Table 4. Summary of regression analysesa.

	Number of studies	Slope parameter estimate (95% CI)	R2 (adjusted)
Primary model – all studies	67	0.32 (0.20, 0.43)	0.30
Studies of hormonal treatments	12	0.58 (0.001, 1.17)	0.24
Studies of anthracyclines	36	0.32 (0.19, 0.43)	0.43
Studies of first-line treatments for MBC	46	0.29 (0.15, 0.42)	0.28
Studies of non first-line treatments	21	0.38 (0.14, 0.62)	0.32
Studies with only HER2+patients	4	0.50 (0.28, 0.71)	0.93
Studies which reported HRs	10	0.52 (0.18, 0.86)	0.52
Studies where TTP in standard group ⩾6 months	37	0.32 (0.18, 0.47)	0.35
Studies with N per group ⩾100	36	0.31 (0.16, 0.47)	0.31

CI=confidence interval.

^aModels without intercept and weighted by sample size.