Use of ureteric stents
The data extraction process is summarised in Supporting Information 1, Supplementary Figure 2 . Data were available for 54,124 patients. The mean age of patients was 47.9 years (SD 17.449) before GIRFT visits and 48.5 years (SD 15.896) after. Procedures were conducted across 123 trusts during the baseline pre-visit period. In the pre-visit period, in the 121 trusts seeing 50 patients or more during the study period, the mean percentage of patients receiving a stent varied between 0% and 46.0% across trusts and ureteroscopy or ESWL use varied from 0.7% to 38.7%. During the pre-visit period 6.4% of patients received ureteroscopy or ESWL during the first emergency admission and 4.3% at a subsequent elective admission in the following 30 days.
The change in the use of ureteric stents and ureteroscopy or ESWL across the study period is summarised in Figures 2 and 3respectively. The ITSAs for both outcomes are presented in Table 1 . At the start of the study period an average of 12.2% of patients received a stent during their first emergency admission. During the pre-GIRFT visit period this proportion rose significantly by an average of 0.105% per 30 day period (1.3% per annum), after the GIRFT visit stent use had no significant trend with time, declining by 0.044% per 30 day period. However, the change in trend from pre- to post-visit was significant at -0.148% per 30 day period, (1.8% per annum).
For use of ureteroscopy or ESWL to treat ureteric stones, at the start of the study period an average of 10.8% of patients received ureteroscopy or ESWL during their first emergency admission or electively within 30 days of this admission without first receiving a stent. During the pre-GIRFT visit period this proportion did not change significantly with time. After the GIRFT visit ureteroscopy or ESWL use increased significantly at a rate of 0.073% per 30 day period (0.9% per annum).