Melatonin does not protect against delirium after major cardiac surgery in older adults

Prophylactic melatonin does not appear to prevent the occurrence of delirium in older adults after major cardiac surgery, a recent study has found.

Researchers randomly assigned 210 participants scheduled for coronary bypass grafting or valve replacement surgery to either 3 mg of melatonin at night (n=105; mean age, 69±8.3 years; 75.2 percent male) or matching placebo (n=105; mean age, 67.6±8 years; 81 percent male). Treatments were initiated 2 days before surgery and lasted for 7 days. Delirium occurring within 7 days of surgery was the primary outcome.

Forty-two patients developed delirium postoperatively: 21 in the melatonin group (21.4 percent) and 21 in the placebo group (20.2 percent; odds ratio [OR], 1.08, 95 percent confidence interval [CI], 0.55–2.13).

Adjusting for age, sex, heart failure, surgical procedure, baseline cognition, diabetes and location of the hospital did not meaningfully alter the relationship between delirium and melatonin prophylaxis (OR, 0.78, 95 percent CI, 0.35–1.75). Neither did an intention-to-treat analysis (adjusted OR, 0.79, 95 percent CI, 0.36–1.76).

The duration of delirium likewise was unaffected by melatonin. The median duration was 3 days and 2 days for those in the melatonin and placebo arms, respectively (p=0.304). The percentage of participants who experienced delirium for >2 days was 66.7 percent and 47.6 percent, respectively (adjusted OR, 2.16, 95 percent CI, 0.56–8.39).

“Although more research in this area is always welcome, our results suggest that melatonin is unlikely to be a helpful intervention for the prevention of delirium,” said the researchers.