TABLE 3.

Model predicting ACA, SCD, or appropriate ICD shock after enrollment in 1,288 LQTS patients with singe LQT1, LQT2, or LQT3 mutation (No. of events = 47, 14 SCD, 7 ACA, and 26 shock).

Variables in the model	β	HR	95% CI		P
QTc, per 10 ms increase	0.02	1.02	0.96	1.09	0.442
Age at enrollment (Ref: 0–10 years)
10–20 years	-0.60	0.55	0.26	1.15	0.112
20–50 years	-1.40	0.25	0.11	0.56	0.001
Time-dependent syncope (Ref: No syncope)
Syncope while off BB	0.87	2.38	1.10	5.16	0.028
Syncope while on BB	1.88	6.54	2.91	14.65	<001
Time-dependent beta-blocker (yes vs. no)	-0.73	0.48	0.25	0.91	0.025
Sex by time-dependent age (female vs. male)
<13 years	-1.92	0.15	0.02	1.13	0.066
≥13 years	0.58	1.79	0.91	3.51	0.090
Genotype (Ref: LQT1)
LQT2	0.36	1.44	0.75	2.77	0.279
LQT3	1.32	3.75	1.74	8.07	0.001
C statistic	0.785 (0.721–0.849)

Robust sandwich estimates of standard errors were used. P-value for interaction between time-dependent age and sex: 0.018.