Background Few studies have investigated the relationship between carbon monoxide (CO) poisoning and risk of deep vein thrombosis (DVT) and pulmonary embolism (PE). Therefore, we conducted a nationwide longitudinal cohort study in Taiwan to determine whether patients with CO poisoning are associated with increased risk of developing DVT and PE.

Methods This study investigated the incidence and risk factors for DVT and PE in 8316 patients newly diagnosed with CO poisoning from the Taiwan National Health Insurance Research Database between 2000 and 2011. The comparison cohort contained 33 264 controls without CO poisoning from the general population. Follow-up was initiated on the date of initial diagnosis of CO poisoning and continued until the date of a DVT or PE event, censoring or December 31, 2011. Cox proportional hazard regression models were used to analyse the risk of DVT and PE according to sex, age and comorbidities.

Results The incidences of DVT and PE were higher in the patients with CO poisoning than in the controls (5.67 vs 1.47/10 000 person-years and 1.97 vs 1.02/10 000 person-years, respectively). After adjusting for age, sex and comorbidities, the patients with CO poisoning were associated with a 3.85-fold higher risk of DVT compared with the comparison cohort, and non-significantly associated with risk of PE. CO poisoning patients with a coexisting comorbidity or acute respiratory failure were associated with significantly and substantially increased risk of DVT.

Conclusion Risk of DVT is significantly higher in patients with CO poisoning than in the general population.