Association between body mass index and osteoporosis in women from northwestern Rio Grande do Sul.

OBJECTIVE

To investigate the association between body mass index (BMI) and bone mineral density (BMD) in postmenopausal women.

METHODS

Observational study with postmenopausal women who underwent bone densitometry in Palmeira das Missões - RS. Sociodemographic data, risk for osteoporosis and food intake were assessed through a specific form. BMI was calculated according to WHO criteria. The assessment of BMD was performed by dual-energy X-ray absorptiometry (DXA) and classified according to WHO. Statistical analysis was performed using prevalence ratios (PR) and their respective 95% confidence intervals for the factors studied. Variables associated with p<0.20 with the different outcomes (osteopenia and osteoporosis) were included in a Poisson regression model with robust variance to adjust for potential confounding factors. A 5% significance level was considered.

RESULTS

393 postmenopausal women with a mean age of 59.6±8.2 years participated. After the adjustments, the normal weight women had 1.2 times the prevalence of osteopenia of obese women (PR=1.2; CI 95% 1.3-1.5). Considering osteoporosis, the PR of euthophic women was twice the PR of obese women (PR=2; CI 95% 1.4-2.9) and was 1.7 times greater for overweight group compared to obese category (PR=1.7; CI 95% 1.2-2.5).

CONCLUSION

Obese women had lower prevalence of osteopenia compared with normal weight subjects and also with lower prevalence of osteoporosis as compared to normal- and overweight women.