Supplementary Material for: A clinical learning curve study of polydimethylsiloxane Urolastic for stress urinary incontinence: does safety improve when expertise grow?

Objectives To characterize the learning curve of bulk injection therapy PDMS-U for SUI. Design Secondary analysis from three clinical studies on efficacy and safety outcomes of PDMS-U. Participants/Materials, Setting, Methods PDMS-U certified physicians who performed ≥4 procedures were included. The primary outcome was the number of PDMS-U procedures needed to achieve acceptable failure rates for ‘complications overall’, ‘urinary retention’ and ‘excision’, using the LC-CUSUM method. For the primary outcome, physicians who performed ≥ 20 procedures were used. For the secondary outcome, logistic and linear regression analysis was used to assess the relationship between number of procedures, complications (complications overall, urinary retention, pain, exposure, excision of PDSM-U) and duration of treatment. Results In total, 203 PDMS-U procedures were performed by nine physicians. Five physicians were used for the primary outcome. For ‘complications overall’, ‘urinary retention’ and ‘excision’, two physicians reached a level of competence: one at procedure 20 and one at procedure 40. The secondary outcome showed no statistically significant association between procedure number and complications. There was a statistically significant increase in the duration of treatment with more physician experience (mean difference 0.83 minutes per 10 additional procedures, 95%CI 0.16 to 1.48). Limitations One limitation is that retrospectively collected data might have underreported the number of complications. Secondly, there was variation in the way the technique was applied between physicians. Conclusions Physicians’ experience in the PDMS-U procedure did not influence safety outcomes. There was large inter-physician variability and most physicians did not reach acceptable failure rates. There was no relationship between PDMS-U complications and the number of performed procedures.