Date: March 3rd, 2022

Reference: Macnow et al. Effect of Screen Time on Recovery From Concussion: A Randomized Clinical Trial. JAMA Pediatrics 2021

Guest Skeptic: Dr. Catherine Varner is an Assistant Professor and Clinician Investigator in the Department of Family and Community Medicine at the University of Toronto. She is an emergency physician at Mount Sinai Hospital and a Clinician Scientist and the Deputy Director of the Schwartz-Reisman Emergency Medicine Institute. Dr. Varner’s research interests are in concussion and pregnancy care in the ED.

Case: An 18-year-old female presents to the emergency department (ED) after falling off a moving snowmobile and hitting her head on the ground. It was a witnessed fall; she was wearing a helmet at the time and there was no loss of consciousness. There were no other injuries reported and she is found to have a GCS score of 15 after the injury. The Acute Concussion Evaluation–Emergency Department (ACE-ED) Tool is used, and she scores a 2 for headache and feeling foggy. She knows about taking it easy physically for the next couple of days but wonders if she must stay off her computer as well?

Background: Concussions or mild traumatic brain injury (mTBI) are commonly diagnosed in the Emergency Department (ED). Most patients recover within the first week; however, 15-30% of patients develop persistent post-concussive symptoms.

An issue that often comes up with minor head injuries is do we need to get advanced imaging. A paper by Dr. Ian Stiell and his group gave us a tool to help us decide who to scan with the now infamous clinical decision instrument called the Canadian CT Head Rule [1]. This classic paper was published in Lancet 2001 and reviewed on SGEM#106.

Another issue that comes up is whether children need strict rest after a concussion. SGEM#112 reviewed a small study by Thomas et al published in Pediatrics 2015 asking if there was a benefit to recommending strict rest after a child has a concussion [2]. The bottom line from that episode was that in children with concussion, two days of rest followed by a gradual return to activity is preferred over five days of rest followed by a gradual return to activity. The longer strict rest period appears to cause more post-concussive symptoms.

Our episode together looked at the impact of light exercise in adults with mild concussions on the likelihood of developing persistent symptoms up to 30 days following their injury (SGEM#331). We found there was not a statistical difference between light activities like walking and 48 hours of rest with gradual return to activity as tolerated. Our conclusions were that early light exercise may be encouraged as tolerated at ED discharge following mTBI, but this guidance is not sufficient to prevent persistent concussion symptoms [3].

The Acute Concussion Evaluation–Emergency Department (ACE-ED) tool is an instrument used by ED clinicians to diagnose a concussion and identify risk factors for prolonged recovery. It is both helpful for diagnosis and future management of symptoms. When a patient is recovering from a concussion, whether you are using ACE or another symptom scoring tool like the Postconcussion Symptom Scale or the Rivermead Post-concussion Symptom Questionnaire, future health care providers caring for the concussion patient may refer to the quantitative assessment of the patient’s symptoms in the acute phase of the injury.

Clinical Question: Does screen time in the first 48 hours after concussion have an impact on the duration of concussive symptoms?

Reference: Macnow et al. Effect of Screen Time on Recovery From Concussion: A Randomized Clinical Trial. JAMA Pediatrics 2021

  • Population: Patients aged 12 to 25 years presenting to the emergency department within 24 hours of sustaining a concussion according to the Acute Concussion Evaluation–Emergency Department (ACE-ED) tool (Giola et al 2008)
    • Exclusions: Attending physician declined participation; their guardian was not present; the patient was younger than 18 years, or they (or their parent or guardian) were not fluent in English; intoxication; had a GCS score < 15; had intracranial abnormalities identified on imaging; had pre-existing intellectual disability, severe psychiatric illness, severe neurological conditions, or substantial previous neurological surgery; or required neurosurgical intervention, intubation, or hospital admission.
  • Intervention: Patients were asked to abstain from screen time for 48 hours after injury. This was the screen time abstinent group.
  • Comparison: Patients were permitted to engage in screen time in the first 48 hours after injury. This was the screen time permitted group.
  • Outcome:
    • Primary Outcome: Number of days until functional resolution of concussive symptoms, which was defined as the first day with a total score of three points or lower on the Post-Concussive Symptom Scale (PCSS)
    • Secondary Outcomes: Amount of screen and sleep time during the intervention period, the day of return to school or work after the intervention period, the day of return to exercise after the intervention period, and daily PCSS scores.
  • Trial: Single-centre, unblinded, randomized clinical trial

Authors’ Conclusions:The findings of this study indicated that avoiding screen time during acute concussion recovery may shorten the duration of symptoms. A multicenter study would help to further assess the effect of screen time exposure.”

Quality Checklist for Randomized Clinical Trials:

  1. The study population included or focused on those in the emergency department. Yes
  2. The patients were adequately randomized. Yes
  3. The randomization process was concealed. Yes
  4. The patients were analyzed in the groups to which they were randomized. Yes
  5. The study patients were recruited consecutively (i.e. no selection bias). No
  6. The patients in both groups were similar with respect to prognostic factors. Yes
  7. All participants (patients, clinicians, outcome assessors) were unaware of group allocation. No
  8. All groups were treated equally except for the intervention. Yes
  9. Follow-up was complete (i.e. at least 80% for both groups). No
  10. All patient-important outcomes were considered. Unsure
  11. The treatment effect was large enough and precise enough to be clinically significant. No
  12. Funding. The stated conflicts of interests by the authors would not likely influence the conclusions of this trial.

Results: They enrolled 125 patients into the study. The mean age was 17 years and 49% were female.

Key Results: Patients with concussions who abstained from screen time recovered quicker than those permitted screen time.

  • Primary Outcome: Median number of days until functional resolution of concussive symptoms, which was defined as the first day with a total score of 3 points or lower on the Post-Concussive Symptom Scale (PCSS)
    • Abstained 3.5 days vs permitted 8.0 days
    • Hazard ratio [HR], 0.51 (95% CI; 0.29-0.90)

  • Secondary Outcomes: 

    • Sensitivity analysis using different PCSS thresholds for recovery

1. Recruitment of Patients – This was a convenience sample when study staff was available. It is very difficult to enroll consecutive patients in the ED 24/7/365. However, we would have liked to know how many people were not approached, why and their characteristics. This would help us know if the patient population included is similar to those being seen at our own centres (tertiary, community or rural). Patients could also be excluded if the physician did not wish to participate. These factors could have introduced an element of selection bias.

2. Who Were These Patients – Let’s talk about generalizability? This study took place in a large volume, tertiary care level 1 trauma centre. They enrolled patients ages 12 to 25 years old, so a population in whom concussions are common. In that regard, this study can be generalized to many of the centres where we work and many of the patients whom we commonly see.

However, just like in nerdy point #1, I want to know more about the clinical characteristics of the included patients. What happened to them in the ED? Did they undergo head CT? Did they need analgesics or antiemetics? Were they at risk of prolonged symptoms based on their pre-injury risk factors such as having anxiety or depression? These are some aspects of generalizability that I can’t answer when I read this trial.

Our group completed a randomized trial in 241 patients with mild traumatic brain injury, published in Academic Emergency Medicine last year, and when we did a secondary analysis to identify risk factors associated with prolonged symptoms, we found, having a history of anxiety or depression increased the risk of persistent symptoms.

Consistently studies looking at predictors of persistent symptoms have identified pre-injury depression or anxiety as risk factors. It would have been helpful to know what proportion of participants in this trial previously identified pre-injury risk factors for prolonged symptoms.

3. Blinding – This is an important aspect of RCTs but not always possible. Patients knew what group they were assigned. Were they aware of the hypothesis and did they have pre-conceived notion of the impact of screen time on concussions? This is important because they self-reported their amount of screen. This reporting could have been biased in the intervention control group. It is unclear if this would have biased the results towards or away from the null hypothesis.

4, Primary Outcome – Ensuring the primary outcome and a priori sample size calculation reflect what has already been published in the preceding literature is, in my opinion, the most important aspect to designing a randomized trial. I found this undertaking a bit confusing. The primary outcome definition was the number of days until functional resolution of concussive symptoms was achieved, which meant a score of 3 or less on the PCSS. This made a few assumptions that were a bit unclear when I went back to the original papers:

  • Screen time avoidance would decrease the PCSS by 12 points.
  • This would result in 2 fewer days to symptom recovery.
  • A previously published study compared days to recovery defined by a PCSS threshold, which was not, as far as I can tell, less than 3.

With those assumptions, the a priori sample size calculation for the primary outcome was 106 patients (53 in each group). However, the authors later decided to do a survival curve analysis rather that simply compare median days to recovery. It does make me worry this study is underpowered to reject the null hypothesis.

5. Attrition – Enrolling patients in the ED is often a challenge. However, following them up after an ED discharge is even more challenging.

Kudos to this team for taking on an RCT in the ED! As someone who does research in this patient population, it did not surprise me at all that this study had a hard time with attrition. Ideally, attrition can be anticipated and included in the sample size calculation of the study. In fact, we almost always include about 20% loss to follow-up in the design of trials taking place in the ED. Another kudos to the authors for using creative follow-up methods for these patients, including text messaging.

Comment on Authors’ Conclusion Compared to SGEM Conclusion: We agree with the authors that abstaining from screen time in the acute period after concussion may or MAY NOT be associated with a shorter duration of symptoms, which supports clinical recommendations to limit screen time in the acute period after concussion.

SGEM Bottom Line: We do not know what impact screen times has on post-concussion symptoms.

Case Resolution: Patient is given standard discharge instructions for a concussion which does not include a recommendation about screen time.

Dr. Catherine Varner

Clinical Application: Based on the limitations we have discussed for this study and the paucity of research in this area, we cannot make screen time recommendations at this point.  

What Do I Tell My Patient?  You have a mild concussion. In the vast majority of patients, your symptoms should resolve with 7 days if not sooner. Light activity seems ok after a concussion. We do not have good information to tell you to stay off your computer, but in my practice I tell patients to limit screen time as much as possible, take breaks if you are unable to limit screen time, and if screentime is making symptoms worse, take a break.

Keener Kontest: There was not winner last week. The pocket umbrella was invented in Uraiújfalu by the Balogh brothers, whose patent request was granted in 1923.

Listen to the SGEM podcast for this weeks’ question.  If you know, then send an email to with “keener” in the subject line. The first correct answer will receive a cool prize.

Remember to be skeptical of anything you learn, even if you heard it on the Skeptics Guide to Emergency Medicine.


  1. Stiell IG, Wells GA, Vandemheen K, Clement C, Lesiuk H, Laupacis A, McKnight RD, Verbeek R, Brison R, Cass D, Eisenhauer ME, Greenberg G, Worthington J. The Canadian CT Head Rule for patients with minor head injury. Lancet. 2001
  2. Thomas DG, Apps JN, Hoffmann RG, McCrea M, Hammeke T. Benefits of strict rest after acute concussion: a randomized controlled trial. Pediatrics. 2015
  3. Varner CE, Thompson C, de Wit K, Borgundvaag B, Houston R, McLeod S. A randomized trial comparing prescribed light exercise to standard management for emergency department patients with acute mild traumatic brain injury. Acad Emerg Med. 2021