Affective outcome following carbon monoxide poisoning: a prospective longitudinal study

To longitudinally assess the prevalence of depression and anxiety following carbon monoxide (CO) poisoning and to assess the contributions of mode of poisoning (accidental versus suicide attempt), cognitive sequelae, and oxygen dose (hyperbaric oxygen versus normobaric oxygen) to depression and anxiety.

CO is the most common cause of poisoning in the United States and may result in neuropathologic changes and cognitive and neurologic sequelae, yet little is known regarding affective outcomes.

We prospectively assessed affect in 127 CO-poisoned patients. Self-report inventories of depression and anxiety were administered at 6 weeks and at 6 and 12 months post CO poisoning. The primary outcome was prevalence of depression and anxiety at 6 weeks. To determine the effect of mode of poisoning, cognitive sequelae, and oxygen dose, odds ratio estimates were calculated at all three times using logistic regression.

Depression and anxiety were present in 45% of patients at 6 weeks, 44% at 6 months, and 43% at 12 months. Patients with suicide attempt and cognitive sequelae had higher prevalence of depression and anxiety at 6 weeks. At 12 months, there were no differences in depression or anxiety regardless of mode of poisoning, presence of cognitive sequelae, or oxygen dose.

CO poisoning results in significant depression and anxiety that persist to at least 12 months. Patients with cognitive sequelae and suicide attempt had a higher rate of depression and anxiety at 6 weeks but not at 12 months. Clinicians need to be aware of affective morbidity following CO poisoning and remain vigilant about CO prevention.