Risk Factors Associated With Poor Neurocognitive Outcome After CO Poisoning

Researchers sought to develop and validate a clinical scoring system to predict poor neurocognitive outcomes following acute CO poisoning.

A reliable prediction model during the early phase of carbon monoxide (CO) poisoning could help identify patients at risk for poor neurocognitive sequalae, a study published in JAMA Network Open suggests.

Every year, about 50,000 people in the US go to the emergency department following CO poisoning. Patients with CO poisoning who show symptoms are recommended to have hyperbaric oxygen (HBO) therapy within 24 hours after the incident as studies have indicated it can help patients avoid developing neurocognitive sequelae. Still, these symptoms develop in many cases. Predicting poor neurocognitive prognosis in acute CO poisoning prompts early rehabilitative interventions, but there is no validated, simple and accurate clinical scoring model for predicting patients’ neurocognitive prognosis in early phase.

This is the first study to create and validate a scoring system with clinical and laboratory parameters for CO poisoning, regardless of severity and HBO therapy, according to the researchers.

In the study, Korean researchers arranged a derivation cohort of data of patients (n=1016) with acute CO poisoning seen between January 2006 and July 2021 at Wonju Severance Christian Hospital and followed up until August 2021. The validation cohort included data collected from August 2016 to June 2020 of 266 patients with CO poisoning at Inha University Hospital.

Patients were treated with 100% oxygen therapy. If they had any loss of consciousness, neurocognitive symptoms, cardiovascular dysfunction, cardiac enzymes, ischemic electrocardiogram changes, severe acidosis or carboxyhemoglobin (HbCO) of at least 25%, they were treated with HBO.

The researchers used logistic regression models to identify predictors of poor neurocognitive outcomes in the derivation cohort using the Global Deterioration Scale (GDS).

The researchers found that 86.1% of scores of derivation cohort individuals didn’t change by 1 year, while 11.6% of individuals’ scores improved, 2.3% of scores dropped.

The final prediction model indicated that age older than 50 years, Glasgow Coma Scale score of no more than 12, shock, serum creatine kinase level exceeding 320 U/L at emergency department presentation, and no use of hyperbaric oxygen therapy were associated with worse outcomes.

The resulting scoring system, COGAS (creatine kinase, hyperbaric oxygen therapy, Glasgow Coma Scale, age, shock), has an area under the receiver curve of .862 (95% CI 0.828-0.895) for the derivation cohort and 0.870 (95% CI 0.779-0.961) for the validation cohort.

Study limitations included any selection bias, generalization outside of Korea, evaluation of outcomes exclusively with GDS scores, and consideration of a new potentially permanent mild cognitive decline or impairment as a good outcome.

“In this prognostic study a prediction model, dubbed COGAS score, using 5 factors associated with poor neurocognitive outcome at 1 month among patients with CO poisoning was developed and externally validated,” the researchers concluded. “This scoring system showed excellent capacity to predict poor neurocognitive outcomes.”


Kim SH, Lee Y, Kang S, et al. Derivation and validation of a score for predicting poor neurocognitive outcomes in acute carbon monoxide poisoning. JAMA Network Open. Published online May 5, 2022. doi: 10.1001/jamanetworkopen.2022.10552