SAT-525 Risk Factors Associated with Bone Mineral Density in Middle-Aged Women in Southern Brazil: A Population-Based Study

Low bone mineral density (BMD) and changes of bone quality are common in postmenopausal women with osteoporosis. Among the factors related to bone loss are the estrogen decrease, aging and alteration of body composition. The aim of this cross-sectional study, nested to the Passo Fundo cohort study(1), was to investigate risk factors associated with BMD among midlife women. A total of 301 women were enrolled in which demographic, anthropometric characteristics, use of hormone therapy (HT), physical activity (PA), smoking status and alcohol intake were obtained. Visceral (VAT) and subcutaneous adipose tissue (SAT) areas were measured using CT scanner. Physical activity was obtained by the International Physical Activity Questionnaire (IPAQ) along with dosages of estradiol and vitamin D. BMD was assessed in lumbar spine (LS), femoral neck (FN) and total femur (TF) by DXA and bone mass status were classified according to NOF(2). The mean age was 57.5±5.4 years, 83.3% women were postmenopausal, 11.6% presented osteoporosis and 43.7% osteopenia. Women with osteoporosis were older (60.0 ±4.8 vs. 56.4 ± 5.2 years, p=0.001), had lower BMI (24.7 ± 3 vs. 30.0 ± 6.3, p<0.001) and estradiol levels (6.4 ± 4.0 vs. 29.6 ± 65.3, p=0.003) than those with normal bone women. VAT [71.9 (35.9 – 107.5) vs. 146.6 (78.3 – 168.9) vs 218.5 (168.3 – 248.4), p=0.003], SAT [223.5 (80.1 – 238.5) vs 169.3 (110.7 – 287.5) vs 282.5 (252.8 – 392.5) p=0.001] and WC [75.5 (64.4 – 80.7) vs 81 (74 – 89.5) vs 93.6 (86.7 – 98.2) p<0.001] were lower when compared to those with osteopenia or normal bone mass. According to a multiple linear regression model using BMD as the dependent variable, age (p=0.004) had an independent negative contribution and BMI (p=0.009) and VAT (p=0.031) had independent positive contributions to the BMD for all three sites. In addition, METs had an independent positive contribution to TF BMD (p=0.041) and current HT had an independent positive contribution to LS BMD (p=0.012) in a model adjusted for smoking. In conclusion, these results suggest that midlife women with osteoporosis are more frequently older, leaner and postmenopausal than those with normal bone mass. BMD is negatively impacted by age and positively by BMI, visceral adiposity, physical activity and hormonal therapy. (1) Oppermann et al., Women's Midlife Health (2015) (2) Cosman et al., Osteoporos Int DOI 10.1007/s00198-014-2794-2 Sources of Research Support: CNPq, FAPERGS