Background
The lifetime risk of osteoporotic fracture (from the age of 60) for a man and woman is 25 and 44%, respectively [
1]. Experiencing a minimal-trauma-fracture (MTF) increases the risk of a subsequent fracture [
2], and increases the risk of mortality [
3,
4]. Importantly, timely diagnosis and optimal treatment has been shown to reduce the risk of subsequent fracture [
5]. It is common that the elderly women and men who experienced MTF, do not receive appropriate assessment to establish the diagnosis of osteoporosis, or optimal treatment to prevent a subsequent fracture [
6‐
8]. To address this challenge Fracture Liaison Services (FLS) [
9] have been introduced to identify an initial fracture and ensure screening for the presence of osteoporosis, and when indicated initiate appropriate treatment to reduce the risk of another fracture.
There is increasing evidence that the introduction of a FLS is effective in reducing subsequent fracture rates [
5,
10‐
12]. As a result, South Western Sydney Local Health District is in the process of establishing a FLS, locally described as
Osteoporosis Refracture Prevention (ORP) Clinics across the local health district’s five acute public hospitals. In a similar manner to many other FLS, patients targeted by the service will be those presenting to hospital, aged 50-years or more, with a minimal-trauma-fracture [
11‐
13]. The absolute risk of subsequent fracture among this group of FLS patients has not been well described, and in doing so, we propose should be part of the establishment of any new hospital based FLS. Therefore, this study was designed to estimate the absolute-risk of subsequent fracture among patients aged 50-years or more, presenting to hospital with a minimal-trauma-fracture, across our local health district, south west of Sydney, Australia.
Results
Between January 2003 and December 2017 15,088 patients presented to the emergency departments of the five hospitals in the SWSLHD (11,149, women [74%]), with minimal-trauma-fractures (MTF). The characteristics of these patients, aged 50-years or more, are presented in Table
1. The average age of the MTF patients was 76-years (SD 12); the highest number of MTF fractures were classified as occurring at major sites (
n = 5212 [35%]), followed by minor, 4778 (32%), hip 4738 (31%), and lumber spine, 360 (2%). Subsequent fractures identified during the follow-up period (median = 4.5 years [IQR, 1.6–8.2), occurred in 2024 (13%) patients. Death during the initial hospital stay was 1.6% (238/15,088), and 2.1% (42/2.024) during a subsequent fracture visit to hospital.
Table 1Characteristics of patients presenting to hospital between January 2003 and December 2017 with minimal-trauma-fractures
Age (yrs), mean (SD) | 76 (12) | 75 (12) | 76 (12) | < 0.001 |
Initial fracture, N (%) | | | | < 0.001 |
Hip | 3375 (30) | 1363 (35) | 4738 (31) | |
Lumbar spine | 237 (3) | 123 (3) | 360 (2) | |
Major | 3661 (33) | 2250 (57) | 5212 (35) | |
Minor | 3876 (35) | 903 (23) | 4778 (32) | |
Subsequent fracture, N (%) | 1599 (14) | 425 (11) | 2024 (13) | < 0.001 |
Death, N (%) | 1050 (9) | 596 (15) | 1646 (11) | < 0.001 |
Follow-up (yrs), median (IQR) | 4.7 (1.7–8.4) | 3.9 (1.3–7.6) | 4.5 (1.6–8.2) | < 0.001 |
Rates of subsequent fracture
Risk of subsequent fracture based on sex, age, and site of initial fracture are presented in Table
2. During the 15-year follow-up period, subsequent fracture rates were higher among women versus men (14.3% versus 10.8%, Rate Ratio (RR) = 1.33, 95% confidence interval (CI) 1.19, 1.48,
p < 0.001); the highest rate of subsequent fracture in terms of age was that among those aged 70–79 years at the time of the initial fracture (14.9%); and, patients with an initial lumbar spine fracture, were observed to have the highest rate of subsequent fracture (15.3%), compared to hip, major and minor sites.
Table 2Risk of subsequent fracture based on sex, age, and site of initial fracture
Sex |
Men | 425 | 3939 | 10.79 | 1.0 (ref) | 1.0 (ref) | |
Women | 1599 | 11,149 | 14.34 | 1.33 (1.19, 1.48) | 1.31 (1.17, 1.46) | < 0.001 |
Age group (yr) |
50–59 | 202 | 1663 | 12.15 | 1.0 (ref) | 1.0 (ref) | |
60–69 | 327 | 2704 | 12.09 | 1.00 (0.84, 1.19) | 1.01 (0.85, 1.20) | |
70–79 | 544 | 3654 | 14.89 | 1.23 (1.04, 1.44) | 1.28 (1.08, 1.50) | |
80+ | 951 | 7067 | 13.46 | 1.11 (0.95, 1.29) | 1.20 (1.00, 1.49) | 0.005b |
Site of initial fracture |
Hip | 545 | 4,738,313 | 11.50 | 1.0 (ref) | 1.0 (ref) | |
Lumbar spine | 55 | 360 | 15.28 | 1.33 (1.01, 1.75) | 1.36 (1.03, 1.79) | 0.031 |
Major | 737 | 5,212,638 | 14.14 | 1.23 (1.11, 1.37) | 1.20 (1.05, 1.38) | < 0.001 |
Minor | 687 | 4778 | 14.38 | 1.25 (1.12, 1.40) | 1.30 (1.15, 1.47) | < 0.001 |
Absolute risk of subsequent fracture
After taking into account the competing risk of death, the cumulative risk of subsequent fracture for 1-year, 3-years and 5-years post initial presentation to hospital, based on sex, and site of initial fracture (any site, proximal or distal) are presented in Table
3. These cumulative risks for various age groups are presented in Table
4. Women were observed to have 7.1% risk of subsequent fracture, at any site, within 1-year following an initial fracture; and, this risk of subsequent fracture after 1-year was 6.2% for men. After 5-years this rate, of fracture at any site, among women was 13.7, and 11.3% for men, respectively. Cumulative risk of subsequent fracture when initial fractures are classified a proximal, or distal are also presented. At 1-year both women (8.7% versus 6.3%) and men (9.2% versus 5.3%) were observed to have greater risk of subsequent fracture among those with a distal site of initial fracture, when compared to those with proximal site.
Table 3Absolute risk of subsequent fracture during follow-up period, based on sex and site of initial fracture
Women |
Any | 0.071 (0.066–0.076) | 0.110 (0.104–0.116) | 0.137 (0.130–0.144) |
Proximal | 0.063 (0.057–0.068) | 0.109 (0.102–0.117) | 0.140 (0.131–0.149) |
Distal | 0.087 (0.078–0.096) | 0.112 (0.102–0.122) | 0.132 (0.121–0.143) |
Men |
Any | 0.062 (0.055–0.070) | 0.094 (0.085–0.104) | 0.113 (0.102–0.124) |
Proximal | 0.053 (0.045–0.062) | 0.086 (0.076–0.097) | 0.106 (0.095–0.119) |
Distal | 0.092 (0.074–0.112) | 0.122 (0.101–0.145) | 0.134 (0.111–0.158) |
Table 4Absolute risk of subsequent fracture during follow-up period, based on sex, age, and site of initial fracture
Women |
50–59 years |
Any | 0.082 (0.068–0.097) | 0.095 (0.080–0.111) | 0.105 (0.089–0.123) |
Proximal | 0.056 (0.037–0.080) | 0.079 (0.055–0.108) | 0.100 (0.072–0.133) |
Distal | 0.094 (0.076–0.114) | 0.103 (0.084–0.123) | 0.108 (0.089–0.130) |
60–69 years |
Any | 0.079 (0.068–0.091) | 0.107 (0.094–0.121) | 0.127 (0.112–0.143) |
Proximal | 0.068 (0.053–0.085) | 0.105 (0.085–0.126) | 0.139 (0.115–0.164) |
Distal | 0.088 (0.072–0.105) | 0.109 (0.091–0.128) | 0.120 (0.101–0.140) |
70–79 years |
Any | 0.068 (0.060–0.078) | 0.109 (0.098–0.121) | 0.143 (0.130–0.157) |
Proximal | 0.058 (0.048–0.069) | 0.105 (0.092–0.120) | 0.144 (0.128–0.162) |
Distal | 0.087 (0.071–0.105) | 0.116 (0.097–0.137) | 0.140 (0.119–0.163) |
80+ years |
Any | 0.067 (0.060–0.074) | 0.116(0.107–0.125) | 0.145 (0.135–0.155) |
Proximal | 0.063 (0.056–0.071) | 0.115 (0.105–0.125) | 0.141 (0.130–0.153) |
Distal | 0.082 (0.066–0.101) | 0.121 (0.100–0.143) | 0.159 (0.135–0.185) |
Men |
50–59 years |
Any | 0.099 (0.076–0.126) | 0.116 (0.090–0.145) | 0.127 (0.099–0.158) |
Proximal | 0.073(0.046–0.108) | 0.092 (0.061–0.131) | 0.115 (0.078–0.160) |
Distal | 0.126 (0.090–0.168) | 0.140 (0.101–0.185) | 0.140 (0.101–0.185) |
60–69 years |
Any | 0.068 (0.052–0.086) | 0.091 (0.072–0.113) | 0.101 (0.081–0.125) |
Proximal | 0.051 (0.034–0.072) | 0.078 (0.057–0.104) | 0.092 (0.067–0.121) |
Distal | 0.099 (0.068–0.137) | 0.115 (0.082–0.156) | 0.120 (0.085–0.161) |
70–79 years |
Any | 0.053 (0.040–0.067) | 0.088 (0.071–0.107) | 0.108 (0.089–0.130) |
Proximal | 0.052 (0.038–0.068) | 0.086 (0.067–0.107) | 0.108 (0.087–0.132) |
Distal | 0.057 (0.030–0.096) | 0.096(0.058–0.145) | 0.111 (0.069–0.164) |
80+ years |
Any | 0.051 (0.041–0.062) | 0.088 (0.075–0.103) | 0.110 (0.095–0.127) |
Proximal | 0.049 (0.039–0.060) | 0.084 (0.070–0.099) | 0.104 (0.088–0.122) |
Distal | 0.067 (0.037–0.108) | 0.125 (0.081–0.179) | 0.156 (0.105–0.216) |
Discussion
This study has described the absolute risk of subsequent fracture, among women and men, presenting to hospital with minimal-trauma-fracture. On average women and men, aged 50+ years or more, were observed to have a 7.1 and 6.2%, respectively - absolute risk of representing to hospital with a subsequent minimal-trauma-fracture within 1-year. These rates were approximately double after 5-years. Importantly, regardless of the site of the initial fracture, approximately 1 in every 10, women and men were at risk of a subsequent fracture in the next 3- to 5-years.
The results of this study confirm previous reports of the risk for subsequent fracture following an initial minimal-trauma-fracture [
2,
4,
20,
21]. However, our estimates of the rates of absolute risk of subsequent fracture will varying from those from population based studies [
2], due to our source population being limited to women and men who present to hospital. In particular, it has been highlighted that among studies based on fracture liaison services [
5,
11‐
13], probably the most common of all osteoporotic fractures, that of the lumbar-spine, are to a significant extent, missed by this method of case finding but nevertheless an opportunity to implement osteoporosis management in this cohort. For example, in the context of clinical fractures of the lumbar spine, among women and men aged 60-years or more, the ratio of that to hip fractures is approximately 1.2–1.5, reported by various population based epidemiological studies [
2,
22]. This fact alone would suggest the approach to capturing minimal-trauma-fractures, using hospital based data under-estimates the true burden, and may be missing an important population of women and men with osteoporosis, and ultimately a missed opportunity to prevent a subsequent fracture [
23].
This study includes a large number of minimal-trauma-fractures, over a 15-year period, across a local health district that services a population of approximately a million people. And therefore, offers a good estimate of the burden of minimal-trauma-fractures, and subsequent fractures among women and men aged 50+ years presenting to hospital. However, a potential limitation of hospital separation fracture data, is that the fracture event must result in a presentation to hospital. And, as noted above in the context of clinical fractures of the lumbar spine, and has been identified among various reports of hospital based fracture liaison services [
5,
11,
12,
23], the true burden of osteoporosis and the associated increased risk of fracture will be under-estimated.
An important clinical implication of this study is that we have been able to develop some estimates of the current baseline risk of subsequent fracture among patients that we plan to capture by implementing a fracture liaison service. These estimates will enable important information to be conveyed to patients who present to hospital with minimal-trauma-fractures and are deciding to commit to follow-up by an Osteoporosis Refracture Prevention (ORP) clinic. Importantly, as part of the implementation of ORP services across our local health district, we will be able to explore the expected and observed rates of representation to hospital with minimal-trauma-fractures. Given the current low rates of screening for osteoporosis (using DXA) among women and men who experience a minimal-trauma-fracture across our local health district, the data that we have obtained from this study will hopefully serve to improve the implementation of ORP services.
Future research in the context of implementing a fracture liaison service will need to improve the way in which women and men with minimal-trauma-fractures are identified. Innovative ways to ensure osteoporotic fractures of the spine are actively identified are currently needed. These important and common osteoporotic fractures of the spine, are obviously under-represented in our initial and subsequent fracture rates. Improvement in this area remains an important task of any fracture liaison service. And, once established, fracture liaison services will need to constantly assess their ability to keep patients on treatment, and ongoing monitoring of bone health.
Conclusion
In conclusion, in the context of implementing a fracture liaison service, this study has estimated the baseline risk of subsequent fracture among women and men presenting to hospital with a minimal-trauma-fracture. Importantly, this information can be used to communicate risk to patients deciding to participate in Osteoporosis Refracture Prevention clinic, and highlight the need for screening, and initiation of treatment when indicated, once a minimal-trauma-fracture has occurred.
Acknowledgements
Abstracts of the results of this project have been submitted to international (IOF-Paris, 2019), and national conferences (ANZBMS Darwin, 2019), and where accepted as poster presentations on both occasions.
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