Time dependency in early major osteoporotic and hip re-fractures in women and men aged 50 years and older: a population-based observational study

Abstract

We analyzed patterns in recurrent major osteoporotic fracture (MOF) following a first major osteoporotic fracture in a large population-based cohort. Re-fracture risk remained elevated over 10 years, with only modest and inconsistent attenuation in risk over time. Recurrent fracture risk remains elevated for up to 25 years, and is reportedly highest in the initial 2 years (imminent risk). Our aim was to characterize early time dependency in re-fracture rates up to 10 years after a first fracture in a population-based cohort. Using Province of Manitoba (Canada) healthcare databases, we performed a matched cohort study in 22,105 women (mean age 74.1\u2009±\u200910.6 years) and 7589 men (mean age 71.8\u2009±\u200911.2 years) after a first MOF (age\u2009≥\u200950 years) during 1989–2006 and matched fracture-free controls (3 for each case). Incident fractures were ascertained over the next 10 years. Fracture rate ratios (RRs, cases versus controls) stratified by sex and age were computed, and tested for linear trend using linear regression. Joinpoint regression was performed to determine non-linear change in fracture rates over time, with particular attention to the first 2-year post-fracture. RRs for incident MOF and hip fracture exceeded unity for the primary analyses in all subgroups and follow-up intervals. There was a tendency of RRs to decline over time, but this was inconsistent. Absolute rates per 100,000 person-years for fracture cases were consistently greater than for controls in all subgroups and observation times. Among fracture cases, there was a tendency for rates to decline gradually in all subgroups except younger women, but these temporal trends appeared monotonic without an inflection at 2 years. Joinpoint regression analyses did not detect an inflection in risk between the first 2 years and subsequent years. No significant time dependency was seen for incident hip fracture. MOF and hip re-fracture risk was elevated in all age and sex subgroups over 10 years. There was inconsistent and only modest time dependency in early MOF risk, most evident in women after age 65 years. No strong transition in risk was seen between the first 2-year post-fracture and subsequent years.