Marieke van Son

32 CHAPTER 2 Table 2 – Balance assessment before and after applying propensity score matching weights Unweighted Weighted Radical Focal SMD Radical Focal SMD Age (mean, SD) 66.4 (7.5) 65.7 (7.4) 0.105 66 (7.3) 66 (7.4) 0.001 PSA (mean, SD) 9.6 (4) 7.9 (3.8) 0.441 8.6 (3.5) 8.5 (3.9) 0.022 ISUP grade 1 (%) 2 (%) 3 (%) 25.4% 52.3% 22.3% 28.5% 60.6% 10.9% 0.309 31.4% 56.4% 12.2% 31.7% 55.8% 12.5% 0.011 MCCL (mean, SD) 6.6 (3.9) 6.5 (4) 0.034 6.3 (3.8) 6.3 (3.4) 0.003 T-stage T1 (%) T2 (%) 12% 88% 13.8% 86.2% 0.051 12.7% 87.3% 12.7% 87.3% 0.002 Year (mean) 2014 2011 1.040 2011 2011 0.026 N or ESS (weighted) 830 530 385.2 376.5 Legend: SMD=standardized mean difference, SD=standard deviation, PSA=prostate specific antigen, ISUP=International Society of Urological Pathology, MCCL=maximum cancer core length, N =number of patients, ESS=effective sample size. Table 3 displays the Cox-estimated average treatment effect on hazard of failure and mortality after weighting, showing no significant differences between both groups. Figure 1 shows the PSW-adjusted Kaplan Meier survival curves estimating FFS (Figure 1a) and OS (Figure 1b). Overall, median time to treatment failure was 36 months (IQR 20-62) and median time to death was 43 months (IQR 25-66). Although there was no clear difference during the first five years of follow-up, FT patients had faster declining FFS afterwards (6-year FFS 80.3%, 95% CI 73.9-87.3 [radical] versus 72.8%, 66.8-79.8 [focal]; p =0.10). After radical treatment, 6-year OS was significantly lower (93.4%, 90.1- 95.2 versus 97.5%, 94-99.9; p =0.02). Table 3 – Estimated average treatment effect on treatment failure and overall mortality Propensity score weighted HR (95% CI) SE p-value Treatment failure Focal versus radical 1.29 (0.96-1.75) 0.15 0.10 Overall mortality Focal versus radical 0.49 (0.22-1.09) 0.41 0.08 Legend: HR=hazard ratio, 95% CI=95% confidence interval, SE=standard error.