In patients suspected of having a concussion after a nontrivial head injury, the presence of headache alone has a sensitivity of 0.76 to 1.0 and a specificity of 0.83 to 0.94 (positive likelihood ratio [LR+] 4.5–17, negative likelihood ratio [LR-] 0–0.29). The Concussion Symptom Inventory and the symptom score portion of the Sport Concussion Assessment Tool 2 (SCAT2) likely have similar accuracy. The King-Devick test, an oculomotor test, has a sensitivity of 0.75 to 1.0 and a specificity of 0.91 to 1.0 (LR+ 8.3 to “rule in” and LR- 0 to 0.27). A 3.5-point decrease compared with baseline on the full SCAT2 multimodal test is 0.96 sensitive and 0.81 specific (LR+ 5 and LR- 0.05) (SOR: B, systematic reviews of low-quality cohort studies).
- K-D Test research has established that the test has a high sensitivity and specificity, which supports its use as an effective sideline concussion test.