Cluster Analysis of Neurobehavioral Symptom Inventory Items: Fifteen+ Years Later Paul King, MA Supervised by Kerry Donnelly, PhD July 8, 2011

Overview Background ▫Debate exists with regard to the nature and structure of post- concussive symptom reporting Methods ▫Factor analytic and cluster analytic procedures compared data from our sample to published studies Results ▫High correspondence found among cognitive and affective symptoms in our sample Discussion ▫Affective complications may provide best explanation for long-term presence of post-concussive symptoms

Background Post-Concussive Symptoms ▫Common after mild traumatic brain injury (mTBI) ▫E.g. difficulty with memory, fatigue, nausea, balance concerns, photo- and phonosensitivity, depression, anxiety… ▫Tend to resolve quickly (usually within weeks to months) ▫Persistent symptoms have been documented (months to several years) Benge et al., 2009; Ryan & Warden, 2003

Critiques Symptoms are subjective and nonspecific Healthy controls endorse symptoms in varying degrees (36-76%) as do non-head-injured medical samples (up to 47%) Among behavioral health patient samples, overlap exists among other physical & affective conditions: – PTSD – Chronic Pain – Depression – GAD Benge et al., 2009; Iverson & Lange, 2003; Lew et al., 2009; Mickeviciene et al., 2004

Polytrauma Clinical Triad Lew et al., 2009

Structure of Symptom Reports Levin et al. (1987)- Somatic, affective, cognitive Cicerone & Kalmar (1995)- Somatic, sensory, affective, cognitive Ryan & Warden (2003)- Physical, cognitive, emotional

VA’s Post-Concussive Symptom Assessment Cicerone & Kalmar’s (1995) Neurobehavioral Symptom Inventory (NSI) 22-item self-report Likert-type rating scale Zero = none; symptom is rarely ever present/ not a problem at all) Four = very severe; symptom is almost always present/ impairs performance at work, school, or home/ individual probably cannot function without help

NSI Cicerone & Kalmar (1995) Small sample of 50 civilian litigants Cluster analysis yielded 4 relatively distinct categories of cases: ▫Somatic ▫Sensory ▫Affective ▫Cognitive

Caplan et al. (2010) 3 large samples of active duty military, primarily paratroopers w/ no combat hx 2 control groups w/ n’s of 2,420 & 4,456 1 clinical group n = 617 Data collected , injuries primarily resulted from parachuting accidents Factor analysis yielded 3 symptom groupings (see appendix): Somatic/sensory Affective Cognitive

Benge et al. (2009) N = 345, derived from chart 2 VAMC’s Prior to controlling for PTSD, 4 factors emerged (see appendix): “Factor 1” (multiple sensory, cognitive, motor concerns) Emotional disturbance Headaches & nausea Sensory sx’s

Benge et al. (2009); cont’d However, PTSD sx’s accounted for 5-38% of variance in post-concussive symptom reports After controlling for PTSD, 6 factors emerged (see appendix): ▫Cognitive factor- difficulties w/ concentration, slowed thinking ▫Vestibular disturbance- loss of balance, dizziness ▫Mood disturbance- depression, frustration, irritability ▫Sensory & sleep ▫Headache factor (+ light sensitivity & anxiety) ▫Hearing factor

But… Consider potential impact of sampling differences (civilian, active military & combat veteran) ▫Our sample is probably more similar to Benge et al.’s (2009) Also, variations in methodology ▫Cluster analysis- attempt to group samples/ cases according to degree of shared variance ▫Factor analysis- attempt to group items according to degree of shared variance

Present Analyses Repeated factor analysis w/ 3- and 4-factor models using our data (see appendix) 4-factor Cognitive, Affective, Somatic/ Vestibular, Sensory 3-factor- better fit for data? Cognitive/ Affective, Somatic/ Vestibular, Sensory Also, repeated 3- and 4-means cluster analysis 3 clusters Cognitive & Affective complaints, Somatic & Vestibular complaints, Sensory complaints 4 clusters Added a group where primary complaints = headache

Persistent Post-Concussion Symptoms… or something else? Assuming post-concussive symptoms reported in sample, would we expect reduction over time? ANOVA yielded no significant differences in NSI scores based on time since injury F(2,267)=1.859, p >.05

Conclusion: Affective symptoms may well be that “something else” Hypothetically… imagine NSI as a predictor of PTSD (using PCL- M data to inform diagnosis, cutoff = 50) ROC analysis yields AUC of.88 (aka 88% chance to I.D. PTSD+ case) ▫AUC of.50 = random chance ▫AUC of 1.0 = 100% accuracy

References Benge, J.F., Pastorek, N.J., & Thornton, G.M. (2009). Postconcussive symptoms and impact of posttraumatic stress. Rehabilitation Psychology, 54, Caplan, L.J., Ivins, B., Poole, J.H., Vanderploeg, R.D., Jaffee, M.S., & Schwab, K. (2010). The structure of postconcussive symptoms in 3 US military samples. J Head Trauma Rehabil, 25, Cicerone, K.D., & Kalmar, K. (1995). Persistent postconcussion syndrome: The structure of subjective complaints after mild traumatic brain injury. J Head Trauma Rehabil, 10, Iverson, G.L., & Lange, R.T. (2003). Examination of “postconcussion-like” symptoms in a healthy sample. Applied Neuropsychology, 10, Levin, H.S., Mattis, S., Ruff, R., Eisenberg, H.M., Marshall, L.F., Tabbador, K., et al. (1987). Neurobehavioral outcome following minor head injury: A three-center study. Journal of Neurosurgery, 66, Lew, H.L., Otis,J.D., Tun, C.T., Kerns, R.D., Clark, M.E., & Cifu, D.X. (2009). Prevalence of chronic pain, posttraumatic stress disorder, and persistent postconcusive symptoms in OIF/OEF veterans: Polytrauma clinical triad. Journal of Rehabilitation Research & Development, 46, Mickeviciene, D., Schrader, H., Obelieniene, D., Surkiene, D., Kunickas, R., Stovner, L.J., et al. (2004). A controlled prospective inception cohort study on the post-concussion syndrome outside the medicolegal context. European Journal of Neurology, 11, Ryan, L.M., & Warden, D.L. (2003). Post concussion syndrome. International Review of Psychiatry, 15,