Validation of a diagnostic probability function for estimating probabilities of acute coronary syndrome.
BACKGROUND
We recently reported about the derivation of a diagnostic probability function for acute coronary syndrome (ACS). The present study aims to validate the probability function as a rule-out criterion in a new sample of patients.


METHODS
186 patients presenting with chest pain and/or dyspnea at one of the three participating hospitals' emergency rooms in Switzerland were included in the study. In these patients, information on a set of pre-specified variables was collected and a predicted probability of ACS was calculated for each patient. Approximately two weeks after the initial visit in the emergency room, patients were contacted by phone to assess whether a diagnosis of ACS was established.


RESULTS
Of the 186 patients included in the study, 31 (17%) had an acute coronary syndrome. A risk probability for ACS below 2% was considered a rule-out criterion for ACS, leading to a sensitivity of 87% and a specificity of 17% of the rule. The characteristics of the study patients were compared to the cases from which the probability function was derived, and considerable deviations were found in some of the variables.


CONCLUSIONS
The proposed probability function, with a 2% cut-off for ruling out ACS works quite well if the patient data lie within the ranges of values of the original vignettes. If the observations deviate too much from these ranges, the predicted probabilities for ACS should be seen with caution.
Lukas
L
Zimmerli
Johann
J
Steurer
Reto
R
Kofmehl
Maria M
MM
Wertli
Horten Centre for Patient Oriented-Research and Knowledge Transfer, University of Zurich, Pestalozzistrasse 24, Zurich 8091, Switzerland. ulrike.held@usz.ch.
Ulrike
U
Held
D054058:Acute Coronary Syndrome / Q000150:complications / Q000175:diagnosis*; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002637:Chest Pain / Q000209:etiology*; D003661:Decision Support Techniques; D004417:Dyspnea / Q000209:etiology*; D004636:Emergency Service, Hospital; D005260:Female; D006801:Humans; D016013:Likelihood Functions; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D018570:Risk Assessment / Q000379:methods; D012680:Sensitivity and Specificity; D055815:Young Adult