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INTRODUCTION
This article presents the outcome trend determined using the Korean Brain Rehabilitation Database (KBRD) V1.0 which includes information on stroke patients from 2007 through 2011. KBRD V1.0 was developed by the Korean Society of Neurorehabilitation (KSNR) in 2005, is an online system (http://www.kbrr.or.kr) for collection of demographic information and clinical data describing subjects with brain disorders. Analysis of brain disorder patients collected from 2009 was previously reported (1). The report included all brain disorders associated with stroke, traumatic brain injury, and brain tumors, but did not provide specific data regarding infarction and hemorrhage. Moreover, although stroke prevalence, length of stay (LOS), and modified Barthel index (MBI) efficiency have been reported, outcome of different stroke subtypes by vascular territories and locations have not described.
Here, we provide information for basic rehabilitation outcomes such as LOS, functional outcome changes after rehabilitation of stroke patients by infarction/hemorrhage classification and by vascular territories and locations. This report provides information from 2007 to 2011 and presents trends in rehabilitation outcomes over time while providing annual summaries. Our goal is to produce data that can serve as resources for rehabilitation researchers.
MATERIALS AND METHODS
Subjects
A total of 46 hospitals across Korea participated in the KBRD, providing 5,572 records. These 46 hospitals represent approximately 67% of all rehabilitation facilities of university hospitals and rehabilitation hospitals in Korea. This report enrolled subjects between January 1, 2007 and December 31, 2011.
Inclusion criteria
We applied five basic criteria for cases to be included in this report: 1) the subject must have been receiving initial rehabilitation services (i.e., no persons were admitted for evaluation or readmission), 2) the records could not have missing data for key variables such as LOS and Korean version of modified Barthel Index (K-MBI), 3) the subject had to be between the ages of 7 and 105 yr at admission, 4) the duration from impairment onset to rehabilitation admission could not exceed 365 days and 5) the total LOS could not exceed 548 days (1.5 yr) (2).
Methods
Demographics and hospital information including age, sex, LOS, and transfer time after onset were analyzed. LOS is the total number of days spent in the rehabilitation facility. Interim days spent in an acute care setting were not included in this value. Transfer time after onset was quantified as the duration (in days) from date of onset to rehabilitation admission.
Information regarding functional status is based on the Korean version of the Modified Barthel Index (K-MBI) (3) and the Korean version of the Mini-Mental State Examination (K-MMSE) (4) for admission and discharge. Treatment outcome was measured by K-MBI gain and K-MBI efficiency. K-MBI gain is the difference between total K-MBI admission and total K-MBI discharge ratings. K-MBI efficiency, which refers to the average change in total K-MBI ratings per day, is calculated for each patient by subtracting K-MBI admission from K-MBI discharge ratings and then dividing by the LOS measured in days. K-MMSE gain and K-MMSE efficiency were measured by the same methods.
Statistical analysis
A t-test was employed for analysis of continuous variables, while a chi-square test was employed for categorical variables upon comparison of groups based on demographic data. For clinical and functional outcome data, analysis of covariance (ANCOVA) was used to report adjusted means for LOS, transfer time after onset, K-MBI, and K-MMSE after correction for age, gender between stroke groups (ischemic, hemorrhagic), ischemic territory groups, and hemorrhagic territory groups. A repeated-measures ANCOVA was used to assess the changes within-subject total K-MBI, K-MBI efficiency, and K-MMSE at admission and discharge and between-subjects categorized by stroke groups (ischemic, hemorrhagic), ischemic territory groups, and hemorrhagic territory groups. Differences in improvement in K-MBI and K-MMSE between brain stroke groups, ischemic groups, and hemorrhagic groups were analyzed with a test of interaction of each category and K-MBI and K-MMSE gain. Within the ANCOVA model, the post hoc Scheffe's test was administered to identify subsets of each category.
Multiple linear regression was performed to identify independent clinical variables associated with the discharge K-MBI, K-MBI gain, K-MBI efficiency and LOS. Independent variables consisted of age, sex, transfer time after onset, admission K-MBI, and admission K-MMSE. These variables were then entered simultaneously into the regression model. The aim of this regression analysis was to determine if knowledge of discharge K-MBI, K-MBI gain, K-MBI efficiency and LOS were significantly associated with the transfer time after onset, admission K-MBI and admission K-MMSE provided by the rest of the variables. The adjusted R2 was calculated for this model to determine whether the independent variables were good predictors of discharge K-MBI, K-MBI gain, K-MBI efficiency and LOS. Probability values of < 0.05 were considered statistically significant. All analyses were conducted using SPSS statistical software, version 22 (SPSS Inc., Chicago, IL, USA).
RESULTS
Demographics, lesion sites, and functional improvement data
A total of 5,212 of 5,572 patient records was analyzed for this study. A total of 360 records were excluded due to missing information. The records of 4,503 hospitalized subjects were taken from university hospitals, while 709 cases were from rehabilitation hospitals. Overall, 59.7% were male and 40.2% were female. Cerebral infarctions were more common (67%) than hemorrhages (33%) in all stroke subjects. Cerebral infarctions in the middle cerebral artery territory were most common, while the basal ganglia and cerebral cortex were the most common areas for hemorrhagic stroke. The average K-MBI at admission was 36.5, while this increased significantly to 54.6 at discharge. The average K-MMSE at admission was 19.0, while this increased to 21.4 on discharge (Table 1). Fig. 1 displays the trends for K-MBI gain and K-MBI efficiency over time, and it shows that K-MBI efficiency increased while K-MBI gain is relatively constant. Fig. 2 shows the trends for LOS and transfer time after onset over time and it shows that LOS decreased from 45 to 28 days and transfer time after onset decreased from 44 to 30 days.
Functional outcome according to general characteristics of subjects
There were significant correlations among the age of onset, time of transfer to the rehabilitation facility after onset, K-MBI at admission, K-MMSE at admission, and the K-MBI at discharge, K-MBI gain, and K-MBI efficiency (Table 2). Decreased transfer time after onset was correlated with improved discharge functional status and decreased LOS. A higher K-MBI and MMSE at admission were positively correlated with the discharge K-MBI, K-MBI gain, and K-MBI efficiency. K-MBI at admission was most closely correlated with K-MBI at discharge (Table 2).
Comparison of ischemic stroke and hemorrhagic stroke
Cerebral infarction tended to increase with age, with most subjects being older than 75 yr at the time of stroke, while cerebral hemorrhages were most common between ages 45 and 64 yr (Table 3). Admission K-MBI and K-MMSE ratings were higher for ischemic strokes than for hemorrhagic strokes, while the gains of K-MBI and K-MMSE were higher in hemorrhagic strokes (Table 3). Median transfer time after onset was shorter for ischemic strokes than hemorrhagic strokes. The mean LOS of hemorrhagic strokes was longer than that of ischemic strokes (Table 3).
Functional outcome measures of patients with ischemic stroke in different vascular territories
Ischemic stroke was re-categorized into six vascular territories based on previously reported criteria in neuroanatomy, neurology, and rehabilitation literature (5, 6). Actually, previous reports agreed on seven lesion location categories; specifically, the anterior cerebral artery (ACA), middle cerebral artery (MCA), posterior cerebral artery (PCA), brain stem, cerebellar, small-vessel stroke, and strokes in more than one vascular territory (MVT). In our brain database (KBRD V1.0), there was no small vessel stroke category. This is because lacunar infarctions experience more favorable outcomes than other ischemic stroke subtypes (6). Therefore, most lacunar infarction patients were discharged without transfer to an RM department. Although lacunar infarctions can result from basilar or cerebellar arteries, if some lacunar infarction patients were transferred to a RM department, they were included in the MCA in our report. Post hoc analysis within the ANCOVA model indicated that the transfer time after onset and LOS is longer for MVT infarctions. Strokes in MCA, MVT and ACA incurred a longer LOS than cerebellar, PCA, and brain stem strokes. Admission and discharge K-MBI of cerebellar and brain stem strokes was higher than those in other groups. PCA and brainstem strokes have a higher admission and discharge MMSE than those in other groups. MVT strokes had the lowest admission and discharge K-MBI and MMSE (Table 4).
Functional outcome measures of patients with hemorrhagic stroke in different brain areas
Hemorrhagic stroke was re-categorized into three different brain areas, the cortex, subcortex, and brainstem. Post hoc analysis within the ANCOVA model indicated that the LOS was longer for cortical hemorrhages than those of subcortical or brainstem hemorrhages. Initial and discharge K-MBI and K-MMSE were the lowest for cortical hemorrhages and highest for brainstem hemorrhages (Table 5).
DISCUSSION
This is a multi-year, multi-center report from the KBRD. A previous annual report of brain disorders for 2009 showed stroke prevalence, length of stay (LOS), and MBI efficiency. Because that report included all brain disorders of stroke, traumatic brain injury, and tumors, it did not show specific stroke outcome data. Here, we focus on stroke patients to present trends in rehabilitation outcomes over time. We applied five inclusion criteria for patient selection from database to analysis based on stroke patient outcome data analysis (2).
The mean LOS decreased over the study period, from 45 days in 2007 to 28 days in 2011 (Fig. 1). These reduced LOS suggest an improved efficacy of rehabilitation because K-MBI gain remained stable during the study period. As a result, the hospital bed turnover rate improved, leading to increased profits.
However, when compared to the LOS of the United States (17 days) (2), the 28 day LOS observed in the present study was still long. These differences may be attributed to differences in healthcare systems and cultural backgrounds between countries. Korean health insurance covers longer hospital stays for both acute care hospitals and rehabilitation hospitals, while the health insurance system of the United States may not cover longer stays (7). Additionally, scarcity of community rehabilitation services in Korea, including daycare centers and nursing homes, could have contributed to this difference (2). In a study of stroke outcome in Japan (8), the average transfer time after onset was 74 days and the average LOS was 115.8 days, which was longer than in the United States and Korea. Japan seems to have a similar hospital and community environment as that in Korea.
Higher scores of K-MBI and K-MMSE at admission were correlated with higher functional status at discharge. Admission K-MBI was the most predictable of discharge K-MBI scores, as in a previous stroke rehabilitation study (9). There have been studies of the impact of cognitive function on functional recovery during rehabilitation in patients with stroke (10, 11).
Decreased transfer time after onset was correlated with improved discharge functional status and decreased LOS. Decreased transfer time after onset means early and intensive rehabilitation. Rehabilitation is possible twice a day only after a patient is transferred to the RM department in Korea. Because early and intensive rehabilitation predicts good functional outcomes and faster recovery (12, 13), decreased transfer time after onset could attribute to the LOS. These results suggest that the sooner a patient with stroke starts rehabilitation, the better the outcome, and consequently the shorter the LOS. This is also supported by a previous study in the United States that showed fewer days from stroke onset to rehabilitation admission was associated with better functional outcomes at discharge and shorter LOS (14).
Comparison of functional outcomes of ischemic and hemorrhagic stroke showed that hemorrhagic stroke survivors had a poorer initial and discharge outcome, but experienced better functional gains during the rehabilitation admission period. This finding of faster recovery in hemorrhagic stroke is consistent with that of previous reports (15, 16). A suggested mechanism that may explain the faster recovery is as follows: hematoma formation and vasogenic edema may only displace tissue, and, as vasogenic edema and hematoma resolve, neurologic functions recover and functional status evaluated by K-MBI improves (16). Poorer initial functional status could have resulted in longer LOS and transfer time after onset. Here, delayed transfer time after onset could have attributed to longer LOS as well.
Functional outcome measures of patients with ischemic stroke in different vascular territories shows that strokes in MVT were the most debilitating because more vascular territories were involved. MCA and ACA infarctions also led to severe disability because of the multiple motor, cognitive, and behavioral impairments that are characteristic in these territories (17, 18, 19). Cerebellar strokes led to less disability, possibly because balance impairments are both less disabling and less well captured by the K-MBI than strength impairments (20). Because cognition is preserved in brainstem infarction, admission and discharge K-MMSE were higher in such cases. One United States hospital registry report with 2,213 patients stated that MVT, MCA, and ACA infarctions yielded significantly lower admission and discharge totals and cognitive functional independence measure (FIM) scores than other stroke groups (21). Severe stroke in MCA, MVT and ACA incurred a longer LOS and transfer time after onset than cerebellar, PCA, and brain stem strokes. Initial severe stroke could have resulted in delayed transfer to RM department and consequently resulting in longer LOS.
Functional outcome measures of patients with hemorrhagic stroke in different brain territories showed better functional outcome in the subcortex and brainstem than in the cortex. Strokes affecting the cerebral cortex classically present with deficits such as neglect, aphasia and hemianopia. Subcortical hemorrhages affect the small vessels deep in the brain, and typically present with purely motor hemiparesis affecting the face, arm, and leg (22). This difference may result in a longer LOS and poorer functional outcomes in cortical hemorrhages. Brainstem hemorrhages often impose devastating conditions that result in severe disability (12.7%), vegetative state (10.8%), or death (57.5%) (23). However, the prognosis has been reported to be highly dependent on the clinical severity at presentation. Because brainstem strokes do not usually affect language ability, if the lesion is not critical, the patient is able to participate more fully in rehabilitation therapy. Most deficits are motor-related, not cognitive (23). We suspect that massive brainstem hemorrhage patients were already died and therefore were not transferred to a RM department. Additionally, many of our subjects with brainstem hemorrhage could have mild impairment, resulting in better functional outcome.
It should be noted that this study was limited in that only patients with stroke requiring inpatient rehabilitation were included. Therefore, this sample does not represent the actual functional disability of each stroke subtype because those with little disability did not require inpatient rehabilitation.
The results of this study were as follows: in all stroke subjects, cerebral infarctions were more common (67%) than hemorrhages. Cerebral infarction in the middle cerebral artery territory was most common, while the basal ganglia and cerebral cortex were the most common areas for hemorrhages. Transfer time after onset decreased, as did the LOS. Initial functional status was correlated with discharge functional status. Decreased transfer time after onset was correlated with improved discharge functional status and decreased LOS. Hemorrhagic stroke presents worse initial and discharge functional status, but patients experience better functional gains during rehabilitation. In ischemic stroke subtypes, cerebellar and brainstem strokes have predictably better outcomes, while strokes with more than one territory have predictably poorer outcomes with more disabilities. In hemorrhagic stroke subtypes, initial and discharge functional status were the lowest for cortical hemorrhages and the highest for brainstem hemorrhages.
Based on the results of this study, consecutive investigations of the status of rehabilitation patients need to be conducted to provide useful information to practitioners. Such studies would provide a better understanding of the status of rehabilitation in Korea.
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