Change point analysis validation of the learning curve in laparoscopic colorectal surgery: Experience from a non-structured training setting

Table 1 Patient characteristics

		Total	Colon operations	Rectal operations	P value
n		214	133	81
Sex	Male	128 (59.8%)	78 (58.6%)	50 (61.7%)	NS
	Female	86 (40.2%)	55 (41.4%)	31 (38.3%)
Age (yr)		70 (13)	71 (14)	68 (13)	NS
BMI (kg/m2)		27 (5)	28 (5)	26.5 (4)	NS
ASA score	I	71 (33.2%)	35 (26.3%)	36 (44.4%)	0.021
	II	117 (54.7%)	79 (59.4%)	38 (46.9%)
	III	26 (12.1%)	19 (14.3%)	7 (8.6%)
Diagnosis	Malignancy	206 (96.3%)	125 (94%)	81 (100%)	NS
	Diverticulitis	6 (2.8%)	6 (4.5%)	0 (0%)
	Volvulus	1 (0.5%)	1 (0.8%)	0 (0%)
	Crohn’s disease	1 (0.5%)	1 (0.8%)	0 (0%)
Previous operation		17 (7.9%)	13 (9.8%)	4 (4.9%)	NS
T	1	51 (24.8%)	33 (26.4%)	18 (22.2%)	NS
	2	63 (30.6%)	39 (31.2%)	24 (29.6%)
	3	85 (41.3%)	47 (37.6%)	38 (46.9%)
	4	7 (3.4%)	6 (4.8%)	1 (1.2%)
N	0	153 (74.3%)	89 (71.2%)	64 (79%)	NS
	1	42 (20.4%)	30 (24%)	12 (14.8%)
	2	11 (5.3%)	6 (4.8%)	5 (6.2%)
M	0	205 (99.5%)	125 (100%)	80 (98.8%)	NS
	1	1 (0.5%)	0 (0%)	1 (1.2%)
Neoadjuvant modality		19 (9.2%)	2 (1.6%)	17 (20%)	< 0.001
Complexity level	1	116 (54.2%)	74 (55.6%)	42 (51.9%)	0.022
	2	82 (38.2%)	44 (33.1%)	38 (46.9%)
	3	6 (2.8%)	6 (4.5%)	0 (0%)
	4	10 (4.7%)	9 (6.8%)	1 (1.2%)
Operation	Right colectomy	76 (35.5%)	76 (57.1%)	-	< 0.001
	Left colectomy	31 (14.5%)	31 (23.3%)	-
	Sigmoidectomy	26 (12.1%)	26 (19.5%)	-
	Low anterior resection	72 (33.6%)	-	72 (88.9%)
	Ultra-low anterior resection	7 (3.3%)	-	7 (8.6%)
	Abdominoperineal resection	2 (1%)	-	2 (2.4%)
Emergency status	Elective	212 (99.1%)	131 (98.5%)	81 (100%)	NS
	Semi-elective	2 (0.9%)	2 (1.5%)	0 (0%)
Laparoscopic approach	Totally laparoscopic	182 (85%)	127 (95.5%)	55 (67.9%)	< 0.001
	Laparoscopy assisted	32 (15%)	6 (4.5%)	26 (32.1%)
Preoperative optimization	Bowel preparation	191 (89.3%)	112 (84.2%)	79 (97.5%)	0.002
	Antibiotic preparation	206 (96.3%)	127 (95.5%)	79 (97.5%)	NS
	Tattoo	51 (23.8%)	28 (21.1%)	23 (28.4%)	NS
Extraction site	Pfannenstiel	95 (44.4%)	40 (30.1%)	55 (67.9%)	< 0.001
	Subumbilical	19 (8.9%)	4 (3%)	15 (18.5%)
	Transumbilical	100 (46.7%)	89 (66.9%)	11 (13.6%)
Anastomosis	Stapled	159 (75%)	80 (60.2%)	79 (100%)	< 0.001
	Handsewn	53 (25%)	53 (39.8%)	0 (0%)
	Intracorporeal	112 (52.8%)	50 (37.6%)	62 (78.4%)	< 0.001
	Extracorporeal	100 (47.1%)	83 (62.4%)	17 (21.5%)
	Protective stoma	66 (30.8%)	9 (6.8%)	57 (70.4%)	< 0.001
Operation duration (min)		180 (51)	180 (50)	200 (60)	< 0.001
Open conversion		20 (9.3%)	6 (4.5%)	14 (17.3%)	0.002
Transfusion		8 (3.7%)	4 (3%)	4 (4.9%)	NS
Tumor diameter (cm)		3 (2.2)	3 (2)	3.75 (2.5)	NS
Specimen length (cm)		20 (9)	21 (7)	15 (7)	< 0.001
Distal margin (cm)		5 (4.35)	5.25 (3.5)	4.5 (4.25)	0.01
Lymph nodes		17 (12)	19 (13)	15 (11)	0.004
Lymph node ratio		0 (2.3)	0 (4)	0 (0)	NS
Histological grade	1	40 (19.4%)	20 (16%)	20 (24.7%)	NS
	2	135 (65.5%)	89 (71.2%)	46 (56.8%)
	3	31 (15%)	16 (12.8%)	15 (18.5%)
R status	0	204 (95.3%)	124 (99.2%)	80 (98.8%)	NS
	1	2 (0.9%)	1 (0.8%)	1 (1.2%)
Resection plane	Mesocolic/mesorectal	183 (88.8%)	108 (86.4%)	75 (88.8%)	NS
	Intramesocolic/intramesorectal	19 (9.2%)	14 (11.2%)	5 (6.2%)
	Muscularis propria	4 (1.9%)	3 (2.4%)	1 (1.2%)
Extramural vascular invasion		54 (26.2%)	33 (26.4%)	21 (25.9%)	NS
Perineural invasion		21 (10.2%)	13 (10.4%)	8 (9.9%)	NS
Mucous	Focal	29 (14.1%)	20 (16%)	9 (11.1%)	NS
	Diffuse	20 (9.7%)	15 (12%)	5 (6.2%)
Complications	Total	49 (22.9%)	33 (24.8%)	16 (19.8%)	NS
	Wound infection	9 (4.2%)	5 (3.8%)	4 (4.9%)	NS
	Wound dehiscence	2 (0.9%)	2 (1.5%)	0 (0%)
	Leak	14 (6.5%)	10 (7.5%)	4 (4.9%)
	Postoperative ileus	11 (5.1%)	8 (6%)	3 (3.7%)
	Urinary tract infection	2 (0.9%)	0 (0%)	2 (2.5%)
	Urinary retention	2 (0.9%)	1 (0.8%)	1 (1.2%)
	Bleeding	3 (1.4%)	1 (0.8%)	2 (2.5%)
	Pulmonary embolism	2 (0.9%)	2 (1.5%)	0 (0%)
	ARDS	1 (0.5%)	0 (0%)	1 (1.2%)
	Other	4 (1.9%)	4 (3%)	0 (0%)
Relaparotomy		11 (5.1%)	8 (6%)	3 (3.7%)	NS
ICU		8 (3.7%)	5 (3.8%)	3 (3.7%)	NS
Mortality		5 (2.3%)	4 (3%)	1 (1.2%)	NS
Length of hospital stay (d)		6 (2)	6 (2)	6 (2)	NS
Follow-up (mo)		2 (3.75)	2 (5.8)	2 (2.5)	NS

NS: Non-significant; BMI: Body mass index; ASA: American Society of Anesthesiologists; ARDS: Acute respiratory distress syndrome; ICU: Intensive care unit.

Table 2 Patient characteristics in different phases of the learning curve

			Overall				Colon			Rectal
			Phase I (1-109)	Phase II (110-144)	Phase III (145-214)	P value	Phase I (1-57)	Phase II (58-133)	P value	Phase I (1-51)	Phase II (52-81)	P value
N			109	35	70		57	76		51	30
Sex	Male		68 (62.4%)	24 (68.6%)	36 (51.4%)	NS	37 (64.9%)	41 (53.9%)	NS	30 (58.8%)	20 (66.7%)	NS
	Female		41 (37.6%)	11 (31.4%)	34 (48.6%)		20 (35.1%)	35 (46.1%)		21 (41.2%)	10 (33.3%)
Age (yr)			71.5 (12)	70 (13)	69.5 (14)	NS	72 (14)	71 (13)	NS	69.5 (12)	67 (16)	NS
BMI (kg/m2)			27 (5)	28 (4)	27 (5)	NS	28 (6)	28 (5)	NS	26 (3)	27.5 (6)	NS
ASA score	I		36 (33%)	13 (37.1%)	22 (31.4%)	NS	14 (24.6%)	21 (27.6%)	NS	21 (41.2%)	15 (50%)	NS
	II		62 (56.9%)	16 (45.7%)	39 (55.7%)		35 (61.4%)	44 (57.9%)		27 (52.9%)	11 (36.7%)
	III		11 (10.1%)	6 (17.1%)	9 (12.9%)		8 (14%)	11 (14.5%)		3 (5.9%)	4 (13.3%)
Diagnosis	Malignancy		106 (97.2%)	34 (97.1%)	66 (94.3%)	NS	54 (94.7%)	71 (93.4%)	NS	51 (100%)	30 (100%)	-
	Diverticulitis		2 (1.8%)	1 (2.9%)	3 (4.3%)		2 (3.5%)	4 (5.3%)		-	-
	Volvulus		1 (0.9%)	0 (0%)	0 (0%)		1 (1.8%)	0 (0%)		-	-
	Crohn’s disease		0 (0%)	0 (0%)	1 (1.4%)		0 (0%)	1 (1.3%)		-	-
Previous operation			13 (11.9%)	2 (5.7%)	2 (2.9%)	NS	9 (15.8%)	4 (5.3%)	0.04	4 (7.8%)	0 (0%)	NS
T	1		24 (22.6%)	6 (17.6%)	21 (31.8%)	NS	12 (22.6%)	21 (29.2%)	NS	12 (23.5%)	6 (20%)	NS
	2		34 (32.1%)	7 ( (20.6%)	22 (33.3%)		16 (30.2%)	23 (31.9%)		18 (35.3%)	6 (20%)
	3		43 (40.6%)	20 (58.8%)	22 (33.3%)		21 (39.6%)	26 (36.1%)		20 (39.2%)	18 (60%)
	4		5 (4.7%)	1 (2.9%)	1 (1.5%)		4 (7.5%)	2 (2.8%)		1 (2%)	0 (0%)
N	0		77 (74.5%)	25 (73.5%)	49 (74.2%)	NS	36 (67.9%)	53 (73.6%)	NS	41 (80.4%)	23 (76.7%)	NS
	1		23 (21.7%)	6 (17.6%)	13 (19.7%)		16 (30.2%)	14 (19.4%)		6 (13.7%)	5 (16.7%)
	2		4 (3.8%)	3 (8.8%)	4 (6.1%)		1 (1.9%)	5 (6.9%)		3 (5.9%)	2 (6.7%)
M	0		106 (100%)	34 (100%)	65 (98.5%)	NS	53 (100%)	72 (100%)	-	51 (100%)	29 (96.7%)	NS
	1		0 (0%)	0 (0%)	1 (1.5%)		-	-		0 (0%)	1 (3.3%)
Neoadjuvant modality			6 (5.5%)	5 (14.3%)	8 (11.4%)	NS	0 (0%)	2 (2.6%)	NS	6 (11.8%)	11 (36.7%)	0.008
Complexity level	1		50 (54.1%)	13 (37.1%)	44 (62.9%)	NS	29 (50.9%)	45 (59.2%)	NS	30 (58.8%)	12 (40%)	NS
	2		42 (38.5%)	20 (57.1%)	20 (28.6%)		21 (36.8%)	23 (30.3%)		20 (39.2%)	18 (60%)
	3		2 (1.8%)	1 (2.9%)	3 (4.3%)		2 (3.5%)	4 (5.3%)		0 (0%)	0 (0%)
	4		6 (5.5%)	1 (2.9%)	3 (4.3%)		5 (8.8%)	4 (5.3%)		1 (2%)	0 (0%)
Operation	Right colectomy		34 (31.2%)	13 (37.1%)	29 (41.4%)	NS	34 (59.6%)	42 (55.3%)	NS	-	-	NS
	Left colectomy		10 (9.2%)	6 (17.1%)	15 (21.4%)		10 (17.5%)	21 (27.6%)		-	-
	Sigmoidectomy		13 (11.9%)	2 (5.7%)	11 (15.7%)		13 (22.8%)	13 (17.1%)		-	-
	Low anterior resection		46 (42.2%)	13 (37.1%)	13 (18.6%)		-	-		45 (88.2%)	27 (90%)
	Ultra-low anterior resection		4 (3.7%)	1 (2.9%)	2 (2.9%)		-	-		4 (7.8%)	3 (10%)
	Abdominoperineal resection		2 (1.8%)	0 (0%)	0 (0%)		-	-		2 (4%)	0 (0%)
Emergency status	Elective		109 (100%)	35 (100%)	68 (97.1%)	NS	57 (100%)	74 (97.4%)	NS	51 (100%)	30 (100%)	-
	Semi-elective		0 (0%)	0 (0%)	2 (2.9%)		0 (0%)	2 (2.6%)		-	-
Laparoscopic approach	Totally laparoscopic		98 (89.9%)	24 (68.6%)	60 (85.7%)	0.009	56 (98.2%)	71 (93.4%)	NS	41 (80.4%)	14 (46.7%)	0.002
	Laparoscopy assisted		11 (10.1%)	11 (31.4%)	10 (14.3%)		1 (1.8%)	5 (6.6%)		10 (19.6%)	16 (53.3%)
Preoperative optimization	Bowel preparation		107 (98.2%)	30 (85.7%)	54 (77.1%)	< 0.001	56 (98.2%)	56 (73.7%)	< 0.001	50 (98%)	29 (96.7%)	NS
	Antibiotic preparation		105 (96.3%)	33 (94.3%)	68 (97.1%)	NS	54 (94.7%)	73 (96.1%)	NS	50 (98%)	29 (96.7%)	NS
	Tattoo		36 (33%)	2 (5.7%)	13 (18.6%)	0.002	17 (29.8%)	11 (14.5%)	0.032	19 (37.3%)	4 (13.3%)	0.021
Extraction site	Pfannenstiel		52 (47.7%)	15 (42.9%)	28 (40%)	NS	15 (26.3%)	25 (32.9%)	NS	37 (72.5)	18 (60%)	NS
	Subumbilical		12 (11%)	4 (11.4%)	3 (4.3%)		2 (3.5%)	2 (2.6%)		9 (17.6%)	6 (20%)
	Transumbilical		45 (41.3%)	16 (45.7%)	39 (55.7%)		40 (70.2%)	49 (64.5%)		5 (9.8%)	6 (20%)
Anastomosis	Stapled		85 (78.7%)	24 (70.6%)	50 (71.4%)	NS	34 (59.6%)	46 (60.5%)	NS	50 (100%)	29 (100%)	NS
	Handsewn		23 (21.3%)	10 (29.4%)	20 (28.6%)		23 (40.4%)	30 (39.5%)		0 (0%)	0 (0%)
	Intracorporeal		57 (52.8%)	16 (47.1%)	39 (55.7%)	NS	18 (31.6%)	32 (42.1%)	NS	38 (76%)	24 (82.8%)	NS
	Extracorporeal		51 (47.2%)	18 (52.9%)	31 (44.3%)		39 (68.4%)	44 (57.9%)		12 (24%)	5 (17.2%)
	Protective stoma		38 (34.9%)	11 (31.4%)	17 (24.3%)	NS	3 (5.3%)	6 (7.9%)	NS	34 (66.7%)	23 (76.7%)	NS
Operation duration (min)			180 (50)	220 (60)	180 (40)	< 0.001	160 (48)	180 (40)	0.003	200 (50)	220 (63)	0.003
Open conversion			13 (11.9%)	2 (5.7%)	5 (7.1%)	NS	4 (7%)	2 (2.6%)	NS	8 (15.7%)	6 (20%)	NS
Transfusion			5 (4.6%)	0 (0%)	3 (4.3%)	NS	3 (5.3%)	1 (1.3%)	NS	1 (2%)	3 (10%)	NS
Tumor diameter (cm)			3 (2.1)	4 (2.4)	3 (2)	NS	3 (1.5)	3.5 (2)	NS	4 (2.4)	3 (3)	NS
Specimen length (cm)			16.25 (7.25)	22.5 (6.5)	24 (8)	< 0.001	20.5 (8)	23 (8.75)	0.001	14.25 (3.75)	21 (6)	< 0.001
Distal margin (cm)			4 (3.5)	7 (2)	7 (5)	< 0.001	4 (2.5)	7 (3.5)	< 0.001	4 (4.25)	5 (4.5)	NS
Lymph nodes			15 (10)	20 (19)	21 (12)	0.016	15 (10)	22 (13)	0.002	15 (10)	12.5 (15)	NS
Lymph node ratio			0 (0)	0 (0.8)	0 (8)	NS	0 (4.5)	0 (3.8)	NS	0 (0)	0 (13.5)	NS
Histological grade		1	26 (24.5%)	1 (2.9%)	13 (19.7%)	0.013	10 (18.9%)	10 (13.9%)	0.009	16 (31.4%)	4 (13.3%)	NS
		2	60 (56.6%)	27 (79.5%)	48 (72.7%)		31 (58.5%)	58 (80.6%)		27 (52.9%)	19 (63.3%)
		3	20 (18.9%)	6 (17.6%)	5 (7.6%)		12 (22.6%)	4 (5.6%)		8 (15.7%)_	7 (23.3%)
R status		0	105 (99.1%)	33 (97.1%)	66 (100%)	NS	53 (98.1%)	71 (100%)	NS	51 (100%)	29 (96.7%)	NS
		1	1 (0.9%)	1 (2.9%)	0 (0%)		1 (1.9%)	0 (0%)		0 (0%)	1 (3.3%)
Resection plane		Mesocoli/mesorectal	91 (85.8%)	31 (91.2%)	61 (92.4%)	NS	43 (79.6%)	65 (91.5%)	NS	47 (92.2%)	28 (93.3%)	NS
		Intramesocolic/intramesorectal	12 (11.3%)	3 (8.8%)	4 (6.1%)		9 (16.7%)	5 (7%)		3 (5.9%)	2 (6.7%)
		Muscularis propria	3 (2.8%)	0 (0%)	1 (1.5%)		2 (3.7%)	1 (1.4%)		1 (2%)	0 (0%)
Extramural vascular invasion			30 (28.3%)	7 (20.6%)	17 (25.8%)	NS	13 (24.5%)	20 (27.8%)	NS	16 (31.4%)	5 (16.7%)	NS
Perineural invasion			13 (12.3%)	4 (11.8%)	4 (6.1%)	NS	7 (13.2%)	6 (8.3%)	NS	6 (11.8%)	2 (6.7%)	NS
Mucous		Focal	11 (10.4%)	12 (35.3%)	6 (9.1%)	0.006	6 (11.3%)	14 (19.4%)	NS	4 (7.8%)	5 (16.7%)	NS
		Diffuse	9 (8.5%)	3 (8.8%)	8 (12.1%)		7 (13.2%)	8 (11.1%)		2 (3.9%)	3 (10%)
Complications		Total	28 (25.7%)	9 (25.7%)	12 (17.1%)	NS	15 (26.3%)	18 (23.7%)	NS	12 (23.5%)	4 (13.3%)	NS
		Wound infection	5 (4.6%)	2 (5.7%)	2 (2.9%)	NS	1 (1.8%)	4 (5.3%)	NS	4 (7.8%)	0 (0%)	NS
		Wound dehiscence	1 (0.9%)	1 (2.9%)	0 (0%)		1 (1.8%)	1 (1.3%)		0 (0%)	0 (0%)
		Leak	8 (7.3%)	4 (11.4%)	2 (2.9%)		5 (8.8%)	5 (6.6%)		2 (3.9%)	2 (6.7%)
		Postoperative ileus	7 (6.4%)	1 (2.9%)	3 (4.3%)		4 (7%)	4 (5.3%)		3 (5.9%)	0 (0%)
		Urinary tract infection	2 (1.8%)	0 (0%)	0 (0%)		0 (0%)	0 (0%)		2 (3.9%)	0 (0%)
		Urinary retention	1 (0.9%)	0 (0%)	1 (1.4%)		0 (0%)	1 (1.3%)		1 (2%)	0 (0%)
		Bleeding	1 (0.9%)	0 (0%)	2 (2.9%)		0 (0%)	1 (1.3%)		1 (2%)	1 (3.3%)
		Pulmonary embolism	1 (0.9%)	1 (2.9%)	0 (0%)		1 (1.8%)	1 (1.3%)		0 (0%)	0 (0%)
		ARDS	0 (0%)	0 (0%)	1 (1.4%)		0 (0%)	0 (0%)		0 (0%)	1 (3.3%)
		Other	3 (2.8%)	0 (0%)	1 (1.4%)		3 (5.3%)	1 (1.3%)		0 (0%)	0 (0%)
Relaparotomy			5 (4.6%)	3 (8.6%)	3 (4.3%)	NS	2 (3.5%)	6 (7.9%)	NS	2 (3.9%)	1 (3.3%)	NS
ICU			6 (5.5%)	1 (2.9%)	1 (1.4%)	NS	4 (7%)	1 (1.3%)	NS	2 (3.9%)	1 (3.3%)	NS
Mortality			4 (3.7%)	1 (2.9%)	0 (0%)	NS	3 (5.3%)	1 (1.3%)	NS	1 (2%)	0 (0%)	NS
Length of hospital stay (d)			6 (2)	6 (3)	6 (2)	NS	6 (2)	6 (2)	NS	6 (2)	5 (1)	NS
Follow-up (mo)			2 (3.25)	0.65 (0)	6 (5)	NS	2 (3.3)	6.8 (4.4)	NS	2 (3)	0.27 (0)	0.032

BMI: Body mass index; ASA: American Society of Anesthesiologists; ARDS: Acute respiratory distress syndrome; ICU: Intensive care unit.