Quantifying, displaying and accounting for heterogeneity in the meta-analysis of RCTs using standard and generalised Qstatistics

Table 2 Subgroup analyses for the two examples.

Trial Group	# trials	Q, P-value, (%)	Fixed Effect HR (CI) P-value	Random Effects HR (CI) P-value
NSCLC data
all	11	39.6 (1.97e-05) 74.8	0.84 (0.74-0.95) 5.42e-03	0.77 (0.59-0.99) 0.042
Cisplatin	8	22.2 (2.34e-03) 68.5	0.73 (0.63-0.85) 6.63e-05	0.70 (0.53-0.93) 0.014
Q _int = 39.62 - (22.20 + 8.72) = 8.70 (p = 0.003)
all*	11		0.84 (0.61-1.16) 0.21
Cervix data
>14 days	11	12.76 (0.24) 22	1.25, (1.07,1.46) 0.005	1.27 (1.06,1.53) 0.0099
≤ 14 days	7	20.74 (0.002) 71	0.83, (0.69,1.00) 0.046	0.87 (0.60,1.25) 0.44
Q _int = 44.48 - (12.76 + 20.74) = 10.98 (p = 9e-04)

Q _intdenotes the subgroup interaction test statistic. * denotes the Henmi-Copas analysis: which puts a 'random effects' confidence interval around the fixed effects estimate.

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