Health burden of hip and other fractures in Australia beyond 2000

Previously, fracture rates in Australia have been extrapolated from rates in Dubbo and Busselton,^2,3 populations that may not be representative of the national population as they are both fairly isolated towns with small numbers of men and women in the oldest age groups. Lord et al investigated changes in hip fracture admissions in New South Wales between 1979 and 1990 using International Classification of Diseases hospital discharge codes.⁴ Although frequently used for ascertaining hip fractures, the limitations of this method are well documented.^5,6

The Geelong Osteoporosis Study is a population-based study of age-, sex- and site-specific fracture rate(s) within a well-defined geographic region sufficiently large to establish reliable rates of fracture. It is the largest Australian epidemiological study of adult fractures, identifying 2184 fractures over two years in people aged 35 years and over. Data from the 1996 national census confirm the findings of an earlier study⁷ that the regional population is typical of the nation in age distribution and socioeconomic range.

The Australian Bureau of Statistics publishes projections of the size, structure and distribution of Australia's population into the next century.¹ Assuming stable age- and sex-specific rates of fracture, we have projected annual numbers of fractures by anatomical site in adults over the next 50 years.

Only reports of definite fractures were included as "cases". Reports referring to "likely" or "possible" fracture were not included unless radiologically confirmed at a later date. Vertebral fractures were included in the study on the basis of the radiological report, provided there was no previous record of a fracture at that level. The initial x-ray demonstrating each fracture was sought and the date of fracture was the date of the radiological diagnosis.

As the region is well provided with medical facilities, few fractures would not have been assessed or followed up by services within the region. The standing orders for the ambulance service are to transport patients from residences within the study region to The Geelong Hospital. The study was well advertised and adults who may have sustained fracture(s) while outside the region were asked to contact study coordinators.

Non-residents and patients with pathological fractures (metastatic cancer, Paget's disease and multiple myeloma) were excluded. We have previously reported that the exclusion of high trauma fractures may underestimate the prevalence of bone-fragility fractures in the community,⁸ so we did not exclude fractures on the basis of trauma classification.

The method of fracture ascertainment has been previously described⁹ and validated, using hip fracture as a model.¹⁰

The study was approved by The Geelong Hospital Human Research and Ethics Advisory Committee.  

X 0.5 (2 year ascertainment)

The study region population was determined from the 1996 Australian Bureau of Statistics census. Annual population projections were also provided by the Australian Bureau of Statistics.¹ This method of projection assumes that the fracture rate in each age group will remain unchanged over time.

Confidence intervals around the projections were calculated by the bootstrap method.¹¹

In 1996, we estimate that about 83 000 Australians aged 35 years and over sustained fractures. We predict that by 2006 the total number of fractures per year will increase by 25%, to 104 000 (Figure 1).

The number of Australians sustaining hip fractures each year is projected to increase by 15% every five years until 2036, then by about 10% every five years until 2051. A fourfold increase in hip fractures is expected by 2051, when about 23% of Australia's projected population will be aged 65 years and over (compared with 12% in 1996) and over 8% of the population will be aged 85 years and over (compared with 2% in 1996).

Hip fractures are likely to increase more than fractures at other sites because the greatest population growth is expected in the oldest age groups, where the hip is the most common site of fracture.⁹

We estimate that in 1996 about 68 000 Australians aged 35 years and over sustained fractures at sites other than the hip, and that the number of non-hip fractures is likely to increase by 9% every five years until 2036, and then by 4% every five years until 2051 (to 147 645 non-hip fractures per year).

Projections for vertebral, Colles, humeral and pelvic fractures (the most common sites of fracture after the hip) are shown in Figure 3. Fractures at these sites are likely to increase more than fractures at other sites where fracture rates do not increase substantially with age.⁹ Population projections suggest that vertebral, humeral and pelvic fractures will increase by 12% every five years to 2036, then by 6% every five years to 2051. Colles fracture rates increase with age in women, but not in men,⁸ and the overall number of adults sustaining a Colles fracture will increase by 10% every five years until 2036, then by 5% every five years until 2051.

Fractures other than hip, vertebral, Colles, humeral and pelvic fractures are predicted to increase at about half the rate predicted for these sites (6% every five years until 2036, then 3% every five years until 2051).

Figure 4 shows the projected distribution of hip fractures across age groups for selected years from 1996 to 2051.

It is likely that hip fracture, which becomes increasingly common with advancing age, contributes significantly to this higher expenditure. Almost all people with a fractured hip are hospitalised, with an average length of stay of 13 days.¹³ Studies in other white populations suggest that 50% of patients who survive hip fracture are discharged to nursing homes, and 25% remain institutionalised one year later.^14,15 Comparable Australian data are not available, although the increased mortality after hip fracture has been confirmed.¹⁶ We estimate that hip fractures accounted for 0.9% of total government health services expenditure for 1995/96.¹² Based on the number of Australian salary earners in 1998 (Australian Bureau of Statistics) and an average cost of $16 000 per hip fracture,¹⁷ treatment alone costs salary earners an average of $28 per year. In current dollar terms, this may escalate to $120 per salary earner per year by 2051 if the projected increase is realised.

The number of adults sustaining a hip fracture is likely to more than double from 15 000 in 1996 to 34 000 in 2026, then almost double again by 2051. Fractures at other sites are expected to increase by 70% from 1996 to 2026, then by a further 26% to 2051. These rates of increase are far above the expected growth in total healthcare costs due to the ageing of the Australian population, which is estimated to be 4% every five years for the next 30 to 40 years.¹⁸

For the number of hip fractures to remain stable, their incidence (per 10 000 population per year) would need to decline from 17.2 in 1996⁹ to 15.6 in 2001, 14.3 in 2006 and 11.3 in 2026. In the United States, an 18% reduction in hip fracture rates between 1988 to 2000 has been targeted by public health strategists.¹⁹ Current therapies (such as hormone replacement therapy and bisphosphonates) may reduce fracture rates by 50%, but their cost-effectiveness remains controversial.^20,21

In most white populations the number of hip fractures is predicted to double between 1990 and 2025, and then plateau as the growth in the aged population ceases.²² However, in contrast with Europe and North America, the aged population and the number of hip fractures in Australia and New Zealand are likely to continue to increase from 2025 to 2050.²²

Current trends suggest that almost three times as many women as men will sustain a hip fracture (Table 1). Largely for this reason, efforts to prevent hip fracture have focused on osteoporosis in women. However, mortality and rate of institutionalisation after hip fracture is higher in men,²³ and increasing hip fracture rates among men, but not women, have been reported.^24,25 The projected increased longevity in men suggests that osteoporosis will affect a growing number of Australian men, yet there are no data concerning efficacy of any drug treatment to prevent hip or vertebral fractures in men.²⁶

Our projected number of vertebral fractures is likely to be an underestimate because our ascertainment relied on clinical indications for medical imaging. Between 50% and 75% of vertebral fractures do not come to medical attention.^27,28 However, our data are likely to include some previously undiagnosed vertebral fractures that occurred before the ascertainment period. Nevertheless, the predicted number of vertebral fractures represents the number likely to come to medical attention each year. Excluding vertebral fractures does not alter the projected rate increase of all fractures.

The validity of these projections is dependent upon reliable and stable incidence rates and accurate population projections. The major strength of our study was the comprehensive ascertainment of all fractures among adult residents of a defined region representative of Australia.⁹ A decline in hip fracture rates has recently been reported,¹⁹ but other studies have pointed to stable age-specific rates in women and younger men and increasing rates in older men.^24,25,29,30

These projections highlight the need to decrease fracture rates among the elderly and can be used for setting goals and evaluating the costs and benefits of interventions in Australia.

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Department of General Practice and Public Health, The University of Melbourne, Melbourne, VIC.
Antony M Ugoni, BSc(Hons), Lecturer in Biostatistics.

Austin and Repatriation Medical Centre, Melbourne, VIC.
Ego Seeman, MD, FRACP, Associate Professor of Medicine, The University of Melbourne.

Reprints will not be available from the authors.
Correspondence: Dr M A Kotowicz, University Department of Medicine, Barwon Health-Geelong Hospital, PO Box 281, Geelong, VIC 3220.
Email: m.kotowiczATmedicine.unimelb.edu.au

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