http://www.medscape.com/viewarticle/564074


American Journal of Clinical Pathology
Studying Critical Values: Adverse Event Identification Following a Critical
Laboratory Values Study at the Ohio State University Medical Center
Posted 10/24/2007

James J. Jenkins II, PhD, MS, MT(ASCP);1 J. Mac Crawford, PhD, MS;2 Michael
G. Bissell, MD, PhD, MPH3




No study to date has used laboratory critical values to evaluate variations
in patient adverse events. We retrospectively analyzed a database of
critical values to determine their distribution by hospital unit over time.
The data were drawn from the Ohio State University Medical Center
Information Warehouse (Columbus) for a 58-month period. Critical values were
plotted over time on statistical control charts and analyzed for unusual
peaks in monthly occurrence rates. Chart review of individual patient
results yielded several predictor variables for the unusual peaks. Of these,
occurrence of patient adverse events was the most relevant independent
predictor variable for a month with an unusual number of critical values vs
a normal month. This result epidemiologically confirms the basic premise of
critical value reporting and suggests that the control-chart method of this
type could be a new statistical tool to compare clinical activity of
different hospital locations at different times.