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Incidence of and Risk Factors for Falls Following Hip Fracture in Community-dwelling Older Adults

A Shumway-Cook, PT, PhD, is Associate Professor, Department of Rehabilitation Medicine, University of Washington, Box 356490, Seattle, WA 98195 (USA) (ashumway{at}u.washington.edu)
MA Ciol, PhD, is Research Assistant Professor, Department of Rehabilitation Medicine, University of Washington
W Gruber, MD, was Medical Director, SAGE Program, Northwest Hospital, Seattle, Wash, at the time of the study
CA Robinson, PT, MS, is Clinical Instructor, Department of Rehabilitation Medicine, University of Washington

Address all correspondence to Dr Shumway-Cook

Submitted August 23, 2004; Accepted December 21, 2004

	Abstract

 
Background and Purpose. Hip fracture is a major medical problem among older adults, leading to impaired balance and gait and loss of functional independence. The purpose of this study was to determine the incidence of and risk factors for falls 6 months following hospital discharge for a fall-related hip fracture in older adults. Subjects. Ninety of 100 community-dwelling older adults (65 years of age) hospitalized for a fall-related hip fracture provided data for this study. Methods. An observational cohort study used interviews and medical records to obtain information on demographics, prefracture health, falls, and functional status. Self-report of falls and performance-based measures of balance and mobility were completed 6 months after discharge. Results. A total of 53.3% of patients (48/90) reported 1 or more falls in the 6 months after hospitalization. Older adults who fell following discharge had greater declines in independence in activities of daily living and lower performance on balance and mobility measures. Prefracture fall history and use of a gait device predicted postdischarge falls. Discussion and Conclusion. Falls following hip fracture can be predicted by premorbid functional status.

Key Words: Aging • Falls • Functional decline • Hip fracture

	Introduction

Top Abstract Introduction Method Results Discussion Conclusions Appendix References

 
Hip fractures in older adults are a major medical problem leading to increased morbidity and mortality.^1–7 Research has shown that hip fractures in elderly people can lead to decreased strength (force-generating capacity of muscle), impaired balance and mobility, and long-term loss of independence. Less than 50% of patients will regain their prior level of function following hip fracture.^2–5,7–10 Following a fracture, older adults are 3 times more likely to be functionally dependent, and 4 times less likely than those who have not fallen to return to walking in the community.⁶ Up to 38% of older adults who previously lived independently in the community and who survive a hip fracture will require long-term care.^5,9

Several studies have identified predictors of morbidity and functional outcomes following hip fracture. Prefracture predictors of functional outcome include age,^3,4,11,12 comorbidities,³ history of falls,¹¹ perceived risk of falling,¹¹ previous fracture and hospitalization,⁸ decreased mobility,^1,11–13 and decreased independence in activities of daily living (ADL).⁸ Ingemarsson et al¹ found that Timed "Up & Go" (TUG) test scores at hospital discharge, prefracture walking habits outdoors, and activity level are strong predictors of walking ability and activity level 1 year after fracture. Individuals are more likely to require nursing home placement if they have decreased balance or poor gait¹³ or if they are confused or delirious on admission to the hospital.¹⁴ Patients who require readmission to the hospital following hip fracture are more likely to require total assistance for ambulation, to require nursing home placement, and to die.¹⁵

There is limited information on the incidence of postfracture falls and the factors associated with those falls among older adults. McKee et al¹² followed 57 patients for 2 months and reported that 17.5% of patients with hip fractures had subsequent falls. Colon-Emeric et al¹⁶ reported that 19% of community-dwelling men and male veterans sustained a second hip or pelvic fracture within 1 year of their initial hip fracture. Decreased quadriceps femoris muscle strength (measured with a strain gauge) and increased postural sway while standing have been reported as indicators of increased risk for falls following hip fracture.¹⁷ Fox et al,¹³ however, concluded that mobility status 2 months after fracture did not predict future falls.

Identifying elderly patients with hip fracture who have an increased risk for postfracture falls is critical in light of research documenting that participation in a fall prevention program can improve balance and mobility and reduce the rate of injurious falls in community-dwelling older adults.^18,19 In addition, identifying factors that predict the likelihood for a poor outcome following a fall-related hip fracture may facilitate discharge planning by identifying patients who will require additional rehabilitation resources to improve functional recovery and reduce the likelihood for future hospitalizations associated with postdischarge falls. Thus, the goals of this study were to examine incidence of falls in older adults with a fall-related hip fracture and to identify factors that would predict falls in the 6 months following hospital discharge.

	Method

Top Abstract Introduction Method Results Discussion Conclusions Appendix References

 
Subjects

The first 100 older adults admitted to Northwest Hospital from May 1994 to August 1995 for care of a fall-related hip fracture who met the inclusion criteria and agreed to participate were included in this study. Of the 100 participants admitted into the study, 90 were available for the 6-month follow-up, 3 had died, 3 had moved from the area, and 4 refused the follow-up contact. Criteria for inclusion in the study were that the subjects: were aged over 65 years and living in the community, either in their own home or in a retirement center; had sufficient cognitive ability to provide informed consent; and had experienced a fall-related hip fracture. Subjects were excluded if they had a prior history of neurological or musculoskeletal impairment that would increase risk for falls, such as cerebrovascular accident or Parkinson disease, or if they had a history of lower-extremity joint replacement. People with unstable cardiac conditions or impaired cognition and dementia (as reported in the medical records) also were excluded.

The mean age of study participants was 83.4 years (SD=6.5, range=68–98). The majority of the study participants were women (83%) and people who were living alone in their own homes (80%). Subjects reported a high level of independence in ADL function (=47.8, SD=1.9) in the month prior to the fall-related hip fracture. Their prefracture and baseline characteristics are presented in Table 1. The number of subjects' comorbidities ranged from 0 to 9 (=3.8, SD=1.9). Sixty percent of the individuals used no ambulation device prior to the hip fracture, whereas 34.4% used a cane and 5.6% used a walker. Of all participants, 36.7% had a diagnosis-related group (DRG) code of "Major Joint and Limb Replacement," 38.9% had a DRG code of "Hip/Femur Procedures With Complications," and 17.8% had a DRG code of "Hip/Femur Procedures Without Complications."²⁰ Length of hospital stay ranged from 2 to 14 days (=5.6, SD=1.9). Ninety percent of the participants were discharged to a transitional care unit, 9% to their own home, and 1% to a nursing home.

Medical factors were determined from the patient's medical record and included the primary DRG,²⁰ including "Major Joint and Limb Replacement" (DRG 209), "Hip/Femur Procedures, >17 Years of Age With Complications (DRG 210)," and "Hip/Femur Procedures, >17 Years of Age, Without Complications" (DRG 211); coexisting medical conditions; and number and type of prescription medications. Length of hospital stay (in days) also was recorded.

Six months following discharge from the hospital, participants were interviewed in their homes regarding their current health status, number of falls in the previous 6 months, and independence in ADL function. In addition, a 1-hour evaluation of balance and gait was conducted. Level of dependence performing ADL was determined by self-report using the same FIM scoring method. Balance was tested using the Berg Balance Scale, which rates balance during the performance of 14 tasks, including sitting, standing, reaching, leaning over, turning, and stepping.²² Gait speed was calculated by timing participants as they walked at a comfortable pace using the assistive device most often used when walking in the community. Time (in seconds) taken to walk the middle 2.4 m (8 ft) of a total distance of 3.7 m (12 ft) was converted to velocity (in meters per second). The evaluations were conducted by 1 of 2 licensed physical therapists. Interrater reliability between the 2 physical therapists on the clinical evaluation protocol was good (intraclass correlation coefficient=.98). Subjects were asked to report the number of falls that had occurred in the 6 months following discharge. A fall was defined as any event that led to an unplanned, unexpected contact with a supporting surface. The number of hospital admissions for fall-related injuries was determined from medical records.

To study whether the type of change in assistive device was different in the 2 groups of subjects (those who had fallen and those who had not fallen), we defined the following categories: no change (indicating the same type of device was used before the fracture and after the 6-month follow-up); higher degree of assistive device (indicating a change to more dependence on a device, such as a change from no device to a cane or from a walker to a wheelchair); and lower degree (indicating less dependence on a device, such as a change from a cane to no device).

Data Analysis

The data were analyzed using the SPSS software program, version 11.5.^* All variables were analyzed using descriptive methods. Differences in outcomes between the 2 groups of subjects (those who fell and those who did not fall during the time period leading up to the 6-month follow-up) were assessed by the Mann-Whitney test²³ for continuous variables and the Fisher exact test²³ for categorical data. The nonparametric Mann-Whitney test was chosen because of the lack of normality of some of the outcome data. Logistic regression was used to study potential predictors of a fall during the 6-month period after fracture. Initial variables chosen as potential explanatory variables included: sex, age, premorbid ADL function, premorbid use of an ambulation device, DRG, length of hospital stay, and premorbid fall history. These variables were selected because we hypothesized that they would be associated with postdischarge falls. Age and sex were entered first into the model. Then all other variables were entered using a forward stepwise method. An alpha level of .10 was used for all tests. This level was chosen because this study was exploratory in nature and because using a less restrictive significance level would avoid discarding potential risk factors.

	Results

Top Abstract Introduction Method Results Discussion Conclusions Appendix References

 
Fall Status at 6 Months

At the time of the 6-month follow-up, 53.3% (48/90) of the patients reported falls, with 62.5% (30/48) of them reporting 2 or more falls. Of the patients who had fallen, 18% reported that they had been readmitted to the hospital with fall-related injuries.

Functional Status

Balance and mobility.
Table 2 compares balance and mobility measures at the 6-month follow-up in the 2 groups of older adults (those who reported falls during the 6-month period versus those who did not report falls). Older adults who reported falls had lower Berg Balance Scale scores and slower gait speed compared with those who did not fall (P<.001 for both measures). Prior to their hip fracture, 23.8% (10/42) of the participants who did not fall used assistive devices (cane or walker). In contrast, 54.2% (26/48) of the participants who fell used assistive devices. At 6 months, 71.4% (30/42) of the participants who did not fall used assistive devices, and 93.8% (45/48) of the participants who fell used assistive devices. Thus, both groups showed a substantial increase in the use of an assistive device for walking at 6 months following hip fracture. The change in the level of assistive device was not different between the 2 groups (P=.33), although the group of people who had fallen had a higher proportion of individuals using a higher degree of assistive device at the 6-month follow-up (Tab. 2).

Factors Predicting Postfracture Falls

A logistic regression analysis was used to determine factors that predicted the probability of falling in the 6-month period following hospital discharge. The resultant model is shown in Table 3, including odds ratios, 95% confidence bounds, and P values for the test of the null hypothesis that the odds ratio was 1. Age and sex were not statistically significant (P=.42 and .57, respectively). In addition, premorbid ADL function was dropped from the model because there was too little variation in scores, thus limiting its usefulness as an explanatory variable. After adjusting for age and sex, premorbid use of a gait assistive device and a history of at least 1 fall in the 6-month period prior to fracture were significant predictors of postdischarge falls (P=.02 and .002, respectively). All other factors being equal, an older adult who used an assistive device was 3.15 times more likely to fall by the 6-month follow-up than a person who did not use an assistive device. Similarly, an older adult with a history of premorbid falls was 8.77 times more likely to fall by the 6-month follow-up than a person who had no history of premorbid falls.

Fixing a cut point and classifying the subjects in terms of whether they will experience a fall or not if their probability is greater or smaller than that value gives us measures of sensitivity and specificity of the model. Using the logistic regression model and a cut point of 0.5, the overall proportion of older adults correctly classified was 73%, sensitivity was 70.8%, and specificity was 76.2%. Sensitivity could be increased to 91.7% with a cut point of 0.29; however, specificity would decrease to 35.7%. These levels of sensitivity and specificity mean that, if we adopted the cut point of 0.29, we would identify correctly those who will experience a fall 91.7% of the time, but we could expect to have a large number of false positive classifications.

	Discussion

Top Abstract Introduction Method Results Discussion Conclusions Appendix References

 
This study showed that about half (53%) of the older adults who sustained a fall-related hip fracture experienced another fall in the 6 months following hospital discharge. This rate of falls is higher than that reported by either McKee et al,¹² who reported that 17.5% of older adults fell again within 2 months of their hip fracture, or Colon-Emeric et al,¹⁶ who reported a fall rate of 19% in community-dwelling men and male veterans in the year following fracture. Differences may be due to variations in methodology. The study by Colon-Emeric et al involved only men, and McKee et al followed older adults for only 2 months. Consistent with higher fall rates, hospital readmissions (18%) in our study also were higher than readmission rates reported by Boockvar et al¹⁵ and Colon-Emeric et al.¹⁶

Fall rates in this study were higher than reported fall rates among older adults hospitalized for any reason. Mahoney and colleagues²⁴ reported that 14% of patients over the age of 70 years who were hospitalized for medical illness fell within 1 month of discharge, indicating a risk for falling in older adults who are hospitalized independent of hip fracture. Similar to results from our study, Mahoney and colleagues reported that decreased walking function and use of an assistive device were predictive of falls among this group of older adults.

Several studies^2–5,7–11 have shown that many older adults do not recover their baseline level of function following hip fracture. Only 40% to 60% of older adults will regain their prefracture mobility status within 6 months following a hip fracture, and less than 50% will regain their ADL status.^{2–5,7–9,11} These studies have suggested that functional decline in older adults following hip fracture is related to the fracture itself, not aging or the presence of comorbidities. Magaziner et al²⁵ compared 594 older adults with hip fracture with 3 groups without hip fracture from different geographic regions and matched for age and comorbidities. They concluded that 25% of the group with hip fracture developed lower-extremity disability that otherwise would not have occurred. Norton et al⁶ compared 911 patients with hip fracture with 910 people without hip fracture and found a decline in physical function (as measured by self reported mobility, dependence in ADL, and level of physical activity) in the group with hip fractures at 2 years, independent of the effects of increasing age or pre-existing medical conditions and disabilities. Although the design of our study does not allow us to determine whether the changes in ADL in our participants were a cause or effect of the falls during the 6-month postdischarge period, our results suggest that declines in ADL function are greatest in older adults who experience postfracture falls. In addition, postdischarge declines in ADL function and falls were associated with impaired balance and mobility at 6 months, suggesting that such declines may be related more to the coimpairments of balance and mobility than to the presence of a hip fracture.

The importance of balance impairments to postfracture outcomes is supported by results from the logistic regression analysis. Factors predicting falls in the 6 months following a fall-related hip fracture included use of an ambulation device and a history of falls prior to the one causing hip fracture. Thus, premorbid factors gathered on admission were useful in identifying older adults who were at risk for postdischarge falls. These findings have important clinical implications for postfracture care in older adults. Studies^18,19 have shown that falls in community-dwelling older adults can be reduced using a multidimensional approach that targets changing underlying risk factors. Exercises designed to increase strength, improve balance, and enhance mobility function have been shown to reduce the risk for falls in elderly people.¹⁹ Identification of older adults at risk for poor outcomes early in their hip fracture care pathway could result in improved discharge planning. Specifically, older adults who are determined to be at risk for falling could be referred for outpatient physical therapy for exercises designed to improve strength, balance, and mobility function. More research is needed to determine whether a change in care pathway to include postdischarge physical therapy results in improved outcomes in older adults with a history of fall-related hip fracture. The sociodemographic characteristics of the older adults with hip fractures included in this study are consistent with those reported in other studies that examined health outcomes following hip fracture, suggesting the generalizability of the results of this study.

Limitations

There were a number of limitations in the current study. Prefracture ADL and fall history were determined by subject report and, therefore, were subject to error. In addition, falls in the 6 months following hospital discharge were reported retrospectively by self-report and, therefore, were subject to reporting error. Accuracy in reporting falls would have been improved by asking subjects to report falls on a monthly basis. The model developed to identify older adults who are at high risk for falling needs to be tested prospectively with a larger sample of older adults. Finally, we could not determine whether the ADL decline identified at 6 months occurred prior to or following the fall(s) reported during that period.

	Conclusions

Top Abstract Introduction Method Results Discussion Conclusions Appendix References

 
Older adults admitted for care of a fall-related hip fracture can be evaluated early in their hospital stay to determine risk for falls following discharge. Indicators may include a previous history of falls and prefracture use of an ambulation device. Elderly patients who fall within the 6 months following a hip fracture are likely to demonstrate poorer balance, slower gait speed, and greater decline in ADL from the prefracture level than those who do not fall. Restoring elderly patients to independent function following a hip fracture may be facilitated by expanding the focus beyond fracture healing to the identification and management of balance and mobility deficits, which may be associated with postfracture falls and loss of functional autonomy.

	Appendix

Top Abstract Introduction Method Results Discussion Conclusions Appendix References

 

View larger version (20K): [in this window] [in a new window] Appendix. Logistic Regression Model

	Footnotes

 
All authors provided concept/idea/research design and consultation (including review of manuscript before submission). Dr Ciol, Dr Gruber, and Ms Robinson provided writing and data analysis. Dr Shumway-Cook provided data collection, project management, writing, and fund procurement. Dr Shumway-Cook and Dr Gruber provided subjects. Dr Gruber provided institutional liaisons.

Study was approved by the institutional review board of Northwest Hospital.

This investigation was supported by a grant from Northwest Hospital Foundation, Seattle, Wash.

^* SPSS Inc, 233 S Wacker Dr, Chicago, IL 60606.

	References

Top Abstract Introduction Method Results Discussion Conclusions Appendix References

 

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