Arthritis, body mass index, and professional advice to lose weight: implications for clinical medicine and public health.

BACKGROUND: Arthritis is the leading cause of disability in the United States. Obesity is a risk factor for arthritis, but the relationship between arthritis and weight has not been well characterized at the population level in the United States. Previous research shows that physicians often fail to advise their obese patients to lose weight.

OBJECTIVES: To describe the relationship between body weight and arthritis in the United States, and to assess predictors of efforts to lose weight among obese adults with arthritis, including the impact of professional advice to lose weight.

METHODS: Data from the 2000 Behavioral Risk Factor Surveillance System (a population-based survey of U.S. adults) from the 35 states that collected information on weight and height, arthritis, and efforts to lose weight. Arthritis was based on self-report of doctor diagnosis or chronic joint symptoms. Main outcome measures were arthritis and efforts to lose weight among adults with arthritis.

RESULTS: Overall, 31.7% of respondents had self-reported arthritis. There was a strong relationship between body weight and arthritis. Specifically, the prevalence of arthritis was 25.9% among normal weight (18.5 to 24.9 body mass index [BMI]) adults; 32.1% among overweight (25 to 29.9 BMI) adults; and 43.5% among obese (>30 BMI) adults. This association persisted after adjusting for other factors (adjusted odds ratio [AOR] for having arthritis among obese individuals compared with healthy weight individuals, 3.6; 95% confidence interval [CI]=3.2-3.8). Among obese adults with arthritis who had a routine checkup within the past 12 months, only 43% were advised to lose weight by a health professional. However, recipients of such advice were more likely to try to lose weight than nonrecipients, and professional advice was the strongest independent predictor of weight loss efforts (AOR=2.8; 95% CI=2.5-3.1).

CONCLUSIONS: Body mass index (BMI) is an important independent risk factor for self-reported arthritis. Although physicians often fail to advise obese adults with arthritis to lose weight, adults who report receiving such advice were more likely to report weight-loss efforts. Improved awareness of the relationship between arthritis and weight might help motivate patients to lose weight, and physician advice to lose weight could contribute to the prevention and treatment of arthritis.