Graph showing cumulative incidence function of reoperation according to each stage. At 5 years, cumulative incidence function was 0% in stage 2 (red line), 5.0 ± 2.87% in stage 3 (blue line) and 4.3 ± 4.15% in stages 4 and 5 (green line) (P = 0.202). A colour version of this figure appears in the online version of this article.