Contribution of functional ratings to prediction of longterm employment ...

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Contribution of functional ratings to prediction of longterm employment outcome after traumatic brain injury M A R K S H E R E R{ { , P A U L A B E R G L O F F } , W A L T E R H I G H , J R .} a n d T O D D G . N I C K# { Mississippi Methodist Rehabilitation Center, Jackson, Mississippi, USA { University of Mississippi Medical Center, Jackson, Mississippi, USA } University of Michigan Medical Center, Ann Arbor, Michigan, USA } Baylor College of Medicine, Houston, Texas, USA # The Institute for Rehabilitation and Research, Houston, Texas, USA

(Received 2 February 1999; accepted 26 May 1999 ) The present study investigated the contribution of functional ratings to prediction of employment outcome after traumatic brain injury (TBI). Previous studies have suggested that functional ratings obtained at a significant time post-injury can supplement neurologic, pre-injury, neuropsychologic, and other post-injury variables in predicting long-term employment outcome. Functional ratings studied were patients’ needs for physical, cognitive, and behavioural supervision. This investigation also addresse d the issue of predicting long-term outcome for the select group of TBI patients who receive post-acute brain injury rehabilitation. Subjects were 76 patients with TBI. The mean age (25th, 50th, and 75th percentiles) was 32 (22, 28, 39) years and mean premorbid education level was 13 (12, 12, 14) years. Predictors studied were severity of injury, premorbid education level, pre-injury substance use, and needs for physical, cognitive and behavioural supervision at discharge from postacute rehabilitation. Supervision needs ratings were obtained an average of 9.6 (4.2, 5.9, 11.2) months post-injury. Productivity status was assessed an average of 22.5 (12.6, 20.7, 30.5) months post-injury and 12.9 (4.9, 12.4, 16.6) months post-discharge from treatment. Spearman correlation coefficients revealed that premorbid educational level, pre-injury substance use, and needs for physical and behavioural supervision were related to long-term functional outcome ( p < 0 : 05). However, multiple logistic regression analysis revealed that only level of pre-injury substance use was predictive of long-term productivity outcome once adjusted for the effects of the other predictors. Patients with no history of pre-injury substance use were more than eight times as likely to be employed at followup as those with a history of pre-injury substance abuse ( p < 0: 01).

Introd uctio n In recent years, numerous studies have investigated factors that predict or influence outcome after traumatic brain injury (TBI) [1± 3]. Prediction of long-term functional outcome has become increasingly important, as survival rates for people sustaining TBI have increased markedly during the past few decades [4] and surviCorrespondence to: Mark Sherer, Ph.D., ABPP, Neuropsychology, Mississippi Methodist Rehabilitation Center, 1350 East Woodrow Wilson, Jackson, MS 39216, USA. e-mail: marks@ mmrcrehab.org Brain Injury ISSN 0269± 9052 print/ISSN 1362± 301X online # 1999 Taylor & Francis Ltd http://www.tandf.co.uk/JNLS/bin.htm http://www.taylorandfrancis.com/JNLS/bin.htm

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vors can expect to enjoy an essentially normal life-span [5]. Outcome following TBI was initially defined by survival rates followed by categorical rankings (i.e. Glasgow Outcome Scale) [6] and/or neuropsychological test performance [7]. In recent years, interest in the measurement of outcome after TBI has shifted more towards long-term functional status such as the ability to return to work or live independently. Long-term functional outcome after TBI is a complex phenomenon that is affected by a variety of pre-injury, injury related, and post-injury factors. Further, long-term functional outcome is a somewhat subjective concept that can be difficult to measure. One type of long-term functional outcome that has been the focus of many studies over the past several years is the ability to return to work after TBI. Measurement of vocational re-entry is of particular importance, because the ability to hold employment is a primary role that is valued by society. Post-injury employment status should be subject to more objective measurement than ill-defined concepts such as `quality of life’. Failure to return to work and school has been described as a devastating consequence of TBI [8]. Employment rates following TBI have ranged from 22± 66% and are considerably lower than pre-injury rates [9]. Cre peau and Scherzer [8] brought greater clarity to the understanding of prediction of work status after TBI through a meta-analysis of 41 studies examining return to work. Though some findings were mixed, results indicated that pretrauma, post-trauma, and severity of injury variables were related to return to work after TBI. For example, age, gender, pre-injury employment status, neuroanatomic findings, level of consciousness, length of hospitalization, neurologic severity of injury, cognitive status, behaviour, loss of autonomy, driving status, post-injury vocational rehabilitation, and family support variables were found to be related to work status after TBI. Of particular importance for the present study, CreÂpeau and Scherzer [8] found that functional ratings such as the Physical Level of Functioning Scale of the Sickness Impact Profile [10] collected post-injury contributed to prediction of long-term employment outcome. Ponsford et al. [11] evaluated the contribution of another score, partially based on functional ratings, to prediction of return to work after TBI. Disability Rating Scale [12] scores are partially determined by clinician ratings of the patient’s functional abilities to live independently and return to work. Ponsford et al. [11] found that age at the time of injury, Glasgow Coma Scale score on acute hospital admission, and total score on the Disability Rating Scale at the time of admission to rehabilitation, correctly classified the employment status of 74% of 74 TBI survivors 2 years following TBI. In the Ponsford et al. [11] study, these ratings of patient functioning were obtained 49 days post-injury. Gollaher et al. [13] also found that Disability Rating Scales scores obtained at admission and discharge from inpatient rehabilitation were predictive of long-term employment outcome. These findings support the potential of functional ratings collected at a significant interval postinjury to assist with prediction of long-term employment outcome. Most studies that have examined long-term productivity outcome have not focused their investigations on the outcome of patients treated in post-acute brain injury rehabilitation settings. Since patients treated in such programmes represent a select sample of TBI survivors, variables that are predictive of long-term employment outcome in the overall population may be less predictive in this group due to restriction of range. Malec and Basford [14] suggested that post-acute settings tend to select patients who have unsatisfactory adjustment and may be more disabled

Employment outcome after TBI Table 1.

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Rating scale for cognitive, behavioural, and physical supervision needs.

Type of supervision

Supervision needs

Cognitive

Poor judgement, memory communication deficits

Behavioural Physical Ratings

Verbally or physically inappropriate behaviour, impulsivity suicidal Mobility, transfers, daily living activities Levels of assistance/supervision

7 6 5 4 3 2 1

Independent Almost independent Structured environment Intermittent supervision Frequent supervision Close supervision Constant supervision

impairment,

lack

of

insight,

than those who are studied in an unselected population. Alternatively, patients treated in a post-acute programme may be those survivors who have recovered sufficiently well that they are determined to have potential to return to work. Given the selection factors that determine admission to such programmes, the authors agree with Malec and Basford [14] that additional investigation of prediction of productivity outcome of the select sample of TBI survivors admitted to post-acute brain injury rehabilitation programmes is needed. The present study sought to contribute to the understanding of prediction of long-term productivity outcome after TBI, by investigating the contribution of functional ratings obtained a significant period post-injury to prediction of longterm employment outcome and by investigating prediction of long-term productivity outcome for the select group of patients that are admitted for post-acute brain injury rehabilitation services. Functional ratings investigated in this study were ratings of patients’ needs for physical, cognitive, and behavioural supervision at admission to post-acute brain injury rehabilitation. The supervision needs rating scales used in this study are presented in table 1. While another scale measuring supervision needs [15] did not distinguish between physical, cognitive, and behavioural needs for supervision, it is believed that such a distinction was important. Previous studies [16, 17] have shown that family members of TBI survivors are more concerned about cognitive and behavioural deficits than physical deficits. Employers may have difficulties accepting cognitive and behavioural deficits that are similar to those reported by family members. Selection of other potential predictors to be examined in this study was based on data available for the patients and results of previous studies demonstrating that these variables are predictive of employment outcome. Those variables included for study were pre-injury level of education [18], level of pre-injury substance use [19], and initial severity of brain injury [20].

Method The study sample consisted of 76 traumatic brain injury survivors who received treatment at The Institute for Rehabilitation and Research Challenge Programme, a

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comprehensive day treatment programme that facilitates community reintegration. The treatment approach used in this programme has been described elsewhere [21] and generally conforms to the model described by Malec and Basford [14] in their review of post-acute brain injury rehabilitation. Subjects received initial evaluation of their cognitive, behavioural, emotional, and social functioning to identify impairments due to traumatic brain injury. Individualized therapy programmes were developed to decrease the impact of these impairments on subject’ daily functioning. Therapy was provided by neuropsychologists, psychologists, speech/language pathologists, occupational therapists, and vocational specialists. The typical therapy day lasted 5 hours and included a mixture of individual and group therapy activities. A common therapy activity would be training in compensatory strategies (such as use of daily organizer) to minimize the impact of memory impairment on ability to perform functional tasks such as taking medications independently or carrying out a list of instructions. Subjects and their significant others also received education regarding recovery from traumatic brain injury and councelling to address any emotional or relationship issues. Once a subject showed improved compensation for impairments on simulated work tasks in the clinic setting, he/she was transitioned to a community setting for additional therapy. This setting might be the eventual job site or a transitional volunteer placement with duties similar to the eventual targeted job placement. Therapists provided onsite services to assist the subject in implementing compensatory strategies and to assist the employer or supervisor in making any job site modifications that would facilitate the subject’ s optimal performance. Subjects who had pre-injury jobs to return to were guided through a gradual resumption of job duties. In many cases job duties were modified to maximize performance. Subjects who could not return to pre-injury jobs were provided assistance in organizing a job search, training in interviewing skills, and other support as needed. In some cases, therapists accompanied the subject to pre-employment interviews. Once a job was obtained, therapists provided onsite services to facilitate optimal performance at the job. Employers were periodically contacted to provide early identification of problems so that they could be addressed before a subject’s job was put in jeopardy. Subjects for this investigation were selected based upon the availability of follow-up data obtained at least 3 months post-discharge. There were 59 males and 17 females in the sample. The mean age (25th, 50th, 75th percentiles) was 32 (22, 28, 39) years and the mean level of education was 13 (12, 12, 14) years. Rancho Level of Cognitive Functioning Ratings (Ranch Levels) [22] were obtained on all subjects at admission to the post-acute programme. Ranch Levels for the 76 subjects were Level V (confused, inappropriate, non-agitated) ˆ two subjects, Level VI (confused, appropriate) ˆ 10 subjects, Level VII (automatic, appropriate) ˆ 37 subjects, and Level VIII (purposeful, appropriate) ˆ 27 subjects. Severity of injury was determined by Glasgow Coma Scale Scores (3± 8 ˆ severe; 9± 12 or 13± 15 with positive CT or MRI ˆ moderate; 13± 15 with negative CT ˆ mild). Patients with GCS ˆ 9± 12 and those with GCS ˆ 13± 15 with positive CT findings were classified together as moderate, based on previous findings that these patient groups have similar functional outcomes [24]. Forty two subjects (55%) had severe injuries, 23 (30%) had moderate injuries, and 11 (14%) had mild injuries. Prior to injury, 55 subjects (72%) were competitively employed, 18 (24%) were in educational/vocational training; one (1%) did volunteer work, and two (3%) were unemployed. At admission to the post-acute programme, three subjects

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(4%) were employed, two (3%) were in education/training, and 71 (93%) were non-productive. The mean interval from injury to admission to the programme was 5.7 (1.2, 2.0, 6.8) months and mean length of treatment was 3.9 (2.3, 3.3, 5.1) months. Pre-injury substance use was determined by interview of a family member/ significant other at admission for post-acute rehabilitation. Level of substance use (primarily alcohol use) was rated on a three point scale, 1 ˆ no or minimal use, 2 ˆ significant use ( 3 drinks, 2 days a week), and 3 ˆ history of substance use treatment or life problem due to substance use (loss of job, arrest for driving under the influence, etc.). Of the 76 subjects, 43 received pre-injury substance use ratings of 1, 17 were rated 2, and 16 were rated 3. Supervision and productivity ratings Supervision has been described as referring to any form of help that requires the care giver to be in the proximity of the patient [15]. Patients in this study were rated on their level of supervision needs for cognitive, behavioural, and physical factors at discharge from the programme. The supervision ratings were determined by consensus of the treatment team. Subjects were also rated on their pre-injury productivity status as well as productivity status at admission, discharge, and follow-up. Subjects who were competitively employed or engaged in educational/vocational training were rated as productive, while subjects who were not employed or engaged in educational/vocational training were rated as non-productive. The mean interval from injury to completion of supervision ratings was 9.6 (4.2, 5.9, 11.2) months. The mean interval from injury to rating of productivity status was 22.5 (12.6, 20.7, 30.5) months. The mean interval from discharge from treatment to rating of productivity status was 12.9 (4.9, 12.4, 16.6) months. Res ults At follow-up, 54 patients (71%) were employed or engaged in educational/ vocational training (productive), while 22 patients (29%) were unemployed (nonproductive). Spearman correlation coefficients were calculated between severity of brain injury, pre-injury level of education, pre-injury substance use, cognitive, physical, and behavioural supervision needs at discharge from post-acute brain injury rehabilitation and productivity status at follow-up for the sample of 76 subjects (see table 2). Education level, pre-injury substance use, behavioural supervision, and physical supervision significantly correlated with productivity status. Intercorrelations of severity, education level, substance use, and the supervision ratings are presented in table 3. Multiple logistic regression analysis was performed to assess each predictor’s relationship with productivity outcome adjusted for effects of all other predictors. After adjusting for the other predictors, only pre-injury substance use was significantly associated with productivity outcome. Inter-quartile-range odds ratios, confidence intervals, and probability values for all variables are presented in table 4. Inter-quartile-range odds ratios compare the likelihood of the criterion event for subjects scoring at the 75th percentile on a variable as opposed to the 25th percentile. The only variable with a statistically significant odd ratios was pre-injury substance use. The inter-quartile-range odds ratio for pre-injury substance was 0.12

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Spearman correlations between predictors and productivity outcome.

Predictor

Correlation

Severity Education Substance use Physical supervision Cognitive supervision Behavioural supervision

0.00 0.29** 7 0.49** 0.24* 0.19 0.24*

*p

0:05; ** p

Table 3. Education Severity Education Substance use Physical supervision Cognitive supervision *p

0:05; ** p

0.28*

0:01.

Intercorrelations of predictor variables. Substance use 7 0.14 7 0.23*

Physical supervision 0.07 0.02 7 0.15

Cognitive supervision 0.37** 0.28* 7 0.35* 0.11

Behavioural supervision 0.39** 0.27* 7 0.43** 0.21 0.67**

0:01.

Table 4. Predictor Education Substance use Severity Physical supervision Cognitive supervision Behavioural supervision

Inter-quartile-range odds ratios for the predictor variables.

Percentile comparison 75th: 25th 14:12 3:1 Moderate:Severe 7:4 7:6 7:6

Odds ratio 1.73 0.12 0.24 3.66 0.75 1.53

95% Confidence interval 0.86, 0.02, 0.06, 0.23, 0.22, 0.47,

3.45 0.62 1.03 58.50 2.64 4.97

p-value 0.12 0.004 0.14 0.36 0.66 0.48

with a 95% confidence interval of (0.02, 0.52). This indicates that patients scoring at the 75th percentile of pre-injury substance use (indicating more use) are 88% less likely to have a productive outcome than those scoring at the 25th percentile. That is, patients are more than eight times more likely to be employed if they scored at the 25th percentile on pre-injury substance use as compared to the 75th percentile. The full logistic regression model accounted for 42% of the variance in prod2 uctivity outcome (Nagelkerke’s R [24]) while pre-injury substance use alone accounted for 31% of the variance. The logistic regression model correctly predicted the actual productivity status of 61 (80%) of the 76 subjects. Table 5 shows a classification table of the actual and predicted productivity outcomes for the subjects.

Employment outcome after TBI Table 5.

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Classification of patients as productive or non-productive by logistic regression analysis. Predicted classification

Actual outcome

Non-productive

Productive

% correct

Non-productive Productive Total

12 5 17

10 49 59

55% 91% 80%

D is c us s io n Bivariate correlations revealed that pre-injury educational level, substance use history, physical supervision needs, and behavioural supervision needs were significantly associated with productivity status assessed almost 2 years post-injury. However, when variables were adjusted for effects of all other predictors using multiple logistic regression, only substance use history was predictive of productivity outcome. The full model with all six predictors accounted for 42% of the variance in productivity outcome, while substance use history accounted for 31% of the variance. The present findings do not indicate that the physical, cognitive, and behavioural supervision needs ratings used in this study make additional contributions to prediction of productivity outcome beyond that made by other variables. This is surprising in the light of other studies indicating that cognitive and behavioural impairments affect functional outcome. Review of the distributions of scores for the three supervision ratings provides a possible explanation. There was very little variability in subjects’ ratings. At least 84% of subjects received a rating of 6 or 7 for each type of supervision. Rating scales constructed to provide a larger number of possible ratings might result in more variability in the ratings and improved prediction of outcome. The present ratings may still be useful to clinicians and care givers. They provide a meaningful way of documenting patient progress towards independence and they reinforce an emphasis on patient safety. Premorbid substance use was found to have a strong relationship to productivity outcome. Subjects with no history of pre-injury substance use were more than eight times as likely to be employed post-injury as subjects with histories of substance abuse. There are several possible explanations for the association between premorbid substance use and long-term employment outcome found in the present study. First, it is possible that pre-injury substance use makes patients susceptible to greater impairment when they subsequently suffer a traumatic brain injury. While excessive alcohol use may by itself cause cognitive impairment, there is no clear evidence that a history of alcohol use makes one more vulnerable to the effects of traumatic brain injury [25]. Second, patients with premorbid substance use may be at greater risk to return to substance use post-injury, which may interfere which employment success. Kreutzer et al. [26] found that, while incidence of excessive alcohol use decreased after traumatic brain injury, a significant percentage of traumatic brain injury survivors returned to excessive alcohol use. Unfortunately, no data was collected on post-injury substance use in the present study and, thus, whether this factor mediates the influence of pre-injury substance abuse on longterm employment outcome can not be determined. Finally, pre-injury substance abuse may be associated with personality characteristics or other psychosocial issues

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that persist post-injury and interfere with post-injury employment success. This interpretation is supported by the negative significant association of substance use history with behavioural supervision needs (Spearman correlation coefficient ˆ ¡ 0.43) in the present study. This finding indicates that patients with significant premorbid substance use are more likely to have behavioural problems after brain injury. This suggests that personality characteristics or other psychosocial factors that influenced pre-injury behaviour continue to influence post-injury behaviour. The failure of initial severity of injury to predict productivity outcome requires explanation, as several previous studies have found that severity of injury is related to post-injury employment [2, 9, 11, 20]. These previous studies examined the outcomes of patients recruited from trauma centers [2, 20] or from inpatient rehabilitation centers [9, 11]. In contrast, the present study examined the outcomes of patients seen in a post-acute brain injury rehabilitation programme with a primary focus on returning patients to work. Patients seen in such a post-acute programme represent a highly selected sample of TBI patients. The patients with severe injuries seen in this programme are those who recovered to the point that return to work was a possible outcome. Those patients with severe injuries with poorer functional recovery were excluded. The patients with moderate and mild injuries are those who were unable to return to work without specialized rehabilitation services. Consequently, the patients with severe injuries seen in a post-acute programme are those with relatively good outcomes compared to other patients with severe injuries, while patients with moderate and mild injuries seen in such a programme may be those with relatively poor outcomes as compared to other patients with moderate or mild injuries. These selection factors decrease the likelihood of a severity of injury effect on productivity outcome. For patients seen in post-acute rehabilitation programmes, measures of premorbid adjustment such as substance use history may be more useful in predicting long-term functional outcome that measures of initial severity of injury.

A cknowled g em ents This work was partially supported by the US Department of Education, National Institute on Disability and Rehabilitation Research grant no. H133A20004, The TBI Model System of TIRR. The authors express their appreciation to the staff of The Institute for Rehabilitation and Research Challenge Programme for their assistance in collecting data for this study.

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