Introduction

Despite decreasing age-standardised hip fracture rates in many countries, the rate of other fall injuries and subsequent fall-related hospitalisations continues to grow [1–4]. In Australia, it has been found that fall-related injury hospitalisations now account for one in ten hospital bed days for people aged 65 and over [2]. This proportion includes older people living in the community and aged care facilities.

Falls are a common occurrence in aged care facilities, where up to 65 % of older residents are estimated to fall in a 6-month period [5]. Admission to hospital after a fall is also common, with the age-standardised rate of fall-related hospitalisation for people in aged care facilities six times the rate for community-dwelling older people [2]. There are conflicting results among the few studies of trends in fall-related hospitalisations in aged care residents. In a Swiss study, the reduction in hip fracture hospitalisation rates observed at a population level were found to be due almost entirely to reducing hip fracture rates in older women from aged care facilities [6]. In contrast, recent Australian research by Cassell and Clapperton [1] revealed that the downward trend in age-standardised hip fracture rates observed among community-dwelling older people was not apparent among older people living in aged care facilities.

People living in aged care facilities are becoming increasingly dependent and frail [7]; hence, investigating patterns and trends in fall-related hospitalisations for people in this setting will inform delivery of prevention services for this population and may have implications for adaptations required in the health and aged care systems. The aims of this research were to investigate (1) trends over time in fall-related hospitalisations and injury types for older people living in aged care and (2) potential differences in trends by demographic characteristics and type of injury.

Methodology

Data for this study were obtained from the Victorian Injury Surveillance Unit’s (VISU) hospital admissions injury dataset. This de-identified dataset includes all externally caused hospital-admitted episodes of care contained in the Victorian Admitted Episodes Dataset (VAED). The VAED is administered by the Victorian Department of Health and holds all public and private hospital-admitted episodes of care in the state of Victoria, the second most populous state in Australia. The data within VAED are audited by the Victorian Department of Health regularly and recognised as being of high quality. Each record in the VAED represents an episode of inpatient care and not an individual patient treated. An episode is not defined by the patient’s arrival at and departure from the hospital but rather by the start and completion of a ‘type of care’. Therefore, one patient may have several episodes of care or only a single episode of care within their one hospital stay. VAED is coded to the International Statistical Classification of Diseases and Related Health Problems, Tenth Revision, Australian Modification (ICD-10-AM) from July 1, 1998 [8].

The inclusion criteria for VAED episodes for this study were as follows:

  • Age at the time of admission 65+ years.

  • A principal external cause recorded as a fall (ICD-10-AM codes: W00-W19) and a principal diagnosis of an injury (ICD-10-AM codes: S00-T75, T79).

  • An admission source indicating a transfer from aged care. Aged care facilities in Australia provide high-level and lower-level nursing care for people who can no longer live independently.

  • An admission occurring between July 1, 2003 and June 30, 2012 (inclusive). This starting date was chosen because the coding of the admission source variable has been consistent since this date.

  • A care type of ‘acute’.

  • A Victorian postcode of residence.

To describe the characteristics of the cases and changes over time, the rates of hospitalisation are reported in the following categories:

  • Gender

  • Injury severity, with serious injury defined by an ICD Injury Severity Score less than 0.941 [9]

  • Age at admission, categorised into 5 year age groups, from 65–69 to 90+

  • Country of birth, categorised as Australian born or non-Australian born

  • Injury type (fracture, intracranial etc.)

The rate denominator was the number of aged care bed years (permanent and respite) in Victoria for each year.

Analysis

To investigate the trends in the incidence of fall-related hospitalisation, rates were age standardised using the direct method and 5-year age groups to 90+ years were used. The internal standard population was the number of bed years from the middle year of the dataset (2007/2008). This standard population was used because there was an unusual age structure in this population compared to the usually employed standard populations, and a similar aged structure is recommended [10].

Due to overdispersion of the data, negative binomial regression (NBR) models, adjusted for age, were employed to analyse changes in rates of fall-related hospitalisations and injury over time. The rate ratios presented from these analyses represent the increase in rate of hospitalisations per year. As the first study year (2003/2004) appeared to be an outlying year with respect to trends, NBR was performed with and without the first year. There was little material difference between the rate ratios; therefore, the results for the full study period are presented, as this produced the more conservative rate ratios. The interaction terms of gender, age and country of birth were added to the analyses for fall-related hospitalisation and hip fracture outcomes. STATA 13 was used for all analyses.

Results

Initially, 211,342 records were retrieved with the search limits of aged 65 and over, period 2003/2004 and 2011/2012, first external cause as a fall and principal diagnosis of injury. Limiting to records with admission source coded to aged care left 7218 relevant admissions. Exclusion of admissions with non-acute care types recorded (n = 95) and non-Victorian residents (n = 25) left 7098 records for analysis.

Over the 9-year period, there was a steady increase in the rate of fall-related hospitalisations for this population, with the exception of a decline in 2004/2005 compared to 2003/2004 (Table 1). Even with this initial decline, from 2003/2004 to 2011/2012, the number of fall-related hospitalisations almost doubled over the 9-year period (Table 1). The doubling in frequency is partially accounted for by the increasing number of bed years in aged care facilities in that time. However, with adjustment for age, the increase in the hospitalisation rates over time remained relatively unchanged from the crude rate, with a relative rate increase of 11 % per year (95 % CI 9 %, 12 %).

Table 1 Crude, age-standardised, age-specific, gender and country of birth specific rate of fall-related hospitalisations per 100,000 bed years in aged care facilities, Victoria, from 2003/2004 to 2011/2012
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Trends in the incidence of fall-related injury hospitalisations by demographics

Over most years, women experienced a higher rate of fall injury hospitalisations than men. However, the relative rate increase over the 9-year period was higher for men than women (Table 1). There were significant increases in the hospitalisation rates over time in all age groups (Table 1). The largest increase was observed in the younger age groups, with annual rates increasing most quickly in the 70 to 74 age group (incidence rate ratio (IRR) 1.14, 95%CI 1.06, 1.22). There were no significant interactions between time and gender, age or country of birth.

Trends in the incidence of fall-related injury hospitalisations by injury type

Less serious injuries increased at a higher rate than serious injuries (12.0 % compared to 7.0 %, Table 1). The rate for serious injury flattened from 2009/2010 in contrast to that for less serious injury, which increased steeply from 2008/2009 (Fig. 1). The largest increase in injury type was observed for intracranial injuries, with a relative rate increase of 20 % per year (95%CI 13 %, 27 %) (Table 2). However, intracranial injuries represented a relatively small proportion of hospitalisations (4.2 % in 2011/2012), with fracture being the most common injury type (47.9 %, 95%CI 46.7, 49.0). Overall, there were significant increases in the age-standardised rates for all types of injury over the study period.

Fig. 1
figure 1

Age-standardised fall-related hospitalisations by severity of injury, 2003/2004 to 2011/2012, aged 65 years and older

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Table 2 Age-standardised rate of fall and injury-related hospitalisations and injury per 100,000 bed years in aged care facilities, Victoria, from 2003/2004 to 2011/2012
Full size table

Hip fracture was the most common fracture type, accounting for 52.0 % (95%CI 50.3, 53.7) of all fractures. Of note, the relative rate increase in hip fracture (3 %, 95%CI 0 %, 6 %) was the lowest of all fractures and injury types. There was no interaction between time and gender and time and age group, with hip fracture as the outcome. The largest increase in fracture rates over time was for skull and face fracture, with a relative rate increase of 20 % (95 % CI 11 %, 30 %) per year. However, skull and face fractures accounted for a relatively small proportion of all fractures (3.6 % in 2011/2012).

Discussion

To our knowledge, this is the first study to specifically investigate the trends in all fall injury-related hospitalisations among people aged 65+ years living in aged care facilities. Overall, there was an age-adjusted relative increase of 11 % per year in the rate of fall injury related hospitalisations for this population. This pattern was consistent across genders, age groups, country of birth and injury types. Intracranial injury and face and skull fractures were the injury types displaying the highest rate of increase, with a 20 % relative rate increase per year. Interestingly, the slowest increase in rate over the 9-year period was observed for hip fracture, with a relative rate increase of only 3 % per year. Despite increases in some serious injuries, such as intracranial injury, contrasting patterns were noted by injury severity, with less serious injury increasing at a greater rate than serious injury.

Some of the results in this paper are consistent with previous studies of community-dwelling older people in which increasing rates of fall-related hospitalisations, particularly due to head injury, were noted [1, 3]. However, some of the results, such as the dramatic increases in all fall injuries (excluding hip fracture), diverge from those of past studies of community-dwelling older people. As an example of this, Cassell and Clapperton found a 1.2 % age adjusted increase in rate of fall-related hospitalisations per year for people aged 60 and over [1]. In comparison, we found an 11 % age adjusted increase per year when limiting the hospitalisations to those recorded as being from an aged care facility.

In one of the few comparable studies of people living in aged care facilities, Guilley and colleagues found a decreasing trend over time in hip fracture rates for women in Switzerland [6]. In comparison, we observed an increasing trend in hip fracture rates, although at a slower rate compared to the other injuries. Guilley and colleagues hypothesised that the decrease in hip fracture over time in their study may have been due to the strong fall prevention and osteoporosis management programs implemented in Switzerland. Research in Australia has identified that the prescription of bisphosphonates has risen in the general population [11]; however, there is no recent research specifically investigating prescribing trends in aged care facilities. This makes it difficult to link any changes in osteoporosis management with the levelling of hip fracture rates observed in this study. There are also other possible reasons for the slowing of hip fracture rates, such as increasing body weights for people in aged care [12] and its protecting effect against hip fracture [13] or possible changes in hospital admission practice, with more people being admitted from aged care facilities with non-hip fracture injuries, when hip fracture has always been a cause for hospitalisation. Certainly in our study, less serious injury hospitalisations are increasing at a greater rate than more serious injuries. Further research into the different rates of change for hip fracture and less serious injury is required.

There are a number of possible reasons for the increases in rates of all injury types observed in this study. First, a trend towards active treatment rather than conservative management in aged care facilities would contribute to the increases. This may occur due to a perception of improving treatment prospects in hospital by staff or relatives or changing standards of care and accreditation requirements in aged care facilities. Second, diagnosis of some injury types may be improving, thus enhancing the recording of injuries and also increasing the likelihood of hospitalisation. This factor has been previously cited as a potential contributing factor to the dramatic increases in hospitalisations for intracranial injuries [4]. Third, people in aged care facilities have increasing morbidity [14] and are requiring higher levels of care [7], even when ageing of this population is taken into account. In regard to increasing morbidity studies have found that depression [13] and diabetes [14] are becoming more prevalent in aged care residents. Dementia is also becoming more prevalent in the older population and in 2009/2010 it was found that 53 % of those in aged care had a diagnosis of dementia [15]. These medical conditions, the psychotropic medications used to treat depression and overall morbidity are associated with an increased risk of falls in aged care facilities [16, 17] and may cause an increase in the number of injurious falls and subsequent requirement for hospitalisation. However, the complexity of the situation should be acknowledged; although morbidity is associated with increased risk of falls, research has also found that older people in aged care facilities are at decreased risk of falls once they become non-ambulant [18]. Without the resident profile, it is difficult to reach conclusions about the cause of the trends seen in this study.

This study has a number of strengths and limitations. The fall injury data were drawn from a state-wide hospitalisation data collection, which is quality controlled by the Health Department and enhanced by VISU, and rates were calculated using bed-years. We limited double counting by excluding transfer episodes but could not entirely eliminate it because the VAED does not record the date of injury which would differentiate an admission due to a new fall and injury from a readmission due to complications from a previous fall. Polinder and colleagues reported a 0.7 to 8.6 % readmission rate for the same injury [19]. A further limitation of this study is the lower numbers available for the analysis, compared to studies of community-dwelling older people. This would have the effect of higher random error in the estimated rates and may explain the variation in the point estimate rates in the earlier years. Also residual confounding within the age groups is a possibility, although this would be unlikely to purely responsible for the results seen. There is no evidence that technical factors contributed to the trends observed. There was no change to the codes available for admission source, and there were no episodes with a missing or unspecified code for admission source over the time period. As we were working with an administrative health care data set, it is possible that changes in policy may influence trends.

In summary, this paper identifies that hospitalisation for fall injury for people from aged care facilities is increasing over time. It is difficult to say whether the rises are due to changes in health-care practice, an increasing number of injurious falls in aged care facilities or a mixture of these reasons. This study offers no evidence that fall prevention strategies within aged care facilities in Victoria have been successful in reducing fall rates in the study period. The slower increase in hip fracture rates may represent possible success in osteoporosis management, increasing body weight or changing aged care facility referral practices but without knowing more about the admission, comorbidities and medications for the admitted episodes, no conclusions can be reached. Further research regarding the cause of the increase seen and potential impacts on emergency departments and the health system is warranted. In the meantime, prevention efforts should focus on evidence-informed fall prevention measures [20] and particularly on hip fracture prevention, [21, 22], given the continuing dominance of this injury type.