Elderly patients over 80 years undergoing colorectal cancer resection: Development and validation of a predictive nomogram for survival

Table 1 Patient demographics, clinicopathologic, and surgical characteristics

Variable	Total, n (%)	Training cohort, n (%)	Validation cohort, n (%)	P value
Total case	295	177	118
Follow-up period (mo)
Median (IQR)	22.68 (13.54, 37.00)	23.43 (14.04, 37.00)	21.00 (12.93, 37.75)	0.798
Age (yr)
Median (IQR)	83 (81, 86)	82 (81, 86)	83 (81, 86)	0.738
80-89	269 (91.19)	161 (90.96)	108 (91.53)	0.867
90-99	26 (8.81)	16 (9.04)	10 (8.47)
Sex
Male	135 (45.76)	81 (45.76)	54 (45.76)	0.998
Female	160 (54.24)	96 (54.24)	64 (54.24)
Race
Chinese	274 (92.88)	165 (93.22)	109 (92.37)	0.491
Malay	6 (2.03)	3 (1.69)	3 (2.54)
Indian	9 (3.06)	4 (2.26)	5 (4.24)
Others	6 (2.03)	5 (2.83)	1 (0.85)
ASA classification
1	2 (0.68)	1 (0.56)	1 (0.85)	0.599
2	90 (30.51)	52 (29.38)	38 (32.20)
3	187 (63.39)	112 (63.28)	75 (63.56)
4	16 (5.42)	12 (6.78)	4 (3.39)
BMI (kg/m2)
Median (IQR)	22.43 (19.82, 25.68)	22.51 (20.08, 25.82)	22.23 (19.31, 25.19)	0.480
≥ 18.5	252 (85.42)	154 (87.01)	98 (83.05)	0.346
< 18.5	43 (14.58)	23 (12.99)	20 (16.95)
Smoking
No	281 (95.25)	170 (96.05)	111 (94.07)	0.434
Yes	14 (4.75)	7 (3.95)	7 (5.93)
Congestive heart failure within 30 d
No	289 (97.97)	174 (98.31)	115 (97.46)	0.686
Yes	6 (2.03)	3 (1.69)	3 (2.54)
COPD
No	291 (98.64)	174 (98.31)	117 (99.15)	0.652
Yes	4 (1.36)	3 (1.69)	1 (0.85)
Diabetes mellitus
No	217 (73.56)	133 (75.14)	84 (71.19)	0.451
Yes	78 (26.44)	44 (24.86)	34 (28.81)
Preoperative dialysis dependent
No	291 (98.64)	174 (98.31)	117 (99.15)	0.652
Yes	4 (1.36)	3 (1.69)	1 (0.85)
CCI
0	2 (0.68)	1 (0.56)	1 (0.85)	0.118
1-2	98 (33.22)	50 (28.25)	48 (40.68)
3-4	62 (21.02)	40 (22.60)	22 (18.64)
≥ 5	133 (45.08)	86 (48.59)	47 (39.83)
Serum albumin (g/dL)
Median (IQR)	3.6 (3.2, 3.9)	3.6 (3.1, 3.9)	3.6 (3.2, 3.9)	0.316
≥ 3.0	261 (88.48)	160 (90.40)	101 (85.59)	0.209
2.5-3.0	27 (9.15)	12 (6.78)	15 (12.71)
< 2.5	7 (2.37)	5 (2.82)	2 (1.70)
Priority of operation
Elective	206 (69.83)	121 (68.36)	85 (72.03)	0.501
Emergency	89 (30.17)	56 (31.64)	33 (27.97)
Method of operation
Open	135 (45.76)	80 (45.20)	55 (46.61)	0.812
Minimally invasive surgery	160 (54.24)	97 (54.80)	63 (53.39)
Type of operation
Right hemicolectomy	110 (37.29)	65 (36.72)	45 (38.14)	0.942
Left hemicolectomy	8 (2.71)	5 (2.83)	3 (2.54)
High anterior resection	86 (29.15)	51 (28.81)	35 (29.66)
Low anterior resection	52 (17.63)	30 (16.95)	22 (18.64)
Subtotal/total colectomy	13 (4.40)	10 (5.65)	3 (2.54)
Abdominoperineal resection	12 (4.07)	7 (3.95)	5 (4.24)
Hartmann's procedure	14 (4.75)	9 (5.09)	5 (4.24)
Stoma
No	205 (69.49)	123 (69.49)	82 (69.49)	0.529
Loop ileostomy	23 (7.80)	10 (5.65)	13 (11.02)
End ileostomy	6 (2.03)	5 (2.82)	1 (0.85)
Ileo-colostomy	8 (2.71)	5 (2.82)	3 (2.54)
Loop colostomy	19 (6.44)	12 (6.78)	7 (5.93)
End colostomy	34 (11.53)	22 (12.44)	12 (10.17)
TNM staging
I	61 (20.68)	40 (22.60)	21 (17.80)	0.274
II	88 (29.83)	50 (28.25)	38 (32.20)
III	129 (43.73)	80 (45.20)	49 (41.53)
IV	17 (5.76)	7 (3.95)	10 (8.47)
Postoperative anastomotic leak
No	289 (97.97)	173 (97.74)	116 (98.31)	0.999
Yes	6 (2.03)	4 (2.26)	2 (1.69)
Postoperative pneumonia
No	276 (93.56)	165 (93.22)	111 (94.07)	0.771
Yes	19 (6.44)	12 (6.78)	7 (5.93)
Postoperative myocardial infarction
No	288 (97.63)	172 (97.18)	116 (98.31)	0.706
Yes	7 (2.37)	5 (2.82)	2 (1.69)
Postoperative 30-d readmission
No	255 (86.44)	154 (87.01)	101 (85.59)	0.729
Yes	40 (13.56)	23 (12.99)	17 (14.41)
Postoperative 30-d mortality
No	289 (97.97)	175 (98.87)	114 (96.61)	0.222
Yes	6 (2.03)	2 (1.13)	4 (3.39)
Postoperative 1-yr mortality
No	206 (69.83)	124 (70.06)	82 (69.49)	0.918
Yes	89 (30.17)	53 (29.94)	36 (30.51)

Continuous variables were presented as median (interquartile range). Categorical variables were presented as n (%). P values of categorical variables were calculated by χ² or Fisher’s exact test; P values of continuous variables were calculated by the Wilcoxon-Mann-Whitney test. IQR: Interquartile range; ASA: American Society of Anaesthesiologists classification; BMI: Body mass index; COPD: Chronic obstructive pulmonary disease; CCI: Charlson comorbidity index; TNM: Tumor-node-metastasis.