Low bone mineral density, grip strength and skinfold thickness are important risk factors for hip fracture in Hong Kong Chinese

Abstract

The purpose of the study was to compare the bone mineral density (BMD) at the hip and spine, the grip strength and the skinfold thickness in Chinese hip fracture patients and controls, and to document the relative risk of hip fracture associated with different levels of these risk factors. The study was conducted on 163 elderly patients with hip fracture (32 men and 131 women) and 317 controls (104 men and 213 women). BMD at the hip and spine was measured by dual-energy X-ray densitometry (Norland NR26). The mean grip strength was measured in both hands by a hand dynamometer; and bicep, tricep and iliac skinfold thicknesses were measured by a caliper (Holstain). Student'st-test was used to compare the mean bone densities, recalled body weight, grip strength and skinfold thickness; and multiple logistic regression was used to calculate the relative risk and 95% confidence intervals in quartiles of bone density, grip strength and skinfold thickness. In women, the mean BMD and anthropometric measurements were significantly lower in patients than controls. However, in men the mean recalled body weight and measured skinfold thickness were not significantly different between patients and controls. In both men and women the relative risk of hip fracture increased significantly with diminishing bone density at the spine, femoral neck and intertrochanteric area, but not at the Ward's triangle. In women the relative risk of hip fracture also increased significantly with a low recalled body weight, grip strength and skinfold thickness. The relative risk of hip fracture in the lowest quartiles compared with the highest quartiles was 4.3 (95% CI 2.3–9.0) for BMD at the femoral neck, 9.7 (95% CI 4.6–20.6) for iliac skinfold thickness and 2.0 (95% CI 4.6–20.6) for grip strength. The results of multiple logistic regression shows that a low iliac skin fold thickness was associated with a higher risk of hip fracture than grip strength and BMD in women, but not in men. It is concluded that low BMD is a significant risk factor for hip fracture in elderly Chinese living in Hong Kong; however, poor muscle strength and lack of subcutaneous fat are as important.