Assessment of risk factors for low bone mineral density in Brazilian postmenopausal women

Abstract

Objective. To assess risk factors associated with low bone mineral density (BMD) in postmenopausal women.

Methods. In this cross-sectional study, a total of 412 Brazilian postmenopausal women, aged 40–75 years, with BMD measured using central dual-energy X-ray absorptiometry, were included. The clinical risk factors assessed were: age, time since menopause, smoking, physical activity, use of hormone therapy (HT) or corticosteroids, personal fracture history, maternal history of fracture, and body mass index (BMI, weight/height²). Low BMD was considered when total spine and/or femoral neck T-score values were ≤ −2.0 standard deviations. Logistic regression was used to determine the odds ratio (OR) for low BMD in the presence of the influential variables analyzed.

Results. Low BMD, which occurred in 36.6% (151/412) of the participants, was observed in 22.4% of women aged 40–49 years, in 34.2% of those aged 50–59 years, and in 60.5% of those > 60 years (p < 0.001). Similarly, low BMD was observed in 21.9% of women with menopause duration ≤ 5 years, in 39.5% with a duration of 6–10 years, and in 57.7% with menopause duration of > 10 years (p < 0.001). Seventy percent of women with BMI < 20 kg/m² were osteopenic/osteoporotic (p < 0.001). The percentage of HT users was 37.4%; 27.7% took regular physical activity and 24.5% were smokers. The risk for low BMD detection increased significantly with age (OR 1.08; 95% confidence interval (CI) 1.02–1.14), time since menopause (OR 1.12; 95% CI 1.04–1.20), smoking (OR 3.43; 95% CI 1.67–6.96), fracture history (OR 2.05; 95% CI 1.11–3.78), and maternal history of fracture (OR 2.16; 95% CI 1.14–4.09). Physical activity, diet, corticotherapy and thyropathies did not influence risk. Contrarily, use of HT (OR 0.38; 95% CI 0.24–0.60) and high BMI (OR 0.89; 95% CI 0.84–0.96) reduced risk (p < 0.05).

Conclusion. In postmenopausal women, age, time since menopause, smoking, and personal or maternal history of fracture were strong clinical indicators of risk for low BMD, whereas the use of hormone therapy and high BMI were shown to be protective factors.

Key words:

• MENOPAUSE
• BONE MINERAL DENSITY
• RISK FACTORS
• HORMONE THERAPY

Conflict of interest  The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this paper.

Source of funding  This study was supported by the State of Sao Paulo Research Foundation (FAPESP) with scientific initiation scholarship; process number 2008/10881-6.