J Head Trauma Rehabil Vol. 30, No. 6, pp. E67–E75 c 2015 Wolters Kluwer Health, Inc. All rights reserved. Copyright
Persistent Sleep Disturbances Independently Predict Poorer Functional and Social Outcomes 1 Year After Mild Traumatic Brain Injury Lai Gwen Chan, MRCP, MRCPsych; Anthony Feinstein, MPhil, PhD, FRCP Objective: To investigate the effect of sleep disturbances on functional and social outcomes after mild traumatic brain injury. Setting: Outpatient traumatic brain injury clinic in a tertiary trauma center. Participants: A total of 374 mild traumatic brain injury patients were assessed within 3 months of injury and followed up every 3 months for 1 year. Design: Analysis of a historical cohort in a naturalistic clinical setting. Main measures: At each visit, symptoms of concussion and psychological distress and indices of functional and social outcomes were measured with the Rivermead Postconcussion Questionnaire, 28-item General Health Questionnaire, and Rivermead Head Injury Follow-up Questionnaire, respectively. Changes in outcome scores over time were explored using repeated measures analysis of variance and compared between subjects with persistent (SD) and recovered (SR) sleep disturbances. Predictors of functional/social outcome were determined using linear regression. Results: The percentages of subjects reporting sleep disturbances at each time point were 71.9%, 57.2%, 55.1%, and 53.7%, respectively. For functional and social outcomes, significant effects of time (F3,315 = 9.54; P < .001), group (SD vs SR) F1,317 = 5.32; P = .022, and time X group interaction F3,315 = 4.14; P = .007 were found. Persistent sleep disturbance (P = 0.011) and higher symptom burden at 6 months postinjury (P < .0001) were independent predictors of poorer outcome. Conclusion: Sleep disturbance, independent of psychological distress, is an important prognostic factor of functional and social outcomes after mild traumatic brain injury. Key words: brain injury, concussion, mild traumatic brain injury, sleep disorders, traumatic brain injury, treatment outcome
I
T IS WELL ESTABLISHED in current literature that the prevalence of objectively diagnosed sleep disorders and subjective sleep disturbances of any type and severity is higher in the traumatic brain injury (TBI) population than in the general population, with a recent meta-analysis estimating it to be about 50%.1 In addition, sleep disturbances have been shown to have a negative impact on acute recovery from TBI by influencing the duration of posttraumatic amnesia (PTA)
Author Affiliations: Department of Psychiatry, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada (Dr Chan), and , Department of Psychological Medicine, Tan Tock Seng Hospital, Jalan Tan Tock Seng, Singapore (Dr Chan); and Department of Psychiatry, University of Toronto and Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada (Dr Feinstein). Supplemental digital content is available for this article. Direct URL citation appears in the printed text and is provided in the HTML and PDF versions of this article on the journal’s Web site (www.headtraumarehab.com). The authors declare no conflicts of interest. Corresponding Author: Lai Gwen Chan, MRCP, MRCPsych, Department of Psychological Medicine, Tan Tock Seng Hospital, 11 Jalan Tan Tock Seng, Singapore 308433 ([email protected]). DOI: 10.1097/HTR.0000000000000119
and rehabilitation length of stay.2,3 Furthermore, neuropsychological outcomes such as communication and sustained attention may be adversely affected as well.4,5 However, interpretation of the results is challenging as the results were often not differentiated by TBI severity. At least 75% of all TBIs in the United States are accounted for by mild TBI (mTBI),6 yet there is relatively little literature on sleep disturbances and their consequences in this specific subpopulation, although at least half of them could potentially be sleeping poorly. Interestingly, studies reporting outcomes of sleep disturbances in the mTBI group have all used self-report measures of sleep, perhaps as an indicator of its relative importance to patient-focused outcomes. A retrospective study by Chaput et al7 found that the prevalence of sleep disturbances after mTBI as measured by the Rivermead Postconcussion Questionnaire (RPQ) increased by more than 2-fold between 10 days and 6 weeks postinjury and was associated with a greater likelihood of concomitant headaches and mood alterations. Lundin et al8 examined the relation between symptoms and disability after mTBI by prospectively studying a cohort of patients up to 3 months after TBI, using the RPQ and E67
Copyright © 2015 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited.
E68
JOURNAL OF HEAD TRAUMA REHABILITATION/NOVEMBER–DECEMBER 2015
the Rivermead Head Injury Follow-up Questionnaire (RHFUQ). The group found that sleep disturbance was one the commonest symptoms reported, and that total symptom scores (not specifically sleep) were correlated with disability at 3 months.8 A more recent study involving longitudinal observation of a sample of mixed severity TBI patients showed that sleep disturbances in the acute post-TBI period predicted symptoms of depression, anxiety, and apathy at the end of 1-year followup.9 There are also a few small studies involving healthy controls that show both subjective and objective sleep difficulties,10–12 suggesting that both types of measures have some degree of correlation. In essence, the use of subjective sleep measures appears to be the more common approach in the existing literature, and these studies point toward an association between subjectively reported sleep disturbances and important outcomes after mTBI such as postconcussion symptoms, psychiatric disturbances, and functional disability. This is an important area that has great clinical implications, as these variables are conceptually interrelated and their individual relative contributions to overall recovery from mTBI need to be determined so as to guide future clinical practice. There is very scant literature on treatment of sleep disturbances after TBI,13,14 and none specifically for mTBI. Hence, a next important research question that has remained unanswered is whether successful treatment/resolution of sleep disturbances after mTBI (or for that matter all TBIs) will have a positive impact on a variety of outcome measures. Therefore, the objectives of our study were first, to investigate the effect of persistent sleep disturbances on other postconcussion symptoms, psychological distress, and functional/social outcomes in mTBI patients as compared with the effect of recovered sleep disturbances, and second, to elucidate predictors of poorer functional/social outcome 1 year after mTBI. METHODS Participants The TBI clinic at Sunnybrook Health Sciences Centre is an outpatient clinic at a tertiary trauma center in Ontario, Canada, and offers an appointment to all mild and moderate TBI patients up to the age of 65 years who are assessed by the trauma service and in the emergency department. Patients are assessed within 3 months of injury, at which treatment recommendations are made and follow-up appointments are offered if clinically necessary every 3 months for up to a year (4 visits in total). Patients whose symptoms resolve sooner are discharged, often well before the 1-year mark. At the baseline visit, patients aged between 18 and 65 years are asked for written consent to use their data for research purposes. The
clinical data obtained via assessment by an occupational therapist and a staff psychiatrist for those who consented are then entered into an electronic database by a research assistant after each appointment. Extraction of data from this database for this study was approved by the institutional review board, and the first author was responsible for data extraction and analysis. Of 2484 patients aged between 18 and 65 years and seen between 1998 and 2014, 374 had an mTBI and had 4 assessments over the course of a year and were included to make up the historical cohort identified for this study. All patients who had fewer than 4 assessments in the 1year follow-up period or TBI not classified as mild were excluded. These inclusion and exclusion criteria were used so as to be consistent with our study objectives and so as to demonstrate the clinical course of the small subgroup of mTBI patients who are still symptomatic at 1 year postinjury (estimated 14%-18%).15 Traumatic brain injury in the adolescent and geriatric subpopulations was beyond the scope of this article. The categorization of the TBI as mild was based on a Glasgow Coma Scale score of 13 -15, PTA of less than 24 hours, and loss of consciousness for less than 20 minutes.16 Demographic and TBI data The following demographic data were collected by an occupational therapist and psychiatrist from 2 sources: face-to-face patient assessment and chart/electronic medical record review: age, gender, educational level, history of TBI, and psychiatric history. The TBI-related data collected were mechanism of injury, computed tomographic (CT) brain scan results (normal/abnormal), and multiple trauma (absent/present). The severity of non-TBI injuries was quantified with the Injury Severity Score (ISS),17 which is a score calculated from the Abbreviated Injury Scale scores for individual body regions.18 The score ranges from 1 to 75, with higher scores indicating greater severity and has been shown to be scored reliably by physicians and nurses.19 No cutoff scores are used for this measurement. Psychometric measurements a. Symptoms of concussion were elicited by patient self-report with the Rivermead Postconcussion Questionnaire (RPQ), which assesses a list of postconcussion symptoms on a 5-point Likert scale (0, absent; 1, no more than before the accident; 2, a mild change after the accident; 3, moderate change; 4, severe change).20 This scale has good test-retest and interrater reliability and is widely used in mTBI research. Higher total scores indicate high-symptom burden, and there are no validated cutoff scores in the literature.20
Copyright © 2015 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited.
Persistent Sleep Disturbances After Mild TBI b. In our study, positive sleep disturbance (sleepdisturbed vs non–sleep-disturbed) was defined as a score of more than 2 (moderate change and above) on the sleep item of the RPQ, which reads “Compared with before the accident, do you now (ie, over the last 24 hours) suffer from Sleep Disturbance?” This was chosen as the means of defining the key independent variable to make it comparable with previous studies10,11 and also because it was not the objective of our study to differentiate between specific types of sleep disturbances or disorders. Subjects with sleep disturbances on baseline assessment were grouped according to whether their sleep disturbance persisted or recovered by the fourth clinic visit at 12 months postinjury. c. Psychological distress was recorded with the 28item General Health Questionnaire (GHQ),21 which is a self-report questionnaire of 4 subscales of 7 items each pertaining to somatic complaints, anxiety, social dysfunction, and depression. A choice of 4 responses is allowed for each question, and scoring was done in binomial fashion (0-0-1-1). We used a cutoff score of more than 12 on the GHQ to indicate clinically significant psychological distress, as recommended for patients with concurrent physical illnesses.22 d. Functional and social outcomes were determined using the Rivermead Head Injury Follow-up Questionnaire (RHFUQ),23 which is a 4-point selfreport scale that assesses 10 aspects of a patient’s subjective rating of outcomes in work; relationships; and social, domestic, and leisure activities after TBI, with a score ranging from 0 to 48, higher scores indicative of poorer recovery. It is an adequately reliable and valid measure of functional and social outcomes particularly after mild to moderate head injury and is correlated with the scores of the RPQ.23 Similar to the RPQ, cutoff scores are not used.
E69
using the Student t test for continuous variables and χ 2 test for categorical variables. We then focused the follow-up on the sleep-disturbed group (see Figure 1) and compared the outcomes between those who still reported sleep disturbances at the end of 1 year (persistent sleep disturbance [SD]) and those whose sleep disturbances recovered by the end of 1 year (sleep recovered [SR]) at each follow-up time point (6 months, 9 months, and 12 months postinjury), with t tests for continuous and χ 2 tests for ordinal variables, respectively. Changes in symptoms of concussion as measured by the RPQ score excluding sleep item, psychological distress as evaluated by the GHQ-28 total score, and indices of functional/social outcomes as indicated by the RHFUQ score over time according to group (SD vs SR) were explored with a repeated measures analysis of variance. Finally, predictors of poorer functional/social outcomes at 1-year post-mTBI were sought with a hierarchical stepwise linear regression. The predictor variables entered into the equation were those that had differentiated the 2 groups (SD vs SR) at each of the 4 time points. Our data met the assumptions for these 2 statistical tests. RESULTS Sample characteristics The demographic and TBI-related variables for the entire sample are shown in Table 1. At baseline assessment, 71.9% of the sample were deemed to have sleep disturbance, with 61.9% of this subgroup rating it as severe, the percentages changing to 57.2% (severe = 52.0%) (P = .008), 55.1% (severe = 53.1%), and 53.7% (severe = 45.2%) at 6 months, 9 months, and 12 months postinjury, respectively (see Supplemental Digital Content, available at http://links.lww.com/JHTR/A133). Comparatively, only 47.0% of the subjects excluded from the study were sleeping poorly at baseline assessment (P < .001). They were also dissimilar from the
Statistical analysis Power analysis revealed that a sample size of 243 was sufficient to provide an α of .05 and β of .8 on the basis of a minimum 20% between group mean score difference on the Rivermead Follow-up Questionnaire at 1 year postinjury. Less than 10% of the sample had missing data, and these cases were excluded listwise in analysis. The prevalence of reported sleep disturbance at each clinical visit was measured according to the study definition as previously described, and the change in sleep status at each time point was determined (McNemar test). Baseline (at first visit within 3 months of injury) comparisons between the groups sleepdisturbed versus non–sleep-disturbed were performed
Figure 1. Consort diagram of study sample. TBI indicates traumatic brain injury.
www.headtraumarehab.com Copyright © 2015 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited.
E70 TABLE 1
JOURNAL OF HEAD TRAUMA REHABILITATION/NOVEMBER–DECEMBER 2015
Characteristics of study sample (N = 374)
Variable Age, y Gender (% male) Mechanism of injury (% MVA) Positive CT, head (%) With multiple trauma (%)c ISS score (mean) History of TBI (%) Psychiatric history (%) Post–high school education (%) Sleep disturbed (%) RPQ score (mean) GHQ score (mean) RHFUQ score (mean)
Sample (N = 374)
Excludeda (n = 1554)
P
37.33 (SD, 13.34) 49.5 83.1 42 87.5 16.00 (SD, 9.67) 18.2 22.7 44.4 71.9 37.33 (SD, 5.20) 16.31 (SD, 7.40) 27.82 (SD, 11.22)
35.07 (SD, 13.70) 66.0 67.4 35.1 85.6 14.81 (SD, 9.87) 25.6 25.0 39.8 47.0 25.36 (SD, 17.54) 11.12 (SD, 8.22) 19.33 (SD, 12.86)
.004b
Persistent Sleep Disturbances Independently Predict Poorer Functional and Social Outcomes 1 Year After Mild Traumatic Brain Injury Lai Gwen Chan, MRCP, MRCPsych; Anthony Feinstein, MPhil, PhD, FRCP Objective: To investigate the effect of sleep disturbances on functional and social outcomes after mild traumatic brain injury. Setting: Outpatient traumatic brain injury clinic in a tertiary trauma center. Participants: A total of 374 mild traumatic brain injury patients were assessed within 3 months of injury and followed up every 3 months for 1 year. Design: Analysis of a historical cohort in a naturalistic clinical setting. Main measures: At each visit, symptoms of concussion and psychological distress and indices of functional and social outcomes were measured with the Rivermead Postconcussion Questionnaire, 28-item General Health Questionnaire, and Rivermead Head Injury Follow-up Questionnaire, respectively. Changes in outcome scores over time were explored using repeated measures analysis of variance and compared between subjects with persistent (SD) and recovered (SR) sleep disturbances. Predictors of functional/social outcome were determined using linear regression. Results: The percentages of subjects reporting sleep disturbances at each time point were 71.9%, 57.2%, 55.1%, and 53.7%, respectively. For functional and social outcomes, significant effects of time (F3,315 = 9.54; P < .001), group (SD vs SR) F1,317 = 5.32; P = .022, and time X group interaction F3,315 = 4.14; P = .007 were found. Persistent sleep disturbance (P = 0.011) and higher symptom burden at 6 months postinjury (P < .0001) were independent predictors of poorer outcome. Conclusion: Sleep disturbance, independent of psychological distress, is an important prognostic factor of functional and social outcomes after mild traumatic brain injury. Key words: brain injury, concussion, mild traumatic brain injury, sleep disorders, traumatic brain injury, treatment outcome
I
T IS WELL ESTABLISHED in current literature that the prevalence of objectively diagnosed sleep disorders and subjective sleep disturbances of any type and severity is higher in the traumatic brain injury (TBI) population than in the general population, with a recent meta-analysis estimating it to be about 50%.1 In addition, sleep disturbances have been shown to have a negative impact on acute recovery from TBI by influencing the duration of posttraumatic amnesia (PTA)
Author Affiliations: Department of Psychiatry, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada (Dr Chan), and , Department of Psychological Medicine, Tan Tock Seng Hospital, Jalan Tan Tock Seng, Singapore (Dr Chan); and Department of Psychiatry, University of Toronto and Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada (Dr Feinstein). Supplemental digital content is available for this article. Direct URL citation appears in the printed text and is provided in the HTML and PDF versions of this article on the journal’s Web site (www.headtraumarehab.com). The authors declare no conflicts of interest. Corresponding Author: Lai Gwen Chan, MRCP, MRCPsych, Department of Psychological Medicine, Tan Tock Seng Hospital, 11 Jalan Tan Tock Seng, Singapore 308433 ([email protected]). DOI: 10.1097/HTR.0000000000000119
and rehabilitation length of stay.2,3 Furthermore, neuropsychological outcomes such as communication and sustained attention may be adversely affected as well.4,5 However, interpretation of the results is challenging as the results were often not differentiated by TBI severity. At least 75% of all TBIs in the United States are accounted for by mild TBI (mTBI),6 yet there is relatively little literature on sleep disturbances and their consequences in this specific subpopulation, although at least half of them could potentially be sleeping poorly. Interestingly, studies reporting outcomes of sleep disturbances in the mTBI group have all used self-report measures of sleep, perhaps as an indicator of its relative importance to patient-focused outcomes. A retrospective study by Chaput et al7 found that the prevalence of sleep disturbances after mTBI as measured by the Rivermead Postconcussion Questionnaire (RPQ) increased by more than 2-fold between 10 days and 6 weeks postinjury and was associated with a greater likelihood of concomitant headaches and mood alterations. Lundin et al8 examined the relation between symptoms and disability after mTBI by prospectively studying a cohort of patients up to 3 months after TBI, using the RPQ and E67
Copyright © 2015 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited.
E68
JOURNAL OF HEAD TRAUMA REHABILITATION/NOVEMBER–DECEMBER 2015
the Rivermead Head Injury Follow-up Questionnaire (RHFUQ). The group found that sleep disturbance was one the commonest symptoms reported, and that total symptom scores (not specifically sleep) were correlated with disability at 3 months.8 A more recent study involving longitudinal observation of a sample of mixed severity TBI patients showed that sleep disturbances in the acute post-TBI period predicted symptoms of depression, anxiety, and apathy at the end of 1-year followup.9 There are also a few small studies involving healthy controls that show both subjective and objective sleep difficulties,10–12 suggesting that both types of measures have some degree of correlation. In essence, the use of subjective sleep measures appears to be the more common approach in the existing literature, and these studies point toward an association between subjectively reported sleep disturbances and important outcomes after mTBI such as postconcussion symptoms, psychiatric disturbances, and functional disability. This is an important area that has great clinical implications, as these variables are conceptually interrelated and their individual relative contributions to overall recovery from mTBI need to be determined so as to guide future clinical practice. There is very scant literature on treatment of sleep disturbances after TBI,13,14 and none specifically for mTBI. Hence, a next important research question that has remained unanswered is whether successful treatment/resolution of sleep disturbances after mTBI (or for that matter all TBIs) will have a positive impact on a variety of outcome measures. Therefore, the objectives of our study were first, to investigate the effect of persistent sleep disturbances on other postconcussion symptoms, psychological distress, and functional/social outcomes in mTBI patients as compared with the effect of recovered sleep disturbances, and second, to elucidate predictors of poorer functional/social outcome 1 year after mTBI. METHODS Participants The TBI clinic at Sunnybrook Health Sciences Centre is an outpatient clinic at a tertiary trauma center in Ontario, Canada, and offers an appointment to all mild and moderate TBI patients up to the age of 65 years who are assessed by the trauma service and in the emergency department. Patients are assessed within 3 months of injury, at which treatment recommendations are made and follow-up appointments are offered if clinically necessary every 3 months for up to a year (4 visits in total). Patients whose symptoms resolve sooner are discharged, often well before the 1-year mark. At the baseline visit, patients aged between 18 and 65 years are asked for written consent to use their data for research purposes. The
clinical data obtained via assessment by an occupational therapist and a staff psychiatrist for those who consented are then entered into an electronic database by a research assistant after each appointment. Extraction of data from this database for this study was approved by the institutional review board, and the first author was responsible for data extraction and analysis. Of 2484 patients aged between 18 and 65 years and seen between 1998 and 2014, 374 had an mTBI and had 4 assessments over the course of a year and were included to make up the historical cohort identified for this study. All patients who had fewer than 4 assessments in the 1year follow-up period or TBI not classified as mild were excluded. These inclusion and exclusion criteria were used so as to be consistent with our study objectives and so as to demonstrate the clinical course of the small subgroup of mTBI patients who are still symptomatic at 1 year postinjury (estimated 14%-18%).15 Traumatic brain injury in the adolescent and geriatric subpopulations was beyond the scope of this article. The categorization of the TBI as mild was based on a Glasgow Coma Scale score of 13 -15, PTA of less than 24 hours, and loss of consciousness for less than 20 minutes.16 Demographic and TBI data The following demographic data were collected by an occupational therapist and psychiatrist from 2 sources: face-to-face patient assessment and chart/electronic medical record review: age, gender, educational level, history of TBI, and psychiatric history. The TBI-related data collected were mechanism of injury, computed tomographic (CT) brain scan results (normal/abnormal), and multiple trauma (absent/present). The severity of non-TBI injuries was quantified with the Injury Severity Score (ISS),17 which is a score calculated from the Abbreviated Injury Scale scores for individual body regions.18 The score ranges from 1 to 75, with higher scores indicating greater severity and has been shown to be scored reliably by physicians and nurses.19 No cutoff scores are used for this measurement. Psychometric measurements a. Symptoms of concussion were elicited by patient self-report with the Rivermead Postconcussion Questionnaire (RPQ), which assesses a list of postconcussion symptoms on a 5-point Likert scale (0, absent; 1, no more than before the accident; 2, a mild change after the accident; 3, moderate change; 4, severe change).20 This scale has good test-retest and interrater reliability and is widely used in mTBI research. Higher total scores indicate high-symptom burden, and there are no validated cutoff scores in the literature.20
Copyright © 2015 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited.
Persistent Sleep Disturbances After Mild TBI b. In our study, positive sleep disturbance (sleepdisturbed vs non–sleep-disturbed) was defined as a score of more than 2 (moderate change and above) on the sleep item of the RPQ, which reads “Compared with before the accident, do you now (ie, over the last 24 hours) suffer from Sleep Disturbance?” This was chosen as the means of defining the key independent variable to make it comparable with previous studies10,11 and also because it was not the objective of our study to differentiate between specific types of sleep disturbances or disorders. Subjects with sleep disturbances on baseline assessment were grouped according to whether their sleep disturbance persisted or recovered by the fourth clinic visit at 12 months postinjury. c. Psychological distress was recorded with the 28item General Health Questionnaire (GHQ),21 which is a self-report questionnaire of 4 subscales of 7 items each pertaining to somatic complaints, anxiety, social dysfunction, and depression. A choice of 4 responses is allowed for each question, and scoring was done in binomial fashion (0-0-1-1). We used a cutoff score of more than 12 on the GHQ to indicate clinically significant psychological distress, as recommended for patients with concurrent physical illnesses.22 d. Functional and social outcomes were determined using the Rivermead Head Injury Follow-up Questionnaire (RHFUQ),23 which is a 4-point selfreport scale that assesses 10 aspects of a patient’s subjective rating of outcomes in work; relationships; and social, domestic, and leisure activities after TBI, with a score ranging from 0 to 48, higher scores indicative of poorer recovery. It is an adequately reliable and valid measure of functional and social outcomes particularly after mild to moderate head injury and is correlated with the scores of the RPQ.23 Similar to the RPQ, cutoff scores are not used.
E69
using the Student t test for continuous variables and χ 2 test for categorical variables. We then focused the follow-up on the sleep-disturbed group (see Figure 1) and compared the outcomes between those who still reported sleep disturbances at the end of 1 year (persistent sleep disturbance [SD]) and those whose sleep disturbances recovered by the end of 1 year (sleep recovered [SR]) at each follow-up time point (6 months, 9 months, and 12 months postinjury), with t tests for continuous and χ 2 tests for ordinal variables, respectively. Changes in symptoms of concussion as measured by the RPQ score excluding sleep item, psychological distress as evaluated by the GHQ-28 total score, and indices of functional/social outcomes as indicated by the RHFUQ score over time according to group (SD vs SR) were explored with a repeated measures analysis of variance. Finally, predictors of poorer functional/social outcomes at 1-year post-mTBI were sought with a hierarchical stepwise linear regression. The predictor variables entered into the equation were those that had differentiated the 2 groups (SD vs SR) at each of the 4 time points. Our data met the assumptions for these 2 statistical tests. RESULTS Sample characteristics The demographic and TBI-related variables for the entire sample are shown in Table 1. At baseline assessment, 71.9% of the sample were deemed to have sleep disturbance, with 61.9% of this subgroup rating it as severe, the percentages changing to 57.2% (severe = 52.0%) (P = .008), 55.1% (severe = 53.1%), and 53.7% (severe = 45.2%) at 6 months, 9 months, and 12 months postinjury, respectively (see Supplemental Digital Content, available at http://links.lww.com/JHTR/A133). Comparatively, only 47.0% of the subjects excluded from the study were sleeping poorly at baseline assessment (P < .001). They were also dissimilar from the
Statistical analysis Power analysis revealed that a sample size of 243 was sufficient to provide an α of .05 and β of .8 on the basis of a minimum 20% between group mean score difference on the Rivermead Follow-up Questionnaire at 1 year postinjury. Less than 10% of the sample had missing data, and these cases were excluded listwise in analysis. The prevalence of reported sleep disturbance at each clinical visit was measured according to the study definition as previously described, and the change in sleep status at each time point was determined (McNemar test). Baseline (at first visit within 3 months of injury) comparisons between the groups sleepdisturbed versus non–sleep-disturbed were performed
Figure 1. Consort diagram of study sample. TBI indicates traumatic brain injury.
www.headtraumarehab.com Copyright © 2015 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited.
E70 TABLE 1
JOURNAL OF HEAD TRAUMA REHABILITATION/NOVEMBER–DECEMBER 2015
Characteristics of study sample (N = 374)
Variable Age, y Gender (% male) Mechanism of injury (% MVA) Positive CT, head (%) With multiple trauma (%)c ISS score (mean) History of TBI (%) Psychiatric history (%) Post–high school education (%) Sleep disturbed (%) RPQ score (mean) GHQ score (mean) RHFUQ score (mean)
Sample (N = 374)
Excludeda (n = 1554)
P
37.33 (SD, 13.34) 49.5 83.1 42 87.5 16.00 (SD, 9.67) 18.2 22.7 44.4 71.9 37.33 (SD, 5.20) 16.31 (SD, 7.40) 27.82 (SD, 11.22)
35.07 (SD, 13.70) 66.0 67.4 35.1 85.6 14.81 (SD, 9.87) 25.6 25.0 39.8 47.0 25.36 (SD, 17.54) 11.12 (SD, 8.22) 19.33 (SD, 12.86)
.004b
