Establishing Baseline Normative Values for the Child Sport Concussion Assessment Tool

Abstract

Importance

The Child Sport Concussion Assessment Tool (SCAT3) is a postconcussion sideline assessment tool measuring symptoms, cognition, and balance in preadolescent children. Minimal normative baseline data exist to aid decision making in clinical and athletic settings.

Objective

To collect normative baseline data for the Child SCAT3 in a large cohort of young athletes.

Design, Setting, and Participants

A cross-sectional study was conducted from May 31 to August 12, 2014, at various sporting events (basketball, soccer, baseball, and swimming) in Central Wisconsin among children 5 to 13 years of age who were English-speaking and did not report a lower leg injury within the past 2 months or a concussion within the past month. Data were analyzed between October 8, 2014, and September 12, 2016.

Main Outcomes and Measures

All Child SCAT3 components were assessed: child and parent report of symptom number and severity, cognition (Standardized Assessment of Concussion–child version [SAC-C]), and balance (modified Balance Error Scoring System [mBESS] and tandem gait). Summary statistics, mean differences, and effect sizes were calculated for each test component.

Results

Participants included 478 children (234 girls and 241 boys; mean [SD] age, 9.9 [1.9] years]) and their parents. Age had the largest effect on all Child SCAT3 components, with children 5 to 7 years of age reporting higher mean (SD) symptom severity scores compared with those 11 to 13 years of age (18.2 [10.0] vs 11.3 [9.0]; mean difference, 6.86 [95% CI, 4.22-9.50]; effect size, 0.74) and performing more poorly on the total SAC-C (mean [SD] score, 19.5 [5.1] vs 26.1 [2.1]; mean difference, –6.59 [95% CI, –7.49 to –5.68]; effect size, –2.1), mBESS (mean [SD] score, 1.67 [1.8] vs 0.76 [1.2]; mean difference, 0.91 [95% CI, 0.53-1.29]; effect size, 0.68), and tandem gait (mean [SD] time, 22.2 [8.3] vs 14.0 [3.7] seconds; mean difference, 8.23 seconds [95% CI, 6.63-9.82]; effect size, 1.55). Sex had a small effect on the mean (SD) number and severity of symptoms reported by the child (severity: boys, 15.1 [9.8] vs girls, 11.8 [9.2]; mean difference, 3.31 [95% CI, 1.60-5.02]; effect size, 0.35), mean (SD) number and severity of symptoms reported by the parent (severity: boys, 11.1 [7.7] vs girls, 9.4 [8.1]; mean difference, 1.63 [95% CI, 0.21-3.05]; effect size, 0.21), mean (SD) total SAC-C score (boys, 23.9 [3.9] vs girls, 24.9 [3.5]; mean difference, –0.92 [95% CI, –1.61 to –0.23]; effect size, –0.25), and mean (SD) mBESS score (boys, 1.21 [1.5] vs girls, 0.71 [1.0]; mean difference, 0.50 [95% CI, 0.27-0.74]; effect size, 0.38).

Conclusions and Relevance

Child SCAT3 baseline normative symptom, cognitive, and balance scores were different, with a large main effect for age and a small effect for sex. These findings may assist health care professionals with interpretation of Child SCAT3 scores for young athletes with a concussion in athletic and clinical settings.

This cross-sectional study collects normative baseline data for the Child Sport Concussion Assessment Tool in a large cohort of young athletes.

Key Points

Question

What is the age- and sex-specific baseline performance of youth athletes on the Child Sport Concussion Assessment Tool?

Findings

In this cross-sectional study of 478 children aged 5 to 13 years, age had a large effect on all Child Sport Concussion Assessment Tool components, with younger children reporting higher symptom scores and performing more poorly on cognitive and balance tests. Sex had a small effect on the number and severity of symptoms reported by the child and the parent as well as cognitive and balance performance.

Meaning

Use of age- and sex-specific norms is important for clinical decision making in the care of young athletes with a concussion.

Introduction

Approximately 38 million US youth are involved annually in athletics, which provide significant physical and psychological benefits. However, from 2001 to 2009, an estimated 173 285 sports and recreation–related nonfatal traumatic brain injuries in individuals 19 years of age or younger were treated in emergency departments. Approximately two-thirds of these head injuries were in children 14 years of age or younger. More than 85% of head injuries among patients presenting to the emergency department are mild. Many studies have investigated sports-related concussion in college and high school athletes. Limited research has been conducted in the preadolescent population (aged 5-12 years).

A major challenge in the management of concussion from sports is lack of a criterion standard for injury assessment and diagnosis. Concussion from sports remains a clinical diagnosis based on symptoms, physical signs, and impairment in function. Medical professionals agree that athletes should be evaluated using valid, reliable, age-appropriate tools that include a clinical impression from a trained medical professional and a multimodal systematic assessment of symptoms, balance, and cognitive function. Many instruments have been developed at International Concussion in Sport consensus meetings, each superseding previous versions. At the 2012 Zurich meeting, the Sport Concussion Assessment Tool (SCAT3) was designed for athletes 13 years of age or older, and the Child SCAT3 was designed for young athletes 5 to 12 years of age.

There is evidence that age affects recovery from concussion, with younger children differing from older adolescents and young adults in recovery time and results of cognitive testing. Development and interpretation of child-specific concussion assessment tools require knowledge of age-specific baseline performance to compare with results after injury. Baseline SCAT2 values in adolescent athletes differ by sex, grade, and previous concussion history, with significant variability within balance and concentration scores. A prospective study comparing children who had sustained a head injury when they were 7 years of age or younger vs those who were older than 7 years found that younger children performed more poorly on cognitive testing. Despite its availability for clinical use since March 2013, minimal Child SCAT3 normative data currently exist to guide interpretation of this tool specific to younger preadolescent athletes. In addition, there are few data on the reliability, responsiveness, and content validity of the Child SCAT3, such as developmental appropriateness of questions and cognitive and balance tasks for younger age groups. Our primary objectives were to obtain baseline normative Child SCAT3 scores in a large cohort of young athletes and to examine differences based on sex, age, and other conditions of clinical interest.

Methods

Participants

This study enrolled 478 male and female athletes 5 to 13 years of age who were participating in competitive organized sport clubs or leagues in Central Wisconsin from May 31 to August 12, 2014. Data were analyzed between October 8, 2014, and September 12, 2016. Athletes were included if they spoke English and had not been treated for a lower leg injury within the past 2 months or a sport-related concussion within the past month. Although the Child SCAT3 is designed for use in children 5 to 12 years of age, those who were 13 years of age were also included, as this is an age at which most children are still in middle school. Those providing care for middle school students are unlikely to use the Child SCAT3 for a 12-year-old child and the SCAT3 for a 13-year-old child on the same team, especially if it is performed for sideline assessment of an injury. This study was approved by the University of Wisconsin–Madison Institutional Review Board. All eligible children and their parents provided written informed assent or consent before testing.

Instrument

The Child SCAT3 is a brief, standardized concussion tool that assesses preadolescents (5-12 years of age) and is designed for use by medical professionals. The background section asks parents to complete a brief medical history, including how many previous concussions the child has experienced and whether their child has “ever been diagnosed” with other specific conditions. The tool contains multiple components assessing number (0-20) and severity (score, 0-60; higher score indicates higher burden) of symptoms as assessed by the child and by the parent, the Standardized Assessment of Concussion–child version (SAC-C [score, 0-30; higher score indicates better performance]), and balance. Cognitive assessment with the SAC-C is composed of orientation (score, 0-4; higher score indicates better performance), immediate memory (score, 0-15; higher score indicates better performance), concentration (digits backward and days in reverse order; total concentration score, 0-6; higher score indicates better performance), and delayed recall (score, 0-5; higher score indicates better performance). Balance is assessed with 1 or both of 2 tests: the modified Balance Error Scoring System (mBESS [score, 0-20; higher score indicates poorer performance and more balance errors]), performed on a hard surface in double leg and tandem stance, and tandem gait (measured in seconds) walking heel-to-toe down and back along a 3-m line. Although the use of a foam surface for mBESS testing is optional, it was included to evaluate differences in balance performance on a stable vs an unstable surface. We also elected to perform both the mBESS and tandem gait to provide baseline data for all possible test components. The Child SCAT3 also contains the Glasgow Coma Scale score, the Maddocks score with questions intended for a sideline diagnosis of concussion only and not serial testing, and the finger-to-nose coordination test.

Testing Procedures

All assessments were administered by study investigators or trained research assistants (M.A.B., B.M., and T.A.M.). All research assistants attended a training session on Child SCAT3 administration and study protocol. Testing was completed in a single session in a gymnasium, athletic training room, or tent at each sporting event. Both the parent and the child completed their respective portions of the Child SCAT3 simultaneously. Parents and older children (8-13 years of age) were given the symptom checklist to rate themselves after receiving standardized instructions. Young children (5-7 years of age) completed the checklist by interview with a study team member. Because testing was completed during the summer, the Maddocks question specific to the last lesson or last class was not relevant and was edited to last practice. All other Child SCAT3 components were assessed and measured by a single researcher with the verbatim instructions and order contained in the published Child SCAT3 tool.

Statistical Analysis

All analyses were completed using R for statistical computing, version 3.0 or later. The mean, SD, 95% CI, median, and interquartile range were calculated for each Child SCAT3 component: child and parent report of symptoms, orientation, immediate recall, concentration, delayed recall, balance, Maddocks score, coordination, and balance. The mean difference, 95% CI, and effect size (Cohen d) were calculated for each Child SCAT3 component score. Separate 2-sided, independent samples t tests or χ² tests, with sex, history of self-reported past concussion(s), history of headaches (HA) or migraines, learning disability (LD) or attention-deficit/hyperactivity disorder (ADHD), and history of anxiety or depression as the independent variables, were conducted to assess for differences in each of the mean Child SCAT3 component scores. Those with LD or ADHD were not excluded from the larger sample but rather were examined for differences. Analysis of variance tests or χ² tests for differences in each Child SCAT3 component score based on age group (5-7, 8-10, or 11-13 years of age) were conducted, and post hoc pairwise tests and Holm P value adjustments for multiple comparisons were made for all significant tests. P < .05 was considered significant.

Results

There were 478 athletes (234 girls and 241 boys; mean [SD] age, 9.9 [1.9] years]) tested at a swim meet (302 [63.2%]) or a baseball (59 [12.3%]), soccer (58 [12.1%]), or basketball (59 [12.3%]) tournament. Based on cognitive and developmental differences most commonly attributed to the work of Piaget and closely aligned with development of the Postconcussion Symptom Inventory, athletes were grouped into the following 3 age categories: 5 to 7 years of age (64 [13.4%]; 37 boys), 8 to 10 years of age (222 [46.5%]; 115 boys), and 11 to 13 years of age (191 [40.0%]; 91 boys); 1 athlete did not provide an age. Only 29 athletes (6.1%; 17 boys) reported a history of concussion. History of HA or migraines was reported by 27 athletes (5.7%; 16 boys), and history of LD or ADHD was reported by 29 athletes (6.1%; 15 boys). Because a history of anxiety or depression was reported by only 12 athletes (2.5%), no additional analyses were performed.

All participants had a Glasgow Coma Scale score of 15, and most children successfully completed the coordination test, although 11 children 5 to 7 years of age (17.5%), 22 children 8 to 10 years of age (10.0%), and 8 children 11 to 13 years of age (4.3%) received a score of 0. The percentage of perfect Maddocks scores was 75.9% for girls (n = 167) and 71.0% for boys (n = 162). However, this percentage differed significantly by age group (5-7 years, 25 [43.1%]; 8-10 years, 151 [70.9%]; and 11-13 years, 155 [87.1%]; P < .001). Younger children struggled to understand and appropriately respond to the question, “Is it before or after lunch?” with incorrect answers from 19 children 5 to 7 years of age (32.8%), 28 children 8 to 10 years of age (13.2%), and 9 children 11 to 13 years of age (5.1%). After confirming the child’s response with the parent, 25 children 5 to 7 years of age (43.1%) responded incorrectly to the question, “When was your last practice?” compared with only 23 children 8 to 10 years of age (10.8%) and 12 children 11 to 13 years of age (6.7%).

Symptom Number and Severity

Although the mean (SD) number of symptoms reported by the child (9.9 [5.1] vs 8.4 [5.3]) and by the parent (8.3 [5.5] vs 7.5 [6.0]) was higher in boys than in girls, as was the mean (SD) severity score of symptoms reported by the child (15.1 [9.8] vs 11.8 [9.2]) and by the parent (11.1 [7.7] vs 9.4 [8.1]) (Table 1), the effect of sex was small. Age had a moderate effect on child-reported symptoms, with those in the youngest age group reporting more severe symptoms than those in older age groups. This finding was true for boys and girls (mean [SD] score: boys aged 5-7 years, 19.5 [9.2]; boys aged 8-10 years, 15.6 [9.5]; boys aged 11-13 years, 12.6 [9.8]; girls aged 5-7 years, 16.5 [11.0]; girls aged 8-10 years, 12.1 [9.3]; and girls aged 11-13 years, 10.2 [8.1]). There was no effect of age on parent-reported symptoms. The mean (SD) number of symptoms was higher in those with a history of concussion when reported by both the child (10.5 [5.1] vs 9.1 [5.3]) and the parent (9.1 [4.8] vs 7.8 [5.8]), but this effect was small (Table 2). The mean (SD) number of symptoms was notably higher in those with LD or ADHD when reported by both the child (11.8 [4.9] vs 9.0 [5.3]) and the parent (12.0 [3.9] vs 7.6 [5.7]), ranging from a moderate to a very large effect (Table 2). Mean (SD) number of symptoms did not differ by history of HA or migraines when reported by the child (10.0 [5.0] vs 9.1 [5.3]), but there was a moderate effect on parent report (10.2 [5.3] vs 7.8 [5.8]); there was also a moderate effect of history of HA or migraines on mean (SD) parent-reported severity of symptoms (14.5 [8.0] vs 10.0 [7.9]).

Table 1. Reported Symptoms, Cognitive Scores, and Balance Scores^a.

Test Domain	Mean (SD)		Mean Difference (95% CI)	Effect Size	Mean (SD) by Age Group, y			Mean Difference (95% CI) [Effect Size]
	Boys (n = 241)	Girls (n = 234)			5-7 (n = 64)	8-10 (n = 222)	11-13 (n = 191)	5-7 y vs 8-10 y	5-7 y vs 11-13 y	8-10 y vs 11-13 y
Reported Symptoms
Child
Symptoms, No. (range, 0-20)	9.9 (5.1)	8.4 (5.3)	1.57 (0.63 to 2.51)	0.3	10.2 (4.5)	9.6 (5.2)	8.3 (5.4)	0.55 (−0.86 to 1.97) [0.11]	1.85 (0.37 to 3.32) [0.35]	1.29 (0.26 to 2.32) [0.24]
Symptom severity score (range, 0-60)	15.1 (9.8)	11.8 (9.2)	3.31 (1.60 to 5.02)	0.35	18.2 (10.0)	14.0 (9.5)	11.3 (9.0)	4.25 (1.56 to 6.93) [0.44]	6.86 (4.22 to 9.50) [0.74]	2.61 (0.81 to 4.42) [0.28]
Parentb
Symptoms, No. (range, 0-20)	8.3 (5.5)	7.5 (6.0)	0.82 (−0.21 to 1.85)	0.14	8.0 (6.2)	8.2 (5.6)	9.8 (7.9)	−0.21 (−1.82 to 1.40) [−0.04]	0.51 (−1.14 to 2.16) [0.09]	0.72 (−0.38 to 1.82) [0.13]
Symptom severity score (range, 0-60)	11.1 (7.7)	9.4 (8.1)	1.63 (0.21 to 3.05)	0.21	10.4 (7.9)	10.6 (7.9)	9.8 (7.9)	−0.25 (−2.45 to 1.95) [−0.03]	0.59 (−1.66 to 2.83) [0.07]	0.83 (−0.70 to 2.37) [0.11]
Standardized Assessment of Concussion–Child Versionc
Cognitive component
Orientation (range, 0-4)	3.2 (1.0)	3.4 (1.0)	−0.15 (−0.33 to 0.03)	−0.15	2.2 (1.5)	3.3 (0.9)	3.6 (0.6)	−1.03 (−1.32 to −0.74) [−1.0]	−1.40 (−1.65 to −1.14) [−1.56]	−0.36 (−0.51 to −0.21) [−0.48]
Immediate memory (range, 0-15)	13.2 (2.0)	13.7 (1.7)	−0.53 (−0.87 to −0.20)	−0.29	11.6 (2.8)	13.4 (1.7)	14.1 (1.1)	−1.88 (−2.44 to −1.33) [−0.95]	−2.58 (−3.06 to −2.10) [−1.53]	−0.69 (−0.98 to −0.41) [−0.47]
Concentration (range, 0-6)	3.8 (1.3)	4.1 (1.3)	−0.32 (−0.55 to −0.09)	−0.25	2.7 (1.2)	3.9 (1.2)	4.5 (1.1)	−1.26 (−1.59 to −0.93) [−1.06]	−1.81 (−2.13 to −1.48) [−1.60]	−0.55 (−0.77 to −0.32) [−0.47]
Delayed recall (range, 0-5)	3.7 (1.3)	3.6 (1.3)	0.11 (−0.12 to 0.34)	0.08	3.0 (1.7)	3.6 (1.3)	3.8 (1.1)	−0.55 (−0.93 to −0.16) [−0.4]	−0.80 (−1.16 to −0.44) [−0.63]	−0.25 (−0.48 to −0.02) [−0.21]
Total score (range, 0-30)	23.9 (3.9)	24.9 (3.5)	−0.92 (−1.61 to −0.23)	−0.25	19.5 (5.1)	24.3 (3.1)	26.1 (2.1)	−4.73 (−5.77 to −3.69) [−1.29]	−6.59 (−7.49 to −5.68) [−2.1]	−1.86 (−2.39 to −1.32) [−0.68]
mBESS and Tandem Gait Balance Scoresd
mBESS component performed on a hard surface
Total score (range, 0-20)	1.21 (1.5)	0.71 (1.0)	0.50 (0.27 to 0.74)	0.38	1.67 (1.8)	0.94 (1.3)	0.76 (1.2)	0.73 (0.34 to 1.11) [0.52]	0.91 (0.53 to 1.29) [0.68]	0.18 (−0.05 to 0.42) [0.15]
Double leg score	0.03 (0.19)	0.03 (0.18)	0.00 (−0.03 to 0.04)	0.02	0.05 (0.21)	0.04 (0.23)	0.01 (0.10)	0.01 (−0.05 to 0.08) [0.05]	0.04 (0.00 to 0.08) [0.27]	0.03 (−0.01 to 0.06) [0.14]
Tandem stance score	1.18 (1.51)	0.68 (0.97)	0.50 (0.27 to 0.73)	0.39	1.62 (1.7)	0.90 (1.2)	0.75 (1.2)	0.71 (0.34 to 1.09) [0.53]	0.87 (0.49 to 1.25) [0.66]	0.16 (−0.07 to 0.39) [0.13]
mBESS component performed on foam surfacee
Total score (range, 0-20)	3.5 (2.5)	3.1 (2.3)	0.46 (0.03 to 0.89)	0.19	4.2 (3.2)	3.2 (2.3)	3.2 (2.1)	1.08 (0.37 to 1.80) [0.43]	1.04 (0.34 to 1.73) [0.43]	−0.05 (−0.48 to 0.39) [−0.02]
Double leg score	0.17 (0.6)	0.20 (0.61)	−0.03 (−0.14 to 0.08)	−0.05	0.30 (0.71)	0.21 (0.67)	0.13 (0.47)	0.09 (−0.10 to 0.28) [0.14]	0.18 (0.02 to 0.33) [0.33]	0.08 (−0.03 to 0.20) [0.14]
Tandem stance score	3.4 (2.4)	2.9 (2.1)	0.49 (0.09 to 0.89)	0.22	3.9 (3.0)	2.9 (2.2)	3.1 (2.0)	0.99 (0.33 to 1.65) [0.42]	0.86 (0.22 to 1.51) [0.38]	−0.13 (−0.53 to 0.28) [−0.06]
Tandem gait time, s	16.4 (6.0)	16.3 (5.9)	0.08 (−1.05 to 1.20)	0.01	22.2 (8.3)	16.7 (5.4)	14.0 (3.7)	5.52 (3.72 to 7.32) [0.9]	8.23 (6.63 to 9.82) [1.55]	2.71 (1.74 to 3.67) [0.58]

Abbreviation: mBESS, modified Balance Error Scoring System.

^aScores are explained in the Instruments subsection of the Methods section.

^bOf these, 242 were parents of boys; 1 boy did not complete the symptom report, with 241 boys responding.

^cData were missing for 1 child in the 11- to 13-year age group.

^dData were missing for 1 girl and for 1 child each in all 3 age groups.

^eFoam surface was included as an optional mBESS test component in the Child Sport Concussion Assessment Tool 3.

Table 2. All Child Sport Concussion Assessment Tool 3 Components^a.

Test Domain	ADHD or LD				Migraine or Headache				Previous Concussion
	Mean (SD)		Mean Difference (95% CI)	Effect Size	Mean (SD)		Mean Difference (95% CI)	Effect Size	Mean (SD)		Mean Difference (95% CI)	Effect Size
	Yes (n = 29)	No (n = 448)			Yes (n = 27)	No (n = 450)			Yes (n = 29)	No (n = 448)
Child
Symptoms, No. (range, 0-20)	11.8 (4.9)	9.0 (5.3)	2.83 (0.87 to 4.79)	0.54	10.0 (5.0)	9.1 (5.3)	0.88 (−1.16 to 2.92)	0.17	10.5 (5.1)	9.1 (5.3)	1.4 (−0.57 to 3.37)	0.27
Symptom severity score (range, 0-60)	21.5 (12.2)	13.0 (9.2)	8.51 (4.96 to 12.05)	0.9	15.0 (8.8)	13.4 (9.7)	1.55 (−2.19 to 5.30)	0.16	15.3 (9.2)	13.4 (9.7)	1.97 (−0.66 to 5.59)	0.2
Parent
Symptoms, No. (range, 0-20)	12.0 (3.9)	7.6 (5.7)	4.37 (2.25 to 6.49)	0.9	10.2 (5.3)	7.8 (5.8)	2.43 (0.20 to 4.65)	0.42	9.1 (4.8)	7.8 (5.8)	1.32 (−0.87 to 3.52)	0.23
Symptom severity score (range, 0-60)	20.4 (8.9)	9.6 (7.4)	10.87 (8.06 to 13.68)	1.45	14.5 (8.0)	10.0 (7.9)	4.5 (1.44 to 7.55)	0.57	12.6 (6.8)	10.1 (8.0)	2.55 (−0.47 to 5.57)	0.32
SAC-C score (range, 0-30)	23.1 (5.1)	24.5 (3.7)	−1.35 (−2.84 to 0.13)	−0.36	25.5 (2.2)	24.3 (3.8)	1.16 (−0.31 to 2.62)	0.31	24.9 (3.0)	24.4 (3.8)	0.5 (−0.92 to 1.92)	0.13
Orientation (range, 0-4)	3.0 (1.2)	3.3 (1.0)	−0.3 (−0.70 to 0.09)	−0.31	3.6 (0.6)	3.3 (1.0)	0.32 (−0.06 to 0.71)	0.33	3.6 (0.63)	3.3 (1.01)	0.28 (−0.09 to 0.65)	0.28
Immediate memory (range, 0-15)	13.3 (2.1)	13.5 (1.9)	−0.15 (−0.87 to 0.56)	−0.08	13.9 (1.1)	13.4 (1.9)	0.41 (−0.32 to 1.14)	0.22	13.3 (1.9)	13.5 (1.9)	−0.2 (−0.90 to 0.50)	−0.11
Concentration (range, 0-6)	3.5 (1.6)	4.0 (1.3)	−0.48 (−0.97 to 0.02)	−0.37	4.1 (1.2)	4.0 (1.3)	0.1 (−0.41 to 0.60)	0.07	4.2 (1.2)	4.0 (1.3)	0.24 (−0.25 to 0.73)	0.18
Delayed recall (range, 0-5)	3.2 (1.6)	3.6 (1.3)	−0.39 (−0.88 to 0.10)	−0.31	4.0 (0.9)	3.6 (1.3)	0.36 (−0.13 to 0.86)	0.28	3.8 (1.1)	3.6 (1.3)	0.22 (−0.26 to 0.70)	0.17
mBESS (range, 0-20)b	1.0 (1.3)	1.0 (1.3)	0 (−0.51 to 0.51)	0	0.8 (1.1)	1.0 (1.3)	−0.16 (−0.68 to 0.36)	−0.12	1.21 (1.5)	0.95 (1.3)	0.26 (−0.24 to 0.76)	0.19
Double leg	0.0 (0.2)	0.0 (0.2)	0.01 (−0.06 to 0.08)	0.05	0.0 (0.0)	0.0 (0.2)	−0.03 (−0.10 to 0.04)	−0.15	0.00 (0.00)	0.03 (0.19)	−0.03 (−0.10 to 0.04)	−0.16
Tandem stance	0.9 (1.2)	0.9 (1.3)	0.01 (−0.48 to 0.51)	0.01	0.8 (1.1)	0.9 (1.3)	−0.13 (−0.63 to 0.37)	−0.1	1.21 (1.5)	0.92 (1.3)	0.29 (−0.20 to 0.77)	0.22
Tandem gait time, s	17.1 (6.9)	16.3 (5.9)	0.79 (−1.60 to 3.19)	0.13	17.6 (6.5)	16.3 (5.9)	1.32 (−1.12 to 3.76)	0.22	16.3 (4.9)	16.4 (6.0)	−0.05 (−2.40 to 2.30)	−0.01

Abbreviations: ADHD, attention-deficit/hyperactivity disorder; LD, learning disability; mBESS, modified Balance Error Scoring System; SAC-C, Standardized Assessment of Concussion–child version.

^aScores are explained in the Instruments subsection of the Methods section.

^bPerformed on a hard surface.

Children most commonly reported the following: “I get distracted easily” (356 [74.8%]), “I have trouble paying attention” (345 [72.5%]), “I forget things” (325 [68.3%]), “I get confused” (308 [64.7%]), and “I have headaches” (287 [60.3%]). Boys more commonly reported, “I have a hard time concentrating.” Boys and older children (11-13 years of age) more commonly reported, “I have problems remembering what people tell me.” Parents most commonly reported the following about their child: “is easily distracted” (347 [72.7%]), “has trouble sustaining attention” (309 [64.8%]), “has difficulty concentrating” (303 [63.5%]), and “has problems remembering what he/she is told” (300 [62.9%]). Parents of boys more commonly reported their child “has difficulty following directions” and “tends to daydream.” Parents of older children (11-13 years of age) more commonly reported their child “is forgetful.”

Cognitive Scores

Boys had lower cognitive scores except for delayed recall, but this effect of sex was small. In contrast, age had a moderate to very large effect on all SAC-C scores, with the younger age groups performing more poorly on all tasks (Table 1). More than one-third of all children did not know the date, with the largest proportion in those 5 to 7 years of age (45 [70.3%]) vs 84 (38.9%) in those 8 to 10 years of age and 43 (22.8%) in those 11 to 13 years of age. In addition, the younger the age, the more likely the child was to not know the month (27 [42.2%] in those 5-7 years vs 40 [18.5%] in those 8-10 years vs 13 [6.9%] in those 11-13 years) or day of the week (21 [32.8%] in those 5-7 years vs 25 [11.6%] in those 8-10 years vs 11 [5.8%] in those 11-13 years). Age had a much larger effect than did sex on concentration score for digits backward, with the younger age groups scoring lower than the oldest age group (mean [SD] score: 5-7 years, 2.1 [0.9]; 8-10 years, 3.0 [1.1]; and 11-13 years, 3.5 [1.1]) (Table 3). None of the children 5 to 7 years of age could repeat 6 digits backward, and only 2 of 63 (3.2%) could repeat 5 digits backward. Overall, 418 children (88%) could correctly say days of the week in reverse. Of the 56 who could not, 28 (50.0%) were 5 to 7 years of age. History of previous concussion did not have an effect on SAC-C performance (Table 2). Presence of LD or ADHD and HA or migraines had a small effect on SAC-C scores: children with LD or ADHD scored lower (mean [SD], 23.1 [5.1]), and those with HA or migraines scored higher (mean [SD], 25.5 [2.2]) (Table 2).

Table 3. Concentration: Digits Backward Test^a.

Characteristic	No. (%)					Mean Difference (95% CI)	Effect Size
	Boys (n = 241)	Girls (n = 233)	Age, y
			5-7 (n = 63)	8-10 (n = 221)	11-13 (n = 190)
Digits, No.
None	4 (1.7)	2 (0.9)	4 (6.3)	0	2 (1.1)	NA	NA
2b	13 (5.4)	13 (5.6)	7 (11.1)	18 (8.1)	1 (0.5)	NA	NA
3	63 (26.1)	53 (22.7)	32 (50.8)	55 (24.9)	29 (15.3)	NA	NA
4	94 (39.0)	68 (29.2)	18 (28.6)	78 (35.3)	66 (34.7)	NA	NA
5	42 (17.4)	55 (23.6)	2 (3.2)	44 (19.9)	51 (26.8)	NA	NA
6	25 (10.4)	42 (18.0)	0	26 (11.8)	41 (21.6)	NA	NA
Score (range, 0-5)
Mean (SD)	3.2 (1.2)	3.0 (1.1)	2.1 (0.9)	3.0 (1.1)	3.5 (1.1)	NA	NA
Sex	NA	NA	NA	NA	NA	0.27 (0.06 to 0.48)	0.23
Age, y
5-7 vs 8-10	NA	NA	NA	NA	NA	−0.91 (−1.21 to −0.61)	−0.85
5-7 vs 11-13	NA	NA	NA	NA	NA	−1.39 (−1.69 to −1.10)	−1.35
8-10 vs 11-13	NA	NA	NA	NA	NA	−0.48 (−0.70 to −0.27)	−0.44

Abbreviation: NA, not applicable.

^aA higher score indicates more correct digits backward.

^bThe Digits Backward section starts with 2 digits, not 1.

Balance Scores

Sex had a small effect on balance performance, with boys having more errors in tandem stance (Table 1). Age had a moderate effect on tandem stance and a large to very large effect on tandem gait, with the youngest age group having more balance errors and both younger age groups having a slower tandem gait time (Table 1). For both sex and age group, the unstable foam surface resulted in more balance errors, primarily in the more difficult tandem stance condition. History of previous concussion, LD or ADHD, or HA or migraines had no effect on balance performance (Table 2).

Discussion

In this large cohort of preadolescent athletes, age had the largest effect on all Child SCAT3 components, with younger children reporting higher symptom scores and performing more poorly on cognitive and balance tests. Sex had a small effect on all Child SCAT3 components. A recent study by Nelson et al assessed the psychometric properties of the Child SCAT3 in 155 children 5 to 13 years of age (100 boys; 25 aged 5-7 years) and focused only on soccer and football athletes. They similarly found that age had the largest effect on child symptom report, with younger children reporting more baseline symptoms than older children, and that this baseline score was well above zero. This finding is not surprising, as many symptoms reported by children and parents likely represent typical child behavior, such as being forgetful and easily distracted. Given good to excellent internal consistency and reliability of symptom report, obtaining individual baseline symptom scores for comparison with acute postinjury scores may be clinically useful. To our knowledge, there are no published, reliable change indices or guidelines for interpretation based on performance percentiles for the Child SCAT3. In 2016, Chin et al reported reliable change scores for high school and college athletes from baseline to 24 hours after injury assessment (2.89 [80% CI] to 4.42 [95% CI]). It is unknown if these change scores can be applied to younger age groups.

We found that boys had slightly higher symptom scores at all ages, and both younger boys and girls reported higher symptoms than did their older counterparts. In contrast, Nelson et al found an interactive effect between age and sex, with older girls reporting higher symptom severity than younger girls. Other studies in older adolescents using the SCAT2 or SCAT3 also found higher symptom burden among girls. Nelson et al found that parents rated symptoms higher for older children, but we did not find an age effect on the parent report. Although the mean (SD) symptom severity score (both child and parent) for the oldest age group was similar between the 2 studies, it was notably higher in our youngest children (5-7 years: child, 18.2 [10.2] vs 13.9 [8.7]; parent, 10.4 [7.9] vs 4.87 [6.01]). The study by Porter et al, which was limited to only young male hockey athletes 7 to 12 years of age, found a higher mean (SD) symptom severity score reported by the children (11.4 [8.4]) compared with the parents (9.8 [7.9]) overall but no significant differences in symptom number or severity by age (9-12 years of age [data from those 7 or 8 years of aged were excluded from analysis]). Differences in total sample size, number of girls to boys overall and by age group, sports included, or method of administration may account for these differences in the symptom report between studies.

Nelson et al also found that age had a large effect on all SAC-C components, with the youngest age group (5-7 years of age) scoring significantly more poorly than their older counterparts on every cognitive task. The athletes in our study scored lower than those in the study by Nelson et al (mean [SD], 19.5 [5.1] vs 23.0 [2.9]), which may reflect our larger number of children in this age group or poor test reliability, which was modest (r = 0.50) for total SAC-C score in children 9 to 13 years of age in the study by Nelson et al. Porter et al found that the youngest age group (9 years) scored lower on the total SAC-C than did the oldest age group (12 years). Nelson et al found an interactive sex effect for boys to score lower on the total SAC-C and the orientation component only if they performed more poorly on general intellectual functioning. We did not assess baseline intellectual function, and the lower SAC-C score for boys may not reflect a clinically meaningful difference. Chin et al reported reliable change scores for high school and college athletes from baseline (mean [SD] total SAC-C, 27.1 [1.9]) to 24 hours after injury assessment (1.66 [80% CI] to 2.54 [95% CI]). This finding may be useful for interpreting clinically meaningful change in older children (11-13 years of age) with similar mean (SD) scores (26.1 [2.1]). Although interpretation of clinically relevant change in younger age groups remains challenging, our data provide some reference point for clinicians to consider.

Digits backward was a difficult task for younger children, with two-thirds of those 5 to 7 years of age and one-third of those 8 to 10 years of age unable to repeat 4 digits or more. Glaviano et al found that 12-year-old children had fewer correct responses on the SCAT2 for repeating 5 and 6 digits compared with older children, with the percentage of correct 6-digit responses increasing with age. Nelson et al reported that 48% of those 5 to 7 years of age, 25% to 27% of those 8 to 11 years of age, and 13% of those 12 to 13 years of age did not know the date. We also found that younger children struggled to correctly answer orientation questions in addition to temporal questions such as, “Is it before or after lunch?” The question about the last class or lesson is not relevant in the summer, and younger elementary school students may not have discrete classes, such as mathematics or English. Middle-school students may have multiple teachers. Future Child SCAT versions need to include more age- and setting-appropriate questions to assess orientation and memory, particularly for children younger than 11 to 12 years of age. This difficulty with children understanding questions highlights the importance for future versions to continue inclusion of parent or caregiver assessment to provide medical history, report child symptoms and behavior, and confirm accurate responses to questions.

Consistent with Nelson et al, we found that the youngest age group performed more poorly on balance tasks, with the largest effect on tandem gait (slower times compared with children of older ages). Porter et al found no significant difference in mBESS performance by age. Although we found that boys had more tandem stance errors, the small difference in the number of errors by both age and sex may not be clinically helpful given the poor mBESS test-retest reliability (r = 0.02). Effect sizes for the mBESS performed on foam vs on a hard surface were similar and did not appear to provide additional benefit. Tandem gait times in our sample were 2 to 6 seconds slower than those reported by Nelson et al in comparable groups, which may reflect modest reliability (r = 0.46) or clinically important variability in testing instructions, timing, and environment.

Consistent with other studies, we found higher report of baseline symptoms by the child and parent for children with other conditions of clinical interest associated with prolonged recovery, including HA or migraines, LD or ADHD, and previous concussion. These conditions had a small effect on cognitive performance, with children with LD or ADHD having lower SAC-C scores and those with HA or migraine having higher scores. Although it is understandable that children with learning or attention difficulties would perform more poorly, there is no clear explanation for better performance in those with HA or migraine. It is important for future studies to oversample these groups to provide more robust normative data specific to each condition.

Limitations

This study has some limitations. It enrolled young athletes representing a broad range of sports, but only in 1 state, which may limit generalizability. Despite formal training and a controlled environment, small differences in testing methods and distractibility of athletes may have occurred. Athletes generally completed testing 15 to 30 minutes after physical activity, but the time of testing (before, during, or after competition) was not standardized. Fatigue at the time of testing could have affected performance. We did not perform intrarater or interrater reliability testing.

Conclusions

We report baseline normative Child SCAT3 scores in a large cohort of male and female young athletes 5 to 13 years of age that provide a reference point for health care professionals trying to interpret postinjury scores for young athletes with concussion in athletic and clinical settings. Application of age- and sex-specific norms to clinical decision making is important, and our findings suggest the need for revisions so that the tool is more developmentally appropriate, specifically for elementary school–age children. Young athletes may display substantial variability at baseline, and developmental and other comorbid factors play an important role in injury assessment. Differences between parent and child responses emphasize the need to integrate both sources of information into decision making.