Z-score

Z-score

One often reads Z-score of various parameters in pediatric cardiology textbooks. Z-score of pulmonary arteries in tetralogy of Fallot is one example. This will decide whether a repair will be followed by right ventricular afterload mismatch or not. Z score correlates the measurement with the body surface area (BSA). Z score checks how many standard deviations the measured value of the structure deviates from the population mean.

Z-score for a given BSA = (Observed measurement − Population mean)/Population standard deviation