Proposal of a Functional Impairment Symptom Scale for Concussion. (December 2020) - McCarthy, Matthew T.
Clinicians currently administer patient-reported symptom scales to quantify and track concussion symptoms. These scales are based on subjective ratings without reference to the degree of functional impairment caused by the symptoms. Our objective was to develop a concussion symptom scale based on functional impairment and compare it to a widely used concussion symptom checklist. We conducted a retrospective chart review evaluating 133 patients age 9-22 with an acute concussion who completed 2 symptom checklists at their initial visit—the Sport Concussion Assessment Tool (SCAT-3) symptom evaluation (22 symptoms, 0-6 scale) and the proposed Functional Impairment Scale (22 symptoms, 0-3 scale related to degree of functional impairment). Mean total symptom score was 27.2±22.9 for Sport Concussion Assessment Tool–3 and 14.7±11.9 for the Functional Impairment Scale. Pearson correlation between the scales was 0.98 ( P < .001). Mean time from concussion to first visit was 6.9±6.2 days, and median clearance time after injury was 19 (95% CI 16-21) days. After adjusting for patient and injury characteristics, an increased score on each scale was associated with longer time to clearance (5-point increase in Sport Concussion Assessment Tool–3 hazard ratio 0.885, 95% CI 0.835-0.938, P < .001; 2.5-point increase in Functional Impairment Scale hazard ratio 0.851, 95% CI 0.802-0.902, P < .001). We propose a concussion symptom scale based on functional impairment that correlates strongly with the Sport Concussion Assessment Tool–3 scale, demonstrates a similar association with time to clearance, and may provide a more intuitive approach to monitoring how symptoms are affecting patients recovering from concussion. Future research should aim to validate this scale through a prospective longitudinal study.