A Preliminary Formula to Predict Timing of Symptom Resolution for Collegiate Athletes Diagnosed With Sport Concussion

ContextSymptom presentation and recovery after sport concussion (SC) are variable. Empirically based models documenting typical symptom duration would assist health care providers in managing return to play after SC.ObjectiveTo develop a prediction model for SC symptom duration.DesignCross-sectional study.SettingTwo National Collegiate Athletic Association Division I university laboratories.Intervention(s)Participants completed the Revised Head Injury Scale (HIS-r), Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT), and Sensory Organization Test within 24 hours of SC diagnosis.ResultsThe final formula consisted of the HIS-r''s self-reported neck pain, drowsiness, tingling, and nervousness duration and ImPACT total symptom severity (R = 0.62, R² = 39%, R²_adj = 34.2%, P < .001). Approximately 29% (R²_cv = 29%) of the variance associated with total days symptomatic after SC was explained by our preliminary formula when cross-validated. The current formula correctly identified 76% of participants who recovered within 10 days of injury.ConclusionsOur results suggest that self-reported duration of 4 symptoms during the initial 24 hours after injury along with total symptom severity as measured by ImPACT accounted for a considerable amount of variance associated with days symptomatic after SC in collegiate athletes. Until the formula is cross-validated in a college-aged sample, caution is warranted in using it clinically.Key Words: traumatic brain injuries, prediction, prolonged recovery, symptom severity, symptom duration

Key Points

• A formula to predict symptom resolution after sport concussion primarily consisting of initial symptom duration and severity correctly identified 76% of National Collegiate Athletic Association Division I collegiate athletes who recovered within 10 days.
• Before it can be used clinically, the formula must be cross-validated on larger samples.

The clinical presentation of and recovery from sport concussion (SC) are variable among athletes. Recovery curves based on animal models suggest the metabolic vulnerability associated with concussion resolves within approximately 7 to 10 days.^1,2 During this period of metabolic dysfunction, athletes experience neurocognitive and motor deficits as well as a constellation of symptoms.^3–5 These sequelae serve as markers that clinicians can measure to track recovery and make informed return-to-play and return-to-learn decisions.⁶The resolution of motor (eg, postural stability) and neurocognitive (eg, memory, reaction time, information-processing speed) deficits, along with self-reported symptoms (eg, headache, nausea, dizziness), varies based on a number of factors. These factors include age, sex, background history, comorbid conditions, and signs and symptoms reported or observed at the time of injury.^7–12 For example, in terms of age, only 50% of high school athletes (14–18 years of age) were reported to recover from SC in approximately 7 days, whereas 90% of adult athletes ≥18 years of age recovered in 7 days.^8,13–15 Regarding sex differences, Covassin et al¹⁶ observed that female high school athletes may take up to 14 days to recover in terms of memory and processing speed after concussion. In a separate study, Covassin et al¹² noted that concussed high school- and college-aged females consistently demonstrated higher symptom levels than male participants up to 14 days after concussion.Though the majority of concussion symptoms in older athletes resolve in ≤7 days of injury, approximately 10% of concussed athletes experience persistent symptoms up to 3 months after their diagnosis.¹⁷ Additionally, a subset of patients may experience 3 or more postconcussion symptoms for 3 months or longer, which is classified as postconcussion syndrome (PCS). Babcock et al¹⁸ found that 29% of pediatric concussion patients diagnosed in the emergency department for whom sport was the primary mechanism of injury (35%) were later diagnosed with PCS, which equates to 105 000 cases of pediatric PCS annually in the United States. The authors suggested that being able to prospectively identify candidates at risk for PCS would assist clinicians in discharge planning (eg, education, medications, and ongoing follow-up), ultimately resulting in improved patient outcomes.Studies examining predictors of SC recovery have usually addressed the dichotomy of typical recovery (7–13 days) versus protracted recovery.^3,12Protracted recovery has been defined as resolution of SC lasting longer than 14,¹⁰ 21,¹¹ 45, or 90 days.^17,19 Several predictors, including loss of consciousness (LOC), posttraumatic amnesia (PTA), retrograde amnesia, total symptom severity, dizziness severity, and headache severity, have been associated with a 1.8- to 6-fold increase in risk for protracted recovery.^11,17,18 Of these predictors, LOC and amnesia are points of debate because of their infrequent occurrence and questionable relationship with injury severity and recovery.^8,11,20The objective of our study was to determine if the number of days an athlete reported concussion-related symptoms could be predicted from dependent variables derived from clinical measures commonly used to manage this injury. The ability to determine how many days an athlete will report SC-related symptoms may assist clinicians by allowing identification of athletes at risk for prolonged recoveries and institution of the appropriate medical and psychosocial infrastructure to assist in a full recovery.