THE INCREASINGLY AGING population presents unique

Transcription

1 1224 Cognitive Status and Ambulation in Geriatric Rehabilitation: Walking Without Thinking? Robert A. Ruchinskas, PsyD, Hedy K. Singer, PhD, Nancy K. Repetz, PsyD ABSTRACT. Ruchinskas RA, Singer HK, Repetz NK. Cognitive status and ambulation in geriatric rehabilitation: walking without thinking? Arch Phys Med Rehabil 2000;81: Objective: To assess the relation between cognitive and ambulatory abilities in geriatric rehabilitation inpatients. Study Design: Survey study of geriatric cohorts. Setting: Inpatient university hospital rehabilitation unit. Patients: One hundred fifty urban geriatric rehabilitation patients with orthopedic, neurologic, or medical diagnoses. Main Outcome Measures: Functional Independence Measure TM (FIM), Mattis Dementia Rating Scale, Neurobehavioral Cognitive Status Examination. Results: Both cognitive measures predicted admission and discharge total FIM scores, continence status, and activities of daily living (ADL) scores. Neither measure could predict admission or discharge FIM ambulation scores better than demographic variables. Conclusion: While cognitive status affects the overall rehabilitation course and ultimate functional status of the geriatric patient, it does not predict walking or stair climbing ability. Key Words: Walking; Cognition disorders; Geriatrics; Rehabilitation by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation THE INCREASINGLY AGING population presents unique challenges for rehabilitation medicine. With older age comes a larger potential for accidental injuries and the subsequent need for intervention by rehabilitation treatment teams. For example, the incidence of elderly individuals falling and causing serious bodily harm is dramatically increasing. 1 In fact, it has been estimated that 1 in 3 community-dwelling elderly individuals will fall in any given year. 2 In opposition to this trend toward increased need for restorative services is the development of marketplace forces geared at scrutinizing and limiting the availability of rehabilitation. Given this potential conflict between increasing demand and decreasing accessibility to services, identification of individuals who will benefit from rehabilitative admissions is imperative. In that regard, there is a well-established association between rehabilitation outcome and cognitive abilities, with diminished intellectual capability negatively affecting rehabilitation goal attainment. Lichtenberg and colleagues 3,4 have shown reduced cognition to be correlated with decreased abilities to perform activities of daily living (ADL) and reduced overall discharge From the Department of Physical Medicine and Rehabilitation, Temple University Hospital, Philadelphia, PA. Accepted February 9, No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the authors or upon any organization with which the authors are associated. Reprints are not available from the authors /00/ $3.00/0 doi: /apmr Functional Independence Measure TM (FIM) scores. Mental status has been found to be a significant predictor of continence status. 5 In addition, individuals who have cognitive difficulties require greater postdischarge supervision and have an increased likelihood of placement in a nursing home. 6 The relationship between cognitive diminution and negative outcome has been demonstrated for geriatric rehabilitation patients, individuals with recent strokes, and survivors of traumatic brain injury. 7-9 Although cognitive abilities are strongly predictive of general rehabilitative outcome, there is growing disagreement that intellectual testing can predict ambulation status. Early studies argued that patients with impaired cognition could not benefit from rehabilitation, 10 potentially limiting services for patients in diagnostic categories accompanied by high incidences of intellectual disorders, such as hip fracture. 11 Recently, however, research has found that dementia in elderly patients with hip fractures did not reduce the likelihood of achieving restorative goals (ie, ambulation) but did lengthen rehabilitation stays and decrease ADL abilities. 12,13 Another report found longer admissions and lessened overall functional gains in hip fracture patients, but concluded that absolute motor gain appeared to be independent of cognitive status. 14 Additionally, a large-scale study of urban geriatric rehabilitation patients reported a negligible influence of cognition on mobility, although participants made minimal gains in ambulating during their hospital stays (approximately 1 FIM point from moderate/minimal assistance to supervision). 15 The dichotomy between ambulation and cognition is particularly important because the ability to walk is frequently the primary variable considered by third-party payers when determining appropriateness for inpatient admission. Both high and low levels of walking are cited as exclusion criteria for potential inpatient treatment, even for diagnoses with expected recovery of ambulation before cognition. For example, individuals who suffer from traumatic brain injury often achieve purposeful motor function (Ranchos Los Amigos level 4 to 5) 16 well before their cognitive abilities have returned to baseline (level 8). Hence, admission for cognitive rehabilitation programs may paradoxically rely more on dysfunction of a patient s motor system than on their cognitive status. Given the importance of ambulation in the aging population, this study was designed to examine further the influence of cognition on independent ambulation. Another goal was replicating the dissociation between cognition and walking found in hip fracture and mixed-diagnosis, geriatric rehabilitation patients. It was hypothesized that, as with prior research, cognitive disorders would play a profound role in predicting general rehabilitation outcome. Cognitive status, however, was postulated to have less significance in predicting a patient s discharge ambulatory status. METHODS Subjects One hundred fifty patients over the age of 60 years who were consecutively admitted to a rehabilitation unit were included in

2 COGNITION AND AMBULATION IN GERIATRIC REHABILITATION, Ruchinskas 1225 this study. Informed consent for participation in the study was obtained at admission to the rehabilitation unit. Two patients were incapable of consenting because of moderate dementia, and consent was obtained through their proxies. Admitting diagnoses for patients included orthopedic involvement (45%, primarily joint replacements but also hip fractures), neurologic conditions (38%, primarily stroke), and general medical deconditioning (17%, pneumonia, post cardiac surgery, etc). Age ranged from 60 to 91 years, with a mean age of 72.6 (standard deviation [SD] 7.68). Mean education was 9.8 years (SD 3.37). Sixty-eight percent were women and 32% were men. Fifty percent of patients were black, with 48% white and 2% Hispanic. Patients had an average of 4.1 prior medical conditions (range, 1 9) listed at admission and took an average of 4.6 prescription medications (range, 1 12). Mean length of stay was 13.4 days (SD 9.47 days; range, 4 78). Table 1 provides the admission and discharge FIM scores of the participants. During the study period, 18 potential patients were excluded because they were too aphasic or hemiparetic to complete the protocol or were transferred to acute care because of medical complications. Five additional patients with a length of stay less than 3 days did not complete the necessary protocol ratings and were excluded from the study. Measures Functional Independence Measure. The FIM consists of a 7-point scale that covers the domains of ADL, continence, motor abilities, and social cognition. 17 The FIM has shown high interrater reliability and demonstrated adequate concurrent validity. 18,19 For the purposes of the study, the FIM was reduced to four aggregate measures: Total FIM score, Total ADL score, Continence, and Ambulation. The Total FIM score consisted of the 13 self-care, continence, and motor items. The Social Cognition items were not included in the Total FIM score because these five scales represent 28% of the FIM and would artifically inflate correlation with the Neurobehavioral Cognitive Status Examination (NCSE) and Dementia Rating Scale (DRS). The Total ADL score consisted of combined FIM scores of ability to eat, groom, bathe, dress the upper body, dress the lower body, and toilet oneself. Continence status combined both bladder and bowel continence scores. The FIM contains five motor scales, composed of transferring to the bed, tub, and toilet, along with walking and stair climbing ability. The Ambulation index combined scores from the Walk and Stairs scales of the FIM. Table 1: Means, Standard Deviations, and Ranges of Admission and Discharge FIM Scores Mean Standard Deviation Range Total Admission Discharge ADL Admission Discharge Continence Admission Discharge Ambulation Admission Discharge Mattis Dementia Rating Scale. The DRS was designed for geriatric populations to aid in detecting dementia. The DRS includes five subscales measuring attention, initiation, visuospatial construction, reasoning, and memory. Addition of these five subscales yields a DRS Total score, with the highest total score being 144. Cognitively intact elderly individuals obtained scores of 137 with a standard deviation of 6.2, with a cutoff for dementia of Although scores are negatively affected by advancing age and lowered education, the DRS has been shown valid with urban minority patients. 3 Neurobehavioral Cognitive Status Examination. The NCSE, now called Cognistat, was designed to detect and characterize cognitive dysfunction at the bedside. The NCSE consists of subtests measuring arousal, orientation, attention, comprehension, repetition, naming, visual constructive skills, memory, calculation, abstract reasoning, and judgment. The instrument uses a screening/metric format, whereby successful passing of the screening question assumes passing of subsequent questions in the section. Adequate reliability and validity of the NCSE has been established. 21,22 In addition, the NCSE has been demonstrated to be sensitive to cognitive dysfunction in elderly inpatients and stroke victims. 23,24 The NCSE manual notes, however, potential difficulty in interpreting subscale scores in the Impaired range for elderly adults. Subsequent research has suggested the potential for an unacceptably high rate of incorrect classifications based on this approach. 25,26 Because the NCSE was found to have a unitary cognitive factor in one recent study, 27 it has been proposed that a single composite score may show the greatest utility in geriatric assessment. 28 Thus, for the purposes of this study, all subtests were combined to form a NCSE Total score, with a maximum possible score of 78 being achieved by passing all screening questions. Procedures As part of an ongoing protocol comparing the utility of the DRS and NCSE, 150 (of 173 potential) patients consecutively admitted during a 9-month period underwent evaluation of functional status, cognition, and affect. A psychologist or doctoral-level psychology trainee evaluated patients during the first 3 days of admission. Receipt of the DRS or NCSE was randomized according to admission room number, with patients in lower numbered rooms receiving the DRS and those in higher numbered rooms getting the NCSE. A nursing policy initiated in the middle of the study affected randomization because certain diagnostic groups were placed in designated rooms. Hence, 83 patients (55%) received the NCSE and 67 (45%) were administered the DRS. The distribution of tests was equivalent among the general medical diagnostic group, although 16 more orthopedic patients received the NCSE than the DRS and 3 more neurologic patients were given the DRS than the NCSE. Patient groups receiving the DRS or NCSE were not significantly different in terms of age, education, number of prescribed medications taken, and number of prior medical conditions. Functional independence was assessed within 48 hours of admission and on the day of discharge. All treatment team members who assigned FIM numbers had passed the rating certification test for the FIM through the Uniform Data System. Statistical Analyses Pearsons product moment correlation was used to examine relationships between the cognitive variables (NCSE, DRS), demographic variables (age, education, prior medical conditions, medications), hospital length of stay, and change in FIM

3 1226 COGNITION AND AMBULATION IN GERIATRIC REHABILITATION, Ruchinskas scores from admission to discharge. Multiple regression, which examines numerous variables and produces a correlation between variables and a criterion, was used to examine the association between the two cognitive tests, demographic variables, and FIM criterion. The order of entry for analysis of admission data consisted of an initial block of demographic variables including patient age, education, number of prior medical conditions, and number of prescribed medications. The cognitive measure, either the NCSE or DRS, was entered as the second block. For discharge FIM data, the admission FIM score was entered as the first block, followed by a block of demographic variables and the third block containing the cognitive measure. RESULTS Sixty-one percent of patients scored above the cutoff on the DRS, suggesting that the majority of patients displayed intact cognitive abilities. The mean score on the DRS was (SD 21.4; range, ), which is below the expected cutoff, yet consistent with studies in lower educated, urban populations. 3 The mean score on the NCSE was 63.7 (SD 11.1; range, 30 78). As expected, level of education played a significant role in influencing the cognitive scores (NCSE Total: r.519, p.0001, n 83; DRS Total: r.373, p.002, n 67). Age was not significantly correlated with either cognitive measure. Both length of stay and change in the Total FIM score from admission to discharge did not correlate with any cognitive tests or the demographic variables of age, education, number of prior medical conditions, and number of prescribed medications. Multiple regression consistently identified either the DRS or NCSE as a significant predictor of admission and discharge FIM status (table 2). These results were consistent for both admission and discharge global abilities as measured by the Total FIM score. In addition, ADL were predicted by cognitive status. Continence status, as measured by combined Bladder and Bowel FIM ratings, was also significantly affected by cognitive state both on admission and at discharge. While cognition significantly entered into the regression equation for the outcome measures listed above, it must be noted that the strongest predictor for discharge abilities ( p.001 for Total FIM, ADL, Continence) was the patient s admission FIM score for that variable. Participants in this study made gains in ambulation (table 1), going from a mean admission level of maximal assistance to minimal assistance/supervision at discharge. In agreement with Table 2: Multiple Regression t Score Prediction of FIM Variables by Cognitive Test FIM Category NCSE DRS Total FIM Admission 2.62* 2.44* Discharge * Total ADL FIM Admission 2.54* 2.39* Discharge 2.97* 1.98* Continence Admission * Discharge * Ambulation Admission Discharge * p.05. p.001. Not significant. previous findings, the cognitive measures, however, did not predict overall ambulation status. There was no significant association between cognitive status and the FIM Ambulation index consisting of the combined ability to walk and climb stairs. This lack of predictive power was present both on admission and discharge. While the NCSE and DRS did not predict walking and stair climbing status, demographic variables also lacked predictive power. Regarding discharge status, only admission FIM Ambulation abilities predicted discharge Ambulation FIM scores (t 3.26, p.002 [NCSE]; t 2.12, p.04 [DRS]). DISCUSSION Consistent with previous research, we found that cognitive status, along with admission physical abilities, exhibit a profound influence on general rehabilitation outcome. Both the NCSE and DRS were better able to predict admission and discharge Total FIM scores than were the demographic variables of age, education, number of prescribed medications, and number of prior medical conditions. In addition, these cognitive measures exhibited predictive ability for admission and discharge ADL skills. Overall mental status also played a highly significant role in continence state, which is an important predictor of the need for postdischarge supervision. 29 Unlike previous studies, cognitive integrity did not have an impact on hospital length of stay, possibly because of the large percentage of patients who participated in a managed health care plan. We also observed that the NCSE and DRS did not predict ambulatory ability. This finding was seen at both admission and discharge. Only admission locomotion status significantly predicted discharge walking and stair climbing ability. The reasons for this separation between general cognition and ambulation are uncertain. There are three possible explanations: the nature of motor learning and ambulation, the structure of the cognitive tests, and the organization of the brain. One possible explanation lies in the nature of motor learning and walking. Studies have hypothesized that overlearned behaviors such as walking are relatively unaffected by cognitive decline. This model is exemplified in conditions such as Alzheimer s disease, where ambulation does not deteriorate until the disease is well advanced. The theory of overlearned behavior has been utilized, however, depending on the research result, to explain not only preserved ambulation but also spared ADL skills in patients In our study, ADL abilities were highly related to cognitive status, while ambulation, another well overlearned act, was unaffected. Hence, it appears difficult to discriminate which of the behaviors that have been performed for over 55 years in these patients are more overlearned and would be differentially affected by declining cognition. A more likely explanation for the conflicting results lies in the role of procedural learning in rehabilitation. It has been hypothesized that psychometric tests and the skills necessary for successful rehabilitation involve separate domains. 30 Motorbased rehabilitation may focus more on procedural knowledge (skills at learning tasks) while mental status examinations rely more on declarative abilities (being able to express verbally knowledge or procedures). Procedural techniques such as errorless learning have shown efficacy in teaching functional skills to patients with severe amnesia. 31 This process focuses more on the performance of an act than the recall or verbalization of a skill, and may better reflect the training of motor skills in rehabilitation practice. In addition to not assessing procedural knowledge, the sensitivity of cognitive screening tests must be examined. An argument can be made that both the DRS and NCSE are

4 COGNITION AND AMBULATION IN GERIATRIC REHABILITATION, Ruchinskas 1227 screening measures and do not substitute for a comprehensive neuropsychologic battery that may better detect cognitive dysfunction. Still, as in the hip fracture literature, these tests were able to detect cognitive compromise in our mixeddiagnosis geriatric rehabilitation population. For example, 39% of our sample scored below the DRS cutoff of 123, which is compatible with the proportion found in the Siedel 5 study of urban elderly geriatric patients. Hence, it appears that neuropsychologic screening tests can adequately gauge general cognitive status and accurately evaluate certain cortically based skills. The neuroanatomy of ambulation suggests, however, that separate neural networks are primarily involved in the acts of ambulation and declarative cognitive processing. Brain areas implicated in walking include the basal ganglia, cerebellum, visual cortex, supplementary motor area, and primary sensorimotor area. 32 While these brain regions certainly contribute to global cognition, the tests utilized in this and other investigations lack an assessment of motor functioning and focus primarily on higher order cognitive skills. Thus, supplementing tests of declarative cognitive abilities with specific scales of motor function and/or procedural memory appears appropriate. It is hoped that addition of such measures will yield better prediction of ambulatory status and increased understanding of the motor learning process. Regardless of the cause, the presence of the dissociation between cognition and ambulation poses both significant promise and challenges for rehabilitation professionals. This finding potentially expands the pool of rehabilitation candidates who can benefit from treatment despite cognitive limitations. In addition, multidisciplinary reexamination of the process of motor learning could yield novel and efficient training methods. Finally, proven techniques such as errorless learning could be attempted in diverse populations in order to maximize outcome in cognitively impaired subjects. Conversely, including individuals with suboptimal cognition in rehabilitation produces inherent difficulties. Patients with reduced mental status are at greater risk for unsafe behaviors and have a greater need for supervision, both in the hospital and at discharge. 2 As a consequence, rehabilitation teams must quickly evaluate cognitive status to identify impaired patients. In addition, given the association between impaired cognition and nursing home placement, 4 family and community resources must also be ascertained during admission and discharge planning. Insurers must be educated regarding cognitively impaired patients, as patients with ambulatory abilities that surpass cognitive skills and safety awareness can be prematurely discharged from the hospital despite numerous remaining restorative goals. The education of third-party payers is particularly important for specialty programs such as those that focus on cognitive or geriatric rehabilitation, because admission and length of stay are likely to be limited by insurers who solely examine ambulatory status. There are several limitations of this study. First, given our sample, the results may only be generalizable to an urban population. While our sample size was adequate, it was reduced by the utilization of two cognitive screening instruments, which increases the possibility of random error. Nonetheless, the results were consistent across the two mental status tests. Bias may also be present in our sample, as those who are grossly demented are often excluded from potential admission. One third of our population, however, displayed cognitive dysfunction and was apparently able to engage in rehabilitation. Finally, our results are limited to predicting short-term (discharge) rehabilitation outcome. Still, discharge and placement decisions are made during the hospital admission, indicating that limitations from cognitive deficiencies can have a long-term impact. In summary, this study elucidated the profound role that cognitive dysfunction plays in rehabilitation outcome. Lowered general functional abilities, such as poorer ADL skills and incontinence, were related to and predicted by the integrity of a patient s mental status. Ambulation was found to function independently of cognitive condition. 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