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Psychometric Assessment of the Neurobehavioral Symptom Inventory (NSI-22)

Psychometric Assessment of the Neurobehavioral Symptom Inventory (NSI-22). Mark Meterko, PhD 1 Errol Baker, PhD 1 Kelly L. Stolzmann, MS 1 Ann Hendricks, PhD 1 Keith D. Cicerone, PhD, ABPP-Cn 2 Henry L. Lew, MD, PhD 3. 1 VA Boston Healthcare System

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Psychometric Assessment of the Neurobehavioral Symptom Inventory (NSI-22)

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  1. Psychometric Assessment of the Neurobehavioral Symptom Inventory (NSI-22) Mark Meterko, PhD1 Errol Baker, PhD1 Kelly L. Stolzmann, MS1 Ann Hendricks, PhD1 Keith D. Cicerone, PhD, ABPP-Cn2 Henry L. Lew, MD, PhD3 1VA Boston Healthcare System 2JFK-Johnson Rehabilitation Institute3Defense and Veterans Brain Injury Center This work supported by VA HSR&D Grant: SDR 08-405

  2. Background 1: Postconcussive Syndrome? • Studies of postconcussive symptoms have raised several issues: • Is there a postconcussive syndrome (PCS)? • If yes, is there a single cluster of symptoms, or several? • What symptom patterns distinguish among them? • Previous studies suggest different answers, depending on: • Etiology of injury • Evaluation instrument • Target population • Statistical procedures

  3. Background 2: The VA Context • VA Policy & Process Regarding TBI • Screening • Comprehensive TBI Evaluation (CTE) • Includes Neurobehavioral Symptom Inventory (NSI-22) • Clinical evaluator’s overall judgment regarding history and course “consistent with a diagnosis of TBI”

  4. Background 3: Prior Work Cicerone KD & Kalmar K, 1995 (JHTR) • 22-item self-report inventory of symptoms • 50 mostly vehicular accident patients • Using cluster analysis, 17 items grouped into 4 factors: • Cognitive • Affective • Somatic • Sensory • 5 orphan items

  5. Background 4: NSI22 Recent Work • Benge JF, Pastorek NJ & Thornton GM, 2009. • Postconcussive symptoms in OEF-OIF Veterans: Factor structure and impact of posttraumatic stress. Rehab Psych, 54(3), 270-278. • Exploratory factor analysis yielded 6-factor model: 1. Cognitive 4. Sensory 2. Vestibular 5. Headaches, Sensitivity to light 3. Affective 6. Hearing, Sensitivity to noise • Caplan LJ, Ivins B, Poole JH, Vanderploeg RD, Jaffee MS, Schwab K, 2010. • The structure of postconcussive symptoms in 3 US military samples. JHTR, 25(6), 447-458. • Exploratory & confirmatory factor analysis • Three models supported: 2,3 and 9 factors • Endorsed 3-factor solution 1. Somatic/sensory 2. Affective 3. Cognitive

  6. Purpose: Study Aims • Examine the factor structure of NSI-22 • In large sample of deployed veterans judged to have mTBI • Examine whether & how pain related to other symptoms in the NSI-22 • Assess utility of the factor-based NSI-22 scales • Compare subgroups defined by: • Etiology of concussion • Presence/absence of PTSD

  7. Methods 1: Sample • VA National CTE database for FY08 & most of FY09 • N=36,919 • Random split into 2 samples • Derivation (n=18,459) • Confirmation (n=18,460) • Applied inclusion/exclusion criteria to both samples • Keep only those with “symptoms consistent with TBI” (n=18,649) • Drop those with either pre- or post-deployment concussion history (n=5945) • Drop cases missing on pain (n=663) • Drop duplicate and invalid (test case) entries (n=53) • Final samples • Derivation (n=6001) • Confirmation (n=5987)

  8. Methods 2: Analyses • Check success of randomization • Compare derivation & confirmation samples on • Demographics & etiology (chi-square) • NSI-22 items and pain item (MANOVA) • Examine factor structure of NSI-22 • Derivation sample • Exploratory factor analysis (EFA) – four runs • Empirical criteria for n of factors retained, NSI-22 only • Empirical criteria, NSI-22 plus pain • Specify 4 factors, NSI-22 only • Specify 4 factors, NIS-22 plus pain

  9. Methods 3: Analyses • Confirm factor structure • Confirmation sample • Confirmatory factor analysis (CFA) • Utility of proposed factor-based scales • Confirmation sample • Stratified respondents by: • Etiology • Blast, Non-Blast, Both (“Blast Plus”) • PTSD co-morbidity • Dichotomous based on clinical evaluator judgment during CTE • Two-way MANOVA • Grouping factors (IV): Etiology, PTSD, Etiology x PTSD • Dependent variables: NSI-22 factor scores, with and without pain

  10. Results 1: Randomization Success • No significant differences, derivation vs. confirmation samples on: • NSI-22 symptoms • Pain • Blast injury exposure • TBI diagnosis • Marital status • Education • Borderline exception (p=.07): Employment status • Derivation sample: 7.2% working part time • Confirmation sample: 7.9% working part time • Very small effect size (Cramer’s V = .02)

  11. Results 2: EFA in Derivation Sample Using empirical criteria for N of factors to retain • Three criteria • Percent variance accounted for • Horn’s parallel analysis • Velicer’s Minimum Average Partial (MAP) test • 2- and 3-factor models emerged • Same results with and without pain • Preponderance of evidence favored 3-factor model • Somatosensory (11 or 12 items) • Pain loaded cleanly here when included • Affective (6 items) • Cognitive (4 items) • Orphan items (2 items) • Hearing difficulties (no loading >=.40) • Change in appetite (equal loadings < .40 on two factors)

  12. Results 3: EFA in Derivation Sample Specify 4 factors a-priori • Three items from Somato-sensory form a separate, Vestibular factor • Loss of balance • Dizziness • Poor coordination/clumsiness • Pain remained affiliated with Somato-sensory • Orphans – same as before

  13. Results 5: CFA in Confirmation Sample

  14. Results 6: Utility Analyses in Confirmation Sample • Significant main effects for both Etiology and PTSD co-morbidity • Regardless of whether 3 or 4 factors were compared • Regardless of whether pain was/was not included • No significant Etiology x PTSD interactions • Results for PTSD and no-PTSD respondents the same across Etiology groups

  15. Results 7: Utility Analyses in Confirmation Sample

  16. Results 8: Utility Analyses in Confirmation Sample

  17. Conclusions

  18. Conclusions • PCS for Veterans injured during deployment as measured by NSI-22 are multi-dimensional • Pain associated with Somto-sensory factor in all solutions • By technical criteria, no substantial difference between 3- and 4-factor models • Prefer 4-factor model • In EFA: No dual-loading items in EFA • In CFA: Fit statistics marginally but consistently better • Interpretability and utility of 4-factor model • Increased potential for differentiation among clinical groups

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