The optimal value of BMI for the lowest risk of osteoporosis in postmenopausal women aged 40-88 years

Abstract

The aim of this paper is to establish the optimal values of the body mass index (BMI) which would indicate the most favourable preservation of the bone mineral density in postmenopausal women. The material consists of the data of 369 healthy women aged between 40 and 88 years (mean age 67.84, SD=6.70) inhabitants of Wrocław, which were followed up between 2001 and 2006. The absolute measure of bone mineral density (BMD) of the femoral neck was assessed using dual energy X-ray absorptiometry (DEXA), expressed in g/(100mm(2)) and was transformed to T-score values. According to the value of BMI, the women were divided into eight groups, the reference group with value between 18.0 and 21.9kg/m(2) and seven other groups beginning with the value 22.0 with a 2-point interval. Postmenopausal status was defined according to the occurrence of menstruation within the last 360 days. The women with osteopenia and osteoporosis were pooled together and comprised the risk group, whereas the other women comprised the normal group (T-score values above -1.0). The adjusted odds ratio showed the highest value for intervals between 24.0 and 25.9 units of BMI, and the lowest value for interval 26.0-27.9 units of BMI. The Youden index showed the lowest value in the 26.0-27.9BMI kg/m(2) interval. For our sample the optimal value of BMI, with the lowest risk of osteopenia and/or osteoporosis was the value of 26.9kg/m(2). A further increase of BMI does not result in a favourable effect on the bones, it rather intensifies negative phenomena in the body resulting in the onset of many diseases.