4 Register-based data on hip fractures – sources and validity
4.1 Hip fracture
Hip fractures are common injuries among older people, and associated with substantial morbidity and mortality [114]. The term hip fracture refers to a fracture of the upper end of the thigh bone (femur). Most hip fractures in persons aged 50 years and over result from moderate low-energy trauma, usually a fall from a standing height or lower [115]. For younger persons it is more likely that a case of hip fracture results from a high-energy trauma, such as traffic accidents or a fall from a height [116]. Prevention has focused on minimizing the risk of falls and on reducing the injury potential of those falls [117]. About 7000 (of which more than 95% occur for patients aged 50 years and over) hip fractures per year occur in Finland currently [5].
Ageing among populations is increasing hip fracture patients’ mean age and the number and severity of their pre-existing co-morbidities, which is likely to cause additional problems in patients’ treatment and rehabilitation in the future [118].
Sometimes the hip fracture can be interpreted as an indication of the “beginning of the end” (patients were doing well until they broke a hip and went downhill quickly) and sometimes as an “end of the beginning” (hip fracture signals that the cumulative effect of small declines has reached a critical level) [119].
4.1.1 Hip fracture treatment in Finland
Virtually all suspected hip fracture patients are first referred for examination and treatment to the nearest hospital with orthopedic services. The main objective in hip fracture treatment is to return the patient to his or her level of function before
4 Register-based data on hips fractures – sources and validity
the fracture [115]. The diagnosis of fracture of the hip is straightforward, using x-ray examination. A surgical operation is performed on the majority of patients.
The main methods used in treatment are reduction of the fracture using internal fixation and hip replacement arthoplasty. The care pathway for a hip fracture patient is rather complex with several phases such as surgical management and rehabilitation [120], and is known to result in diverse episode profiles in Finland [121]. Typically a patient is transferred for rehabilitation to the health center serving the patient’s resident municipality after a short postoperative hospital treatment [122]. Finnish health centers are local primary health care units, which also contain inpatient wards. Other institutional environments of care include residential homes and service housing with 24-hour assistance, which both correspond to the nursing home type of care. Non-institutional services utilized by hip fracture patients include outpatient health services, home nursing, ordinary service housing, home-help services, and support for informal care [75].
For six Finnish hospitals, patients aged 50 and over had an average mortality at 30 days after the fracture of about 7%, 17% at four months, 26% at one year, and about 50% at four years [123]. At four months, about 40% of patients lived at home, about 15% were unable to walk, and about 8% had a lot of pain in the injured hip [123]. The functional capacity of the patients does not typically revert to the level prior to the fracture [124]. Hip fractures are also costly to the society. The average patient-specific costs during the first post-fracture year in Finland were estimated to be around €14 410 and more than €35 000 in case of a previously home-dwelling individual who becomes a long-term care patient following the fracture [125].
Treatment processes as well as the outcomes vary considerably between areas and hospitals, and improved auditing of hip fracture treatment has been suggested [126, 127]. A recent Finnish current care guideline on the management of hip fracture patients proposes that a nationwide hip fracture register allowing continuous auditing should be established in Finland [128]. In this sense, there is a pragmatic justification for the methodological studies aimed at transforming routinely collected register data into relevant hip-fracture-specific information about the performance of the health system. In addition, hip fracture is a good choice for a pilot study on performance assessment, because it can also be viewed as a tracer condition in health systems, testing how well health and social services are integrated in the provision of acute care, rehabilitation, and continuing support for a large and vulnerable group of patients [129].
4.1.2 Register data on hip fractures in Finland
Finland has a long history of collecting data on health and social services. At the
4 Register-based data on hips fractures – sources and validity
number is used in all Finnish registers which can be utilized as a linkage key in order to combine data from multiple sources. A particularly important register for the purposes of health services research is the Finnish Health and Social Welfare Care Registers (including the Finnish hospital discharge register). These registers contain data on all inpatient care periods in hospitals, in health centers, in residential homes and in service housing with 24-hour assistance. The data warehouse of the Finnish Hospital Benchmarking Project (nowadays a part of the Finnish Health Care Register) is the corresponding register for hospitals, but also incorporates data on outpatient visits. In general, the complete registration combined with easily linkable registers makes large, longitudinal population-based studies feasible in Finland.
4.1.3 Previous register-based hip fracture studies in Finland
The first nationwide register data based on hospital discharges in Finland are available for the year 1960, although the continuous hospital discharge data collection began no earlier than 1967. Hip fractures were not reported separately, but were combined with other fractures of limbs [130]. The register data from 1968 included hip fractures as a separate group [131]. The hospital discharge data from 1968 is also a data source for the first hip-fracture-specific register-based study in Finland [132]. Most of the register-register-based studies concerning hip fractures have had an epidemiological perspective [133–137]. In the late 1980s and early 1990s, a project aimed at improving the reporting of treatment and costs data based on registers had hip fractures as a separate group [138]. At the same time, the first register-based small-area analyses examining treatment practices in terms of surgical operations reported data on hip fractures treated with arthoplasty [139]. The next step in the utilization of register-based data on the description of hip fracture treatment practices was the reconstruction of the care episodes of the patients [121, 140]. There followed a pilot study examining the effectiveness of hip fracture treatment using register-based data [141, 142].
4.1.4 Register data for the current study
The data used in this study were also based on Finnish registers. As virtually all hip fracture patients are treated at the hospital inpatient ward and given that hip fracture is easy to diagnose, it is very likely that the patient population can be easily identified from the hospital discharge data by using a simple database query with a list of diagnosis codes. To make sure that all hip fracture patients were included in the study population, a total population of fracture of femur (corresponding to
4 Register-based data on hips fractures – sources and validity
ICD-10: S72) in the period 1998–2002 was identified in the Finnish Health Care register.
In order to capture the medical histories of these patients, data on all inpatient (1987–2002) and outpatient hospital care (1998–2002), residential home care and care in service houses with 24-hour assistance (1997–2002), and deaths for this population were obtained from the Finnish hospital discharge register, the Finnish Health and Social Welfare Care Register, the data warehouse of the Finnish Hospital Benchmarking Project and the National Causes of Death statistics using the unique national identification numbers of the patient population. It was first time that the hospital outpatient visits from the benchmarking project data and the data on inpatient care in social institutions from the Social Welfare Care Register were included in a hip fracture specific register-study.
The results of simple database queries were integrated into a new data set containing 988 762 records for 39 041 patients. Each record in this data set corresponded to one care period in inpatient institutional care or outpatient visit in hospital (or death), and included variables such as patient and provider ID-numbers, age, sex, area codes, and diagnosis and operation codes, as well as dates of admission, operation and discharge (or death).