Table 1. Study, Patient, and Testing Characteristics of Included Studies of Changes in Reoperation.

Variable	Studies, No.	Patients, No. (%)	Study-level estimates, median (range)
All included studies
No.	30	599 016 (100.0)	487 (100-521 578)
Publication type
Full text	15	559 723 (93.4)	846 (201-521 578)
Conference abstract	15	39 293 (6.6)	417 (100-33 966)
Country
United States	20	590 947 (98.7)	449 (100-521 578)
Canada	3	2223 (0.4)	599 (512-1112)
United Kingdom	6	5284 (0.9)	457 (317-2858)
Australia	1	562 (0.1)	562
Study design, change
Actual	21	592 348 (98.9)	599 (100-521 578)
Projected	9	6668 (1.1)	450 (317-2858)
Studies of actual change in reoperation rates
Years of recruitment (midpoint)
Preguideline	20a	151 178 (25.5)	2012 (2006-2013)
Postguideline	20a	441 170 (74.5)	2014 (2014-2016)
Study setting
Institutional	17	8726 (1.5)	463 (100-1205)
Population	4	583 622 (98.5)	30 034 (1976-521 578)
Preguideline margin
1 mm	3b	1645 (31.8)	562 (237-846)
≥2 mm	6b	3534 (68.2)	572 (119-1112)
Studies of projected change in reoperation rates
Years of recruitment (midpoint)
Preguideline	9c	6668 (100.0)	2012 (2005-2016)
Study setting
Institutional	9	6668 (100.0)	450 (317-2858)
Population	0	NA	NA
Preguideline margin
1 mm	3	3592 (53.9)	417 (317-2858)
≥2 mm	6	3076 (46.1)	456 (436-779)

Abbreviation: NA, not applicable.

^aOne study²¹ did not report sufficient information to derive midpoints of recruitment.

^bTwelve of 21 studies (57.1%)^{17,19,21,23,26,28,30,32,33,37,38,40} of actual changes in reoperation did not report the preguideline margin threshold.

^cTwo studies^35,43 of projected changes included women in the postguideline period. The Society of Surgical Oncology–American Society for Radiation Oncology guideline was not used in this period.