrumental Activities of Daily Living (ADL and IADL) and mobility. Adjustment variables: age, educational level, lifestyle, cognitive functioning, smoking and drinking history, depression, dyspnea, diabetes and indicator of cardiovascular disease. RESULTS: Obesity (BMIgreater than or equal to30 kg/m(2)) was significantly associated with disability in each domain for women. The relationship tended to be linear for ADL and for continence; whereas for IADL, underweight women (BMI <21 kg/m(2)) were also at higher risk of disability. In men, relationships were weaker since BMI was only associated with mobility restriction, with a higher risk for both underweight and obese subjects. CONCLUSION: These results are in favor of a strong association between obesity and the three domains of disability and incontinence. Weaker relationships between underweight and disability were observed. Results suggest that maintaining a BMI in the healthy range could contribute to independence in activities of daily living.