Long-term prognosis of patients with carbon monoxide poisoning: A nationwide cohort study

Background: Carbon monoxide poisoning (COP) often produces severe complications and can be fatal. Because this topic has not been well delineated, we investigated long-term prognoses of patients with COP (COP^[+]). Methods: In this retrospective nationwide cohort study, 441 COP^[+] patients and 8820 COP^[-] controls (120) from 1999 to 2010 were selected from Taiwan's National Health Insurance Research Database. Results: Thirty-seven (8.39%) COP^[+] patients and 142 (1.61%) controls died (P<0.0001) during follow-up. Incidence rate ratios (IRR) of death were 5.24 times higher in COP^[+] patients than in controls (P<0.0001). The risk of death was particularly high in the first month after COP (IRR: 308.78; 95% confidence interval [CI]: 40.79-2337.56), 1 to 6 months after (IRR: 18.92; 95% CI: 7.69-46.56), and 6-12 months after (IRR: 4.73; 95% CI: 1.02-21.90). After adjusting for age, gender, and selected comorbidities, the hazard ratio of death for COP^[+] patients was still 4.097 times higher than for controls. Moreover, older age (≥30 years old), male gender, diabetes mellitus, hypertension, and low income were also independent mortality predictors. Conclusions: COP significantly increases the risk for long-term mortality. Early follow-up and secondary prevention of death are needed for patients with COP.