Background

Intensive care unit (ICU) delirium is associated with a proinflammatory state and poor outcomes. An epigenetic mechanism may modify inflammation.

Objective

To identify inflammatory gene methylation trajectory groups and explore their clinical and demographic variability.

Methods

Patients were at least 18 years old; received mechanical ventilation for at least 24 hours; had no brain disorder/injury, preexisting dementia, or positive toxicology screen; and were admitted to a medical or surgical/trauma ICU. Delirium was assessed (Confusion Assessment Method for the ICU) and blood samples were collected daily for up to 10 days. Methylation of 3 genes in the inflammatory pathway was quantified. Latent class analysis identified gene methylation trajectories, and variables (including delirium) were compared between trajectory groups.

Results

Of 68 patients (53% female, 88% White), 65% developed delirium. Of 3 methylation trajectories for IL6ST, the group with low initial methylation increasing over time included younger male patients who were less likely to have delirium, and the group with high initial methylation decreasing over time included older (P = .01) female (P = .05) patients who more often had delirium (P = .05). IL17C had 2 methylation trajectories without significant differences in delirium, age, or sex. IL13RA1 had 2 methylation trajectories without differences in delirium or age; the group with sustained high methylation had more female patients (P = .003).

Conclusions

Temporal variability in inflammatory gene methylation occurs after ICU admission. Delirium, female sex, and older age were more common with higher IL6ST methylation that decreased over time. Larger studies are needed to further elucidate these relationships.

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