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Measurement of Symptoms Following Sports-Related Concussion:
Reliability and Normative Data for the Post-Concussion Scale
MEASUREMENT OF SYMPTOMSLOVELL ET AL.
Mark R. Lovell
University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA
Grant L. Iverson
University of British Columbia & Riverview Hospital, Vancouver, British Columbia, Canada
Michael W. Collins
University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA
Kenneth Podell
Henry Ford Health System, Detroit, Michigan
Karen M. Johnston
McGill University, Montreal, Quebec, Canada
Dustin Pardini
University of Pittsburgh, Pittsburgh, Pennsylvania, USA
Jamie Pardini
University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA
John Norwig
Pittsburgh Steelers Football Club, Pittsburgh, Pennsylvania, USA
Joseph C. Maroon
University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA
It is important to carefully evaluate self-reported symptoms in athletes with known or sus
-
pected concussions. This article presents data on the psychometric and clinical properties of a
commonly used concussion symptom inventory—the Post-Concussion Scale. Normative and
psychometric data are presented for large samples of young men (N = 1,391) and young
women (N = 355). In addition, data gathered from a concussed sample of athletes (N = 260)
seen within 5 days of injury are presented. These groups represent samples of both high school
and collegiate athletes. Data from a subsample of 52 concussed athletes seen 3 times
post-injury are presented to illustrate symptom reporting patterns during the initial recovery
period. General guidelines for the clinical use of the scale are provided.
Key words: concussion, symptoms, traumatic brain injury, sports
Clinical strategies for the diagnosis and management
of concussion have evolved considerably over the past
decade. There has been a trend toward more sophisti
-
cated and individualized approaches to managing this
injury (Collins, Lovell, & McKeag, 1999; Johnston,
McCrory, Mohtadi, & Meeuwisse, 2001). More con
-
temporary concussion management strategies have em
-
phasized multiple diagnostic elements including clini
-
cal history, sideline evaluation, neuropsychological
testing, and neuroimaging, when appropriate.
Concussion has recently been defined as “a complex
pathophysiological process affecting the brain, induced
166
Applied Neuropsychology
2006, Vol. 13, No. 3, 166–174
Copyright 2006 by
Lawrence Erlbaum Associates, Inc.
Correspondence should be addressed to Mark R. Lovell, ABPN;
UPMC Center for Sports Medicine; 3200 South Water Street; Pitts
-
burgh, PA 15203, USA. E-mail: lovellmr@upmc.edu
by traumatic biomechanical forces” (Aubry et al.,
2002). Contemporary definitions of this injury assume
a neurophysiological rather than neuroanatomical basis
for concussion, and traditional neuroimaging proce
-
dures are of little value in the detection of injury and
monitoring of recovery. Although newer functional
brain imaging (fMRI) protocols show promise as a di
-
agnostic technology, fMRI is currently not available for
widespread clinical use (Lovell et al., 2004). Therefore,
neuropsychological assessment has played an increas
-
ingly prominent role in concussion management. Char
-
acteristic neuropsychological deficits following con
-
cussion in the areas of attentional processes, memory,
and neurocognitive speed following concussion have
been documented by multiple researchers (Echemendia
& Cantu, 2003; Erlanger et al., 2003; Lovell et al.,
2004a, 2004b; McCrea et al., 2003). However, in addi
-
tion to these common deficits that can be documented
by standardized neuropsychological assessment proto
-
cols, many symptoms reported by injured athletes are
of a more subjective nature.
In recognition of the need for better concussion man-
agementstrategies,theInternationalIceHockeyFedera-
tion (IIHF), in conjunction with the International Olym-
pic Committee (IOC) and the Federation Internationale
de Football Association (FIFA), convened in Vienna in
October of 2001 to evaluate the current status of concus-
sion management guidelines and to draft practical rec-
ommendations for making return-to-play decisions
(Aubry et al., 2002). As a prominent piece of the concus-
sion evaluation process, the Concussion in Sport (CIS)
group recommended the careful evaluation of individual
symptoms following a suspected concussion and further
suggested that any report of symptoms should lead to
more in-depth evaluation.
The measurement of symptoms is very common in
the sport concussion literature (e.g., Echemendia,
Putukian, Mackin, Julian, & Shoss, 2001; Erlanger et
al., 2003; Guskiewicz et al., 2003; Macciocchi, Barth,
Alves, Rimel, & Jane, 1996; Macciocchi, Barth,
Littlefield, & Cantu, 2001; McCrea et al., 2003). Al
-
though the importance of player symptoms in making
return-to-play decisions is almost universally accepted,
the availability of formal evaluation scales with known
psychometric properties is rather limited, with the nota
-
ble exception of the Head Injury Scale (Piland, Motl,
Ferrara, & Peterson, 2003). In addition, differences in
symptom reporting by different groups (e.g., men vs.
women, high school vs. college) have not been ade
-
quately explored.
This article presents data on the psychometric and
clinical properties of a single commonly used concus
-
sion symptom inventory—the Post-Concussion Scale
(PCS). Normative data will be presented and discussed.
In addition, data gathered from a concussed sample of
athletes will be presented to illustrate changes in symp
-
tom reporting following concussion. General guide
-
lines for the clinical use of the scale will be provided.
METHODS
Participants
Normative data for the PCS were derived from 1,746
high school and university student athletes. All student
athletes completed the computerized version of the test,
as administered within ImPACT Version 1. The stu
-
dents represented more than 15 high schools and 10
universities. There were 707 high school students and
1,039 university students. The high school sample was
comprised of 588 (83.2%) young men and 119 (16.8%)
young women. On average, they had completed 10.3
years of school (SD = 1.0). The university sample was
comprised of 803 (77.3%) young men and 236 (22.7%)
young women. On average, they had completed 13.6
years of school (SD = 1.3).
A separate clinical sample was comprised of 260
high school and university athletes who were evaluated
within 5 days of sustaining a sports-related concussion
(M = 2.0, SD = 1.2) by either a certified athletic trainer
or team physician. A concussion was diagnosed based
on recent international criteria (Aubry et al., 2002).
Prior to the beginning of the study, all athletic trainers
were formally trained in the on-field diagnosis of con
-
cussion by one of the authors (Drs. Lovell or Collins).
A concussion was diagnosed if the athlete reported
symptoms such as headache, dizziness, or balance dys
-
function, or if he or she exhibited a decline in cognitive
functioning as demonstrated by poor performance on a
brief mental status examination, which tested aspects of
retrograde and post-traumatic amnesia (Lovell, Collins,
Iverson, Johnston, & Bradley, 2004).
The majority of the concussed athletes were seen
within 72 hours (88%). Their average age was 16.5
years (SD = 2.0), and their average education was 10.2
years (SD = 1.8). The majority of athletes were in high
school (85%). The sample was 83.5% men and 16.5%
women. From this sample, a subsample of 52
concussed athletes who were evaluated three times
within specified intervals was selected. An athlete was
selected from the larger sample, for this subsample, if
he or she was evaluated the first time within 72 hours,
the second time between 4 and 8 days, and the third
167
MEASUREMENT OF SYMPTOMS
time between 7 and 30 days. The time intervals were al
-
lowed to overlap slightly to increase the sample size for
these analyses. The actual breakdown of mean number
of days post- injury for each assessment period was as
follows: Time 1 = 1.4 days post (Mdn =1,SD = .7,
range = 0–3), Time 2 = 5.6 days post (Mdn =5,SD =
1.3, range = 4–8), and Time 3 = 11.7 days post (Mdn =
11, SD = 4.2, range = 7–24).
Measure
The PCS is a 22-item scale designed to measure the
severity of symptoms in the acute phase of recovery
from concussion (Lovell, 1996, 1999; Lovell & Collins,
1998). This scale was developed in the late 1980s
within the context of the Pittsburgh Steelers concussion
management program, and variants of this scale have
been formally adopted by the National Football League
(Lovell, 1996), National Hockey League (Lovell &
Burke, 2002; Lovell, Echemendia, & Burke, 2004), by
numerous colleges and high schools, and more recently
by automobile racing leagues such as the Competitive
Automobile Racing League and the Indianapolis
Racing League (Olvey, 2002). This scale has been a de
-
pendent measure in several published studies (e.g., Col
-
lins et al., 2003; Iverson, Gaetz, Lovell, & Collins,
2004a, 2004b; Lovell et al., 2003; Lovell, Collins et al.,
2004). The scale is presented in Figure 1.
The PCS was developed to provide a formal method
of documenting post- concussion symptoms, as per
-
ceived and reported by the athlete. In particular, the
goal in developing this scale was to more objectively
document the often highly subjective symptoms re
-
ported by athletes following concussion by assigning
numeric values to each symptom. This scale was devel
-
oped to provide an adjunct to other tools such as
neuropsychological testing. Symptom items were
based on earlier experience gathering symptom data
168
LOVELL ET AL.
Figure 1. Post-Concussion Scale.
from the Pittsburgh Steelers and later from thousands of
amateur and professional athletes. Scale items were
constructed to reflect actual player reports rather than
medical jargon. For instance, the term fogginess was
employed based on the recurrent report of this symp
-
tom by concussed athletes. The original scale was
based on a 7-point Likert scale with 0 and 6 reflecting
the anchor points. The written instructions that accom
-
pany the scale request the athletes to report symptoms
based on the severity of each symptom that day. The
scale is currently available in paper form through the
senior author at no cost and has also been incorporated
into the ImPACT computerized neuropsychological
program (Lovell et al., 2003; Lovell, Collins et al.,
2004; Maroon et al., 2000). The scale has also been
suggested as a management tool by other organizations
as well (Aubry et al., 2002).
RESULTS
Descriptive Statistics and
Normative Data
Descriptive statistics and psychometric analyses are
provided in Table 1. The mean, median, standard devia-
tion, range, skewness, and kurtosis of total scores for
each sample are presented. As seen from the measures
of central tendency (mean and median), skewness, and
the ranges, the distributions of total symptom scores are
clearly skewed. That is, a large percentage of athletes
score between zero and three points at baseline testing.
The distribution of scores for the concussed athletes is
not severely skewed; it is much more evenly distrib
-
uted.
There was no significant difference in total symptom
scores between the high school students and the univer
-
sity students (M = 5.31, SD = 9.21, and M = 5.28, SD =
8.36, respectively). However, there was a significant
difference between men and women in both samples.
That is, the young women reported more symptoms
than the young men in the high school (p < .03, Cohen’s
d = .33, small–medium effect size) and the university
sample (p < .001, d = .43, medium effect size). In the
concussed sample, there was no significant difference
in total symptom scores between high school athletes
and university athletes (M = 24.4, SD = 19.5, and M =
20.7, SD = 21.7, respectively). In addition, there was no
significant difference in total scores for young men ver
-
sus young women (M = 23.3, SD = 19.4, and M = 27.9,
SD = 22.6, respectively), although there was a trend to
-
wards greater symptom reporting in women.
Given that there were no significant differences be-
tween high school students and university students,
normative data for the PCS are presented by gender. As
previously noted, the distributions of total scores are
skewed because healthy young people tend to report
few symptoms on this scale. With this degree of skew,
forced-normalization of the distributions will (a) distort
the true nature of the construct being measured, that is,
healthy young people’s total symptoms are not nor-
mally distributed in the population; and (b) result in in
-
169
MEASUREMENT OF SYMPTOMS
Table 1.
Descriptive and Psychometric Analyses for Concussion Symptom Reporting at Baseline and Postconcussion for High School and
College Men and Women Athletes
Group
N M Mdn SD Range Skew Kurtosis Alpha
1
SEM
2
.80
3
Normative
High school
Young men 588 4.8 2 7.9 0–54 2.8 9.7 .89 2.62 3.35
Young women 119 7.7 3 13.7 0–78 3.1 10.8 .94 3.36 4.30
College
Young men 803 4.5 2 7.5 0–56 2.9 10.6 .88 2.60 3.33
Young women 236 8.0 5 10.3 0–55 2.1 5.2 .88 3.57 4.57
Combined sample
Young men 1,391 4.6 2 7.7 0–56 2.9 10.2 .88 2.66 3.40
Young women 355 7.9 4 11.5 0–78 2.7 9.2 .91 3.46 4.43
Athletes with concussions
Young men 217 23.3 19 19.4 0–94 1.1 .8 .93 5.13 6.57
Young women 43 27.9 23 22.4 0–82 .8 –.3 .92 6.34 8.12
Combined sample 260 24.0 19 20.0 0–94 1.0 .5 .93 5.29 6.77
Note. The statistics presented in this table are stratified by concussion status, level of competition, and gender.
1
Cronbach’s Unstandardized Alpha; this represents the lower bound of reliability.
2
Standard error of measurement.
3
.80 and confidence interval.
creased interpretation error. Therefore, the natural dis
-
tribution of scores was examined, and classification
ranges were created that reflect proportions of norma
-
tive subjects. Classification descriptors were created
that reflect raw score ranges and percentile rank ranges
in the natural distribution of scores. For example, in Ta
-
ble 2, 42% of young men obtained a total score of zero
on the scale. Thus, a score of zero would be considered
“Low–Normal”. In contrast, 89% scored 12 or less, so
only 11% scored 13 or higher. Thus, scores between 13
and 26 are considered “Very High.” The percentile rank
values represent the percentage of students who scored
at the lower and upper bound of that raw score range.
For the “Very High” range, 91% of young men scored
13 or less and 97% scored 26 or less; therefore, scores
above 26 are considered “Extremely High.”
As seen in Table 3, young women report more symp
-
toms than young men. Approximately 28% obtained a
score of zero. The “Broadly Normal” range is from 1 to
9 points, and the “Borderline” range is from 10 to 20
points. Ninety percent of young women scored 20 or
less on the scale.
As seen in Table 1, the concussed athletes have high
total scores for the PCS. The breakdown of concussed
athletes into the total score normative classification
ranges is provided in Table 4. The percentages of the
normative sample that fall in each classification range
are presented for comparison. Combining the two low-
est classification ranges provides a “Broadly Normal”
range of total scores. For the normative sample, 74% of
young men and 73% of young women fell in this range.
In contrast, 21% of concussed young men and approxi
-
mately 26% of concussed young women fell in this
range. If the “Very High” and “Extremely High” classi
-
fication ranges are combined, 10% of healthy young
men and 9% of healthy young women fell in this com
-
bined category. In contrast, 67% of concussed young
men and 51% of concussed young women fell in this
combined category.
Scale Reliability
Reliability can be viewed as the ability of an instru-
ment to reflect an individual score that is minimally in-
fluenced by error. Reliability should not be considered
a dichotomous concept, rather it falls on a continuum.
One cannot say an instrument is reliable or unreliable,
but more accurately should say it possesses a high or
low degree of reliability for a specific purpose, with a
specific population (Franzen, 2000).
An important aspect of reliability is internal consis
-
tency. Internal consistency can be estimated using
Cronbach’s alpha (Cronbach, 1951). Alpha is believed
to represent the lower bound for the true reliability of
the scale and is influenced by the number of items on
the scale, the average inter-item covariance, and the av
-
erage item variance (SPSS, 1998).
As seen in Table 1, internal consistency reliability of
the PCS ranged from .88 to .94 across the various sam
-
ples of healthy high school and college students in this
study. The standard error of measurement (SEM) is
considered an estimate of measurement error in a per
-
son’s observed test score. SEMs for the different groups
also are presented in Table 1. These SEMs were used to
create confidence intervals. A confidence interval rep
-
resents a range or band of scores, surrounding an ob
-
served score, in which the individual’s true score is be
-
170
LOVELL ET AL.
Table 2.
Classifications, Raw Scores, and Percentile Ranks
Based on a Sample of 1,391 Healthy Young Men
Classification
Raw Scores Percentile Ranks
Low–normal 0 42
Broadly normal 1–5 49–74
Borderline 6–12 77–89
Very high 13–26 91–97
Extremely high 27+ 98
Table 3. Classifications, Raw Scores, and Percentile Ranks
Based on a Sample of 355 Healthy Young Women
Classification
Raw Scores Percentile Ranks
Low–normal 0 28
Broadly normal 1–9 35–73
Borderline 10–20 76–90
Very high 21–43 91–97
Extremely high 44+ 98
Table 4. Percentage of Normative Participants and Concussed
Athletes Falling in Each Classification Range
Normative Sample Concussed Sample
Classification
Young
Men
Young
Women
Young
Men
Young
Women
Low–normal 42 28 6.5 2.3
Broadly normal 32 45 14.7 23.3
Borderline 15 17 11.5 23.2
Very high 8 7 32.7 25.6
Extremely high 2 2 34.6 25.6
lieved to fall. For young men, the 80% confidence
interval for the total score was ±3.4 points. For young
women, the 80% confidence interval was ±4.4 points
(i.e., the SEM multiplied by a z-score of 1.28).
For the concussed athletes, the internal consistency
of the PCS was very high (r = .93). The standard error
of measurement is 5.3 points, and the 80% confidence
interval is 6.8 points.
Individual Symptom Reporting
The frequencies of individual symptom endorse
-
ment by level of severity for the concussed athletes are
presented in Table 5. The most frequently endorsed
symptoms, at a severity of mild or greater, were as fol
-
lows: headaches, fatigue, feeling slowed down, drowsi
-
ness, difficulty concentrating, feeling mentally foggy,
and dizziness. These individual symptoms were en
-
dorsed by 60–79% of the sample. The least frequently
endorsed symptoms were nervousness, feeling more
emotional, sadness, numbness or tingling, and vomit-
ing. These individual symptoms were endorsed by less
than 25% of the sample.
A sample of 52 concussed athletes was evaluated
three times, within 72 hours (M = 1.4 days), between 4
and 8 days (M = 5.6 days), and between 7 and 30 days
(M = 11.7 days). Forty-seven of these athletes were men
and only 5 were women. Therefore specific data by
gender are not presented in this current study. As seen
in Figure 2 and Table 6, there was a linear decrease in
total symptoms reported across the three intervals. Dur
-
ing the first time period, subjects reported numerous
symptoms. By the third time period, their symptom re
-
porting was essentially normal. However, as seen by the
error bars, there is considerable variability in symptom
reporting within each time period. A small percentage
of athletes were still quite symptomatic at the third time
interval. At 11 days, 15% scored greater than 10 points
and 10% scored greater than 17 points. Notably, the sig
-
nificant minority of athletes reporting high levels of
symptoms at 11 days probably reflects a selection bias,
given that symptomatic athletes are more likely to be
seen in follow-up on a third occasion.
The distributions of difference scores were exam
-
ined to determine if there was a consistent trend toward
improvement across all participants. From Time 1 to
Time 2, 90.4% of the participants reported fewer symp-
toms. From Time 1 to Time 3, 92.3% reported fewer
symptoms. From Time 2 to Time 3, 84.6% reported the
same or fewer symptoms. Therefore, for the vast major-
171
MEASUREMENT OF SYMPTOMS
Table 5.
The Frequencies of Symptom Endorsements for the Post-Concussion Scale in Concussed Athletes
Mild Moderate Severe
Symptom
None 1 2 3 4 5 6
Headache 21.5 14.6 16.5 18.5 15.0 11.2 2.7
Fatigue 30.8 21.5 12.3 11.9 13.1 6.9 3.5
Feeling slowed down 33.1 19.6 20.0 14.6 6.9 3.8 1.9
Drowsiness 33.8 18.8 15.0 10.8 11.2 6.5 3.8
Difficulty concentrating 34.2 16.9 15.0 18.1 8.1 6.2 1.5
Feeling mentally “foggy” 37.7 18.1 16.2 15.8 5.4 4.6 2.3
Dizziness 38.8 20.4 20.8 10.0 6.2 3.1 0.8
Difficulty remembering 45.0 20.0 18.1 5.4 5.8 4.6 1.2
Sensitivity to light 46.2 16.2 13.1 9.2 4.2 8.1 3.1
Balance problems 50.8 21.2 14.2 9.6 2.7 1.5 —
Nausea 53.8 21.9 12.3 8.1 2.7 1.2 —
Sensitivity to noise 54.2 15.0 8.5 8.1 7.3 6.5 0.4
Irritability 61.2 11.2 14.6 6.5 2.7 1.9 1.9
Trouble falling asleep 65.4 8.1 8.5 6.2 6.9 2.7 2.3
Sleeping more than usual 66.2 8.5 6.2 6.2 7.3 3.5 2.3
Visual problems 70.4 11.5 6.9 6.9 1.9 2.3 —
Sleeping less than usual 75.0 6.2 6.2 4.2 2.7 4.6 1.2
Nervousness 78.8 9.6 6.5 1.9 1.9 1.2 —
Feeling more emotional 82.3 7.7 2.7 5.8 0.8 0.8 —
Sadness 85.0 6.2 4.2 2.3 1.5 0.8 —
Numbness or tingling 85.4 7.7 2.7 3.5 0.8 — —
Vomiting 91.2 6.2 2.3 0.4 — — —
Note. N = 260.
ity of athletes, there was steady improvement across the
test intervals. Worsening in symptoms was very un
-
common across these time intervals. From Time 1 to
Time 2, only one participant (2%) reported a worsening
by 5 or more points. From Time 1 to Time 3, 3 partici-
pants (5.8%) reported a worsening by 5 or more points.
From Time 2 to Time 3, 4 participants (i.e., 7.7%) re-
ported a worsening by 5 or more points.
DISCUSSION
Preliminary psychometric data and information re-
garding the clinical interpretation of the PCS has been
previously reported (Iverson & Gaetz, 2004; Iverson,
Lovell, & Collins, 2003). This article provides com-
prehensive normative data and additional psycho-
metric data for the inventory. This scale was originally
developed to provide information to athletes, physi-
cians, and athletic trainers regarding post-concussive
symptoms and their resolution over time. Although
the normative and psychometric work that has been
completed thus far has been limited to the English
language version, this inventory is currently available
in Spanish, French, Russian, and Czech, and research
studies are underway to study its utility in other cul
-
tural groups.
The measurement of subjective symptoms repre
-
sents an important component in the evaluation of the
concussed athlete. Resolution of post-concussion
symptoms, in combination with normal neuro
-
psychological test results, is generally regarded as a re
-
quirement for return to play (Aubry et al., 2002;
Echemendia & Cantu, 2003). Although all self-report
scales are subjective in nature, it is hoped that the inves
-
tigation of psychometric properties of this scale will
provide clinicians and researchers with additional in
-
formation regarding the significance of symptom re
-
porting following sports-related concussion.
The internal consistency reliability of the PCS is
very high in healthy and concussed adolescents and
young adults. There is no baseline or post-concussion
difference in total symptom scores between high school
students and university students. There is a difference,
172
LOVELL ET AL.
Figure 2. Total symptoms reported at approximately 1, 5, and 11 days post injury (N = 52). The bars represent the mean and the error
bars represent one standard deviation. Median scores were 26, 8, and 1 for the three time periods, respectively.
Table 6.
The Frequencies of Serial Symptom Endorsements for
the Post-Concussion Scale in Concussed Athletes
Symptoms
Time 1 Time 2 Time 3
Headache 88.5 61.5 32.7
Difficulty concentrating 82.7 51.9 23.1
Feeling slowed down 78.8 40.4 19.2
Dizziness 78.8 30.8 17.3
Nausea 77.3 21.2 15.4
Fatigue 76.9 50.0 21.2
Feeling mentally “foggy” 75.0 46.2 19.2
Drowsiness 73.1 48.1 17.3
Difficulty remembering 69.2 50.0 23.1
Sensitivity to light 57.7 40.4 17.3
Balance problems 55.8 26.9 11.5
Sensitivity to noise 50.0 40.4 15.4
Trouble falling asleep 45.0 25.0 15.4
Irritability 38.5 36.5 11.5
Sleeping more than usual 34.6 28.8 9.6
Visual problems 32.7 19.2 7.7
Sleeping less than usual 30.8 15.4 7.7
Nervousness 30.8 15.4 7.7
Feeling more emotional 19.2 11.5 7.7
Sadness 19.2 7.7 5.8
Numbness or tingling 15.4 7.7 1.9
Vomiting 11.5 7.7 1.9
Note. N = 52.
however, in baseline symptom reporting between
young men and young women; healthy young women
tend to report more symptoms. Therefore, normative
data for the PCS were provided by gender (see Tables 2
and 3). It is interesting to note that although the samples
of men and women differed with regard to report of
symptoms at baseline, these differences were not sig
-
nificant following injury. However, there was a trend to
-
wards greater symptom reporting in the group of
women. In another recent study, Broshek, Kaushik,
Freeman, Erlanger, Webbe, and Barth (2005) did find
significantly higher post-injury symptom reporting in a
group of high school and collegiate women athletes,
compared to a group of men. Therefore, this issue con
-
tinues to warrant further exploration.
An advantage of the PCS is that it is a “state” mea
-
sure of perceived symptoms. It is designed to provide
an estimate of symptoms experienced on that day. As
such, it can be used over short retest intervals (in con
-
trast to other scales which require the respondent to rate
symptoms over the past week, 2 weeks, month, or in
general). As a state measure, however, the scale can re-
flect an unusually good or unusually bad day for the
athlete, which might mislead the clinician. This can
occur during the preseason evaluation or during
post-injury evaluations. Moreover, people with depres-
sion, anxiety, life stress, or pain report very similar
symptoms. Potential comorbid factors or frank differ-
ential diagnoses influencing symptom reporting are es-
sential to consider in athletes with protracted recovery
periods. The authors have seen athletes with presumed
slow recoveries from concussions whose primary prob
-
lem several months post-injury was a pre-existing anxi
-
ety disorder that appeared to be mimicking a post
-
concussion syndrome. The PCS is simply a tool that
can be used to quantify symptoms; it should not be used
in isolation. Rather it should be used within the context
of a thorough clinical evaluation.
One limitation of this study is that we did not con
-
duct a direct comparison of the concussed group who
were tested three times post-injury with a non-injured
control group who also underwent multiple assess
-
ments. The addition of this component to future studies
would help to determine variability in symptom report
-
ing in non-injured (“normal”) athletes. In addition,
through future studies we intend to examine the factor
structure of the scale and determine whether reliable
subscales can be identified. If so, these subscales will
be normed. In addition, we will evaluate the reliability
of the subscales and provide information regarding how
to interpret statistically reliable and clinically meaning
-
ful change.
ACKNOWLEDGMENTS
A portion of this study was presented at the Interna
-
tional Neuropsychological Society, Honolulu, Hawaii
in February of 2003.
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