The utility of the Convergence Insufficiency Symptom Survey (CISS) post-concussion

Background: The Convergence Insufficiency Symptom Survey (CISS) is being utilized as an assessment measure following concussion despite minimal research. This study explored the sensitivity and specificity of the CISS in identifying receded near point of convergence (NPC) post-concussion. Methods: Prospective study of 130 patients post-concussion aged 11-25, classified into normal NPC (n = 94) and CI (n = 36) groups (i.e., NPC >5 cm), completed the CISS, VOMS, and PCSS. Sensitivity and specificity identifying receded NPC were explored with published CISS cutoff score (>16). ROC with AUC analysis was conducted to determine an alternate CISS cutoff score to yield optimal sensitivity and specificity in patients with concussion. Results: Utilizing the published cutoff score, the CISS demonstrated adequate sensitivity (.78 [95% CI = .60-.89]) but poor specificity (.35 [95%CI = .26-.46]). ROC curve demonstrated that CISS score was significant (P = .01) in predicting a positive test result (i.e., NPC >5) with AUC of .65 (95%CI .54-.76). An alternative cutoff score (CISS>23) maximized sensitivity (.70) and specificity (.53) for identifying receded NPC. Conclusions: Both the previously published CISS cutoff and our sample-based cutoff score yielded a high rate of false positives for receded NPC. CISS scores post-concussion may help the clinician understand difficulties with visual tasks but is not a suitable diagnostic tool in this patient population.