Table 2.

Incidence rate ratios of univariable analysis using Poisson regression

Variable	IRRa (95% CIb)	P
Male	0.96 (0.64, 1.44)	0.845
Age	1.06 (1.03, 1.08)	<0.001
Cardiac condition	1.13 (0.74, 1.72)	0.583
Pulmonary condition	1.24 (0.83, 1.87)	0.297
CCId	1.15 (1.07, 1.23)	<0.001
BMIc	0.99 (0.95, 1.03)	0.572
Heart rate	1.00 (0.99, 1.01)	0.937
Systolic blood pressure	0.99 (0.98, 0.99)	0.004
Haemoglobin	0.99 (0.99, 1.00)	0.209
logCRPe	1.16 (1.02, 1.32)	0.027
logCreatinine	1.57 (1.13, 2.18)	0.007
Number of operations	1.02 (0.81, 1.30)	0.842
Cancer	1.32 (0.88, 1.98)	0.178
PRBf Transfusion	2.05 (1.36, 3.09)	0.001
Physiology Score	1.00 (0.97, 1.03)	0.932
Operative Severity Score	0.98 (0.91, 1.06)	0.618
logMorbidity P-POSSUM	0.73 (0.44, 1.21)	0.224
logMortality P-POSSUM	0.98 (0.80, 1.20)	0.843
Osteopenia	1.65 (1.07, 2.52)	0.022
Post-operative infection	0.93 (0.60, 1.43)	0.738
ASAg class
1	Ref
2	0.52 (0.083, 3.26)	0.484
3	1.21 (0.22, 6.79)	0.830
4	2.25 (0.34, 12.68)	0.358
5	4.00 (0.73, 21.93)	0.110
Surgery indication
Ileus/obstruction	Ref
Perforation	1.20 (0.73, 2.00)	0.476
Ischaemia	1.90 (1.13, 3.18)	0.015
Infection	N/A	N/A
Bleeding	1.80 (0.85, 3.83)	0.125
Other	0.83 (0.30, 2.35)	0.728
Surgical procedure
Resection	Ref
Adhesiolysis	0.49 (0.24, 1.01)	0.052
Stoma formation	0.92 (0.57, 1.49)	0.736
Other	0.64 (0.30, 1.35)	0.237
Bowel repair	0.76 (0.32, 1.81)	0.531
Vascular	0.66 (0.12, 3.71)	0.638

^aIRR: Incidence Rate Ratio,

^bCI: Confidence Interval,

^cBMI: Body Mass Index,

^dCCI: Charlson’s Comorbidity Index,

^eCRP: C-Reactive Protein,

^fPRB: Packed Red Blood cells;

^gASA: American Society of Anaesthesiologists.