Fig. 6
Subgroup analysis of the association between restenosis and different follow-up times. The vertical dashed lines indicate the pooled summary estimate (95% CI) for all studies in Fig. 6 (‘More than 1 year’ subgroup, RR = 1.41, 95% CI, 1.16–1.70; I2 = 58.7%, P = 0.018, ‘Equal to or less than 1 year’ subgroup, RR = 1.44, 95% CI, 1.19–1.74; I2 = 60.8%, P = 0.003.). The area of each square is proportional to the inverse variance of the estimate. The horizontal lines indicate the 95% confidence intervals of the estimate