To study the long term effects of delirium in elderly hip-surgery patients on cognitive outcome.

Prospective matched controlled cohort study. Medical school-affiliated general hospital in Alkmaar, The Netherlands.

Hip-surgery patients (n=112) aged 70 and older who participated in a controlled clinical trial of haloperidol prophylaxis for delirium, were followed for an average of 30 months after discharge. Patients with a diagnosis of dementia or mild cognitive impairment (MCI) were identified based on psychiatric interviews. Proportions of patients with dementia or MCI were compared across patients who had postoperative delirium and selected control patients matched for preoperatively assessed risk factors who had not developed delirium during hospitalization. Other outcomes were mortality rate and rate of institutionalization.

During follow-up 54.9% of delirium patients had died compared to 34.1% controls (relative risk = 1.5, 95% CI = 1.04-2.1). Dementia or MCI was diagnosed in 77.8% of the surviving patients with postoperative delirium and in 40.1% of control patients (relative risk = 2.7, 95% CI = 1.2-5.8). Group differences for rate of institutionalization were not significant.

The risk of dementia or MCI at follow-up is more than doubled in elderly hip-surgery patients with postoperative delirium compared with patients without delirium.