Risk factors for longitudinal bone loss in the hip of 70-year-old women; the importance of weight maintenance

Abstract

Risk factors for bone loss among the elderly are largely unknown. The objective of the study was to examine longitudinal bone loss in the hip in two hundred and twenty-five 70-year-old women. The mean time between examinations was 5.6 years. Bone mineral density (BMD, g/cm2) was measured with dual X-ray absorptiometry (DXA). The relationship between changes in BMD during follow-up and the following factors; baseline BMD, baseline weight, weight change, baseline lean and fat body mass (measured with DXA), biochemical markers, hormonal, nutritional and lifestyle factors, according to a questionnaire was assessed. Mean BMD decreased significantly more in the femoral neck (- 1.22%/year) than in the total trochanter (- 0.54%/year) and the total hip (- 0.66%/year), p < 0.01. Multivariate regression analyses were conducted separately for pro- and retrospective risk factors at each site. For all sites, women gaining weight had little or positive changes in BMD, whereas those loosing weight suffered bone loss. Weight loss in 70-year-old women was a significant risk factor for bone loss in the hip, and elderly women should be advised to maintain their body weight. Despite the large number of variables examined in this study, bone loss occurring with increased age is not thoroughly explained.