Hong Kong Med J 2016 Feb;22(1):6–10 | Epub 9 Oct 2015
© Hong Kong Academy of Medicine. CC BY-NC-ND 4.0
Excess mortality for operated geriatric hip fracture in Hong Kong
LP Man, MB, BS, MRCSEd; Angela WH Ho, MB, ChB, FHKAM (Orthopaedic Surgery); SH Wong, MB, BS, FHKAM (Orthopaedic Surgery)
Department of Orthopaedics and Traumatology, Caritas Medical Centre, Shamshuipo, Hong Kong
Corresponding author: Dr LP Man (email@example.com)
Introduction: Geriatric hip fracture places an increasing burden to health care systems around the world. We studied the latest epidemiology trend of geriatric hip fracture in Hong Kong, as well as the excess mortality for patients who had undergone surgery for hip fracture.
Methods: This descriptive epidemiology study was conducted in the public hospitals in Hong Kong. All patients who underwent surgery for geriatric hip fracture in public hospitals from January 2000 to December 2011 were studied. They were retrieved from the Clinical Management System of the Hospital Authority of Hong Kong. Relevant data were collected using the Clinical Data Analysis and Reporting System of the Hospital Authority. The actual and projected population size, and the age- and sex-specific mortality rates were obtained from the Census and Statistics Department of Hong Kong. The 30-day, 1-year and 5-year mortality, and excess mortality following surgery for geriatric hip fracture were calculated.
Results: There was a steady increase in the incidence of geriatric hip fracture in Hong Kong. The annual risk of geriatric hip fracture was decreasing in both sexes. Female patients aged 65 to 69 years had the lowest 1-year and 5-year mortality of 6.91% and 23.80%, respectively. Advancing age and male sex were associated with an increase in mortality and a higher excess mortality rate following surgery.
Conclusion: The incidence of geriatric hip fracture is expected to increase in the future. The exact reason for a higher excess mortality rate in male patients remains unclear and should be the direction for future studies.
New knowledge added by this study
- Advancing age and male sex were associated with an increase in mortality and a higher excess mortality rate in Hong Kong following surgery for hip fracture.
- The burden of geriatric hip fracture is expected to increase.
- Future studies should investigate the cause of an increased excess mortality in male patients who sustain a geriatric hip fracture.
Geriatric hip fracture places an increasing burden on health care service providers around the world. Previous studies have shown that it is associated with significant morbidity and mortality.1 2 3 With the ageing population in many parts of Asia, it has been estimated that over half of all hip fractures will occur in Asia in 2050.4 Studies in France5 and the US6 have reported a drop in the incidence rate of geriatric hip fracture in the elderly population. This trend, however, has not been echoed by similar studies in Korea7 and Japan.8 Epidemiological studies performed in Hong Kong in 2007 and 2012 showed that, similar to western countries, there was a drop in the incidence rate of hip fracture in the territory.9 10
Hong Kong has one of the longest life expectancies in the world.11 The total number of geriatric hip fractures is expected to increase. It will therefore be important for policy-makers and society as a whole to adequately forecast future trends in the disease to prepare for the challenges ahead. This study aimed to analyse the latest trend in the epidemiology of geriatric hip fracture in Hong Kong, as well as to investigate the mortality rate and excess mortality rate in patients who underwent surgery for geriatric hip fracture.
Approximately 98% of geriatric hip fractures are managed in public hospitals run by the Hospital Authority of Hong Kong.10 All patients admitted to a public hospital in Hong Kong are assigned a code in the Clinical Management System by the attending doctor(s). The system also includes information on age, sex, principal diagnosis, and period of hospitalisation. Relevant data, including date of death, were collected using the Clinical Data Analysis and Reporting System (CDARS) from the Hospital Authority. All cases between January 2000 and December 2011 with a disease coding of acute hip fracture (ICD-9-CM diagnosis codes 820.8, 820.09, 820.02, 820.03, 820.20, and 820.22) were retrieved. Operations for geriatric hip fracture were defined as a patient-episode with ICD-9-CM procedure code of 81.52, 51.51, 81.40, 79.15, 79.35, or 78.55.
Only patients with a disease code for acute hip fracture and procedure code for geriatric hip fracture were included in the current study. Patients who were non-Chinese, who had an old fracture, were managed non-operatively, had a second hip fracture or complications of primary hip fracture were excluded. Based on the date of death, we analysed the 30-day and 1-year mortality regardless of cause of death. Postoperative 5-year mortality rate was calculated based on data from patients who underwent surgery from year 2000 to 2006.
Excess mortality is defined by the World Health Organization as “Mortality above what would be expected based on the non-crisis mortality rate in the population of interest.”12 In this study, the excess mortality rate was calculated by subtracting the age- and sex-specific mortality from the age- and sex-specified 1-year mortality of operated geriatric hip fracture. The age- and sex-specific mortality rates for the year 2006 were used for analysis. The actual and projected population size, and the age- and sex-specific mortality rates13 were obtained from the Census and Statistics Department of the HKSAR Government.
From January 2000 to December 2011, the annual number of patients admitted to public hospitals and who underwent surgery for hip fracture increased from 3678 to 4579. The annual incidence of geriatric hip fracture during the study period is shown in Figure 1. A slightly decreasing annual risk of hip fracture was observed for both male and female patients (Figs 2 and 3).
A total of 48 992 cases were retrieved after excluding non-Chinese patients, old fractures, cases managed non-operatively, second hip fractures, repeated admission for the same fracture, and complications of primary hip fracture.
Patient age ranged from 65 to 112 years with a mean and median age of 82.1 and 82.0 years, respectively. The overall 30-day and 1-year mortality was 3.01% and 18.56%, respectively.
The age- and sex-specific mortality after 30 days, 1 year, and 5 years for operated hip fracture are shown in Table 1. Female patients aged 65 to 69 years had the lowest 1-year and 5-year mortality of 6.91% and 23.80%, respectively. An increase in mortality was observed with advancing age and male sex.
The excess mortality rate in different age and sex groups is shown in Table 2 and Figure 4. Male gender and increasing age were associated with a higher excess mortality rate after operation for geriatric hip fracture. The excess mortality for a male patient aged ≥85 years was 23.45%.
A slight decrease in the annual risk of geriatric hip fracture was noted in this study. This trend echoes that of similar studies in the territory and in some western countries.5 6 10 Such a decrease has been postulated to be related to improved availability of medical intervention to prevent osteoporosis, increased attention to menopause and hormonal replacement therapy, changes in lifestyle, and community fall prevention programmes. Nonetheless few studies have been able to prove any causal relationship.
Surgery is generally offered to patients with geriatric hip fracture in order to decrease the morbidity and mortality associated with prolonged immobilisation. In this study, patients who were managed non-operatively were excluded as they represented a very small proportion of patients (estimated to be <1%) with poor pre-morbid medical conditions and very high anaesthetic risk.
Despite the decreasing annual risk of geriatric hip fracture, it is important to relate this to the ageing population in the territory. Using the projected percentage of elderly aged ≥65 years in Hong Kong,11 and assuming that the annual risk of hip fracture remains the same, we estimate that there will be more than 6300 cases of hip fracture in the year 2020. In the year 2040, the annual incidence of geriatric hip fracture will be more than 14 500, more than a 3-fold increase from 2011. Unless effective primary prevention measures are put in place, the burden of geriatric hip fracture on the public health system will continue to increase. Policy-makers should invest in the relevant specialties and departments in order to tackle the inevitable challenges ahead.
To our knowledge this is the first study to review the excess mortality of operated geriatric hip fracture in the territory. A systematic epidemiological review by Abrahamsen et al14 showed that the 1-year excess mortality rate following hip fracture ranged from 8.4% to 36%. In this study, the 1-year excess mortality following surgery for geriatric hip fracture ranged from 6.22% to 23.45%. Echoing the result of Abrahamsen et al,14 we also identified that men had a higher excess mortality rate after operation for geriatric hip fracture. The reasons for this higher excess mortality rate in males remain unclear. Endo et al15 reported that male gender was a risk factor for sustaining postoperative complications such as pneumonia, arrhythmia, delirium, and pulmonary embolism, even after controlling for age and the American Society of Anesthesiologists rating, as well as a higher mortality 1 year after hip fracture. Another study by Wehren et al16 reported an increased rate of death from infection in males for at least 2 years after hip fracture, suggesting that infection may contribute to the differential risk of death.
There are limitations to the present study. Patients with geriatric hip fracture who were treated in the private sector were not included, although they constituted only a small proportion of the total number of cases. Chau et al10 reported that approximately 98% of hip fractures were managed in the Hospital Authority.
In the CDARS of the Hospital Authority, the date of death was provided by the death registry of the Immigration Department of Hong Kong. We were unable to capture data for deaths that occurred outside the territory. Under the laws of Hong Kong, only deaths that occur in Hong Kong are registered with the Deaths Registries. According to the Census and Statistics Department, approximately 9% of the elderly population resides in the mainland.17 As Hong Kong residents are currently not eligible for free or subsidised health services in the mainland, we believe many elderly people will return to Hong Kong for medical treatment.
Other risk factors that may contribute to the excess mortality such as smoking and pre-morbid health status were not included in the present study. Further studies should also investigate the incidence and mortality of other fragility fractures. The effect of primary and secondary prevention by anti-osteoporotic medications on the incidence of geriatric hip fracture is also a potential area for further study.
Geriatric hip fracture will continue to be a major challenge for the health care system in the foreseeable future. Despite the emphasis on early surgery for geriatric hip fractures in recent years, the risk of premature death remained high for patients who underwent surgery for hip fracture. Future studies should be directed to identify the causes of this excess mortality and patients who are at increased risk of premature death, so that early interventions can be initiated to reduce their risk.
The authors would like to thank Mr Tony Kwok and the CDARS team of Hospital Authority for their help in data retrieval.
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