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Abstract
Osteoporotic fractures represent a major public health problem because of their increased morbidity, mortality and cost to the community. This thesis aimed to examine the long-term risk and predictors of poor outcomes following fracture including refracture and mortality as well as the effect of osteoporosis medication on mortality risk. All minimal trauma fractures and mortality data were collected from 2245 women and 1760 men aged 60 + years participating in Dubbo Osteoporosis Epidemiology Study between April 1989 and May 2007.
Initial fracture risk increased exponentially with age and was higher in women. Following the initial fracture, re-fracture risk was increased by 1.6-2.4-fold for women and 2.8-4.3-fold for men, resulting in an overall re-fracture risk that was comparable for women and men and worse than that of an initial fracture risk of women 10 years older. Re-fracture risk was highest for those with osteoporosis, but still increased for those with non-osteoporotic BMD.
Mortality risk was increased by 1.7- 3.6-fold following hip, vertebral and major fractures for all ages and minor fractures in the elderly. Low BMD, having smoked and increased sway were independent mortality predictors in women, and physical inactivity and fewer falls in men.
Mortality and re-fracture risks were highest in the first 5 years post-fracture. During this interval 26% of women and 41% of men died and 37% of women and 24 % of men re-fractured. Both re-fracture and mortality risks subsequently declined. However, following re-fracture, mortality risk again increased 2-fold.
Individuals who received bisphosphonate had better survival than those not treated. In multivariable analysis this reduction remained significant in women with a similar but non-significant effect size in men likely due to smaller numbers. Hormone therapy and calcium ±vitamin D supplements were not associated with survival benefit.
These data have shown a high cumulative risk (>80%) of multiple adverse events following an osteoporotic fracture. Those who survive the initial fracture have increased re-fracture risk which further increases mortality risk. Bisphosphonate may improve survival in women and perhaps men. Thus, this thesis give an insight into the overall burden of post-fracture events and provided evidence that osteoporosis treatment may help improve survival.