Objectively Verified Parental Hip Fracture Is an Independent Risk Factor for Fracture: a Linkage Analysis of 478,792 Parents and 261,705 Offspring

Parental hip fracture (HF) is considered a major risk factor for offspring major osteoporotic fracture (MOF), but all studies to date have relied on self-reported information of uncertain accuracy. We tested the association of objectively verified parental HF with offspring MOF and HF. We used a population-based historical cohort study of 261,705 offspring (age 40 years) with at least one linked parent (total 478,792 parents) for the province of Manitoba, Canada. Cox proportional hazards models were developed to test hazard ratio (HR) for offspring MOF and HF for 1997 to 2014 according to prior parental HF dating back to 1970. The median age of offspring at study entry was 40 years (range, 40 to 50 years), and 48.3% were women. During 2.9 million person-years of offspring follow-up (median per offspring, 12 years), we identified 7323 incident MOF (4.4% versus 2.7% for those with and without a parental HF, p<0.001), including 331 HF (0.3% versus 0.1%, p<0.001). Parental HF was independently associated with increased risk of offspring MOF (HR, 1.30; 95% confidence interval [CI], 1.20 to 1.41). The strength of the association decreased with older parental age at HF (p(trend)<0.001), and was no longer significant if parental HF occurred after age 80 years (adjusted HR, 1.07; 95% CI, 0.96 to 1.19). The relationship between parental HF and offspring HF was even stronger than for MOF (adjusted HR, 1.64; 95% CI, 1.21 to 2.23). Associations with MOF or HF were not affected by either the gender of the parent with HF or the gender of the offspring. Parental HF increased the risk for offspring MOF and HF but not when parental HF occurred after age 80 years. This suggests a more nuanced approach for clinicians trying to stratify fracture risk, and illustrates the enormous potential of parent-offspring record linkage for other familial disorders. (c) 2016 American Society for Bone and Mineral Research.