Volume 89, Issue 8 , Pages 1522-1527, August 2008
Subcortical Vascular Lesions Predict Falls at 12 Months in Elderly Patients Discharged From a Rehabilitation Ward
Article Outline
Abstract
Guerini F, Frisoni GB, Marrè A, Turco R, Bellelli G, Trabucchi M. Subcortical vascular lesions predict falls at 12 months in elderly patients discharged from a rehabilitation ward.
Objective
To test whether subcortical vascular lesions are associated with falls in elderly patients with gait disorder discharged from a rehabilitation ward.
Design
Secondary 12-month follow-up analysis of an observational survey focusing on the prevalence of subcortical vascular lesions in a population of elderly patients discharged from rehabilitation hospitals.
Setting
A rehabilitation and aged care unit.
Participants
Consecutively admitted elderly patients (N=214) with gait disorder.
Interventions
Not applicable.
Main Outcome Measures
On admission, all patients underwent comprehensive geriatric assessment including sociodemographics, cognitive and depressive symptoms, nutritional status, physical health, and functional status. Subcortical vascular lesions were assessed on computed tomography films with a validated rating scale. All patients received a standardized rehabilitative program. Twelve months after discharge, all patients were interviewed by telephone, mainly focusing on the occurrence of falls during the follow-up period. Potential predictors of falls were assessed in univariate and multivariate analyses.
Results
Univariate predictors of falls were age, sex, Mini-Mental State Examination, Barthel Index on admission, and subcortical vascular lesions. In multivariate analyses, subcortical vascular lesions were the only significant predictor of risk of falling; patients with moderate and severe subcortical vascular lesions scores had a greater risk of falling (odds ratio [OR]=3.0; 95% confidence interval [CI], 1.3–7.1; P=.012; OR=3.9; 95% CI, 1.6–9.2; P=.002, respectively) than those with no subcortical vascular lesions.
Conclusions
Subcortical vascular lesions are associated with falls at 12 months in elderly patients with gait disorder discharged from a rehabilitative ward. Future research is needed to confirm our results.
Key Words: Accidental falls, Elderly, Gait, Rehabilitation
List of Abbreviations: CI, confidence interval, CT, computed tomography, GDS, Geriatric Depression Scale, MMSE, Mini-Mental State Examination, MRI, magnetic resonance imaging, OR, odds ratio, RACU, rehabilitation and aged care unit
FALLS ARE COMMON in elderly persons and associated with considerable morbidity, mortality, and risk of institutionalization.1, 2 More than one third of persons aged 65 years and older fall every year, and the rates rise for those older than 75 years.3, 4
In recent years, many efforts have been aimed to identify causative factors of falls in the attempt to develop preventive strategies. In the interaction between predisposing and precipitating risk factors, the following has been associated with the risk of falling: muscle strength, balance, gait, depressive symptoms, cognitive impairment, arthritis, and medications.4 Within this line of research, cerebral subcortical vascular lesions have been consistently reported as related to functional deficits, possibly predisposing to falls.5, 6, 7, 8 In a recent study,9 subjects with mobility impairment had a greater volume of abnormal cerebral white matter on MRI compared with those with normalized mobility. Similarly, another study10 reported that gait disorders were associated with a gradual and progressive onset of subcortical vascular disease. Other studies11, 12 found that subcortical vascular lesions are associated with cognitive deficits and depression, which are also known to be risk factors for falls.
Studies showing a direct relationship between subcortical vascular lesions and falls are scarce.5 Kerber et al13 found that the degree of white-matter lesions was associated with the number of falls at a 5-year interval, but the study was limited because only few subjects completed the follow-up. More recently, Syrjälä et al14 found an association between the incidence of falls and cerebral white-matter hypodensities and cortical atrophy, but other clinical variables had a greater predictive power on falls in a multivariate analysis.
Within this framework, a clear definition of the relationship between subcortical vascular lesions and falls has not yet been provided. In the present study, we evaluated the association of subcortical vascular lesions with the occurrence of falls within a 12-month follow-up as a secondary analysis of a project aiming at assessing the prevalence of subcortical vascular lesions in a population of elderly patients discharged from rehabilitation hospitals.
Methods
Participants
The population was selected among all patients aged 65 years and older (N=625) firstly and consecutively admitted to our RACU from January 1, 2004, to June 30, 2005. The study was a secondary 12-month follow-up analysis of an observational survey on the prevalence of subcortical vascular lesions in the patients admitted to our unit. Patients were admitted to the RACU after recent functional impairment developed during a recent hospitalization or according to a physician report.
On admission, patients underwent a clinical examination by 2 trained geriatricians aimed at evaluating the nature of functional impairment and the presence of gait disorder, which was defined according to previous studies as a difficulty initiating gait, shuffling, instability while turning, and poor balance noted on bedside testing and not attributable to a lack of motivation. Functionally, patients may have difficulty rising out of a chair or getting out of bed and loss of the rhythm of walking.15, 16 Gait disorder was attributable to multiple medical conditions that were grouped into 5 main categories: (1) musculoskeletal, including arthritis, low back pain, previous vertebral fractures because of osteoporosis, or previous trauma; (2) central nervous system, including parkinsonism, previous transitory ischemic attacks or strokes without hemiparesis (lasting >6mo), and dementia (either degenerative, vascular, or mixed forms); (3) peripheral nervous system, including peripheral neuropathy caused by organic diseases and visual loss; (4) peripheral vascular, including intermittent claudication, chronic venous diseases, or previous venous thromboembolism; and (5) other conditions, including iatrogenic gait disorder or deconditioning.
The diagnosis of gait disorder was made separately by the 2 geriatricians, and, in case of disagreement, which occurred in 17% of cases, a consensus was reached through face-to-face discussion on clinical and instrumental findings.
Patients not eligible for the standardized rehabilitative program were excluded. These patients had either a clinical instability caused by recent surgery (ie, orthopedic, abdominal, cardiovascular surgery; n=201), stroke with severe neurologic lesions in the last 6 months (n=58), advanced malignancy (n=11), acute medical illnesses (ie, pneumonia, urinary tract infections, sepsis; n=45), or severe dementia (MMSE score, ≤10; n=15). Patients staying in nursing homes at follow-up were also excluded.
All eligible patients and, whenever available, caregivers were asked to sign an informed consent to take part in the study and, to measure subcortical cerebrovascular severity, were asked to undergo a CT brain scan during the RACU stay. Thirty-two patients (9.2%) refused to give informed consent, whereas 263 were included in the study and followed at 12 months. Of these, 10 had died and 27 were untraceable. Twelve were excluded because they were residents in nursing homes and therefore, data were not available. The remaining 214 patients were interviewed together with their primary caregivers.
Approval for the study was obtained from the ethics committee of the Geriatric Research Group, Brescia, Italy.
Comprehensive Geriatric Assessment
On admission, all patients underwent a comprehensive assessment including sociodemographics (age, sex, education, living condition), cognitive status (MMSE),17 depressive symptoms (15-item GDS),18 nutritional status (serum albumin, body mass index),19 physical health (Charlson Index, number of drugs, number of adverse clinical events occurring during RACU stay),20 and functional status (instrumental activities of daily living, Barthel Index, Tinetti scale).21, 22, 23
Classification of Cerebrovascular Severity
Cerebrovascular disease was assessed on CT films with a standardized rating scale for subcortical vascular lesions.24, 25 The CT rater was a neurologist blind to the clinical conditions or history of falls of patients.
Three types of lesions (leukoaraiosis, fuzzy or patchy lesions, lacunes) were rated separately for the right and left hemispheres in a number of brain regions as follows.
LeukoaraiosisThe degree of hypodensity of the white matter was quantified separately in 3 regions (frontal, parietal, occipital). A score of 0 indicated no hypodensity, 1 questionable hypodensity (might be regarded as “normative for age”), 2 definite hypodensity but confined to the periventricular area or not reaching the cortex, and 3 marked hypodensity reaching the cortex or extending into the white matter of the gyral digitations.
Patchy hypodensitiesThe presence of focal areas of hypodensity with indistinct boundaries was separately assessed in 7 regions: frontal, temporal, parietal and occipital lobes, basal ganglia, internal capsule, external capsule, and cerebellum. The total number of patchy hypodensities was recorded.
LacunesThese were assessed in the same 7 regions as the patchy hypodensities and were defined as well-defined areas of marked and homogeneous hypodensity with a well-defined and regular contour measuring generally from 5 to 10mm across. The total number of lacunes was recorded.
The 3 types of lesions were computed by using an algorithm (previously validated by our group as part of the standardized assessment of cerebrovascular disease on CT films)24 to obtain a global measure of subcortical vascular lesions: (.63 × leukoaraiosis + .96 × patchy hypodensities + .98 × lacunes) × 10 = subcortical vascular lesion sum score.
Finally, an ordinal (0–3) 4-level variable was created by dividing the continuous score of subcortical vascular lesions (range, 0–64) into quartiles based on a percentile distribution, where 0 indicated absent or very mild disease, subcortical vascular lesions were less than or equal to 12.6 (fig 1A); 1 indicated mild disease, subcortical vascular lesions ranged from 12.7 to 22.4 (fig 1B); 2 indicated moderate disease, subcortical vascular lesions ranged from 22.5 to 41.8 (fig 1C); and 3 indicated severe disease, subcortical vascular lesions were greater than or equal to 41.9 (fig 1D).
Fig 1.
CT scans of 4 patients with increasing severity of subcortical vascular lesions. (A) Absent or very mild disease with questionable white-matter hypodensity that might be regarded as “normal for age.” Subcortical vascular lesions: 0 (level 0/3). (B) Mild disease with class C leukoaraiosis or class B patchy and class A lacunes. Subcortical vascular lesions: 18.9 (level 1/3). Note the hypodense frontal periventricular caps. (C) Moderate disease with class C patchy and class A lacunes irrespective of class of leukoaraiosis. Subcortical vascular lesions: 35 (level 2/3). Note the isolated focal patchy lesion in the white matter of the right hemisphere. (D) Severe disease with class B or higher patchy lesions and class B or higher lacunes, irrespective of leukoaraiosis. Subcortical vascular lesions: 54.2 (level 3/3). Note the multiple, bilateral, patchy hypodense lesions in the white matter and the associated lacunes in the basal ganglia. Abbreviations: L, left; P, posterior; R, right.
Rehabilitation Training
During RACU stay, all subjects received a standardized rehabilitative program, with a global amount of 80 minutes a day, 6 days a week for 3 consecutive weeks. Each session of physical therapy started with a 10-minute warm-up and ended with a 10-minute cool-down phase and included strengthening and range of motion exercises, flexibility exercises, trunk and upper-extremity positioning, transfer, postural and gait training, functional and self-care retraining, and adaptive equipment training. None of the patients received specific rehabilitative training for fall prevention.
Follow-Up
At discharge from the RACU, an information booklet including physical activities to be performed at home and strategies to prevent falls were given to patients and relatives. An explicit definition of falls was also provided as subject's unintentionally and abruptly hitting the ground not as a result of a major intrinsic event or overwhelming hazard (defined as a hazard that would result in a fall by most young, healthy persons). To increase the accuracy of information collection at follow-up, patients and caregivers were asked to pay specific attention to fall occurrence during the study period and told that they should expect to receive telephone contact in 12 months. The follow-up interview was performed 12 months after RACU discharge by a psychologist trained in geriatrics and blinded to the aim of this study. Thus, the occurrence of falls was investigated through cross-checking the detailed report of the fall from the patient and the principal caregiver. In case of disagreement between patient and caregiver, the patient's report was accepted when the MMSE score was 24 or above, whereas the caregiver's report was accepted when the MMSE score was 23 or lower. Fallers were defined as those patients who fell at least once in the follow-up period.
Data Management and Statistical Methods
Independent predictors of falls were tested in univariate logistic regression models with falls (yes, no) as the dependent variable and demographic, clinical, and functional features as independent variables. The independent association of subcortical vascular lesions with falls was tested in a multivariate logistic regression model with stepwise selection of variables proven significant in the bivariate analyses (age, sex, MMSE score, Barthel Index score on admission) to adjust for confounders (P<.05 of the score statistic for variable entry). Subcortical vascular lesions were entered as 3 dummy variables to denote quartiles, the lowest quartile (absent-very mild subcortical vascular lesions) being the reference group. All analyses were performed by using the SPSS package.a
Results
On average, patients were old (mean age, 79.5±5.8), predominantly women (n=167 [78%]), with cognitive impairment (MMSE score, 21.8±5.4) and depressive symptoms (GDS score, 6.7±3.5) of mild severity. They had about 3 co-occurrent diseases (Charlson Index score, 3.1±1.9) and moderate functional impairment on admission (Barthel Index score, 65.5±26.3). The mean subcortical vascular lesions degree was moderate (26.9±16.3). Sixty-five patients (30%) experienced 1 or more falls in the follow-up period. The main medical conditions affecting gait were arthritis or musculoskeletal problems in 33%, muscular fatigue due to cardiovascular or respiratory chronic illnesses in 11%, and central nervous system diseases in 9%, whereas 47% of subjects had multiple co-occurring clinical conditions affecting gait. Notably, physical comorbidity was not different in the 4 quartiles of increasing subcortical vascular lesion severity (subcortical vascular lesion level 0, 2.9±1.9; subcortical vascular lesion level 1, 3.1±1.5; subcortical vascular lesion level 2, 2.9±1.9; subcortical vascular lesion level 3, 3.4±1.7; P=.45).
Table 1 shows that patients who fell and those who did not at follow-up had similar age, comorbidity, nutritional status, depressive symptoms, and length of stay in the RACU. Cognitive status and functional status on admission (Barthel Index), but not at discharge, were significantly different in these 2 groups. The subcortical vascular lesion score was also significantly greater in the faller group.
Table 1. Demographics and Clinical Characteristics of 214 Patients With Gait Disorder Consecutively Admitted to the RACU Stratified by Falling at 12 Months
| Variable | Nonfalling (n=149 [69.6%]) | Falling (n=65 [30.4%]) | OR⁎ | 95% CIs | P† |
|---|---|---|---|---|---|
| Age (y) | 78.9±6.1 | 80.4±5.3 | 1.057 | 1.002–1.116 | .043 |
| Sex (women) | 119 (79.9) | 48(73.8) | 0.973 | 0.507–1.869 | .935 |
| MMSE score (0–30) | 22.3±4.6 | 20.7±6.1 | 0.949 | 0.900–1.002 | .057 |
| GDS score (0–15) | 6.6±3.1 | 7.3±3.1 | 1.069 | 0.975–1.171 | .156 |
| Charlson Index score | 3.1±1.9 | 3.0±1.9 | 0.943 | 0.797–1.116 | .496 |
| Serum albumin (g/dL) | 3.3±0.4 | 3.3±0.4 | 0.587 | 0.286–1.207 | .147 |
| Body mass index (kg/m2) | 25.1±4.9 | 24.8±5.3 | 0.972 | 0.908–1.041 | .423 |
| Drugs | 5.4±2.2 | 5.5±2.7 | 0.999 | 0.882–1.132 | .987 |
| Instrumental activities of daily living (functions lost, 0–8) | 4.2±3.9 | 4.0±2.6 | 1.012 | 0.934–1.096 | .774 |
| Barthel Index admission score (0–100) | 68.6±24.3 | 61.0±28.90 | 0.990 | 0.979–1.001 | .078 |
| Barthel Index discharge score (0–100) | 80.9±19.3 | 79.0±20.7 | 0.995 | 0.981–1.008 | .431 |
| Tinetti admission score (0–28) | 14.6±7.3 | 13.9±6.5 | 0.995 | 0.955–1.037 | .827 |
| Tinetti gait admission score (0–12) | 5.7±3.7 | 5.4±3.4 | 0.974 | 0.895–1.059 | .537 |
| Tinetti discharge score (0–28) | 20.4±6.1 | 19.8±5.0 | 0.984 | 0.938–1.032 | .503 |
| Tinetti gait discharge score (0–12) | 8.6±2.9 | 8.4±2.4 | 0.962 | 0.865–1.071 | .479 |
| Subcortical vascular lesions‡ | 25.8±16.0 | 32.4±15.5 | 1.025 | 1.003–1.043 | .025 |
| Length of stay (d) | 22.8±9.2 | 21.9±8.4 | 1.006 | 0.977–1.035 | .709 |
⁎OR denotes the increase of risk of falling for a 1-unit increase of the predictor variable, in bivariate logistic regression models. |
†P significance on bivariate logistic regression models. |
‡Subcortical vascular lesions; greater values indicate higher degrees of cerebrovascular disease. |
Figure 2 shows the multivariate regression model assessing the predictive power on falls of variables significantly different on bivariate analysis. In this model, after stratification of subcortical vascular lesions in quartiles by using 3 dummy variables (lowest subcortical vascular lesion quartile being reference), subcortical vascular lesion was the only significant predictor even when age, MMSE score, and Barthel Index score on admission were forced into the model as continuous variables together with sex, indicating that patients with moderate and severe subcortical vascular lesion scores (3rd and 4th quartiles) had a significantly higher risk of falling (OR=3.0; 95% CI, 1.3–7.1; P=.012; OR=3.9; 95% CI, 1.6–9.2; P=.002, respectively) compared with the lowest quartile. The association of the second quartile (OR=1.8; 95% CI, 0.7–5.0) was not significant (P=.22).
Fig 2.
The predictive power of increasing severity of subcortical vascular lesions on falling at the 12-month follow-up in 214 patients consecutively admitted to the RACU. Bars denote 95% CIs in a logistic regression model adjusted for age, sex, MMSE score, and Barthel Index score at admission. SVLs 0 (ref) ≤12.6; SVLs 1, 12.7–22.4; SVLs 2, 22.5–41.8; SVLs 3, ≥41.9. Abbreviation: SVLs, subcortical vascular lesions.
Discussion
This study shows that moderate to severe degrees of subcortical vascular lesions are associated with falls at 12 months in a population of elderly patients admitted to an RACU with gait disorder. The relationship is independent from a number of variables that are commonly recognized to be associated with falls (eg, age, cognitive and functional impairments, depression).1, 2, 26
The mechanisms linking subcortical vascular lesions to falls might involve damage to the motor or cognitive subcortical networks. Subcortical vascular lesions may interrupt frontal lobe circuits, long loop reflexes of deep white-matter motor tracts,5 and descending motor fibers arising from medial cortical areas,6 all pathways that are crucial to ensure muscle motor activity and normative gait. In line with this hypothesis, Syrjälä et al,14 in a population of community-dwelling older persons, found that accidental falls correlated with greater severity of white-matter hypodensities on CT scans. Our study strengthens these findings, confirming the correlation between subcortical vascular lesions and falls in a population of older patients with a gait disorder. Alternatively, or in addition to this hypothesis, subcortical vascular lesions may affect fibers connecting frontal cortex and subcortical structures, which are responsible for executive functions including volition, planning, purposive action, and multitask performance, all of which are critical functions for normative gait.7 In this framework, Verghese et al27 showed that limited attentional resources (measured with the walking when talking test) may decrease the ability to perform 2 or more simultaneous tasks, increasing the risk for falls in a population of older nondemented individuals.
Interestingly, subcortical vascular lesions may precede the onset of both motor and cognitive impairment. For example, a recent study on 2450 high-functioning elderly subjects found that subclinical structural abnormalities on brain MRI (ventricular enlargement, white-matter hyperintensities, subcortical, and basal ganglia small brain infarcts) were significantly associated with the risk of developing physical disabilities (self-reported physical impairment) and decline in motor performance.28 Another study, in a population of 554 nondemented elderly patients, found that the volume of periventricular white-matter hyperintensities at baseline was associated with reduced mental processing speed at the 3-year follow-up.29 In line with these findings, it is noteworthy that the association between subcortical vascular lesions and 12-month falls in our population is independent of cognition, functional status, and other possible confounders (age, depression). In the etiopathogenetic relationship of these variables with subcortical vascular lesions, may the latter represent an early, preclinical marker of other impairments predisposing to falls?
It is remarkable that we found a dose-effect relationship between subcortical vascular lesions and a 12-month risk of fall, although only moderate or higher severity was significantly associated with a greater risk. This suggests that the rehabilitative intervention should be different according to the severity of subcortical vascular lesions. Although preventive strategies may be implemented for subjects with absent or mild subcortical vascular lesions, intensive rehabilitation aimed at stimulating neuroplastic processes of motor and somatosensory neuronal networks should perhaps be preferred for those with moderate to highest subcortical vascular lesion severity. Future data are needed to support this hypothesis.
Study Limitations
Some limits of this study must be highlighted. First, on admission we did not record patients' prior history of falls nor did we use a baseline fall risk-assessment measure, therefore limiting the generalizability of our findings. In fact, many studies1, 2, 3 have shown that a history of falls is a significant risk factor for further falls in elderly people. However, it should be highlighted that this study represents a secondary exploratory analysis of a project aiming at assessing the prevalence of subcortical vascular lesions in elderly patients with gait disorder and that it was not designed to assess primarily the relationship between falls and subcortical vascular lesions. Furthermore, it should be underlined that patients in both groups had similar Tinetti scores (on admission and at discharge), indirectly supporting the notion that functional impairment (and thus the risk of fall) was equally distributed among groups. Second, we cannot exclude that some relatives may have underreported the occurrence of falls during the 12-month follow-up and that medical conditions determining gait disorder may have progressed in the ensuing year. However, there is no reason to believe that patients with lower subcortical vascular lesion scores and their caregivers systematically underreported the occurrence of falls. Moreover, because medical conditions at baseline (as measured with the Charlson Index score at baseline) were not different by subcortical vascular lesion quartile, there is no reason to believe in a systematic worsening of these conditions over the follow-up in those with higher subcortical vascular lesion scores. Third, subcortical vascular lesions were assessed with a CT scan, a less sensitive method than the state-of-the-art magnetic resonance. However, it should be underlined that a CT scan has greater specificity30 and that, in view of a possible generalization of the results of this study, magnetic resonance is presently more expensive and less frequently available to rehabilitative wards than a CT scan.31 Furthermore, brain CT scans could have underestimated subcortical vascular lesions degree and not vice versa, possibly reinforcing and not thwarting the relationship between subcortical vascular lesions and falls.
Conclusions
This study suggests that elderly patients with gait disorder who reported falling at 12 months after discharge had a greater degree of subcortical vascular lesions than those who did not report falls. Future research is needed to confirm our results using more rigorous methods and larger study groups, especially in recording falls and excluding the many patients who had gait disorder related to specific diseases predicting itself falls (Parkinson's, arthritis, neuropathy, peripheral vascular disease).
Supplier
Acknowledgments
The authors thank Emanuela Barisione, MD, Elena Lucchi, PsyD, Francesca Magnifico, PsyD, Salvatore Speciale, MD, and Tiziana Torpilliesi, MD, for their support in collecting data and the team of physical therapists for their support in rehabilitation activities.
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- a Version 11.5; SPSS Inc, 233 S Wacker Dr, 11th Fl, Chicago, IL 60606.
No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit on the authors or on any organization with which the authors are associated.
PII: S0003-9993(08)00379-1
doi:10.1016/j.apmr.2008.01.018
© 2008 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation. Published by Elsevier Inc. All rights reserved.
Volume 89, Issue 8 , Pages 1522-1527, August 2008
