Cognitive and affective outcomes of more severe compared to less severe carbon monoxide poisoning

Primary objective: To assess cognitive sequelae, depression and anxiety following carbon monoxide (CO) poisoning. Research design: Prospective cohort study. Methods and procedures: This study prospectively followed 256 patients, 55 with less severe and 201 with more severe CO-poisoning. The prevalence of cognitive sequelae, depression and anxiety at 6 weeks, 6 months and 12 months was compared in patients with less severe and more severe CO-poisoning. Main outcomes and results: Of the less severe CO-poisoned patients, 39% had cognitive sequelae, 21% depression and 30% anxiety at 6 weeks. Of the more severe CO-poisoned patients, 35% had cognitive sequelae, 16% depression and 11% anxiety at 6 weeks. There was no difference in the prevalence of cognitive sequelae at any time. The prevalence of depression was higher in patients with less compared with more severe CO-poisoning at 6 months (p=0.04), but not 6 weeks or 12 months. The prevalence of anxiety was higher in patients with less compared to more severe CO-poisoning at 6 weeks (p=0.008), but not 6 or 12 months. Anxiety decreased over time in the less severe group (p < 0.01). Conclusion: CO-related cognitive sequelae, depression and anxiety are common and may be independent of poisoning severity.