MOST PATIENTS RECOVERING from traumatic brain

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1 42 ORIGINAL ARTICLE Effect of Severity of Post-Traumatic Confusion and Its Constituent Symptoms on Outcome After Traumatic Brain Injury Mark Sherer, PhD, Stuart A. Yablon, MD, Risa Nakase-Richardson, PhD, Todd G. Nick, PhD ABSTRACT. Sherer M, Yablon SA, Nakase-Richardson R, Nick TG. Effect of severity of post-traumatic confusion and its constituent symptoms on outcome after traumatic brain injury. Arch Phys Med Rehabil 2008;89:42-7. Objective: To investigate the prognostic significance of severity of post-traumatic confusion (PTC) and its constituent symptoms for early and late outcome after traumatic brain injury (TBI). Design: Prospective cohort study. Setting: Inpatient brain injury rehabilitation program. Participants: A total of 168 patients meeting study criteria from 195 consecutive Traumatic Brain Injury Model Systems neurorehabilitation admissions. Interventions: Not applicable. Main Outcome Measures: Employability at neurorehabilitation discharge and productivity status at 1 year postinjury. Results: More severely confused patients had poorer outcomes for both employability and productivity. Multivariable logistic regression revealed that after adjustment for all other predictors, time to follow commands, and confusion severity predicted employability at discharge and age and confusion severity predicted productivity status at 1 year. Each symptom showed an unadjusted effect on discharge employability. All symptoms except nighttime sleep disturbance or daytime decreased arousal had effects on productivity at 1 year. Presence of psychotic-type symptoms was associated with especially poor productivity outcomes. Conclusions: PTC constituent symptoms and severity predict outcome after TBI. Presence or absence of psychotic-type symptoms on a single evaluation at approximately 21 days postinjury may have particular prognostic significance for productivity outcome. Key Words: Amnesia; Brain injuries; Confusion; Delirium; Psychotic disorders; Rehabilitation; Treatment outcome by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation From the Memorial Hermann/TIRR, Houston, TX (Sherer); Baylor College of Medicine, Houston, TX (Sherer); Methodist Rehabilitation Center, Jackson, MS (Yablon, Nakase-Richardson); University of Mississippi Medical Center, Jackson, MS (Yablon, Nakase-Richardson); Center for Epidemiology & Biostatistics, Cincinnati Children s Hospital Medical Center, Cincinnati, OH (Nick); and University of Cincinnati College of Medicine, Cincinnati, OH (Nick). Supported by the National Institute on Disability and Rehabilitation Research (grant no. H133A020514) and the Traumatic Brain Injury Model System of Mississippi. 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 author(s) or upon any organization with which the author(s) is/are associated. Reprint requests to Mark Sherer, PhD, ABPP-Cn, Dept of Research, Memorial Hermann/TIRR, 1333 Moursund, Houston, TX, 77030, Mark.Sherer@ memorialhermann.org /08/ $34.00/0 doi: /j.apmr MOST PATIENTS RECOVERING from traumatic brain injury (TBI) transiently manifest a period of disorientation and inability to form and later recall new memories. 1 This period of recovery has been called post-traumatic amnesia (PTA). 2 Patients generally show continued improvement while in PTA and most eventually recover to be oriented and to have some capacity to form new memories. 3 The duration of the period of PTA is a commonly used index of TBI injury severity. 4,5 Most investigations of the phenomenology of PTA focus on the characteristics of memory and other cognitive impairments, 6-8 to the exclusion of the broader range of neurobehavioral impairments exhibited by these patients. Recently, Stuss et al 9 found that PTA is not simply a state characterized by attentional and memory impairments but that it is also characterized by disturbed consciousness, reduced or increased psychomotor activity, and disrupted sleep-wake cycle. For this reason, these investigators proposed that the term post-traumatic confusion (PTC) replace PTA as the designation for this early period of recovery after TBI. More recently, we 10 developed a procedure, the Confusion Assessment Protocol (CAP), for assessing the various manifestations of PTC in patients in early recovery from moderate and severe TBI. Based on analysis of data from several instruments designed to measure attentional abilities, orientation, agitation, and symptoms of confusion, we identified 7 key symptoms of PTC and developed diagnostic criteria for its classification. In a second investigation, PTC classification results at neurorehabilitation hospital admission were predictive of functional outcome at discharge. 10 In another study using a related delirium rating measure, confusion severity at 30 days postinjury was predictive of employment outcome at 1 year after TBI. 11 The present study sought to extend these findings by again investigating the prognostic significance of severity of confusion in patients in early recovery from TBI and, for the first time, investigating the prevalence and prognostic significance of each symptom of confusion at a fixed time postinjury. We hypothesized that severity of confusion as measured by the CAP at a set time postinjury would be predictive of early functional status at discharge from inpatient rehabilitation and of productivity status at 1 year postinjury even after adjustment for other known predictors of outcome after TBI. In addition, we hypothesized that presence (or absence) of each symptom of confusion at a set time postinjury would be predictive of early functional status and productivity outcome at 1 year. METHODS Study Population The study population for the present study consisted of all qualified persons with TBI who were admitted to an inpatient brain injury neurorehabilitation program within a free-standing rehabilitation hospital during the study period, April 2003 through February Data collection for this investigation

2 POSTTRAUMATIC CONFUSION, Sherer 43 was approved by the appropriate institutional review board. Participants were recruited as part of the National Institute on Disability and Rehabilitation Research Traumatic Brain Injury Model Systems (TBIMS) program. Inclusion criteria for the TBIMS program 12 include: medically documented TBI; treatment at an affiliated level 1 trauma center within 24 hours of injury; receipt of inpatient rehabilitation at the TBIMS-affiliated rehabilitation unit; admission to inpatient rehabilitation within 72 hours of discharge from acute care; age of 16 years or older at the time of injury; and provision of informed consent by the person with injury or an appropriate proxy. Additional inclusion criteria for the present investigation were: (1) recovery to a responsive state prior to rehabilitation discharge (vegetative or minimally conscious patients were excluded) and (2) clinical presentation and reason for rehabilitation primarily reflective of TBI. There was no upper limit on participant age. Data Collection We collected demographic data (age, sex, years of education) and injury severity data (Glasgow Coma Scale [GCS] score, time to follow commands [TFC], acute care length of stay [LOS], rehabilitation LOS) through review of medical records. GCS scores were obtained at admission to the emergency department. TFC was defined as the interval in days from the date of injury to the date that the participants followed simple motor commands on 2 consecutive assessments. Data on severity and symptoms of confusion were collected using the CAP. CAP data were collected serially on all participants, but assessments closest to 21 days postinjury were used for this investigation. This time was selected because the majority of potential participants had evaluations available close to this time. The number of symptoms of confusion (range, 0 7) at the 21-day postinjury CAP was the measure on severity of confusion used in this investigation. We included participants who did not meet our criteria for PTC because our previous investigations have shown that persons in early recovery from TBI continue to have some symptoms of confusion even after they no longer meet full criteria for PTC. 10 These ratings were collected by neuropsychologists, neuropsychology fellows, and neuropsychology technicians, all with extensive training in the use of this instrument. One study outcome, employability, was collected using the Disability Rating Scale (DRS). These data were based on a consensus rating of the treatment team at discharge from inpatient rehabilitation. Most members of the treatment team were not aware of the goals of the present investigation. The other study outcome, productivity, was collected at 1 year postinjury by a research assistant who was unaware of the goals of this investigation. Persons who were employed earning at least minimum wage or who were in school (high school or college) making academic progress toward a degree were coded as productive. All others were coded as nonproductive. Measures Confusion Assessment Protocol. The CAP 10 provides a structured and easily repeatable method for measuring and tracking 7 key symptoms of PTC. The 7 symptoms are disorientation, cognitive impairment, fluctuation in symptom presentation, agitation, nighttime sleep disturbance, decreased daytime arousal, and psychotic-type symptoms. CAP items were largely derived from existing measures used to assess PTA, delirium, or agitation. These measures included the Galveston Orientation and Amnesia Test, 13 Delirium Rating Scale Revised, 14 Toronto Test of Acute Recovery after TBI, 9 Cognitive Test of Delirium, 15 and Agitated Behavior Scale. 16 CAP data can be used to classify patients as in PTC or not in PTC based on patients showing (1) 4 or more symptoms being classified as in PTC or (2) patients with 3 symptoms being classified as in PTC if one of these symptoms is disorientation. Sherer et al 10 provided evidence of the validity of the CAP by showing that patients classified as in PTC at admission to inpatient rehabilitation based on CAP data had poorer functional outcomes at discharge from rehabilitation than those classified as not in PTC, even after adjustment for other known predictors of TBI outcome such as age, years of education, initial GCS score, TFC, and acute and rehabilitation LOS. The version of the CAP used in the present study had a minor modification from the version described by Sherer and colleagues. In the original version, patients could be scored as having psychotic-type symptoms if they showed delusions, hallucinations, or symptoms suggestive of possible delusions or hallucinations or if they showed evidence of thought process abnormalities. This latter criterion was eliminated in the present investigations due to concern that thought process abnormalities could not be reliably and meaningfully distinguished from the highly distractible, disjointed conversation expected in acutely confused patients. Administration time for the CAP varies but is generally around 30 minutes. Disability Rating Scale. The DRS 17 is a 30-point scale with 8 areas of functioning being rated: eye opening; verbalization; motor response; level of cognitive ability for daily activities of feeding, toileting, and grooming; overall level of dependence; and employability. Each area of functioning is rated on a scale of 0 to 3, 0 to 4, or 0 to 5, with a higher score representing a lower level of functioning. Scores on each item are summed to yield a total score between 0 and 30, with a higher score indicating greater disability. For this investigation, an outcome measure (employability) was derived from the eighth (final) item of the DRS rated at patient discharge from inpatient rehabilitation. A rating of 0 (not restricted competitive), 1 (selected jobs competitive), or 2 (sheltered workshop noncompetitive) on the employability item was coded as employable, whereas a rating of 3 (not employable) on the employability item was coded as not employable. Data Analysis We presented descriptive data for demographic characteristics (age, years of education, sex), injury severity (GCS, TFC, acute LOS, rehabilitation LOS), confusion severity and symptoms (days from injury to CAP evaluation [CAP days], total number of CAP symptoms [total CAP], presence of each of the 7 symptoms [disorientation, cognitive impairment, fluctuation, agitation, nighttime sleep disturbance, decreased daytime arousal, psychotic type symptoms]), and study outcomes (employability, productivity) as quartiles for continuous variables and frequency and proportions for nominal variables. Participants classified as confused on the 21-day postinjury CAP were compared with participants classified as nonconfused on a variety of study measures using chi-square tests for dichotomous variables and Wilcoxon and Mann-Whitney tests for continuous variables. The primary study hypotheses regarding prediction of employability and productivity outcomes were examined using multivariable logistic regression models with age, years of education, GCS score, TFC, and total CAP as candidate predictors and employability and productivity as separate outcomes. Missing values of predictor variables were imputed. The TFC interval was censored at 45 days to prevent undue effects of outliers. Effects for all predictors are odds ratios (ORs). For all continuous predictors, the ORs indicate the change in the odds of the outcome (employability, productivity) as the value of the predictor variable changes from the 25th

3 44 POSTTRAUMATIC CONFUSION, Sherer Table 1: Description of the Study Sample on Demographic, Injury Severity, Confusion, and Outcome Variables (N 168) All (N 168) Nonconfused (n 85) Confused (n 83) Descriptors Median (25th, 75th Percentiles) Median (25th, 75th Percentiles) Median (25th, 75th Percentiles) Continuous Age (y) 27.0 (20.0, 45.5) 24.4 (18.6, 44.1) 28.6 (20.7, 48.6) Education* (y) 12.0 (10.0, 12.2) 12.0 (10.0, 13.5) 11.0 (10.0, 12.0) GCS score 7.0 (5.0, 11.2) 9.0 (6.0, 13.0) 7.0 (4.0, 10.0) TFC (d) 4.0 (1.0, 11.2) 2.0 (1.0, 5.0) 7.0 (2.0, 17.0) Acute LOS (d) 19.0 (12.0, 27.0) 13.0 (10.0, 19.5) 23.0 (18.0, 30.0) Rehabilitation LOS (d) 16.0 (13.0, 22.8) 14.0 (11.0, 17.5) 20.0 (15.0, 25.0) CAP days 21.0 (19.0, 29.0) 19.0 (16.0, 22.5) 24.0 (21.0, 31.0) Total CAP 3.0 (2.0, 5.0) 2.0 (0.0, 2.0) 5.0 (4.0, 6.0) Categorical n (%) n (%) n (%) Sex Male 113 (67) 57 (67) 56 (68) Female 55 (33) 28 (33) 27 (32) GCS score Very severe (3 5) 44 (26) 18 (21) 27 (33) Severe (6 8) 52 (31) 24 (28) 27 (33) Moderate (9 12) 34 (20) 17 (20) 17 (20) Mild (13 15) 38 (23) 26 (31) 12 (14) Outcomes Employability Yes 69 (41) 53 (62) 16 (19) No 99 (59) 32 (38) 67 (81) Productivity (n 132) Yes 48 (36) 34 (49) 14 (23) No 84 (64) 36 (51) 48 (77) *P.05; P.02; P.001 (differences between nonconfused and confused participants). percentile to the 75th percentile and are called interquartile range coefficients. We examined the secondary, exploratory hypothesis regarding the prognostic value of presence (or absence) of each symptom of confusion for predicting employability at rehabilitation discharge and productivity at 1 year postinjury using simple, binary logistic regression analyses. Separate predictive models were calculated for each of the 7 symptoms for each of the 2 outcomes. For these analyses, presence of a symptom was coded 0 and absence of the symptoms was coded 1. RESULTS Study Population During the study period, 195 potential participants were admitted to the study site. Of these, 16 did not recover to a responsive state and 3 had clinical presentations that were substantially influenced by non-tbi disorders (spinal cord injury, dementia, deafness). An additional 5 potential participants declined to give consent and 3 participants who were enrolled were inadvertently missed for collection of key study measures. The resulting study sample comprised 168 participants. This study sample included 38 participants (23% of the current study sample) who were reported on in our previous investigation of confusion and outcome after TBI. 11 The productivity outcome was collected at median time of days postinjury (25th percentile, 339.5; 75th percentile, 414.0). At follow-up, 1 participant was deceased, 9 were retired, 5 could not be contacted, and 21 were not due for follow-up at the time of analysis. These 36 participants were excluded from the productivity analyses, but the remaining 132 participants were included in these analyses. All other data were complete for all participants except for 2 missing values for TFC. These values were predicted using GCS scores and these imputed values were used in all subsequent analyses. Table 1 shows descriptive data for demographic, injury severity, CAP days, total CAP, and study outcomes for all participants, nonconfused participants, and confused participants. Participants were classified as nonconfused or confused based on the CAP evaluation obtained closest to 21 days postinjury. Figure 1 shows the proportions of all, nonconfused, and confused participants rated positive for each symptom of confusion on the 21-day postinjury CAP. Mann-Whitney U analyses revealed that nonconfused patients differed significantly from confused patients on years of education, GCS, TFC, acute LOS, rehabilitation LOS, CAP days, and total CAP. As expected and consistent with our previous findings, confused patients sustained more severe injuries as indicated by GCS, TFC, and both LOS variables. The longer interval from injury to CAP evaluation was due to confused patients being more likely to be admitted to rehabilitation at greater than 21 days postinjury. By definition, confused patients had greater severity of confusion (total CAP) than nonconfused patients. The significance of the difference in years of education is unclear but it could indicate that patients with a lower level of functioning prior to TBI were at greater risk for confusion. Chi-square analyses revealed that confused participants were more likely to show each of the 7 confusion symptoms. The confused group did not differ from the nonconfused group in sex composition. Consistent with prior investigations, confused patients had poorer outcomes for both the employability and productivity outcomes.

4 POSTTRAUMATIC CONFUSION, Sherer 45 Participants with Confusion Symptoms (%) Disorient Cog imp Fluct Agitation Sleep dist Arouse Psychotic All Non-confused Confused Fig 1. Percentages of all, nonconfused, and confused patients showing confusion symptoms (N 168). Abbreviations: Arouse, decreased daytime arousal; Cog imp, cognitive impairment; Disorient, disorientation; Fluct, fluctuation in symptom presentation; Psychotic, psychotic-type symptoms; Sleep dist, sleep disturbance. Table 2: Multivariable Logistic Regression Model for Predicting Employability at Discharge From Inpatient Rehabilitation (N 168) Predictor Comparison OR 95% CI P Age 20.0, Education 10.0, GCS 5.0, TFC 1.0, Total CAP 2.0, Abbreviation: CI, confidence interval. Table 3: Multivariable Logistic Regression Model for Predicting Productivity at 1 Year Postinjury (n 132) Predictor Comparison OR 95% CI P Age 20.2, Education 10.0, GCS 5.0, TFC 1.0, Total CAP 2.0, Multivariable Logistic Regression Analyses Table 2 shows the multivariable logistic regression model for predicting employability at discharge from inpatient rehabilitation. After adjustment for all other predictors, TFC and total CAP made unique contributions to prediction of this outcome. Participants with TFC values at the 75th percentile (indicating more severe injuries) had only.54 times the odds of being rated as employable at rehabilitation discharge as compared with participants at the 25th percentile. Stated another way, participants at the 25th percentile of TFC had almost twice the odds of being employable as those at the 75th percentile. Participants with total CAP values at the 75th percentile (more confused) had only.34 times the odds of being employable as compared with those at the 25th percentile. Stated another way, those at the 25th percentile had almost 3 times the odds of being employable as those at the 75th percentile. There was a trend for an effect for years of education with higher levels of education tending to be associated with a greater likelihood of being employable. Table 3 shows the multivariable logistic regression model for predicting productivity at 1 year follow-up. After adjustment for all other predictors, age and total CAP made unique contributions to prediction of this outcome. Participants at the 75th percentile of age had only.39 times the odds of being productive as compared with younger participants at the 25th percentile of age. Stated another way, participants at the 25th percentile of age had 2.56 times the odds of being productive as those at the 75th percentile. Participants at the 75th percentile of confusion severity had only.50 times the odds of being productive as those at the 25th percentile. Stated another way, less confused participants were twice as likely to be productive at 1 year follow-up as participants who were more confused on the 21-day postinjury CAP evaluation. Again there was a trend for those with higher preinjury levels of education to have more favorable outcomes. Simple Binary Logistic Regression Analyses Results of simple binary logistic regression analyses examining prediction of employability and productivity outcomes from the presence or absence of each of the 7 symptoms of confusion at the 21-day postinjury CAP evaluation are presented in table 4. Each symptom showed a simple (unadjusted) effect on employability at rehabilitation discharge. ORs ranged from 1.85 to Participants who were not rated as having nighttime sleep disturbance on the 21-day postinjury CAP were 1.85 times as likely to be employable as those who did have nighttime sleep disturbance. Participants who were not disoriented on the 21-day postinjury CAP were 7.14 times as likely to be employable as those who were disoriented. ORs for other symptoms ranged from 3.57 to Presence of all symptoms except nighttime sleep disturbance or daytime decreased arousal had effects on productivity at 1 year follow-up. These ORs ranged from 3.12 to Participants who were not disoriented at the 21-day postinjury CAP were 3.12 times as likely to be productive at 1 year follow-up as those who were disoriented. The effect for agitation was of the same magnitude with those who were not agitated having 3.12 times the odds of being productive as compared with those who were agitated. Participants who did not have psychotictype symptoms at the 21-day postinjury CAP were times as likely to be productive at 1 year follow-up as those who did have psychotic-type symptoms. ORs for cognitive impairment and fluctuation were 4.54 and 3.33, respectively. DISCUSSION Results of the present investigation provide strong support for our hypothesis that severity of confusion measured at a set time postinjury would make unique contributions to prediction of functional status at rehabilitation discharge and prediction of productivity status at 1 year postinjury. These findings are consistent with our previous investigation 11 that used a different assessment instrument and a longer time postinjury for the assessment of confusion severity. After adjustment for age, years of education, GCS score, and TFC, those with lower confusion severity were almost 3 times as likely to have higher functional status at rehabilitation discharge and twice as likely to be productive at 1 year postinjury. Given the large number of factors that can influence employment outcomes, it is especially remarkable that degree of confusion measured once on a set day postinjury would be so predictive of this complex outcome. Confusion severity made a contribution to outcome prediction beyond that made by common indices of injury

5 46 POSTTRAUMATIC CONFUSION, Sherer Table 4: Simple Binary Logistic Regression Analyses Examining Prediction of Employability (N 168) and Productivity (n 132) from the 7 Symptoms of Confusion Employability Productivity Symptoms OR 95% CI P OR 95% CI P Disorientation Cognitive impairment Fluctuation Agitation Nighttime sleep disturbance Decreased daytime arousal Psychotic-type symptoms severity because confusion severity was predictive of the outcomes of interest even after adjustment for GCS and TFC. Clinically, we have observed that patients with very similar demographic and injury characteristics may show very different patterns of symptoms of confusion and very different courses of resolution of confusion. Our findings also provided strong support for our hypothesis regarding the significance of simple presence or absence of specific symptoms of confusion for employability and productivity outcomes. Occurrence of each on the 7 symptoms on the 21-day postinjury CAP evaluation was predictive of employability ratings at rehabilitation discharge. Effect sizes varied with symptoms; sleep disturbance had only a modest impact on employability ratings but other symptoms had robust effects. Absence of fluctuation of presentation or psychotic-type symptoms was associated with a greater than 4-fold increase in the odds of a more favorable outcome, and absence of disorientation resulted in a greater than 7-fold increase in the odds of a more favorable outcome. Even more remarkable findings were observed for the effects of occurrence of symptoms on employment outcome at 1 year postinjury. Absence of disorientation, severe cognitive impairment, fluctuation in presentation, or agitation resulted in 3- to 4-fold increases in the odds of employment at 1 year. Although disorientation has been considered to be the hallmark symptom of PTA, it tied for fourth as a predictor of late outcome after TBI suggesting that other symptoms of early confusion are just as important, if not more important, in evaluating early recovery. The effect of absence of psychotic-type symptoms on employment was especially striking with those not having psychotic-type symptoms having over 14 times the odds of being employed at follow-up. It is surprising that such strong effects were obtained based on a single observation for participants who were all improving from the acute effects of TBI on a daily basis and for whom symptoms presentation fluctuated from 1 observation to another. Our report of the prevalence of each of these symptoms of confusion at 21 days postinjury is a novel contribution to this literature. The present findings on the effects of severity of confusion and incidence of individual symptoms of confusion on outcome after TBI support the conceptualization of the acute period of recovery after TBI as a multifaceted confusional state manifested in a variety of neurobehavioral impairments. The view of Stuss 9 and Sherer 10 and colleagues that the term posttraumatic confusion is more appropriate than the term posttraumatic amnesia is also supported, because symptoms other than disorientation and memory impairment appear to be important aspects of this state. Additional investigation is needed to determine what factors (eg, neuropathologic, demographic) contribute to the development of various patterns of symptoms of confusion and to examine the patterns of recovery of these symptoms. Such findings might have implications for medical and behavioral management of confused patients. We were particularly surprised by the very large effect of presence of psychotic-type symptoms on employment outcomes. Psychotic symptoms, particularly hallucinations and delusions, have been described among patients in posttraumatic amnesia, 18,19 yet few studies address their presence, prevalence, or clinical importance early after TBI. Most reports in the psychiatric literature that describe delusions or hallucinations in patients with TBI usually address their occurrence in syndromes with onset long after the PTC state has resolved Among patients in the present investigation, the occurrence of psychotic symptoms was transient and was associated with various other symptoms of confusion. We do note that the confidence interval (CI) for this effect was very wide indicating that the result of the current investigation may lack precision as an estimate of the true population effect size. However, even if the true population effect is at the lower bound of the current 95% CI (3.03), the presence of these symptoms would still warrant additional investigation. The current investigation added to our earlier study on acute confusion and employment outcome 11 by replicating this finding in a largely new sample, with a different instrument that was designed specifically for study of acute confusion after TBI, while demonstrating, for the first time, the prognostic significance of individual symptoms of confusion. The present findings provide support for the utility of the CAP in early evaluation of patients with TBI. Number of symptoms of confusion observed on CAP evaluation appears to be a valid index of confusion severity as indicated by the prognostic utility of this score in predicting early and late outcome. Consistent with many prior investigations, 23 we found that TFC was a predictor of early outcome after TBI. However, for late outcome, severity of confusion exceeded TFC in prognostic significance. Also consistent with prior investigations, we found that age at time of injury was an important prognostic factor with older age at injury associated with poor employment outcomes. Study Limitations We regard the current findings as preliminary and requiring replication in new samples. For the current study sample, detailed histories of premorbid psychiatric history or family psychiatric history were not obtained. It is possible that these factors may influence the patterns of symptoms of confusion seen in these patients. Also, the severity of confusion at the time of the CAP evaluation was confounded with the time interval from injury until the CAP evaluation. As noted above, this was due to more confused patients having longer acute care hospital LOSs. For this investigation, we included participants not meeting PTC criteria because, as shown in figure 1, these

6 POSTTRAUMATIC CONFUSION, Sherer 47 persons often have some symptoms of confusion. A later study could investigate the impact of confusion severity on outcome among only those patients who meet criteria for PTC. CONCLUSIONS Findings of the current investigation indicate that assessment of confusion severity at approximately 21 days after moderate or severe TBI has prognostic utility for predicting functional status at rehabilitation discharge and for predicting employment outcome at 1 year postinjury. Additional analyses also indicated that simple presence or absence of individual symptoms of confusion was of prognostic value. Presence or absence of psychotic-type symptoms may be of particular importance. Further investigation is needed to replicate these findings. The current findings provide strong support for the conceptualization of the early period of recovery after TBI as a multifaceted confusional state and for the use of the designation post-traumatic confusional syndrome in preference to PTA. Because the time postinjury for assessment of confusion severity was selected arbitrarily, it is possible that assessment of confusion severity conducted earlier or later in the course of recovery would have similar or greater prognostic value. For the present study sample, selection of a shorter interval postinjury would have resulted in exclusion of patients with more severe injuries because these patients have longer acute care LOSs and would not have been available for confusion assessment on the neurorehabilitation unit at a shorter period postinjury. Similarly, selection of a longer interval postinjury would have resulted in exclusion of patients with milder injuries because some of these patients have short acute and rehabilitation LOS and may be discharged from the neurorehabilitation unit and not available for confusion assessment. By selecting the postinjury period for which we had the most confusion assessment data available, we hope that we have maximized the generalizability of our findings to other neurorehabilitation settings where patients may be admitted at similar postinjury intervals. An ideal study would involve serial assessments of patients beginning in the neuro-intensive care unit and continuing after rehabilitation discharge. Such a study would permit determination of the optimal postinjury interval for assessing confusion to predict future outcomes. Even so, it is likely that the optimal postinjury interval would depend on the outcome to be predicted. References 1. Levin HS. 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