Predicting early versus late recovery from sport-related concussion using decision tree analysis

Objective: Accurately predicting early (≤ 14 days) versus typical (15-27 days) or delayed (≥ 28 days) recovery from sport-related concussion (SRC) may allow for improved resource utilization and precision in planning and carrying out rehabilitation. In this study, the authors sought to develop an algorithm that enables accurate differentiation of recovery periods and duration after SRC. The authors hypothesized that data regarding initial symptom burden as quantified by a Post-Concussion Symptom Scale (PCSS) score, time to presentation, and number of prior concussions would be the most useful for analyzing predictive factors for concussion recovery duration.

Methods: A retrospective case-control study was conducted to assess the primary outcome of days to clinical recovery following SRC in pediatric patients. Data from patients 12-18 years old presenting within 28 days of injury to an SRC clinic between November 11, 2017, and October 10, 2020, were analyzed. Patients with positive evidence of injury on head imaging or incomplete records were excluded. The primary outcome was duration of clinical recovery, grouped as early (≤ 14 days), typical (15-27 days), or delayed (≥ 28 days). Recovery was defined as follows: 1) symptom resolution or return to baseline, or 2) initiation of graduated return to play. CHAID (chi-square automatic interaction detection) analysis was used to optimize a decision tree based on 16 input factors, including age, sex, initial PCSS score, time to clinic presentation, number of prior concussions, and presence of defined symptom clusters. The cohort was randomized into training (70%) and test (30%) samples for algorithm validation.

Results: A total of 493 patients met the inclusion criteria (mean age 15.7 ± 1.5 years, 68.2% male, 70.0% White). The median time to presentation was 5 days (IQR 2-10 days). Most patients (52.3%) recovered within 14 days of injury, 21.5% recovered within 15-27 days, and 26.2% had a recovery period of 28 days or longer. The variables most predictive of recovery were initial PCSS score (cutoffs ≤ 6, 7-28, or ≥ 29), time to presentation (≤ 7 vs > 7 days), or prior concussions (0 vs ≥ 1). The model accurately discriminated between early versus typical or delayed recovery duration groupings (area under the curve 0.80, Youden index 0.44), and correctly classified > 90% of patients who recovered early.

Conclusions: This novel three-factor predictive tool enabled accurate discrimination of early versus typical or delayed SRC recovery to better allocate resources, counsel patients, and make timely referrals.