Table 2. Stratified analyses in subgroups.

Type of meta-analyses	No. of studies	Model	RR (95% CI)	I 2 (%)	P_hetero	P_Begg	P_int
Spatial QRS-T angle predicts all-cause death (wide angle versus normal one)
Type of clinical presentation
General population	6	Fixed	1.37 (1.29–1.46)	0	0.44	0.452	0.197
Suspected CHD	4	Fixed	1.47 (1.28–1.65)	19.3	0.293	0.734
No. of participants
>4000	5	Fixed	1.37 (1.28–1.46)	14.8	0.32	0.806	0.103
<4000	6	Fixed	1.48 (1.33–1.64)	35.2	0.173	0.707
Duration of follow-up
>5 years	8	Fixed	1.38 (1.31–1.46)	0	0.583	0.266	0.000
<5 years	3	Fixed	2.36 (1.65–2.39)	0	0.987	1
Spatial QRS-T angle predicts cardiac death (wide angle versus normal one)
Type of clinical presentation
General population	5	Fixed	1.66 (1.47–1.88)	0	0.909	0.462	0.319
Suspected CHD	3	Fixed	1.81 (1.50–2.19)	6.6	0.343	0.296
No. of participants
>4000	5	Fixed	1.66 (1.47–1.88)	0	0.909	0.462	0.319
<4000	3	Fixed	1.81 (1.50–2.19)	6.6	0.343	0.296
Duration of follow-up
>5 years	7	Fixed	1.71 (1.54–1.90)	0	0.714	1	0.954
<5 years	1	–	–	–	–	–
Frontal QRS-T angle predicts all-cause death (wide angle versus normal one)
Type of clinical presentation
General population	3	Random	1.29 (1.03–1.62)	83.1	0.003	1
Suspected CHD	4	Fixed	1.74 (1.41–2.14)	45.4	0.139	1
Heart failure	6	Random	1.51 (1.18–1.94)	64.2	0.016	1
No. of participants
>2000	4	Random	1.30 (1.11–1.51)	75.2	0.007	0.734	0.432
<2000	6	Random	1.57 (1.19–2.08)	53.2	0.06	0.454
Duration of follow-up
>5 years	3	Random	1.29 (1.03–1.62)	83	0.003	1	0.518
<5 years	7	Random	1.51 (1.21–1.88)	57.1	0.03	1

P_hetero: P value of heterogeneity across studies; P_Begg: P value from Begg’s test; P_int: P value of interaction in subgroups. CI: confidence intervals; RR: relative risks.