Comparison of prognosis between carbon monoxide poisoning only and combinations of other toxic exposures.

Introduction: There is a paucity of research comparing the prognosis of patients with carbon monoxide (CO) poisoning only and CO poisoning with other toxic exposures. This study compared a group of patients with CO poisoning only and a group of patients with CO poisoning combined with other toxic exposures in terms of mortality and morbidity (ischemic stroke, venous thromboembolism (VTE), and myocardial infarction).

Method: This study used claims data from the National Health Insurance Service in South Korea. Propensity score matching was used to balance covariates between the two groups and the Cox proportional-hazard model was used to calculate hazard ratios (HR).

Results: Using 1:4 propensity score matching, data from 3240 patients with CO poisoning plus other toxic exposures, and 12,960 with CO poisoning only, diagnosed between 2005 and 2020, were analyzed. The median follow-up was 4.98 years for mortality in patients with CO poisoning only and 4.04 years for mortality in patients with CO poisoning plus other toxic exposures. In the overall period, the HR for mortality in patients with CO poisoning plus other toxic exposures compared to those with CO poisoning only was 1.16 (95 % confidence interval [CI] 1.05-1.27); for VTE, the HR was 1.31 (95 % CI 1.02-1.69). For the 30-day follow-up period, the HR for VTE was 1.66 (95 % CI 1.01-2.72), while in the target group after 30 days, the HR for mortality was 1.18 (95 % CI 1.06-1.32).

Conclusion: CO poisoning plus other toxic exposures was associated with a higher risk for long-term mortality and VTE compared with CO poisoning alone. Active screening for VTE in the acute stages of CO poisoning plus other toxic exposures and ongoing monitoring for the occurrence of long-term mortality are necessary.