PREDICTING POST-OPERATIVE DELIRIUM IN HIP AND KNEE ARTHROPLASTY PATIENTS.

Abstract

Perioperative delirium (POD) is not uncommon in orthopaedics. We prospectively followed one hundred and thirty-two arthroplasty patients and thirty hip fracture patients using POD as the outcome. Patient interviews, chart reviews and application of the Mini Mental Status Exam (MMSE) were used to identify risk factors for POD. Having two or more risk factors or low scores on the MMSE was predictive of POD. Development of POD significantly increased patient length of stay. It may be possible to identify “at risk” patients for POD and intervene preoperatively so as to improve outcomes.

The purpose of this study was to identify risk factors for delirium in arthroplasty and hip fracture patients among routinely collected data.

Risk factors for perioperative delirium (POD) in arthroplasty and hip fracture patients can be identified. In elderly hip fracture patients, cognitive impairment as measured by preoperative performance on the Mini Mental Status Exam (MMSE), appears to have a strong association with development of POD.

As delirium is associated with adverse outcomes, it may be possible to target interventions to reduce the incidence of POD in patients who are at greatest risk, and potentially improve outcomes.

The incidence of POD was lower in elective orthopaedic patients (13.6%) than in fracture patients (40%). Among elective arthroplasty patients, having two or more risk factors was associated with an eight-time increase in the incidence of delirium and increased length of stay (9.5 days versus six days). Length of stay was considerably higher in hip fracture patients with two or more risk factors (18.9 days vs. 9.9). A low score on the MMSE was the best predictor of developing POD in hip fracture patients.

We recorded age, sensory impairment, functional status, history of previous POD, and use of alcohol or benzodiazepines, in one hundred and thirty-two hip or knee arthroplasty patients, and thirty elderly patients awaiting surgery for hip fracture. All patients completed the MMSE preoperatively.

Delirium was documented prospectively by the Confusion Assessment Method.

POD has an adverse effect on outcomes and is not uncommon in orthopaedics. Risk factors have been identified that could be used for preoperative screening and intervention.