Table 2. Results of Subgroup Analyses of Comparisons by Various Characteristics That Indicate Quality of Comparison in Publications.

Characteristics	No. of comparisons	Pooled HR random model		Heterogeneity		Significance P valuea
		HR (95% CI)	P value	Q	Q P value
All comparisons	85	0.76 (0.69-0.82)	<.001	688.6	<.001	NA
Patient characteristics
Accounts for age	53	0.85 (0.77-0.93)	<.001	301.7	<.001	.002
Does not account for age	32	0.66 (0.59-0.75)	<.001	204.2	<.001
Accounts for sex	57	0.85 (0.77-0.93)	<.001	348.0	<.001	<.001
Does not account for sex	28	0.64 (0.56-0.72)	<.001	173.7	<.001
Accounts for race/ethnicity	42	0.89 (0.79-1.00)	.056	276.4	<.001	<.001
Does not account for race and ethnicity	43	0.68 (0.61-0.75)	<.001	268.0	<.001
Accounts for comorbidities	14	0.81 (0.66-1.00)	.05	214.7	<.001	.40
Does not account for comorbidities	71	0.74 (0.68-0.81)	<.001	349.9	<.001
Accounts for stage	47	0.87 (0.78-0.97)	.01	291.1	<.001	<.001
Does not account for stage	38	0.67 (0.60-0.74)	<.001	217.9	<.001
Accounts for histology	34	0.94 (0.82-1.07)	.33	246.5	<.001	<.001
Does not account for histology	51	0.68 (0.62-0.75)	<.001	286.2	<.001
Accounts for performance status	23	0.80 (0.68-0.94)	.01	256.1	<.001	.39
Does not account for performance status	62	0.74 (0.67-0.81)	<.001	320.2	<.001
Accounts for line of treatment	43	0.72 (0.64-0.82)	<.001	575.0	<.001	.15
Does not account for line of treatment	42	0.81 (0.73-0.90)	<.001	112.0	<.001
Accounts for trial eligibility	17	0.85 (0.75-0.97)	.01	37.0	.002	.17
Does not account for trial eligibility	52	0.73 (0.66-0.81)	<.001	244.1	<.001
Missing data on trial eligibility	16	0.76 (0.63-0.92)	.004	266.5	<.001
Routine care group does not include trial refusers	2	0.96 (0.73-1.26)	.76	0.1	.74	.004
Routine care group includes trial refusers	14	0.93 (0.83-1.04)	.18	19.2	.12
Missing data on the inclusion of trial refusers	69	0.73 (0.66-0.81)	<.001	653.9	<.001
Treatment characteristics
Accounts for treatment effect (same treatments)	45	0.69 (0.62-0.77)	<.001	291.8	<.001	.01
Does not account for treatment effect (different treatments)	30	0.87 (0.76-0.99)	.04	58.3	<.001
Missing data on treatment effect	10	0.88 (0.69-1.11)	.28	191.8	<.001
Setting characteristics
Similar time period for comparison groups	59	0.80 (0.72-0.88)	<.001	460.1	<.001	.08
Different time period for comparison groups	26	0.69 (0.60-0.78)	<.001	149.8	<.001
Compares routine care group to a single trialb	54	0.73 (0.65-0.82)	<.001	301.4	<.001	.32
Compares routine care group to multiple trialsb	31	0.79 (0.70-0.90)	<.001	322.4	<.001
Other characteristics
Routine care group data source is registries	67	0.75 (0.67-0.82)	<.001	632.8	<.001	.42
Routine care group data source is medical records	18	0.80 (0.70-0.91)	.001	53.7	<.001
Accounts for the same trial and routine care group sourcesc	29	0.82 (0.74-0.90)	<.001	70.8	<.001	.18
Does not account for the same trial and routine care group sourcesc	56	0.74 (0.65-0.83)	<.001	617.3	<.001
Trial sample size of ≥200	48	0.75 (0.67-0.84)	<.001	613.1	<.001	.73
Trial sample size of <200	37	0.77 (0.69-0.85)	<.001	69.1	<.001

^a Shows whether there is a significant difference between items in each subgroup (eg, in the first category, the P value of .002 shows that there is a statistically significant difference in survival estimates for comparisons that did vs did not account for age.

^b Studies that compared routine care patient groups to the same trial only included 1 trial in the trial group, whereas comparing to multiple trials included more than 1 trial in the trial participant group.

^c Studies accounting for the same trial and routine care sources indicated that both groups were from the same source. For example, the Surveillance, Epidemiology, and End Results (SEER) Program covers all the US, so it is not the same location, but if both trial and routine care groups are from the SEER database, then they accounted for similar group sources.