TABLE 5.

Cox Regression With Multiple Predictor Variables Including Ion Channel Dysfunction for First Cardiac Events

Variable	Hazard Ratio	95% CI	P
Netherlands:United States	2.78	1.48–5.23	<0.01
Japan:United States	1.63	1.02–2.63	0.04
Male <13 y:female <13 y	1.94	1.29–2.91	<0.01
Female 13–40 y:male 13–40 y	1.95	0.99–3.87	0.06
QTc 500–530 ms:QTc <500 ms	1.88	1.18–2.99	<0.01
QTc >530 ms:QTc <500 ms	3.22	2.06–5.05	<0.001
QTc missing*:QTc <500 ms	2.07	1.29–3.33	<0.01
Dominant-negative:haploinsufficiency	2.26	1.56–3.25	<0.001
Time-dependent β-blocker use	0.21	0.09–0.48	<0.001

The analysis involved 354 subjects with known or suspected ion channel dysfunction; 2 subjects were not included because of missing data about the date of their first cardiac event.

^*The QTc missing category involves 26 patients who died suddenly at a young age without a prior ECG.