Table 2. Subgroup analysis.

Outcomes	Group	RR and 95%CI	P value	Heterogeneity (%)	P value for heterogeneity	Ratios of RR	P value between subgroups
Overall failure	Publication year
	After 2000	2.12 (1.18–3.82)	0.012	3.9	0.353	0.86 (0.43–1.73)	0.679
	Before 2000	2.46 (1.69–3.59)	<0.001	0.0	0.807
	Country
	Europe	2.46 (1.69–3.59)	<0.001	0.0	0.807	1.16 (0.58–2.33)	0.679
	Asia	2.12 (1.18–3.82)	0.012	3.9	0.353
	Sample size
	100 or more	2.39 (1.62–3.51)	<0.001	0.0	0.870	1.04 (0.53–2.02)	0.961
	<100	2.30 (1.34–3.97)	0.003	0.0	0.438
	Mean age
	40 or more	1.92 (0.93–3.97)	0.078	0.0	0.742	0.74 (0.33–1.67)	0.473
	<40	2.58 (1.81–3.67)	<0.001	0.0	0.802
	Percentage male (%)
	70 or more	3.14 (1.97–4.98)	<0.001	0.0	0.927	1.62 (0.85–3.07)	0.140
	<70	1.94 (1.25–3.01)	0.003	0.0	0.821
Relapse	Publication year
	After 2000	2.45 (1.03–5.83)	0.044	0.0	0.432	0.86 (0.32–2.33)	0.770
	Before 2000	2.84 (1.75–4.61)	<0.001	0.0	0.975
	Country
	Europe	2.84 (1.75–4.61)	<0.001	0.0	0.975	1.16 (0.43–3.13)	0.770
	Asia	2.45 (1.03–5.83)	0.044	0.0	0.432
	Sample size
	100 or more	2.89 (1.61–5.21)	<0.001	0.0	0.926	1.12 (0.48–2.60)	0.798
	<100	2.59 (1.41–4.76)	0.002	0.0	0.807
	Mean age
	40 or more	3.15 (1.07–9.31)	0.038	0.0	0.596	1.18 (0.36–3.83)	0.783
	<40	2.67 (1.68–4.25)	<0.001	0.0	0.909
	Percentage male (%)
	70 or more	3.16 (1.79–5.60)	<0.001	0.0	0.906	1.39 (0.59–3.27)	0.457
	<70	2.28 (1.20–4.34)	0.012	0.0	0.797