Height and lower extremity length as predictors of hip fracture: results of the NHANES I Epidemiologic Follow-up Study.

Abstract

The relationship between height, lower extremity length (LEL), and hip fracture was examined in 4264 women followed for 22 years. Greater height predicted fracture among younger women, whereas LEL predicted risk for all ages. LEL is a better predictor of hip fracture risk than height among older women. The significance of height as a risk factor for hip fracture is controversial. Age-related height loss, caused by nonpathological processes and vertebral deformities, may confound the relationship between standing height and hip fracture. In contrast, LEL might be less subject to age-related changes and thus be a better index of fracture risk for older individuals. We evaluated data available from 4264 white women who participated in the NHANES I Epidemiologic Follow-up Survey. There were 203 incident hip fractures over the 22-year follow-up period. The effect of height and LEL on hip fracture risk was determined for three age groups: 40-59, 60-69, and 70-74 year olds. After controlling for potential confounders, the hazard ratio (HR) for hip fracture for each SD greater standing height was 1.81 for the youngest age group (p = 0.002), 1.29 for 60-69 year olds (p = 0.02), and 1.10 for 70-74 year olds (p = 0.49). In contrast, LEL predicted hip fracture risk for all age groups, with HRs of 1.43 (p = 0.02), 1.30 (p = 0.002), and 1.33 (p = 0.02), respectively. Similarly, higher tertile of standing height did not confer increased hip fracture risk among the oldest women, but higher tertile of LEL did. Among women that were 70-74 years old, those in the highest tertile of LEL had a 1.83-fold (p < 0.05) greater risk of hip fracture than those in the lowest tertile. The results support the hypothesis that LEL is a better predictor of hip fracture than standing height among older women, the group at highest risk for these fractures.