Posttraumatic Stress Disorder and Spinal Cord Injury

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ORIGINAL ARTICLE

Posttraumatic Stress Disorder and Spinal Cord Injury James S. Krause, PhD, Lee L. Saunders, PhD, Susan Newman, PhD ABSTRACT. Krause JS, Saunders LL, Newman S. Posttraumatic stress disorder and spinal cord injury. Arch Phys Med Rehabil 2010;91:1182-7. Objectives: To identify the prevalence of posttraumatic stress disorder (PTSD) after spinal cord injury (SCI) in a sample averaging over 2 decades postinjury at assessment. Related objectives are to confirm the factor structure, compare subscales with those reported in a nonclinical sample, and identify the relationship of PTSD with depression. Design: Survey. Setting: A medical university in the Southeastern United States. Participants: Participants were initially identified through specialty hospitals in the Midwest and Southeastern United States. A cohort of adults (N⫽927) with traumatic SCI of at least 1 year duration at enrollment in 2002 to 2003 and a minimum of 7 years at the time of assessment completed the study materials. Interventions: Not applicable. Main Outcomes Measures: PTSD was measured by the Purdue Posttraumatic Stress Disorder Scale-Revised, and depression was measured by the Patient Health Questionnaire 9-item. Results: PTSD was reported by less than 10% of the participants. Item endorsement decreased as a function of years postinjury, primarily because of low rates of endorsement among those 21 or more years postinjury. Confirmatory factor analysis did not result in an acceptable fit for subscales, item sets, or factors previously reported in the literature. Participants scored higher than a nonclinical sample (reported in the literature) on the arousal and avoidance subscales but lower on the re-experiencing subscale. Item endorsements were lower for the first set of items that relate directly to the SCI itself, with the highest item endorsement for “have difficulty remembering important aspects of event.” PTSD rarely occurred in the absence of a depressive disorder. Conclusions: PTSD does not appear to be highly prevalent in long-term SCI survivors, and endorsement of items related to re-experiencing and even recalling the injury are rare. Because SCI often is accompanied by mild traumatic brain injury, difficulty recalling the event may have an organic rather than psychologic component.

Key Words: Depression; Factor analysis, statistical; Rehabilitation; Spinal cord injuries; Stress disorders, post-traumatic. © 2010 by the American Congress of Rehabilitation Medicine RAUMATIC SPINAL CORD injury most commonly reT sults from the occurrence of a motor vehicle collision, act of violence, fall, or sporting activity, potentially leading to an 1

elevated risk of PTSD.2 PTSD is unique among psychiatric diagnoses because it emphasizes a causative event, with actual or threatened death or serious injury or other threat to a person’s physical integrity (Criterion A).2 The characteristic symptoms of PTSD include persistent re-experiencing of the event (Criterion B), avoidance of stimuli associated with the trauma and numbing of general responsiveness (Criterion C), and increased arousal (Criterion D). The full symptom picture must be present for more than 1 month (Criterion E), and the disturbance must cause clinically significant distress or impairment in social, occupational, or other important areas of functioning (Criterion F).2 The National Comorbidity Survey Replication, conducted between February 2001 and April 2003, estimated the lifetime prevalence of PTSD among adult Americans to be 6.8%.3 Studies of PTSD after SCI have often resulted in contradictory findings. Some research has suggested a similar prevalence of PTSD after SCI of 7% to 8%,4,5 whereas other estimates are greater than 60%.6 Variability related to methods of assessment and the sample population (ie, veteran vs civilian) likely contributes to these variations. Kennedy and Duff7 observed a lack of clarity in whether PTSD is a consequence of the traumatic event resulting in SCI, the actual SCI itself, or both. There are a wide variety of PTSD measures, as some are designed to assess the DSM-IV diagnostic criteria and symptom severity of PTSD, while others provide a screening tool for the frequency and severity of PTSD symptoms but are not intended to be diagnostic.8 The CAPS,9 a 30-item structured interview that corresponds to the DSM-IV criteria for PTSD, is considered to be the criterion standard in PTSD assessment10 and has been used primarily in veteran populations in post-SCI PTSD research.11-14 The reList of Abbreviations CAPS

From the Medical University of South Carolina, Charleston, SC. Supported by the Department of Education, National Institute of Disability and Rehabilitation Research (grant no. H133G060126). The contents of this publication do not necessarily represent the policy of the Department of Education, and you should not assume endorsement by the Federal Government. No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit on the authors or on any organization with which the authors are associated. Correspondence to James S. Krause, PhD, Dept of Health Sciences and Research, College of Health Professions, Medical University of South Carolina, 77 President St, Suite 117, MSC 700, Charleston, SC 29425, e-mail: [email protected]. Reprints are not available from the author. 0003-9993/10/9108-00258$36.00/0 doi:10.1016/j.apmr.2010.05.012

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CFA DSM-IV IES MDD PHQ-9 PTSD PPTSD-R RMSEA SCI TBI

Clinician-Administered Posttraumatic Stress Disorder Scale confirmatory factor analysis Diagnostic and Statistical Manual of Mental Disorders, 4th edition Impact of Events Scale major depressive disorder Patient Health Questionnaire 9-item posttraumatic stress disorder Purdue Posttraumatic Stress Disorder ScaleRevised root mean square error of approximation spinal cord injury traumatic brain injury

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ported prevalence of PTSD based on CAPS criteria in this population was 11% to 12%. Martz15 found a similar prevalence (10.3%) among a mixed sample of veterans and civilians using the PPTSD-R.16 There has been much greater inconsistency in prevalence estimates among civilian samples, possibly because of the use of generally shorter measures designed for self-report survey studies rather than the comprehensive CAPS used with veteran samples. Nielsen,5 using the Harvard Trauma Questionnaire, reported a low prevalence rate (7.1%) among a sample of 168 Danish civilians with SCI. Studies using the IES-Revised17 generally provide more conservative prevalence estimates, 8% to 10%,4,18 than those using the original IES.19 Studies using the IES as the primary measure of PTSD have reported a wide range of prevalence, from no evidence of post-SCI PTSD,20 to moderate prevalence of approximately 20% of the sample,21 to a high prevalence of 61.8%.6 This variance may be in part a result of the fact that the IES consists of 2 subscales measuring the PTSD symptoms of intrusion and avoidance only and does not include an assessment of hyperarousal symptoms (the symptoms directly linked to the traumatic event itself). Additionally, IES total score thresholds for clinical concern are arbitrary and not related to specific PTSD diagnostic status; thus, their utility is uncertain.8,22 Other civilian-based studies report rates significantly higher after SCI than the general population. Agar et al23 found 24% of their sample of 50 patients with SCI, who were 3 to 24 months postinjury, met criteria for PTSD using the PostTraumatic Diagnostic Scale.24 Chung et al25,26 report “full blown”25(p254) PTSD in 44% of their sample of 62 Greek patients with SCI using the PTSD Checklist.27 In this study, participants were asked to focus on the incident causing the SCI when completing the PTSD Checklist. However, the sample sizes in these studies were very small, making it difficult to draw conclusions about PTSD in the SCI population. There has been minimal research addressing the relationship between PTSD and other mental health problems after SCI. The few studies that have explored the relationship between PTSD and other emotional distress after SCI have consistently reported a positive correlation between symptoms of PTSD and depression.4,28,29 Goldman et al11 explored the relationship between PTSD and MDD in veterans with SCI using the CAPS and the Beck Depression Inventory.30 Results of this study indicated 28% of participants who had current PTSD also had current MDD, and 36% of those who had lifetime PTSD also had lifetime MDD. This rate of comorbidity is consistent with past research.3,28,31 Purpose Our purpose was to identify the prevalence of PTSD and relative frequency of the 3 types of PTSD symptoms (reexperiencing, arousal, avoidance), confirm the factor structure of the PPTSD-R, and identify the relationship of PTSD symptoms with depression after SCI. We used a larger cohort of participants who were injured for a greater number of years than has been used in previous research. We used a relatively large sample of persons with SCI (N⫽927) and chose to use the PPTSD-R because it contains items that directly refer to the event itself (ie, the actual onset of the SCI)32 rather than the disability associated with SCI. METHODS Participants All participants are from a 35-year longitudinal study and were first identified from 1 of 3 rehabilitation hospitals. The 3

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inclusion criteria were traumatic SCI, minimum of 18 years of age, and minimum of 1 year postinjury (the first cohort required 2 years postinjury). At the time of the previous follow-up in 2002 to 2003, there were a total of 1543 active participants. Of these, 942 participated during the most recent follow-up in 2008 to 2009 (61.0% response rate). There were 237 deaths (72.1% adjusted response rate among those known alive). Of the 942 participants, 15 were eliminated because of missing data on the measure of PTSD (answered less than 16 questions on the PPTSD-R), leaving 927 participants. Most were men (71.4%) and white (78.1%). The mean age at injury ⫾ SD was 28.1⫾12.2y, and the mean years postinjury was 22.5⫾10.7 (range, 8 – 61). Of participants, 14.7% were 10 years or less postinjury, 33.8% were 11 to 20 years postinjury, and 51.5% were 21 or more years postinjury. The most commonly reported etiology was motor vehicle/transportation (56.2%), followed by falls/flying objects (14.7%), sports (12.9%), and violence (10.0%). In terms of injury severity, 23.6% of the participants reported motor-functional injuries (regardless of level), with another 9.2% C1 to C4, 29.4% C5 to C8, and the remaining 37.8% noncervical. Procedures Institutional review board approval was obtained. We conducted a mortality search through the Social Security Death Index prior to sending materials. Participants were first contacted via letter to alert them materials would be forthcoming, to remind them of their previous participation, and to assist with identifying current addresses. Questionnaires were mailed 4 to 6 weeks later. A follow-up phone call and mailing were implemented for nonrespondents. If the participants agreed to participate but had lost or discarded the original survey, another was sent. All materials were reviewed for completeness. Participants were offered $30 in remuneration. Measures The PPTSD-R32,33 is a 17-item measure of PTSD with items that match the diagnostic criteria from the Diagnostic and Statistical Manual of Mental Disorders, 4th edition, Revised. The total score and 3 subscales have been found to have high internal consistency.16 We used the mean of the subscale to impute missing values if only 1 item was missing. The total score was the sum of each item in the scale. The 3 subscales are (1) arousal, (2) avoidance, and (3) re-experience. We also created separate factors for the 2 sections of the measure. Factor 1 included the first 8 items (5 re-experience, 3 avoidance), and factor 2 included the last 9 items (4 avoidance, 5 arousal). Items in factor 1 refer specifically to the SCI event, while items in factor 2 refer to problems since the event. A dichotomous variable was created (PTSD, yes or no) using the following DSM-IV criteria: (a) at least 1 re-experience item, (b) at least 3 avoidance items, and (c) at least 2 arousal items. The items of the PHQ-933 reflect the symptoms of a depressive disorder. The participant is asked the frequency of each symptom in the 2 weeks prior to the assessment: (1) not at all, (2) several days, (3) more than half of the days, and (4) nearly every day. We used 2 methods of classifying depressive disorder. MDD was defined by “more than half the days” on 5 of the 9 items with 1 of those being either “having little interest or pleasure in doing things” or “feeling down, depressed or hopeless.” For the item “thoughts of being better off dead or of hurting yourself in some way,” several days or more was used as the criterion (rather than half the days or more). A cutpoint of 10 was also used to indicate a depressive disorder. The PHQ-9 has been found to have internal consistency (.89) and to be stable over time (.84).33 Arch Phys Med Rehabil Vol 91, August 2010

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Analyses Descriptive statistics were used to summarize the participant characteristics. The portion of participants who endorsed each response category for the 17 PTSD items was identified. We used a 1 sample t test to compare the scores with those reported by Lauterbach and Vrana,16 who used a nonclinical sample. We classified participants according to the diagnostic criteria for PTSD and depressive disorders. We then compared item endorsement (dichotomized), subscales, PTSD diagnosis, and MDD as a function of years postinjury broken down into 3 groups (10 or less, 11–20, 21 or more). We evaluated the factor structure of the PPTSD-R by performing 3 sets of CFA using Mplus softwarea and the maximum likelihood method of extraction. RMSEA was used to determine model fit. The RMSEA is a function of N, the chi-square, and the degrees of freedom. It reflects the discrepancy per degrees of freedom and corrects for model complexity. Values of less than .050 represent excellent fit, whereas those .050 to .080 represent acceptable fit.34 Last, we assessed the relationship between the PHQ-9 and PTSD. Pearson correlation coefficients were calculated among the PPTSD-R total score, 3 subscales, and 2 factors, and the PHQ-9. The chi-square statistic was used to identify the association of PTSD and a depressive disorder. We used t tests to compare the PPTSD-R subscales with a depressive diagnosis using the PHQ-9 cutoff point of ⱖ10. RESULTS Item Responses Endorsement rates for the first set of items (those related to the event itself) were relatively low (table 1). For instance, less than 5% of the sample endorsed any item as “often,” with the exception of “have difficulty remembering important aspects of event.” Endorsement of the second set of items was much higher (these items related to problems since the event). Item endorsement was significantly related to years postinjury (table 2), with the lowest rates consistently reported among those 21 or more years postinjury. Differences between those with 10 or

less years postinjury and those with 11 to 20 years postinjury were less pronounced, with a mixed pattern of endorsement rates between the 2 groups. Factor Analysis CFA suggested an unacceptable fit for the 3 subscale model (RMSEA⫽.111). The CFA for the 2 sets of items fell outside of the acceptable range but was within the marginally acceptable range (RMSEA⫽.085). Because of the poor fit, we conducted an exploratory factor analysis. Two factors had eigenvalues greater than 1.0, yet the fit remained in the marginally acceptable range (RMSEA⫽.083). These factors divided the items along the 2 item sets (ie, the event, consequences) with the exception of 1 item not loading with either factor (having difficulty remembering important aspects of event). Subscales The mean total score ⫾ SD on the PPTSD-R was 33.6⫾13.9, with 7.2% meeting the criteria for PTSD. The subscale means were 11.2⫾5.3 for arousal, 14.6⫾6.2 for avoidance, and 7.9⫾4.1 for re-experience. When scale scores were compared with the nonclinical sample reported by Lauterbach and Vrana,16 we found that our sample had a significantly higher total score and higher scores on arousal and avoidance. However, our sample had a significantly lower score on the re-experience scale. The percentage of participants meeting the criteria for each subscale to be counted toward PTSD decreased with increasing years postinjury, especially for those over 20 years postinjury. PTSD and Depression Scale Scores The mean depression score ⫾ SD was 5.5⫾5.8. Approximately 19% met the criteria for a depressive disorder using the cutpoint of 10, and 11.7% were classified as having MDD. The PPTSD-R total score was highly correlated with the PHQ-9 (r⫽⫹.74) (table 3). Of the 3 subscales, re-experience was the least correlated with depression (r⫽⫹.55). Additionally, Factor 1 (all of the re-experience items) was less correlated with depression than Factor 2. While the average of all 3 subscales

Table 1: Frequencies of the Items from the PPTSD-R Sometimes PPTSD-R Item

In the last month, how often . . . Bothered by memories of the event Upsetting dreams about event Suddenly felt were experiencing event again Feel upset when something happened to remind of the event Avoid activities that might remind of the event Avoid thoughts or feelings about event Have difficulty remembering important aspects of event React physically to things reminding you of the event Since the event have you/are you . . . Lost interest in one or more of your usual activities Felt distant or cut off from people Felt emotionally numb Been less optimistic about your future Had more trouble sleeping Been more irritable or angry Had more trouble concentrating Found yourself watchful or on guard More jumpy or easily startled by noises

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Scale

Not at All

Re-experience Re-experience Re-experience Re-experience Avoidance Avoidance Avoidance Re-experience

55.9 74.9 79.7 59.8 73.2 64.4 63.7 78.5

13.8 9.6 9.5 17.7 9.7 12.3 10.7 9.5

22.1 10.5 7.3 14.5 9.2 15.2 11.9 8.4

Avoidance Avoidance Avoidance Avoidance Arousal Arousal Arousal Arousal Arousal

35.1 39.6 48.9 33.7 34.8 36.5 45.4 50.4 52.0

12.2 15.6 14.9 16.2 16.0 19.4 17.9 16.8 17.2

30.6 25.9 23.1 26.1 20.2 25.1 21.0 18.5 15.9

Often

Mean ⫾ SD

3.6 2.1 1.8 3.9 3.1 4.2 4.4 1.4

4.6 3.0 1.6 4.2 4.8 3.9 9.4 2.2

1.87⫾1.15 1.49⫾0.97 1.36⫾0.82 1.75⫾1.10 1.56⫾1.09 1.71⫾1.11 1.85⫾1.33 1.39⫾0.87

10.4 8.9 6.3 13.2 11.1 11.4 8.3 7.0 6.5

11.8 10.0 6.9 10.9 17.9 7.6 7.3 7.2 8.5

2.52⫾1.37 2.34⫾1.34 2.07⫾1.26 2.52⫾1.36 2.61⫾1.49 2.34⫾1.28 2.14⫾1.28 2.04⫾1.27 2.02⫾1.31

Row (%)

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POSTTRAUMATIC STRESS DISORDER AND SPINAL CORD INJURY, Krause Table 2: Item Endorsement as Related to Years Postinjury Years Postinjury Item

1–10y (n⫽135)

11–20y (n⫽315)

21⫹ y (n⫽477)

P

Column (%)* In the last month, how often . . . Bothered by memories of the event Upsetting dreams about event Suddenly felt were experiencing event again Feel upset when something happened to remind of the event Avoid activities that might remind of the event Avoid thoughts or feelings about event Have difficulty remembering important aspects of event React physically to things reminding you of the event Since the event have you/are you . . . Lost interest in one or more of your usual activities Felt distant or cut off from people Felt emotionally numb Been less optimistic about your future Had more trouble sleeping Been more irritable or angry Had more trouble concentrating Found yourself watchful or on guard More jumpy or easily startled by noises PTSD Arousal† Re-experience† Avoidance† MDD

12.6 10.4 10.4 11.9 10.4 17.0 20.7 8.2

10.2 7.0 3.5 11.1 11.4 8.6 18.4 5.4

5.7 2.3 1.5 5.0 4.8 5.2 8.8 1.1

.010 ⬍.001 ⬍.001 .002 .002 ⬍.001 ⬍.001 ⬍.001

23.7 21.5 17.0 24.4 33.3 28.9 21.5 24.4 20.7 10.4 37.8 23.0 20.0 18.3

27.0 22.9 16.5 29.2 35.2 22.9 18.4 16.8 17.8 8.6 27.9 17.8 22.5 13.3

18.5 15.5 9.9 20.6 23.7 13.6 12.2 9.6 11.5 3.4 18.7 9.0 12.2 8.7

.016 .025 .009 .020 .001 ⬍.001 .008 ⬍.001 .071 ⬍.001 ⬍.001 ⬍.001 ⬍.001 .006

*Percentage of participants within each years postinjury group who met the criteria for endorsement of each item or scale. Percentage of participants who met the criteria for the subscale to be counted toward affirmative PTSD (ie, percentage of persons who reported at least 1 re-experience item, 3 avoidance items, or 2 arousal items). †

was higher among those with MDD (table 4), the difference was smallest for the re-experience subscale. Similar to PTSD, when assessed over time, the percentage of participants classified as having MDD decreased with increasing years postinjury. PTSD was significantly associated with a depressive diagnosis, such that PTSD almost always occurred in the presence of depression (table 5). For instance, only 3.2% of those who did not meet the criteria for a MDD met the criteria for PTSD, whereas 38.5% who were positive for a depressive diagnosis also reported PTSD.

DISCUSSION The results of the current study suggest that PTSD after long-standing SCI, as defined by a minimum of 8 years postinjury, at first assessment, and an average of over 20 years, is similar to the prevalence in the general population.3 First, less than 10% of the sample met the diagnostic criteria. This figure is not substantially different than that observed in nonclinical samples from the general population3 or several studies using participants with SCI.4,5 Second, the item with the highest endorsement in the first set of items that refer to the event was

Table 3: Correlations Between the Purdue Total Score, Subscales, and 2 Factors and the PHQ-9 PHQ-9

PTSD

Arousal

PHQ-9

Item

1.00

PTSD

0.74 ⬍.001 0.72 ⬍.001 0.67 ⬍.001 0.55 ⬍.001 0.55 ⬍.001 0.74 ⬍.001

0.74 ⬍.001 1.00

0.72 ⬍.001 0.90 ⬍.001 1.00

Arousal Avoidance Re-experience Factor 1 Factor 2

0.90 ⬍.001 0.94 ⬍.001 0.80 ⬍.001 0.85 ⬍.001 0.93 ⬍.001

0.78 ⬍.001 0.57 ⬍.001 0.59 ⬍.001 0.95 ⬍.001

Avoidance

0.67 ⬍.001 0.94 ⬍.001 0.78 ⬍.001 1.00 0.65 ⬍.001 0.76 ⬍.001 0.90 ⬍.001

Re-experience

Factor 1

Factor 2

0.55 ⬍.001 0.80 ⬍.001 0.57 ⬍.001 0.65 ⬍.001 1.00

0.55 ⬍.001 0.85 ⬍.001 0.59 ⬍.001 0.76 ⬍.001 0.95 ⬍.001 1.00

0.74 ⬍.001 0.93 ⬍.001 0.95 ⬍.001 0.90 ⬍.001 0.57 ⬍.001 0.59 ⬍.001 1.00

0.95 ⬍.001 0.57 ⬍.001

0.59 ⬍.001

*P values are not given when correlating a variable with itself (ie, PHQ-9 with PHQ-9) because the correlation will always be 1.0.

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“having difficulty remembering important aspects of the event,” which is consistent with a comorbidity (occurring at the time of the SCI) of TBI often associated with SCI.35 Similarly, re-experiencing the traumatic event is a significant component of PTSD, yet the current sample scored lower than a national nonclinical sample on the re-experiencing subscale. Although the current sample scored higher on the arousal and avoidance subscales, these scales may be more heavily influenced by the disability related to SCI than the SCI itself. Alcohol intoxication at SCI onset36,37 and comorbidity of TBI35 may help to account for the rare reports of re-experiencing. Factor analysis of the PPTSD-R did not support either the subscales or factors reported in previous research.16 Exploratory factor analysis suggested the 2 item sets represent the primary dimensions of the instrument, because all items loaded with others from the items set, with the only exception the item requiring memory of the event. This suggests the 2 items sets are relatively independent. The finding that the item “having difficulty remembering important aspects of the event” did not fit with either factor further suggests memory loss related to SCI onset mitigates the development of PTSD (How can someone re-experience what they do not remember?). Although PTSD was not highly prevalent in the decades after SCI onset, it was accompanied by a depressive diagnosis in nearly all cases. While PTSD did decrease over time, the endorsement of MDD also decreased. Therefore, rehabilitation professionals should screen for both depression and PTSD when patients present with 1 of the 2 disorders, and clinicians should consider the circumstances of injury, such as the patient’s ability to recall and therefore re-experience the event, when making assessments. Because depressive disorders were more prevalent than PTSD, it is likely that PTSD will be present in combination with a depressive disorder, whereas depressive disorders are more likely to occur in the absence of PTSD. Study Limitations Our study is limited to a single measure of PTSD. Although other measures may produce somewhat different results, the PPTSD-R was selected because it specifically relates symptoms back to the event of SCI itself. Scales with more vague language may confound the event of SCI with a disability that results from the SCI. Second, there are no independent assessments of PTSD or depression. Therefore, all classifications should be qualified by being considered probable rather than a true diagnosis. Third, there is no information on use of medications or other treatments that could affect the reports. We do not know how medications would affect overall reporting of either PTSD or depression. This is an unknown issue in most outcomes studies. However, it would not likely change the fundamental relationships between PTSD and depression because, on average, the effects of medication may reduce all symptoms (ie, the correlation would remain about the same). Fourth, we do not have information on TBI as a comorbid condition and therefore, could not assess its relationship with Table 4: Relationships of the Purdue Subscales With MDD PHQ-9: MMD Characteristic

Yes

No

P

Avoidance Arousal Re-experience

22.9⫾5.5 18.3⫾4.4 12.7⫾5.7

13.4⫾5.3 10.2⫾4.6 7.2⫾3.4

⬍.001 ⬍.001 ⬍.001

NOTE. Values are ⫾ SD unless otherwise stated.

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Table 5: Occurrence of PTSD by Depressive Disorders PTSD Characteristic

Yes

No

P

38.5 3.2

61.5 96.8

⬍.001

28.7 2.0

71.4 98.0

⬍.001

Row (%) PHQ-9: MDD Yes No PHQ (ⱖ10) Yes No

the ability to remember specific aspects of the event. Studies of comorbidity between SCI and TBI are rare and do not clarify issues related to PTSD.38 Last, our study relates to chronic SCI among persons who have lived nearly a decade or more with SCI. Therefore, the findings do not address PTSD shortly after SCI onset, and symptoms of endorsement decreased over time, primarily after 20 years postinjury. Notably, endorsement of MDD also decreased over time. Nevertheless, PTSD is a stable disorder (war veterans frequently experience symptoms throughout their lives), so using participants who are well after the injury onset is a rigorous test of its occurrence. Future Research Additional studies are needed to identify risk factors for the development of PTSD. Because PTSD occurs in less than 1 of every 10 individuals, at least based on the current findings, particular attention should be paid to the unique circumstances surrounding the development of PTSD. Clearly, it occurs only in special cases, and we need to shift the focus toward understanding the circumstances that bring about this relatively rare disorder. Second, although we were not able to demonstrate a high rate of PTSD related to the initial SCI, there are many circumstances that occur for people well after the SCI that could become sources of extreme stress. For instance, physical or mental abuse, abandonment, or further incidents leading to additional injuries could alter stress levels and potentially lead to PTSD. We simply do not know how often these things occur. Third, more research is needed to delineate risk of depression and PTSD related to mediating factors, such as additional injuries, social support, and income. It is only through continuing research that we will fully understand the complications of SCI, physical as well as psychologic. CONCLUSIONS PTSD was relatively rare in the participant sample, which was substantially larger than that reported in previous studies. In particular, re-experiencing the event was rare, less than that reported in a nonclinical sample in the general literature. Because we used the PPTSD-R that explicitly referred back to the event of SCI, it is less likely that the PTSD diagnosis was confounded with disability resulting from the injury. PTSD appears to be comorbid in a substantial portion of cases of depressive disorders and infrequently occurs in the absence of a depressive diagnosis. References 1. National Spinal Cord Injury Statistical Center (NSCISC). Annual statistical report. Birmingham: Univ of Alabama; 2009. 2. APA. Diagnostic and statistical manual of mental disorders. 4th ed. Washington (DC): American Psychiatric Association; 1994. 3. Kessler RC, Berglund P, Demler O, Jin R, Merikangas KR, Walters EE. Lifetime prevalence and age-of-onset distributions of

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