Concussions take time — CJSM Blog Post Journal Club

Our Jr. Assoc. Editor Jason Zaremski MD looking for some help from a friend with the newest CJSM Blog Post Journal Club

Our March 2020 issue has just published, and right out of the gate one of the studies that has received the most buzz is one from a team of researchers in New Zealand demonstrating that less than 50% of concussed individuals recover within two weeks of a sports-related concussion.

Jason Zaremski, MD, CJSM’s Jr. Assoc. Editor, explores this new study today in our most recent CJSM Blog post Journal Club.  It is a two year prospective study with some revealing findings. We’re sure you will enjoy the blog post and the study itself!


Jason Zaremski MD

Kara S, et al. Less Than Half of Patients Recover Within 2 Weeks of Injury After a Sports-Related Mild Traumatic Brain Injury: A 2-Year Prospective Study. Clin J Sport Med 2020;30:96–101.

Introduction:  Sports related concussion (SRC) is a common and significant concern, challenging not only sports medicine practitioners, but also athletes, coaches, family members, and all sports performance team members. While diagnostic skills and research in this area have dramatically improved in the past 10 years, our patients still have several questions, including: How long until I can go back and play? Some data has suggested the majority of SRC patients recover in approximately a 2-4 week recovery time frame. According to the consensus statement in concussion in sport (5th iteration) held in Berlin, Germany, in October 2016—“the expected duration of symptoms in children with SRC is up to 4 weeks.” (McCrory, et al. BJSM 2017).  Kara and colleagues  have looked into the validity of this stated time frame.

Purpose: To describe clinical recovery time and factors that could impact recovery after a sports-related mild traumatic brain injury (SR-mTBI, aka “concussion”).

Methods/Design:  This is a prospective cohort study with level IV evidence. A SR-mTBI is defined as a TBI based on consensus statements previously published. All participants were evaluated by a sports medicine doctor, exercise physiologist, and a physiotherapist with postgraduate vestibular therapy qualifications. Approval for study participation was obtained via the Accident Compensation Corporation New Zealand Ethics Committee. Informed consent and/or when appropriate assent was obtained from each participant.

Participants: 822 patients presenting within 14 days of a SR-mTBI/concussion over a 2-year period (January 2017-December 2018) to a community based Auckland, New Zealand Sports Medicine Concussion clinic. 594 participants were eligible for analysis (range 7-64 years, mean age 20.3 years, 77% males).  39% (n = 88) of the participants were deemed ineligible due to incomplete or missing information.  Age groups were delineated as: children (≤12 years, n=45), adolescents (13-18 years, n=290), and adults (≥19 years, n=259). Sport participation included: Rugby Union (54.2%), Rugby League (6.2%), Football/Soccer (11.6%), Field Hockey (2.4%), and Netball (1.7%), and other (23.9%).

Exclusion Criteria:

  • Patients presenting 14 days after injury
  • Patients with a non–SR-mTBI


The initial consultation involved an injury history, previous SR-mTBI history, and an assessment of any “concussion modifiers” (such as patient-reported pre-injury history of migraine or mental health issues). An age-appropriate SCAT5 assessment was then performed. Afterwards, a physical examination including full neurological, vestibular, and cervical-spine examination was completed. For any follow-up evaluations, a SCAT5 evaluation and a review of previous abnormal physical findings was performed.

Interventions/Management:  Interventions included the use of  standardized protocols consisting of relative rest for 24-48 hours followed by controlled cognitive and physical loading with a reassessment 14 days after injury. This included the initiation of an active rehabilitation program consisting of a sub-symptom threshold exercise (SSTE) program and/or cervico-vestibular rehabilitation (as needed) for participants who remained symptomatic. Participants were defined as “clinically recovered” or “still symptomatic” at each evaluation. Once a participant was clinically recovered, they begun a graduated return to a sport (GRTS) program with reevaluation before return to full competition. Those participants who were “still symptomatic” underwent graded aerobic exercise testing using the Buffalo Concussion Treadmill Test with subsequent development of a SSTE program.  Participants were assessed every 2 weeks until clinical recovery.

Definition of Clinical Recovery:

Clinical recovery definition = SCAT5 symptom score and symptom severity score were ≤5 for males and ≤6 for females based upon the normative data for this population (Alla S, Sullivan S, McCrory P. Defining asymptomatic status following sports concussion: fact or fallacy? BJSM. 2012). Participants were also required to have resolution of any previous abnormal clinical examination findings and “normal” exercise tolerance. Normal exercise tolerance was defined as being asymptomatic when exercising at 85% to 90% of predicted heart rate if measured or return to the participants’ usual preinjury exercise levels.

Data Acquisition:

Outcome Measures: Clinical recovery measured as number of days after injury.

Statistical Measures/Analysis:  Statistical analyses were conducted using Stata version 15.1. Participant analyses were performed based on age groupings. A Kruskal–Wallis test was used for continuous variables. A 2×2 test was used to assess potential differences in gender, sport type, and concussion modifier by the age group. Length of recovery (measured by time to clinical recovery) was summarized overall and within each age group. Multiple linear regression was used to determine mutually adjusted associations of participant characteristics with length of recovery, measured by the number of days to clinical recovery. A natural log transformation was used for the outcome due to a skewed distribution


  • The average number of days until the initial consultation was approximately 9 days after injury.
  • Rugby Union accounted for 54% of the all consultations.
  • The ≤12 years age group had a significantly lower proportion of females (P=0.008) than the older age groups.
  • There was also an association between age group and the number of previous concussions, with older participants having had more previous concussions (P<0.0001).
  • The number of days until clinical recovery was 43% longer for females, whereas those with modifiers had a 48% longer recovery time.
  • For a 7 day increase in time to the initial appointment there was an approximate 15% increase in the number of days until clinical recovery.
  • There was no significant difference in recovery time between age groups, length of recovery, and previous concussions.
  • Prolonged recovery was more common in females (P<0.001), participants with “concussion modifiers” (P<0.001), sports participated in other than Rugby Union, and with increased time between injury and the initial appointment (P<0.003).
  • 5% of participants did not achieve clinical recovery under this model of care.
  • 45% of participants recovered clinically within 14 days of injury, 77% by 4 weeks after injury, and 96% by 8 weeks after injury.
  • 5% of participants received cervical rehabilitation, 28% received vestibular rehabilitation, and 10% received cervico-vestibular rehabilitation.
  • Vestibular rehabilitation alone or in combination with cervical rehabilitation was more likely in adults (44% of patients) than younger age groups.


Large Study with multiple age groups using standardized, best practice model of care

  • Strict evaluation criteria
  • Prospective study
  • Large study group


  • Time points were every 2 weeks versus daily or even weekly assessments could improve accuracy of clinical recovery
  • There is a preponderance of male participants even though we know female football/soccer has nearly the same rate of SRC as American Football
  • Rugby (>60%) was the primary sport and “other” was nearly 24% but sports in this category were not listed. Thus, data results are only applicable only to this cohort of participants
  • There did not appear to be any analysis of individuals with prior SR-mTBI versus without
  • Lack of baseline neurocognitive data
  • Potential selection bias as patients could self-refer (as the authors noted)
  • The number of participants in the youngest age group is much lower than the other two age groups
  • While there is a “concussion modifier” datapoint included (which includes patient-reported preinjury history of migraine or mental health issues, there is no mention of prior concussions included in the data analysis. This would be very useful and be interesting to compare clinical recovery times in first time versus repeat SR-mTBI.

Conclusion: Participants in this study indicated that those with a SR-mTBI do not recover within 10 to 14 days as previously indicated in the literature. Additionally, age is a determinant of recovery rate. Active rehabilitation results in greater recovery rates after SR-mTBI. Furthermore, delay in presentation for evaluation leads to a delay in recovery.

Clinical Relevance: This information will be useful for health care providers as they educate patients, family members, and sports medicine team members as well as coaches on typical recover rates from SR-mTBI as well as setting recovery expectations for all individuals involved. Based on the data from this study, approximately 75% of SR-mTBI will be recovered in 4 weeks and nearly all, but not all, by 8 weeks.

About sportingjim
I work at Nationwide Children's Hospital in Columbus, Ohio USA, where I am a specialist in pediatric sports medicine. My academic appointment as an Associate Professor of Pediatrics is through Ohio State University. I am a public health advocate for kids' health and safety. I am also the Deputy Editor for the Clinical Journal of Sport Medicine.

Comments are closed.

%d bloggers like this: