Do Sex Differences Exist in Rates of Falls and Fractures in Hutterite, Rural, and Nonrural Populations, Aged 20 to 66 Years?

Abstract

Background: Falls and fractures are a major public health concern with an economic impact of more than USD 19 billion per year. Extensive research into the risk of falls and fractures in elderly populations has been performed; however, little is known about fall or fracture risk in younger populations. Additionally, sex- and population-specific (rural versus nonrural) fall and fracture risk may be important in identifying groups most at risk in an effort to develop preventive measures.

Questions/purposes: The purpose of this study was to determine whether sex and population (rural versus nonrural) differences exist in fall and fracture rates.

Methods: Data from 1256 (538 men) participants of the South Dakota Rural Bone Health Study, a population-based cohort study, including those living a rural lifestyle (n=349 non-Hutterites and 572 Hutterites) and a nonrural lifestyle (n=335), were used to address our a priori hypotheses. Health histories, physical activity recall, anthropometric measurements, and dual-energy xray absorptiometry measurements of body composition were obtained longitudinally from participants every 18 months for 7.5 years. Falls and fractures were self-reported and fractures were confirmed through medical record review. Incidence rates were calculated as the number of falls or fractures per 1000 person-years and generalized estimating equations determined the association of sex and population group with fall and fractures rates while accounting for the repeated longitudinal measurements on the same person. All models adjusted for age group, percent time in moderate and vigorous physical activity, lean and fat mass, grip strength, and previous diagnosis of osteoarthritis.

Results: Males aged 39 years and younger had a 135% greater fall risk than females in the same age category (p=0.03), but there was no differences between males and females 40 years of age or older (p=0.26; age-by-sex interaction, p=0.05). No sex differences were observed for fracture risk. After controlling for covariates, rural and nonrural individuals fell at higher rates than Hutterites (84% and 50%, respectively, p<0.001). Additionally, rural individuals fractured at a 72% greater rate than Hutterites after controlling for covariates (p=0.03).

Conclusions: Sex differences in fall risk among younger individuals along with population differences in fall and fracture rates suggest that sex and lifestyle factors may have an impact on fall and fracture risk. Future studies focusing on sex- and population-specific risk factors are necessary to develop prevention strategies tailored to specific populations.

Level of evidence: Level III, prospective study.

Fig. 1A–B

Sex differences in fall and fracture rates are shown. (A) Males younger than 40 years of age had a greater fall rate than females (p = 0.03), but this difference was not apparent in males and females aged 40 years or older (p = 0.26) (age-by-sex interaction, p = 0.05). (B) There were no sex differences in fracture rates, and fracture rates were greater among individuals aged 40 years and older at enrollment compared with individuals 20 to 39 years of age (younger than 40 years versus 40 years and older: 0.52 [0.31–0.86, p = 0.01]). Covariates included in longitudinal analyses include age group, percent time in moderate plus vigorous activity, lean and fat mass, grip strength, and presence of osteoarthritis before the fall or fracture.

Fig. 2A–B

Population differences in fall and fracture rates are shown. (A) Hutterites had lower fall rates than both rural NH and nonrural individuals (both, p < 0.001), and (B) fracture rates were higher in the rural NH population than in the Hutterite population (p = 0.03). Covariates included in longitudinal analyses include age group, percent time in moderate plus vigorous activity, lean and fat mass, grip strength, and presence of osteoarthritis before the fall or fracture.