Vitamin D and delirium in critically ill patients: a preliminary investigation

The pathophysiology of delirium in critical illness is unclear. 25-OH vitamin D (25-OHD) has neuroprotective properties but a relationship between serum 25-OHD and delirium has not been examined. We tested the hypothesis that low serum 25-OHD is associated with delirium during critical illness.

In a prospective cohort of 120 medical intensive care unit (ICU) patients, blood was collected within 24 hours of ICU admission for measurement of 25-OHD. Delirium was identified once daily using the Confusion Assessment Method for the ICU. Multivariable logistic regression was used to analyze the association between 25-OHD and delirium assessed the same day and the subsequent day after 25-OHD measurement, with adjustments for age and severity of illness.

Median age was 52 years (interquartile range, 40-62), and Acute Physiology and Chronic Health Evaluation II was 23 (interquartile range, 17-30). Thirty-seven patients (41%) were delirious on the day of 25-OHD measurement. 25-OHD levels were not associated with delirium on the day of 25-OHD measurement (odds ratio, 1.01; 95% confidence interval, 0.98-1.02) or on the day after measurement (odds ratio, 1.01; 95% confidence interval, 0.99-1.03).

This pilot study suggests that 25-OHD levels measured early during critical illness are not important determinants of delirium risk. Since 25-OHD levels can fluctuate during critical illness, a study of daily serial measurements of 25-OHD levels and their relationship to delirium during the duration of critical illness may yield different results.