Introduction

Nearly all hip fractures occur as a result of a fall [1] and many fall again soon after sustaining the fracture [2]. Osteoporosis with low bone mineral density (BMD) puts older people who fall at high risk of sustaining fractures [3, 4]. A first hip fracture is associated with a 2.5-fold increased risk of a subsequent fracture [5]. A population-based study among people aged 85 years or older showed that 21% of those with a hip fracture had suffered at least two hip fractures [6].

Previous research has identified several fall risk factors such as comorbidity, functional disability, previous falls, and use of drugs [7–11] but also aging [12, 13] and among the oldest old, male sex [14]. Delirium, which is very common after hip fracture surgery, especially among those with a cognitive decline [15, 16], has been found to be one of the most important risk factors for falls among older people [10].

Multi factorial intervention strategies among community-living older people can prevent falls [17–20] and are the recommendations in fall prevention interventions nowadays [21]. The recommendations in fall prevention programs is that they should include gait training, advice on use of assistive devices, medication reviews, exercise programs including balance training, treatment of hypotension, environmental modification, and treatment of cardiovascular disorders. In long-term care the program recommends also to include staff education [21]. Most fall prevention studies are performed in the community, but multidisciplinary and multifactorial interventions have also been shown to be beneficial in residential care facilities [22].

Few fall prevention studies have been carried out in hospitals; there have been a few studies with single interventions among older patients in rehabilitation units, without any significant effects [23–25]. Recently two studies, one using multiple interventions [26] and one using a multidisciplinary fall prevention approach [27], have demonstrated a reduction in falls. None of these fall prevention studies have focused on hip fracture patients or tried to reduce postoperative complications as a fall prevention measure.

Considering the lack of fall prevention studies in hospitals, especially after recent hip fracture surgery, this is an area of interest for study. The aim of this study was thus to evaluate if a postoperative multidisciplinary, multifactorial intervention program could reduce inpatient falls and fall-related injuries in patients with femoral neck fractures.

Methods

Recruitment and randomization

This study included patients with femoral neck fracture aged ≥70 years, consecutively admitted to the orthopedic department at the Umeå University Hospital, Sweden, between May 2000 and December 2002, and the study was designed according to the CONSORT guidelines [28].

In Sweden different surgery methods are used depending on the displacement of the femoral neck fracture. In the present study patients with undisplaced fracture were operated on using internal fixation (IF) and patients with displaced fracture were operated on using hemiarthroplasty (HAP). If patients had severe rheumatoid arthritis, severe hip osteoarthritis, or pathological fracture they were excluded, by the surgeon on duty, because of the need for a different surgery method, such as total hip arthroplasty (THA). Patients with severe renal failure were excluded, by the anesthesiologist, because of their morbidity. Patients being bedridden before the fracture occurred were also excluded.

In the emergency room the patients were asked both in writing and orally if they were willing to participate in the study. The next of kin was always asked prior to the inclusion in patients with cognitive impairment. The patients or their next of kin could at any time decline participation. A total of 258 patients met the inclusion criteria; 11 patients declined to participate and 48 patients were not invited to participate because they had sustained the fracture in the hospital or the inclusion routines failed (Fig. 1). These 59 patients were more likely to be men (p = 0.033) and living in their own house/apartment (p = 0.009), but there was no difference in age (p=0.354) compared to the participating patients. The remaining 199 patients (Table 1) consented to participate. All patients received the same preoperative treatment.

Patients were randomized, to postoperative care in a geriatric ward with a special intervention program or to conventional care in an orthopedic ward, in opaque sealed envelopes. The lots in the envelopes were sequentially numbered. All participants received this envelope while in the emergency room but the envelope was not opened until immediately before surgery to ensure that all patients received similar preoperative treatment. Persons not involved in the study performed these procedures.

The randomization was stratified according to the operation methods used in the study. Depending on the degree of dislocation, the patients were treated with IF using two hook-pins (Swemac Ortopedica, Linköping, Sweden) (n=38 intervention vs n = 31 control) or with bipolar hemiarthroplasty (Link, Hamburg, Germany) (n = 57 vs 54). Basocervical fractures (n = 7 vs 10) were operated on using a dynamic hip screw (DHS, Stratec Medical, Oberdorf, Switzerland) and one had a resection of the femoral head due to a deterioration in medical status and one died before surgery (both were in the control group).

Fig. 1
figure 1

Flow chart for the randomized trial

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Table 1 Basic characteristics and assessments during hospitalization among participants in the intervention and control groups. SD standard deviation, ADL activity of daily living
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Intervention

The intervention ward was a geriatric unit specializing in geriatric orthopedic patients. The staff worked in teams to apply comprehensive geriatric assessments, management, and rehabilitation [29, 30]. Active prevention, detection, and treatment of postoperative complications such as falls, delirium, pain, and decubitus ulcers was systematically implemented daily during the hospitalization (Table 2). The staffing at the intervention ward were 1.07 nurses/aides per bed.

Table 2 Main content of the postoperative program and differences between the two groups
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The control ward was a specialist orthopedic unit following the conventional postoperative routines. A geriatric unit, specializing in general geriatric patients, was used for those who needed longer rehabilitation (n = 40). The staffing at the orthopedic unit was 1.01 nurses/aides per bed and 1.07 for the geriatric control ward. The main content of both the intervention program and the conventional care is described in Table 2.

The staffs on the intervention and control wards were not aware of the nature of the present study.

Data collection

Two registered nurses were employed and performed the assessments during hospitalization.

Medical, social, and functional data were collected from the patients, relatives, staff, and medical records on admission. Complications during hospitalization, including falls, length of stay, morbidity, and mortality, were systematically registered in the medical and nursing records. Nurses are obliged by law to document any falls in the records [31]. A fall was defined as an incident when the patient unintentionally came to rest on the floor and included syncopal falls. Numbers of falls and time lapse to first fall after admission were calculated. The Abbreviated Injury Scale (AIS) [32] was used to classify the injuries resulting from a fall. The maximum injury (MAIS) connected with each incident was recorded.

A few days after surgery, patients were assessed and interviewed regarding their cognitive status using the Mini Mental State Examination (MMSE) [33]. The modified Organic Brain Syndrome Scale (OBS Scale) [34] was used to assess cognitive, perceptual, emotional, and personality characteristics as well as fluctuations in clinical states. Mental state changes were also documented from medical records. Depression during hospitalization was diagnosed due to current treatment with antidepressants and depression screened using the Geriatric Depression Scale (GDS-15) [35] in combination with depressive symptoms observed and registered by the OBS Scale. The patients’ vision and hearing were assessed by their ability to read 3-mm block letters with or without glasses, and their ability to hear a normal speaking voice from a distance of 1 m. Activities of daily living (ADL) prior to the fracture were measured retrospectively using the Staircase of ADL [36].

A geriatrician, unaware of study group allocation, analyzed all assessments and documentation, after the study was finished, for completion of the final diagnoses according to the same criteria for all patients.

The Ethics Committee of the Faculty of Medicine at Umeå University approved the study (§ 00-137).

Statistical analysis

The sample size was calculated to detect a 50% reduction of number of fallers between the intervention and control groups at a significance level of 0.050, based on our previous multifactorial fall intervention study in institutional care [22]. Student’s t-test, Pearson’s χ2 test, and the Mann-Whitney U test were performed to analyze group differences regarding basic characteristics and postoperative complications.

We analyzed outcomes on an intention to treat basis. The incidence of falls between intervention and control groups was compared in three ways. First, an unadjusted comparison using Pearson’s χ2 and Fisher’s exact test regarding number of patients who fell and injuries. Second, the fall incidence rate was compared between intervention and control groups by calculating the fall incidence rate ratio (IRR) using a negative binomial regression, with adjustment for observation time and for overdispersion. Negative binomial regression (Nbreg) is a generalization of the Poisson regression model and is recommended for evaluating the efficacy of fall prevention programs [37]. Third, a Cox regression was used to compare the time lapse to first fall between groups (hazard rate ratio, HRR). The difference in fall risk between groups was further illustrated by a Kaplan-Meier graph.

Basic characteristics that differed between the intervention and the control groups, corresponding to a p value  <0.150 (depression, antidepressants, and dementia, Table 1), were considered as covariates in the Poisson (Nbreg) and the Cox regression models. However, the inclusion of these variables had only marginal effects on the log-likelihood values of the models as well as on the IRR and HRR values and standard errors for the group allocation variable (intervention or control). In addition, none of the variables showed significant effects on the dependent variable and are therefore not included in the Poisson (Nbreg) and Cox regression analyses.

Pearson’s χ2 test and Fisher’s exact test were also used to analyze the associations between falls and days with delirium between the groups.

All calculations were carried out using SPSS v 11.0 and STATA 9 statistical software for Macintosh. A p value  <0.050 was considered statistically significant.

Results

During hospitalization 12 patients in the intervention group sustained 18 falls (range: 1–3) and in the control group 26 patients sustained 60 falls (30 falls in the orthopedic unit and 30 in the geriatric control unit) (range: 1–11). Among patients with dementia 1 patient sustained a single fall in the intervention group and 11 patients sustained 34 falls in the control group (Table 3).

Table 3 Falls during hospitalization. CI confidence interval, IRR incidence rate ratio
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The crude postoperative fall incidence rate was 6.29/1,000 days in the intervention group vs 16.28/1,000 days in the control group. Using a negative binomial regression, the fall incidence was significantly lower in the intervention group, IRR 0.38 (95% CI: 0.20–0.76, p = 0.006), and among patients with dementia, IRR 0.07 (95% CI: 0.01–0.57, p = 0.013) (Table 3). In Fig. 2, a Kaplan-Meier survival analysis of time lapse to first fall illustrates the difference between the two groups with a significantly reduced fall rate in the intervention group (log rank p value 0.008).

Fig. 2
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Kaplan-Meir survival graph

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The difference in fall risk, expressed as time lapse to first fall, was compared between intervention and control groups in a Cox regression (HRR). Including all patients in the calculation, the fall risk was significantly lower in the intervention group, HRR 0.41 (95% CI: 0.20–0.82, p = 0.012).

There were in total 3 minor or moderate injuries (MAIS 1-2) in the intervention group compared to 15 in the control group according to the AIS. The serious injuries (MAIS 3) were new fractures of which four, two hip fractures, one rib fracture with pneumothorax, and one with multiple skull fractures, occurred in the control group and none in the intervention group (Fisher’s exact test: p = 0.055).

Three of the patients who fell in the intervention group (25%) and 12 in the control group (46%) fell during a day when they were delirious (p = 0.294). Analyzing the number of falls revealed that 4 of 18 (22%) falls in the intervention group and 27 of 60 (45%) in the control group occurred on a day when the patient was delirious, p = 0.083.

Apart from the falls there were fewer other postoperative complications in the intervention group, such as fewer patients with postoperative delirium (p=0.003) and fewer delirious days (p ≤ 0.001), urinary tract infections (p = 0.005), sleeping disturbances (p = 0.009), nutritional problems (p = 0.038), and decubitus ulcers (p = 0.010). The postoperative in-hospital stay was shorter in the intervention group, 28.0 ± 17.9 days vs 38.0 ± 40.6 days, p = 0.028. Among those ten with the longest postoperative in-hospital stays in the control group there were eight patients with any fall and two had had new fractures.

Discussion

The present study shows that the number of falls and time lapse to first fall can be reduced during in-hospital rehabilitation after a femoral neck fracture. A multidisciplinary, multifactorial geriatric care program with systematic assessment and treatment of fall risk factors as well as active prevention, detection, and treatment of other postoperative complications resulted in fewer patients who fell, a lower total number of falls, and fewer injuries.

To our knowledge this is the first fall intervention study in this group of patients, despite the fact that this is a group of patients with a high fall risk. In general there are few fall prevention studies in hospital settings. Two [26, 27] with positive outcomes in other patient groups and on subacute wards have recently been published. The first one [26] reduced falls at three subacute rehabilitation wards, but the differences were most obvious after 45 days of observation. Thus the results were not comparable with those from the present study, which included both the acute and rehabilitation hospital stay. The other study [27] resulted in fewer fallers, falls, and injuries on a geriatric ward but the differences disappeared when the results were adjusted for observation time. Those studies used a multidisciplinary approach in their fall intervention similar to that used in the present study, but in the present study we have, in addition, focused on inpatient complications associated with falls such as delirium and urinary tract infections. One of those studies [27] tried to manage the delirious patients using bedrails, alarms, and changing the furniture arrangements for the patients, but no mention was made of any prevention and treatment of the underlying causes of delirium. The use of physical restraints was not included in the intervention program in the present study. The studies above used fall risk assessment tools to recognize those with a high fall risk. In the present study, we used a rehabilitation and care program including assessment of risk factors for falls and global ratings for each patient during team meetings. A critique of fall risk assessment tools is that few have been tested for validity and reliability testing in a new independent sample. When using fall prediction tools in different clinical settings the specificity decreases [38].

A limitation in the present study is that some falls could have been missed, but we presume that there were very few. For one thing the nurses are obliged to document falls in the records. Also hip fracture surgery patients can hardly get up by themselves after a fall so soon after the surgery and are, therefore, bound to be noticed; but if there were any missing falls there would probably be no difference between the groups. Another limitation is that the fall registration could not be blinded regarding group allocation, but the staffs on each ward were not aware of the comparison with another ward regarding falls and injuries. The study sample is also quite small, but the sample size is calculated according to the results from a previous study [22]. The method of concealment could have been improved, but one strength was that none from the research team performed this procedure and the envelopes were not opened until the intervention was to begin. Other strengths were the intention to treat analyses, the few patients who refused to participate, and that there were no crossover effects due to staff changing wards during the study period.

One may speculate that the successful reduction in number of falls in the present study could be a result of the active prevention, detection, and treatment of postoperative complications after surgery. During the period of hospitalization there were differences between the groups regarding some complications associated with falls among older people in residential care facilities and in hospitals, such as delirium and urinary tract infections. The reduction of postoperative delirium can probably explain much of the difference between the groups regarding the numbers of falls and the number of patients who fell. There are studies that have found that delirium is an important risk factor for falls [10]. Demented patients especially are at high risk of developing delirium when they are treated for femoral neck fractures [15, 16] and these patients seemed to have benefited most in this study from the intervention program regarding prevention of postoperative falls. Our findings support an earlier non-randomized study that fewer injurious falls occur when the incidence and duration of delirium was reduced [39].

The investigation into why the patients had fractured their hip and why they fell may also have influenced the result, as well as the investigation and rehabilitation concerning external fall risk factors such as the use of walking aids, safe transfers, balance, and mobility. It seems that teamwork and individual care planning alone do not have the same effect on falls, as half the falls in the control group occurred in the geriatric control ward, a ward specializing in geriatric patients where teamwork, as well as individual care planning, is applied.

In the community and residential care facilities, interdisciplinary and multifactorial fall prevention studies have shown positive effects on the reduction in the number of falls and injuries [19, 22]. Among those with cognitive decline or dementia there is no evidence that such strategies prevent falls [40, 41], but the present study allowed the conclusion that at least during the in-hospital stay, this group of patients could benefit from such strategies. The reduced number of falls and injuries also probably contributed to the shorter hospitalization seen in the intervention group. The program seems easy applicable both in the acute postoperative care as well in the post-acute rehabilitation settings and except for the staff education there were no increased costs.

Conclusion

A team applying comprehensive geriatric assessment and rehabilitation, including prevention, detection, and treatment of fall risk factors, can successfully prevent inpatient falls and injuries, even in patients with dementia.