Changes in hip fracture rates in southeastern Australia spanning the period 1994–2007

Julie A Pasco, Sharon L Brennan, Margaret J Henry, Geoffrey C Nicholson, Kerrie M Sanders, Yu Zhang, Mark A Kotowicz

Hip fracture incidence rates appear to be declining in Western populations. Utilizing comprehensive incident hip fracture data from radiology reports, we determined changes in hip fracture rates in southeastern Australia between 1994-1996 and 2006-2007 for residents aged 55 years or older. During this period, the population at risk increased by 47% for men and 40% for women. Although the absolute number of hip fractures increased by 53% in men and 4.4% in women, standardized hip fracture ratios were 0.92 [95% confidence interval (CI) 0.79-1.08] and 0.69 (95% CI 0.62-0.77), respectively. Marked reductions in hip fracture rates were observed for women: 32% for ages 75 to 84 years and 29% for ages 85 years or older. Data from the Geelong Osteoporosis Study were used to identify changes in body composition and lifestyle that might have influenced hip fracture risk in women during this period. Between 1993-1997 and 2004-2008, there was an increase in adiposity, bone mineral density (BMD), healthy lifestyles, and exposure to bone-active drugs; use of hormone therapy declined. Thus hip fracture incidence rates have decreased from the mid-1990 s to the mid-2000 s, the effect being greater among women. Our data also suggest that the recent increase in adiposity and consequent increase in BMD at the hip may have contributed to this decline. However, improved efficacy and increased uptake of antifracture drug treatments, other cohort effects, or other environmental influences cannot be excluded.