Glasgow coma scale and APACHE II system data--are they normally distributed?
OBJECTIVE
To verify whether the Glasgow Coma Scale (GCS) and APACHE II system scores are normally distributed.


METHODS
Medical records of seventy four head injured patients were reviewed. GCS and APACHE II data were compared to a standard normal distribution. The chi2 goodness of fit test, the one sample Kolmogorov-Smirnov test, the Lilliefors test, the Shapiro-Wilk test, and calculation of skewness and kurtosis were performed. Frequency histograms and normal probability plots were also constructed.


RESULTS
GCS data were not found to be normally distributed with a Kolmogorov-Smirnov statistic of 3.181 (p=0.000). In contrast, APACHE II data presented a normal distribution with a Kolmogorov-Smirnov statistic of 0.704 (p=0.704).


CONCLUSIONS
We demonstrated that GCS data do not follow the normal distribution, and thus nonparametric tests should be employed when dealing with such data. Furthermore, APACHE II data follow the normal distribution, and parametric tests could be considered, even though nonparametric tests are still preferred.
Matis
G
G
Department of Neurosurgery, University Hospital of Alexandroupolis, Democritus University of Thrace Medical School, Alexandroupolis, Greece.
Birbilis
Th
T
Kontogianidis
K
K
D018806:APACHE; D000328:Adult; D000465:Algorithms; D003128:Coma / Q000175:diagnosis* / Q000401:mortality; D006259:Craniocerebral Trauma / Q000175:diagnosis* / Q000401:mortality; D005260:Female; D015600:Glasgow Coma Scale; D006801:Humans; D008297:Male; D008499:Medical Records; D008875:Middle Aged; D016011:Normal Distribution; D012016:Reference Values; D012189:Retrospective Studies; D012720:Severity of Illness Index; D018709:Statistics, Nonparametric