Long-term cognitive outcome of delirium in elderly hip surgery patients. A prospective matched controlled study over two and a half years.

OBJECTIVE: To study the outcome of delirium in elderly hip surgery patients.

DESIGN: Prospective matched controlled cohort study. Hip surgery patients (n = 112) aged 70 years 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 using psychiatric interviews. Proportions of patients with dementia/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 index hospitalization. Other outcomes were mortality rate and rate of institutionalization.

RESULTS: During the follow-up period, 54.9% of delirium patients had died compared to 34.1% of the controls (relative risk = 1.6, 95% CI = 1.0-2.6). Dementia or MCI was diagnosed in 77.8% of the surviving patients with postoperative delirium and in 40.9% of control patients (relative risk = 1.9, 95% CI = 1.1-3.3). Half of the patients with delirium were institutionalized at follow-up compared to 28.6% of the controls (relative risk = 1.8, 95% CI = 0.9-3.4).

CONCLUSION: The risk of dementia or MCI at follow-up is almost doubled in elderly hip surgery patients with postoperative delirium compared with at-risk patients without delirium. Delirium may indicate underlying dementia.