Gender differences in modifiable risk factors for hip fracture: 10-year follow-up of a prospective study of 0.5 million Chinese adults.

Abstract

ImportanceReliable evidence on modifiable risk factors for hip and major osteoporotic fractures in untreated populations could inform prevention strategies for hip fracture worldwide.ObjectivesTo estimate the age- and sex-specific incidence of hip, major osteoporotic and any fractures and examine their associated risk factors in Chinese adults.Design, Setting, and ParticipantsProspective study of 512,715 adults, aged 30-79 years, recruited for the China Kadoorie Biobank from 10 diverse areas in China in 2004-2008 and followed up for 10 years.ExposuresSociodemographic factors (e.g. age, sex, and education), medical history (e.g. CVD, diabetes, fracture, and rheumatoid arthritis), anthropometry (e.g. weight, waist-hip ratio) and lifestyle factors (e.g. smoking, alcohol drinking, physical activity, diet).Main Outcomes and MeasuresAge- and sex-specific incidence rates of fracture types, and adjusted hazard ratios (HR) and population attributable fractions (PAF) for individual risk factors associated with fracture types.ResultsThe incidence rates of hip fracture in Chinese adults were 5.1 (95%CI 5.0-5.3) per 10,000 person-years (2616 cases); and were higher in women than men (5.8 [5.5-6.1] vs 4.2 [3.9-4.5]) and increased by about 2 to 3-fold per 10 years older age. Among men, five risk factors for hip fracture including low education (HR=1.23; 95%CI 1.04-1.45), regular smoker (1.22, 1.03-1.45), lower weight (lowest vs other quintiles: 1.59, 1.34-1.88), alcohol drinker (1.18, 1.02-1.36), and prior fracture (1.62, 1.33-1.98) accounted for 44.3% of hip fractures. Among women, five risk factors including lower weight (lowest vs other quintiles: 1.30, 1.15-1.46), low physical activity (lowest vs other quintiles: 1.22, 1.10-1.35), diabetes (1.62, 1.41-1.86), prior fracture (1.54, 1.33-1.77), and self-rated poor health (1.29, 1.13-1.47), accounted for 24.9% of hip fractures. Associations of these risk factors with major osteoporotic (6857 cases) or any (15762 cases) fractures were weaker than those with hip fracture.ConclusionsThe age- and sex-specific incidence rates of hip fracture in Chinese adults were comparable with those in Western populations. Five potentially modifiable factors accounted for half of all hip fractures in men and one quarter in women.