Evaluation of postoperative delirium in geriatric patients given acetaminophen with and without melatonin: A retrospective cohort study.

Objective: Postoperative delirium has many consequences and should be prevented when possible. Non-opioid pain treatments have known delirium prevention benefits, while melatonin has promising prevention data in non-surgical populations. The incidence of postoperative delirium was retrospectively compared in patients prescribed acetaminophen with and without melatonin following orthopedic surgery.

Methods: Retrospective data was analyzed in adults ≥65-years-old who were hospitalized within one health system following an orthopedic procedure. Patients receiving at least acetaminophen 1000 mg/day with and without melatonin 1 mg/day for at least 48 hours perioperatively were included. Patients were excluded if they had prior delirium, an intensive care unit placement >24 hours, or other risk factors for developing delirium to reduce confounders. The primary outcome was delirium incidence or positive CAM-ICU score. Key secondary endpoints included hospital length of stay and 30-day hospital readmission.

Results: Two hundred patients were assessed, and 134 patients were included in the analysis (ie, 66 acetaminophen plus melatonin, 68 acetaminophen alone). There was a lower rate of delirium when comparing the combination vs acetaminophen alone (5% vs 25%; = 0.001). There were no differences in 30-day readmission. Patients taking the combination had a longer length of stay than acetaminophen alone (5 vs 4 days; = 0.04).

Conclusion: Geriatric patients taking acetaminophen plus melatonin after orthopedic surgery had a significantly lower risk of delirium than patients receiving acetaminophen alone. Using combination melatonin and acetaminophen before orthopedic surgery is a promising delirium prevention strategy and should be considered in future prospective trials.