Table 3 Patient demographics, preoperative staging, and treatment according to the inflection points in the three learning curves

Consecutive no. of patients

1–42

43–104

1–43

44–75

76–104

1–68

69–98

Sex, n (%)

0.186

0.395

 Male

34 (81.0%)

43 (69.4%)

35 (81.4%)

23 (71.9%)

19 (65.5%)

51 (75.0%)

20 (66.7%)

 Female

8 (19.0%)

19 (30.6%)

8 (18.6%)

9 (28.1%)

10 (34.5%)

17 (25.0%)

10 (33.3%)

Age, mean (SD)

64.5 (10.7)

59.5 (11.7)

0.028

63.8 (11.4)

58.6 (10.8)

61.2 (12.0)

60.8 (10.5)

60.4 (12.6)

0.883

BMI, kg/m², median (IQR)

24.2 (21.6–26.1)

24.1 (22.5–26.0)

0.691

24.2 (21.6–26.1)

24.6 (22.6–26.2)

23.9 (22.2–26.0)

24.4 (22.4–26.1)

23.9 (22.3–26.0)

0.988

Comorbidity, n (%)

22 (52.4%)

26 (41.9%)

0.294

22 (51.2%)

12 (37.5%)

14 (48.3%)

29 (42.6%)

14 (46.7%)

0.712

ASA, n (%)

0.058

0.745

 I

6 (14.3%)

3 (4.8%)

6 (14.0%)

1 (3.1%)

2 (6.9%)

6 (8.8%)

3 (10.0%)

 II

26 (61.9%)

51 (82.3%)

27 (62.8%)

26 (81.2%)

24 (82.8%)

51 (75.0%)

24 (80.0%)

 III

10 (23.8%)

8 (12.9%)

10 (23.3%)

5 (15.6%)

3 (10.3%)

11 (16.2%)

3 (10.0%)

Neoadjuvant therapy, n (%)

18 (42.9%)

33 (53.2%)

0.299

19 (44.2%)

23 (71.9%)

9 (31.0%)&

40 (58.8%)

9 (30.0%)

0.009

Previous abdominal surgery, n (%)

10 (23.8%)

11 (17.7%)

0.449

10 (23.3%)

7 (21.9%)

4 (13.8%)

15 (22.1%)

4 (13.3%)

0.314

Distance from anal verge, mm, median (IQR)

48.0 (40.2–58.0)

52.5 (39.8–70.8)

0.428

47.0 (40.0–58.0)

46.0 (38.8–64.0)

58.0 (43.0–77.0)

46.5 (40.0–58.5)

59.0 (43.0–79.2)

0.035

Middle rectum, n (%)

16 (38.1%)

32 (51.6%)

0.175

16 (37.2%)

13 (40.6%)

19 (65.5%)

26 (38.2%)

20 (66.7%)

0.009

Lower rectum, n (%)

26 (61.9%)

30 (48.4%)

0.175

27 (62.8%)

19 (59.4%)

10 (34.5%)

42 (61.8%)

10 (33.3%)

0.009

Preoperative CRM involvement, n (%)

10 (23.8%)

12 (19.4%)

0.585

11 (25.6%)

8 (25.0%)

3 (10.3%)

18 (26.5%)

3 (10.0%)

0.067