Prediction of overall survival following colorectal cancer surgery in elderly patients

Table 3 Unadjusted hazard ratios of individual predictors in association with 3-year survival duration obtained via univariate Royston-Parmar regression

Predictors	n	HR (95%CI)	P value
Gender	1267	1.03 (0.81-1.31)	0.807
Age	1267	1.00 (0.98-1.03)	0.826
Race
Chinese	1148	1.00 (ref)
Malay	50	1.14 (0.60-2.14)	0.682
Indian	30	1.43 (0.78-2.68)	0.272
Others	39	0.67 (0.25-1.82)	0.433
Smoking status
Non-smoker	1055	1.00 (ref)
Smoker	212	1.07 (0.78-1.47)	0.692
Primary lesion site
Colon	790	1.00 (ref)
Rectum	477	1.40 (1.09-1.80)	0.008
Tumor stage
Tis/T1	97	1.00 (ref)
T2	188	1.52 (0.31-7.41)	0.605
T3	752	10.8 (2.7-43.1)	0.001
T4a	97	42.9 (10.5-173.5)	< 0.001
T4b	133	37.9 (9.38-153.2)	< 0.001
Tumor grade
Well differentiated	117	1.00 (ref)
Moderately differentiated	1009	3.85 (1.82-8.15)	< 0.001
Poorly differentiated or mucinous	141	8.59 (3.90-18.94)	< 0.001
Past medical history
Diabetes Mellitus	331	1.07 (0.81-1.41)	0.655
Hypertension	416	1.17 (0.91-1.51)	0.217
End stage renal failure	26	1.73 (0.54-5.53)	0.354
Previous myocardial infarction	47	0.95 (0.50-1.81)	0.881
Previous PCI, cardiac surgery or angina	140	1.36 (0.88-2.09)	0.161
Congestive heart failure	41	1.18 (0.52-2.69)	0.698
Peripheral vascular disease	30	1.14 (0.52-2.53)	0.744
Impaired sensorium, e.g., dementia	14	2.77 (0.40-19.2)	0.304
Chronic obstructive pulmonary disease	61	0.44 (0.29-0.68)	< 0.001
Previous stroke or TIA	90	1.08 (0.66-1.76)	0.758
Previous stroke with neurological deficits	38	1.19 (0.53-2.69)	0.675
Dependent functional status	60	0.81 (0.43-1.54)	0.529
ECOG
0	751	1.00 (ref)
1	404	0.98 (0.76-1.28)	0.903
2 or more	116	1.13 (0.72-1.79)	0.595
ASA
1	178	1.00 (ref)
2	857	0.75 (0.53-1.06)	0.099
3 or more	232	0.78 (0.51-1.19)	0.250
Laboratory parameters
Serum albumin (g/L)	1119	0.94 (0.92-0.96)	< 0.001
Carcinoembryonic antigen (µg/L)	1196	1.01 (1.00-1.01)	< 0.001
White blood cell count (× 109/L)	1267	1.11 (1.06-1.15)	< 0.001
Platelet count (× 103/L)	1267	1.00 (1.00-1.00)	< 0.001
Serum sodium (mmol/L)	1247	0.95 (0.91-0.98)	0.002
Serum creatinine (µmol/L)	1265	1.00 (0.99-1.00)	0.244
Serum potassium (mmol/L)	1263	0.75 (0.56-0.99)	0.049
Serum urea (mmol/L)	1264	0.98 (0.93-1.04)	0.517
Hemoglobin (g/dL)	1243	0.85 (0.79-0.91)	0.002
Lesion size (cm)	1267	2.03 (1.53-2.70)	< 0.001
Dichotomized predictorsa
Age ≥ 80 yr	1267	0.92 (0.70-1.21)	0.540
Serum albumin < 35 g/L	1266	2.16 (1.69-2.76)	< 0.001
Carcinoembryonic antigen ≥ 20 µg/L	1247	4.33 (3.39-5.54)	< 0.001
White blood cell count ≥ 8.5 × 109/L	1265	1.78 (1.40-2.28)	0.001
Platelet count ≥ 450 × 103/L	1263	2.36 (1.67-3.35)	< 0.001
Serum sodium < 135 mmol/L	1264	1.62 (1.20-2.20)	0.002
Serum creatinine ≥ 135 µmol/L	1243	0.56 (0.31-1.02)	0.057
Serum potassium < 3.5 mmol/L	1267	1.37 (1.01-1.85)	0.043
Serum urea ≥ 7 mmol/L	1267	1.00 (0.71-1.40)	0.999
Hemoglobin < 11 g/dL	1243	1.48 (1.16-1.89)	0.002
Lesion size ≥ 4 cm	1267	2.03 (1.53-2.70)	< 0.001

^aCorrected P values for dichotomized variables due to multiple testing. ECOG: Eastern Cooperative Oncology Group; Ref: Reference; PCI: Percutaneous coronary intervention; TIA: Transient ischemic attack.