M ILITARY M EDICINE, 179, 8:879, 2014
Psychometric Properties of the Beck Depression Inventory-ll for OEF/OIF Veterans in a Polytrauma Sample Glen A. Palmer, PhD, ABN; Maggie C. Happe, PsyD; Janine M. Paxson, PhD; Benjamin K. Jurek, PsyD; Joseph J. Graca, PhD; Stephen A. Olson, BA
ABSTRACT Objective: The Beck Depression Inventory-II (BDI-II) is widely used as a screening instrument for depressive symptomatology in clinical settings. The factor structure has been researched in a variety of settings with results ranging front a single factor to a five-factor structure. The purpose of this study was to examine several identified factor structures when applied to a mixed polytrauma sample. Method: A sample of 310 veterans was used for this study. All subjects were administered the BDI-II screening measure as part of an evaluation in an outpatient polytrauma clinic. Confirmatory factor analysis was used to determine the best model. Results: Confirmatory factor analysis revealed that a three-factor model provided a best fit. A model previously identified for individuals in residential treatment for substance abuse provided a best fit for this sample. Conclusions: The BDI-II may provide additional information for clinicians when examining the three-factor model with veterans in polytrauma settings.
INTRODUCTION The term “polytraum a” has been used by the D epartm ent of V eterans A ffairs to describe injuries to m ultiple body parts and organs occurring as a result o f blast-related w ounds seen in O peration Enduring Freedom (OEF) and O peration Iraqi Freedom (O IF ).1 T raum atic brain injury (TBI) frequently occurs in com bination with other disabling conditions includ ing post-traum atic stress disorder (PTSD), depression, and other m ental health/m edical conditions. M ild traum atic brain injury (m TBI) as defined by the A m erican C ongress o f R eha bilitation M edicine (ACRM ) includes traum atically induced changes in at least one or m ore areas including (1) loss o f consciousness for < 30 m inutes and/or initial G lasgow Com a Scale score o f 13-15 after 30 m inutes, (2) loss o f any m em ory o f events that occurred w ithin 24 hours before or after the accident (i.e., post-traum atic am nesia), (3) alteration of consciousness/m ental state at the tim e o f the accident (e.g., feeling confused, dazed, or disoriented), and/or (4) presence o f focal neurological deficits.2’3 A ccording to the ACRM , several other sym ptom s may be present as evidence o f m TBI (e.g., nausea, headache, cognitive deficits). D epression is a com m only reported problem for both o ut patient and inpatient populations follow ing a T B I.4 Research on prevalence and incidence rates o f depression and TBI has been highly variable. Studies have reported frequency of depression follow ing TBI from anyw here betw een 6% and 77% .4 s Som e o f the variability betw een studies is likely because o f m ethodological differences and lack o f uniform ity with the diagnosis o f m ajor depressive disorder.5 Som e stud ies that have incorporated m ore stringent criteria (e.g., use o f
Department of Psychology, St. Cloud VA Health Care System, 4801 Veterans Drive, EC-117; St. Cloud, MN 56303. The contents of this manuscript do not represent the views of the Depart ment of Veterans Affairs or the United States Government, doi: 10.7205/MILMED-D-14-00048
M ILITARY MEDICINE, Vol. 179, August 2014
structured interview versus use o f depression rating scales) have found rates betw een 17% and 61% .7 The Beck D epression Inventory (BD I)9 and its latest rev i sion, the Beck D epression Inventory-II (B D I-II),10 have been w idely studied with a variety o f different populations. C hristenson et al w ere perhaps the first researchers to explore the factor structure o f the BDI with individuals receiving rehabilitation in a TB I sam p le.11 They reported a five-factor structure with the follow ing descriptors: (1) sym ptom s of m ajor depression, (2) sym ptom s o f TBI, (3) hopelessness/ anhedonia, (4) negative self-appraisal, and (5) cognitive dis tortions. A lternatively, G reen et al reported a three-factor structure labeled: (1) affective/perform ance com plaints, (2) negative attitudes tow ard self, and (3) som atic co m p lain ts.12 Initial factor analysis o f the BD I-II was conducted by Beck et a l.1(1 T hey identified a tw o-factor solution based on a sample of 500 psychiatric outpatients. The first factor consisted o f cognitive sym ptom s (item s 4, 10, 11, 12, 13, 15, 16, 17, 18, 19, 20, and 21). The second factor consisted o f som atic/ affective sym ptom s (item s 1, 2, 3, 5, 6, 7, 8, 9, and 14). Since the developm ent o f BD I-II, the factor structure o f the BDI-II has been exam ined with a variety o f different sam ples with different results. Findings suggest the factor structure o f the BD I-II varies am ong, and has been inconsis tent w ithin, clinical populations. Row land et al evaluated the factor structure o f the BDI-II for individuals with TBI and found a three-factor structure labeled: (1) N egative S elf E val uation (items 3 , 4 , 5 , 6 , 7 , 8, and 12), (2) Sym ptom s o f D epres sion (item s 1, 2, 9, 10, 13, 14, 15, 17, 19, and 20), and (3) V egetative sym ptom s (item s 11, 16, 18, and 2 1 ).13 The study was one of the first to explore the factor structure of BD I-II with a TB I sam ple, although the sam ple size was very small (N = 51). Injury severity o f the sample was reported to be roughly evenly divided betw een m ild/m oderate (49% ) and severe (51 %). A bout 26% o f this sam ple also had a substance abuse history. Findings o f the study revealed that V egetative sym ptom s o f depression were unique to the TB I sam ple.
879
Psychometric Properties of the BDI-1I for Veterans in a Polytrauma Sample
FIGURE 1.
Three-factor substance abuse model (as identified in Buckley et at15).
Siegert et al examined the factor structure of the inventory with an inpatient neurorehabilitation sample.14 Confirmatory factor analysis (CFA) was conducted that revealed, in addi tion to a general depression factor, two underlying specific factors labeled: (1) Cognitive/Affective (items 1, 2, 3, 5, 6, 7, 8, 9, 10, 11, and 14) and (2) Somatic (items 4, 12, 13, 15, 16, 17, 18, 19, and 20). Two items for the two-factor model did not correlate well with either factor (i.e., item 17-Irritability; and item 21-Loss of Interest in Sex), but item 17 was included in the Somatic factor structure as listed above.
880
The authors combined items into parcels for portions of their analyses. Buckley et al examined the factor structure of the BDI-II in a sample of veterans (N = 416) admitted to a 28-day residential treatment program for chemical dependency in the southern United States.1'’ The authors conducted a series of CFAs (i.e., one-, two-, three-factor models) and concluded that a three-factor model provided the best fit for the data. The model consisted of (1) Cognitive (items 1, 2, 3, 5, 6, 7, 8, 9, and 14), (2) Affective (items 4, 10, 12, and 13); and
MILITARY MEDICINE, Vol. 179, August 2014
Psychometric Properties of the BDl-Il for Veterans in a Polytrauma Sample (3) Somatic (items 11, 15, 16, 17, 18, 19, 20, and 21) factors. Figure 1 describes the three-factor model. Given the various findings regarding factor structure of the BDI-II, research is needed to determine what factor structure is most appropriate for polytrauma and dual diagnosis samples. To date, little research exists regarding the factor structure of this instrument with veterans in a polytrauma sample. The purpose of this study was to identify the best factor structure for the BDI-II in a mixed polytrauma sample of veterans by use of CFA. It was hypothesized that the factor structure would be similar to findings of a TBI sample,13 given the majority of subjects were referred because of subjective report of head trauma. Therefore, theoretically one might expect that vegetative symptoms of depression as outlined in the three-factor TBI model would provide a unique contribution to veterans with mTBI when compared with other models (e.g„ two-factor model for psychiatric samples). To the authors’ knowledge, CFA with the BDI-II has not been conducted specifically with veterans in a polytrauma sample. In general, little research has been published regard ing subjects served specifically in level 3 polytrauma settings. Findings in these particular settings are relevant to a variety of other outpatient (e.g., rehabilitation, mental health, or other clinical settings) settings because of the increasing number of veterans in the clinic settings who have suffered mTBI and/or other comorbid conditions. In the VA system, level 3 polytrauma settings usually have outpatient teams with rehabilitation expertise that deliver follow-up services with supportive consultation from regional and/or network facilities (e.g., level 1 or level 2 facilities) as needed.16 Eval uation of the factor structure of the BDI-II with polytrauma samples is extremely important as the instrument is commonly used for assessment of depressive symptoms in a variety of settings. If a three-factor model exists, elevated scores on certain factors (e.g., Vegetative symptoms) might be attrib uted to mTBI versus true depressive symptomatology, which could affect treatment recommendations and outcomes. Further, post hoc analyses were planned to see if select models could be improved by adding a higher order single factors (i.e., total depression score) to existing two- and three-factor models. M ETHOD
Participants
Retrospective data collection was used for this study with a sample of 310 veterans. The sample of veterans used in this particular study was referred to an outpatient level 3 polytrauma clinic for evaluation. All of the patients for this particular research investigation were administered the BDI-II as part of the evaluation process. All of the BDI-II screening instruments were administered, scored, and interpreted by licensed psychologists. This research study was approved by the facility’s affiliate Institutional Review Board and local Research and Develop
MILITARY MEDICINE, Vol. 179, August 2014
TABLE I. Characteristic N Male Female Ethnicity White A frican-A m erican Hispanic Native Am erican Other or Unknown Age Branch o f the M ilitary Army Army National Guard Navy Marines Arm y Reserves Airforce Other Concussions Psychiatric Diagnosis PTSD Depression Anxiety Adjustm ent Disorders Other M ental Health Alcohol and/or Other Substance No Diagnosis Com orbid Conditions
Characteristics of the Sample n (%) or M (SD)
Range
310 299 (96.5%) 11 (3.5%) 289 (93.2%) 9 (2.9%) 4 (1 .3 % ) 4(1.3% ) 4(1.3% ) 30.07 (7.56)
20-57
85 (27.4%) 135 (43.5%) 11 (3.5%) 37 (11.9%) 25 (8.1%) 13 (4.2%) 4 (1 .3 % ) 257 (82.9%) 148 (47.7%) 150 (48.4%) 84 (27.1%) 48 (15.5%) 24 (7.7%) 121 (39.0%) 31 (10.0%) 23 (7.4%) 189 (61.0%)
ment Committee. A thorough review and consideration of human subjects’ protections for vulnerable populations was conducted as part of the process. Waiver of informed consent for this minimal risk study was obtained by the affiliate Institutional Review Board and all data containing personal health information were deidentified before analysis. Demographic characteristics of the sample are presented in Table I. The sample was predominantly male (299 males and 11 females). Mean age of the sample was 30.07 years (SD = 7.56). Ethnicity of the sample was predominantly white (n = 289; 93.2%). Based on self-report and record review of the patient’s TBI evaluation (conducted by a licensed psychologist and physiatrist), the majority of the veterans met criteria for having suffered from mTBI (n = 239; 77.1%). A small percentage of those in the sample met criteria for moderate to severe TBI (n = 18; 5.8%). Various branches of the military were represented, with the majority of subjects having served in the Army (n = 85; 27.4%) or Army National Guard (« = 139; 43.5%) at the time of deployment and/ or injury. Measures
The BDI-II10 was used as a screening measure to assess for depressive symptoms in the polytrauma clinic. The screening measure consists of 21 items assessing affective, cognitive, and physiological symptoms associated with depression. The
881
Psychometric Properties of the BDI-II for Veterans in a Polytrauma Sample
RESULTS
BDI-II is a self-report screening measure that asks the patient to evaluate symptoms based on a series of sentences (for each item) presented in ascending order from no symptoms (score of 0) to severe symptoms (score of 3). The patient is asked to rate symptoms in the context of experiences within the last 2 weeks. The instrument has been demonstrated to have good reliability and validity.10
Internal reliability of the BDI-II with the sample was excellent (a = 0.93). The mean BDI-II total score was 21.20 (SD = 11.76; range = 0-51) for the sample. A score of 21 is in the range for moderate symptoms of depression on the BDI-II. Confirmatory factor analyses were first conducted to com pare the three-factor TBI, two- factor psychiatric, three-factor substance abuse, and two-factor neurorehabilitation samples described previously. Results of the analyses are presented S ta tis tic a l A n a ly s is Descriptive statistics were calculated with 1BM/SPSS Statis in Table II. To test our hypothesis that the three-factor TBI tics (IBM/SPSS version 21.0, IBM/SPSS, Chicago, Illinois, model provided the best fit for the data, a CFA was conducted 2012). Data were examined for skewness and kurtosis for by comparing models in the following order: the three-factor each item of the BDI-II. Cutoff scores of greater than + 1 were TBI model, three-factor substance abuse model, two-factor used as criteria for determining skewness and/or kurtosis of psychiatric model, and two-factor neurorehabilitation model. the distributions. Items 6 (Punishment Feelings), 9 (Suicidal Unexpectedly, the three-factor TBI model provided the poorest Thoughts or Wishes), 10 (Crying), and 14 (Worthlessness) fit for the data. Chi-square tests for all models were significant (p < 0.001). exceeded values + 1 for skewness and/or kurtosis. Therefore, statistic, log transformations were conducted for these items before For CFA, a nonsignificant result is desired for the further analyses. Internal reliability of the sample was calcu as this would suggest the model fits the data. However, a lated with a coefficient.17 There was very little missing data significant j 2 finding for CFA is not unusual, especially as (i.e.,
Psychometric Properties of the Beck Depression Inventory-ll for OEF/OIF Veterans in a Polytrauma Sample Glen A. Palmer, PhD, ABN; Maggie C. Happe, PsyD; Janine M. Paxson, PhD; Benjamin K. Jurek, PsyD; Joseph J. Graca, PhD; Stephen A. Olson, BA
ABSTRACT Objective: The Beck Depression Inventory-II (BDI-II) is widely used as a screening instrument for depressive symptomatology in clinical settings. The factor structure has been researched in a variety of settings with results ranging front a single factor to a five-factor structure. The purpose of this study was to examine several identified factor structures when applied to a mixed polytrauma sample. Method: A sample of 310 veterans was used for this study. All subjects were administered the BDI-II screening measure as part of an evaluation in an outpatient polytrauma clinic. Confirmatory factor analysis was used to determine the best model. Results: Confirmatory factor analysis revealed that a three-factor model provided a best fit. A model previously identified for individuals in residential treatment for substance abuse provided a best fit for this sample. Conclusions: The BDI-II may provide additional information for clinicians when examining the three-factor model with veterans in polytrauma settings.
INTRODUCTION The term “polytraum a” has been used by the D epartm ent of V eterans A ffairs to describe injuries to m ultiple body parts and organs occurring as a result o f blast-related w ounds seen in O peration Enduring Freedom (OEF) and O peration Iraqi Freedom (O IF ).1 T raum atic brain injury (TBI) frequently occurs in com bination with other disabling conditions includ ing post-traum atic stress disorder (PTSD), depression, and other m ental health/m edical conditions. M ild traum atic brain injury (m TBI) as defined by the A m erican C ongress o f R eha bilitation M edicine (ACRM ) includes traum atically induced changes in at least one or m ore areas including (1) loss o f consciousness for < 30 m inutes and/or initial G lasgow Com a Scale score o f 13-15 after 30 m inutes, (2) loss o f any m em ory o f events that occurred w ithin 24 hours before or after the accident (i.e., post-traum atic am nesia), (3) alteration of consciousness/m ental state at the tim e o f the accident (e.g., feeling confused, dazed, or disoriented), and/or (4) presence o f focal neurological deficits.2’3 A ccording to the ACRM , several other sym ptom s may be present as evidence o f m TBI (e.g., nausea, headache, cognitive deficits). D epression is a com m only reported problem for both o ut patient and inpatient populations follow ing a T B I.4 Research on prevalence and incidence rates o f depression and TBI has been highly variable. Studies have reported frequency of depression follow ing TBI from anyw here betw een 6% and 77% .4 s Som e o f the variability betw een studies is likely because o f m ethodological differences and lack o f uniform ity with the diagnosis o f m ajor depressive disorder.5 Som e stud ies that have incorporated m ore stringent criteria (e.g., use o f
Department of Psychology, St. Cloud VA Health Care System, 4801 Veterans Drive, EC-117; St. Cloud, MN 56303. The contents of this manuscript do not represent the views of the Depart ment of Veterans Affairs or the United States Government, doi: 10.7205/MILMED-D-14-00048
M ILITARY MEDICINE, Vol. 179, August 2014
structured interview versus use o f depression rating scales) have found rates betw een 17% and 61% .7 The Beck D epression Inventory (BD I)9 and its latest rev i sion, the Beck D epression Inventory-II (B D I-II),10 have been w idely studied with a variety o f different populations. C hristenson et al w ere perhaps the first researchers to explore the factor structure o f the BDI with individuals receiving rehabilitation in a TB I sam p le.11 They reported a five-factor structure with the follow ing descriptors: (1) sym ptom s of m ajor depression, (2) sym ptom s o f TBI, (3) hopelessness/ anhedonia, (4) negative self-appraisal, and (5) cognitive dis tortions. A lternatively, G reen et al reported a three-factor structure labeled: (1) affective/perform ance com plaints, (2) negative attitudes tow ard self, and (3) som atic co m p lain ts.12 Initial factor analysis o f the BD I-II was conducted by Beck et a l.1(1 T hey identified a tw o-factor solution based on a sample of 500 psychiatric outpatients. The first factor consisted o f cognitive sym ptom s (item s 4, 10, 11, 12, 13, 15, 16, 17, 18, 19, 20, and 21). The second factor consisted o f som atic/ affective sym ptom s (item s 1, 2, 3, 5, 6, 7, 8, 9, and 14). Since the developm ent o f BD I-II, the factor structure o f the BDI-II has been exam ined with a variety o f different sam ples with different results. Findings suggest the factor structure o f the BD I-II varies am ong, and has been inconsis tent w ithin, clinical populations. Row land et al evaluated the factor structure o f the BDI-II for individuals with TBI and found a three-factor structure labeled: (1) N egative S elf E val uation (items 3 , 4 , 5 , 6 , 7 , 8, and 12), (2) Sym ptom s o f D epres sion (item s 1, 2, 9, 10, 13, 14, 15, 17, 19, and 20), and (3) V egetative sym ptom s (item s 11, 16, 18, and 2 1 ).13 The study was one of the first to explore the factor structure of BD I-II with a TB I sam ple, although the sam ple size was very small (N = 51). Injury severity o f the sample was reported to be roughly evenly divided betw een m ild/m oderate (49% ) and severe (51 %). A bout 26% o f this sam ple also had a substance abuse history. Findings o f the study revealed that V egetative sym ptom s o f depression were unique to the TB I sam ple.
879
Psychometric Properties of the BDI-1I for Veterans in a Polytrauma Sample
FIGURE 1.
Three-factor substance abuse model (as identified in Buckley et at15).
Siegert et al examined the factor structure of the inventory with an inpatient neurorehabilitation sample.14 Confirmatory factor analysis (CFA) was conducted that revealed, in addi tion to a general depression factor, two underlying specific factors labeled: (1) Cognitive/Affective (items 1, 2, 3, 5, 6, 7, 8, 9, 10, 11, and 14) and (2) Somatic (items 4, 12, 13, 15, 16, 17, 18, 19, and 20). Two items for the two-factor model did not correlate well with either factor (i.e., item 17-Irritability; and item 21-Loss of Interest in Sex), but item 17 was included in the Somatic factor structure as listed above.
880
The authors combined items into parcels for portions of their analyses. Buckley et al examined the factor structure of the BDI-II in a sample of veterans (N = 416) admitted to a 28-day residential treatment program for chemical dependency in the southern United States.1'’ The authors conducted a series of CFAs (i.e., one-, two-, three-factor models) and concluded that a three-factor model provided the best fit for the data. The model consisted of (1) Cognitive (items 1, 2, 3, 5, 6, 7, 8, 9, and 14), (2) Affective (items 4, 10, 12, and 13); and
MILITARY MEDICINE, Vol. 179, August 2014
Psychometric Properties of the BDl-Il for Veterans in a Polytrauma Sample (3) Somatic (items 11, 15, 16, 17, 18, 19, 20, and 21) factors. Figure 1 describes the three-factor model. Given the various findings regarding factor structure of the BDI-II, research is needed to determine what factor structure is most appropriate for polytrauma and dual diagnosis samples. To date, little research exists regarding the factor structure of this instrument with veterans in a polytrauma sample. The purpose of this study was to identify the best factor structure for the BDI-II in a mixed polytrauma sample of veterans by use of CFA. It was hypothesized that the factor structure would be similar to findings of a TBI sample,13 given the majority of subjects were referred because of subjective report of head trauma. Therefore, theoretically one might expect that vegetative symptoms of depression as outlined in the three-factor TBI model would provide a unique contribution to veterans with mTBI when compared with other models (e.g„ two-factor model for psychiatric samples). To the authors’ knowledge, CFA with the BDI-II has not been conducted specifically with veterans in a polytrauma sample. In general, little research has been published regard ing subjects served specifically in level 3 polytrauma settings. Findings in these particular settings are relevant to a variety of other outpatient (e.g., rehabilitation, mental health, or other clinical settings) settings because of the increasing number of veterans in the clinic settings who have suffered mTBI and/or other comorbid conditions. In the VA system, level 3 polytrauma settings usually have outpatient teams with rehabilitation expertise that deliver follow-up services with supportive consultation from regional and/or network facilities (e.g., level 1 or level 2 facilities) as needed.16 Eval uation of the factor structure of the BDI-II with polytrauma samples is extremely important as the instrument is commonly used for assessment of depressive symptoms in a variety of settings. If a three-factor model exists, elevated scores on certain factors (e.g., Vegetative symptoms) might be attrib uted to mTBI versus true depressive symptomatology, which could affect treatment recommendations and outcomes. Further, post hoc analyses were planned to see if select models could be improved by adding a higher order single factors (i.e., total depression score) to existing two- and three-factor models. M ETHOD
Participants
Retrospective data collection was used for this study with a sample of 310 veterans. The sample of veterans used in this particular study was referred to an outpatient level 3 polytrauma clinic for evaluation. All of the patients for this particular research investigation were administered the BDI-II as part of the evaluation process. All of the BDI-II screening instruments were administered, scored, and interpreted by licensed psychologists. This research study was approved by the facility’s affiliate Institutional Review Board and local Research and Develop
MILITARY MEDICINE, Vol. 179, August 2014
TABLE I. Characteristic N Male Female Ethnicity White A frican-A m erican Hispanic Native Am erican Other or Unknown Age Branch o f the M ilitary Army Army National Guard Navy Marines Arm y Reserves Airforce Other Concussions Psychiatric Diagnosis PTSD Depression Anxiety Adjustm ent Disorders Other M ental Health Alcohol and/or Other Substance No Diagnosis Com orbid Conditions
Characteristics of the Sample n (%) or M (SD)
Range
310 299 (96.5%) 11 (3.5%) 289 (93.2%) 9 (2.9%) 4 (1 .3 % ) 4(1.3% ) 4(1.3% ) 30.07 (7.56)
20-57
85 (27.4%) 135 (43.5%) 11 (3.5%) 37 (11.9%) 25 (8.1%) 13 (4.2%) 4 (1 .3 % ) 257 (82.9%) 148 (47.7%) 150 (48.4%) 84 (27.1%) 48 (15.5%) 24 (7.7%) 121 (39.0%) 31 (10.0%) 23 (7.4%) 189 (61.0%)
ment Committee. A thorough review and consideration of human subjects’ protections for vulnerable populations was conducted as part of the process. Waiver of informed consent for this minimal risk study was obtained by the affiliate Institutional Review Board and all data containing personal health information were deidentified before analysis. Demographic characteristics of the sample are presented in Table I. The sample was predominantly male (299 males and 11 females). Mean age of the sample was 30.07 years (SD = 7.56). Ethnicity of the sample was predominantly white (n = 289; 93.2%). Based on self-report and record review of the patient’s TBI evaluation (conducted by a licensed psychologist and physiatrist), the majority of the veterans met criteria for having suffered from mTBI (n = 239; 77.1%). A small percentage of those in the sample met criteria for moderate to severe TBI (n = 18; 5.8%). Various branches of the military were represented, with the majority of subjects having served in the Army (n = 85; 27.4%) or Army National Guard (« = 139; 43.5%) at the time of deployment and/ or injury. Measures
The BDI-II10 was used as a screening measure to assess for depressive symptoms in the polytrauma clinic. The screening measure consists of 21 items assessing affective, cognitive, and physiological symptoms associated with depression. The
881
Psychometric Properties of the BDI-II for Veterans in a Polytrauma Sample
RESULTS
BDI-II is a self-report screening measure that asks the patient to evaluate symptoms based on a series of sentences (for each item) presented in ascending order from no symptoms (score of 0) to severe symptoms (score of 3). The patient is asked to rate symptoms in the context of experiences within the last 2 weeks. The instrument has been demonstrated to have good reliability and validity.10
Internal reliability of the BDI-II with the sample was excellent (a = 0.93). The mean BDI-II total score was 21.20 (SD = 11.76; range = 0-51) for the sample. A score of 21 is in the range for moderate symptoms of depression on the BDI-II. Confirmatory factor analyses were first conducted to com pare the three-factor TBI, two- factor psychiatric, three-factor substance abuse, and two-factor neurorehabilitation samples described previously. Results of the analyses are presented S ta tis tic a l A n a ly s is Descriptive statistics were calculated with 1BM/SPSS Statis in Table II. To test our hypothesis that the three-factor TBI tics (IBM/SPSS version 21.0, IBM/SPSS, Chicago, Illinois, model provided the best fit for the data, a CFA was conducted 2012). Data were examined for skewness and kurtosis for by comparing models in the following order: the three-factor each item of the BDI-II. Cutoff scores of greater than + 1 were TBI model, three-factor substance abuse model, two-factor used as criteria for determining skewness and/or kurtosis of psychiatric model, and two-factor neurorehabilitation model. the distributions. Items 6 (Punishment Feelings), 9 (Suicidal Unexpectedly, the three-factor TBI model provided the poorest Thoughts or Wishes), 10 (Crying), and 14 (Worthlessness) fit for the data. Chi-square tests for all models were significant (p < 0.001). exceeded values + 1 for skewness and/or kurtosis. Therefore, statistic, log transformations were conducted for these items before For CFA, a nonsignificant result is desired for the further analyses. Internal reliability of the sample was calcu as this would suggest the model fits the data. However, a lated with a coefficient.17 There was very little missing data significant j 2 finding for CFA is not unusual, especially as (i.e.,
