Table 3

Cox Proportional Hazard Regression Analysis for the risk of DVT and PE-Associated carbon monoxide poisoning with Joint effect of Comorbidity and acute respiratory failure

Variables		N	Event n	Adjusted HR† (95% CI)
DVT
Carbon monoxide poisoning	Comorbidity‡
No	No	27 608	14	1 (Reference)
No	Yes	5656	12	3.22 (1.45 to 7.13)**
Yes	No	5929	13	5.25 (2.46 to 11.2)***
Yes	Yes	2387	10	6.97 (3.05 to 16.0)***
Carbon monoxide poisoning	Respiratory failure
No	No	33 264	26	1 (Reference)
Yes	No	7337	20	3.71 (2.04 to 6.73)***
Yes	Yes	979	3	5.17 (1.55 to 17.2)***
Carbon monoxide poisoning	Hyperbaric oxygen therapy
No	No	33 264	26	1 (Reference)
Yes	No	6380	16	3.21 (1.70 to 6.07)***
Yes	Yes	1936	7	6.89 (2.95 to 16.1)***
PE
Carbon monoxide poisoning	Comorbidity‡
No	No	27 608	13	1 (Reference)
No	Yes	5656	5	2.00 (0.68 to 5.88)
Yes	No	5929	3	1.26 (0.36 to 4.42)
Yes	Yes	2387	5	5.07 (1.76 to 14.6)**
Carbon monoxide poisoning	Respiratory failure
No	No	33 264	18	1 (Reference)
Yes	No	7337	7	1.59 (0.65 to 3.90)
Yes	Yes	979	1	2.42 (0.32 to 18.3)
Carbon monoxide poisoning	Hyperbaric oxygen therapy
No	No	33 264	18	1 (Reference)
Yes	No	6380	8	2.03 (0.86 to 4.82)
Yes	Yes	1936	0	−

*p<0.05, **p<0.01, ***p<0.001.
†Adjusted HR: adjusted for age and sex.
‡Comorbidity: Patients with any one of the comorbidities hypertension, diabetes, CVA, heart failure, all cancer, pregnancy and lower leg fracture or surgery were classified as the comorbidity group.
CVA, cerebral vascular disease; DVT, deep vein thrombosis; PE, pulmonary embolism.