Chubb et al reported equations for estimating the z-score for a patient's QRS duration using estimates for age and sex. The authors are from Stanford University.
Patient selection: age 0 to 55 years
Parameters:
(1) sex
(2) age in years
(3) QRS duration in ms
QRS z-score for a female =
= ((QRS duration) - ((0.00038 * ((age)^3)) - (0.046 * ((age)^2)) + (1.8 * (age)) + 67)) / ((0.000046 * ((age)^3)) - (0.0053 * ((age)^2)) + (0.2 * (age)) + 8.1)
QRS z-score for a male =
= ((QRS duration) - ((0.00029 * ((age)^3)) - (0.043 * ((age)^2)) + (2 * (age)) + 68)) / ((0.000076 * ((age)^3)) - (0.0083 * ((age)^2)) + (0.29 * (age)) + 8.4)
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