Delirium in hip fracture patients: consequences, prevention strategies and pathophysiological mechanisms

Abstract

Background A hip fracture is a dramatic event with serious consequences. Many patients do not survive the first year after the fracture, and those who survive will often experience loss of function and increased need of assistance. Patients suffering a hip fracture are often elderly and frail, and many suffer from several medical conditions in addition to the fracture. The patients often use several medications, have malnutrition and poor social support. Dementia is very common. All these conditions are often seen among patients treated by geriatricians, and it has therefore been argued that a hip fracture is a geriatric, rather than an orthopedic disease. In many countries geriatricians have been involved in the care of such patients. A structured collaboration between orthopedic surgeons and geriatricians is labeled an orthogeriatric service. There exists a wide range of models of orthogeriatric care, and despite a lot of research, it is still not concluded which orthogeriatric model is most effective. Due to demographic changes, an increase in the number of hip fractures can be expected in the future. With limited resources it is therefore interesting to know which orthogeriatric model is best. Delirium, an acute change in cognition and alertness, is a common complication in hip fracture patients and is associated with poor outcome, including a dramatically increased risk of dementia. There is little knowledge concerning what happens in the brain during delirium, and no effective drug treatment exists. Delirium can in many cases be prevented through optimizing the quality of medical care. Multidisciplinary geriatric intervention has been shown to be particularly effective in preventing delirium in hip fracture patients. When this study first was planned, the main objective was to evaluate the orthogeriatric service in use at Oslo University Hospital - Ullevaal from June 2008 to January 2012. We hypothesised that the intervention could be effective in reducing delirium and thus prevent long term cognitive decline. During the work, some further aims have emerged, including studying the long-term consequences of delirium and its pathophysiology.

Methods From September 2009 to January 2012, 329 patients acutely admitted with a hip fracture were included in this study. All patients were included in the Emergency Room (ER) at Oslo University Hospital, Ullevaal. In the ER, the patients were randomized to stay in either the acute geriatric ward or the orthopedic ward. The patients were sent directly from the ER to the allocated ward, and had their whole hospital stay in the same ward, except for surgery and a few hours in the post operative care unit. While the patients were admitted in the hospital they were closely monitored for complications, especially delirium. The care givers were interviewed for pre-fracture cognitive function and function in activities of daily living (ADL). Since the hip fracture patients often are elderly and frail, we believed that they could benefit of the expertise and routines established in the acute geriatric ward. We hypothesised that this intervention could be effective in reducing delirium and thus prevent long term cognitive decline. To explore this hypothesis, the patients were assessed with cognitive tests four and twelve months after surgery. In addition to evaluate the effect of the orthogeriatric model, we could use these data to explore the effect delirium had on cognition in the long run. In relation to the surgery, cerebrospinal fluid (CSF) and blood samples were collected. These samples have been analyzed in order to explore possible pathogenic mechanisms in delirium. In these analyses we have also included samples collected from hip fracture patients in Edinburgh, and elderly patients undergoing other elective surgery in Oslo.

Results We found no evidence that cognitive function four months after surgery was improved in patients treated pre- and postoperatively in an acute geriatric ward, compared to usual care in an orthopaedic ward. The intervention had, however, a positive effect on mobility in patients not admitted from nursing homes. Delirium was an important predictor of accelerated cognitive decline in patients that had dementia before the fracture. Anticholinergic activity was not higher in CSF or serum in patients with delirium compared to those that did not have delirium. In those patients that developed delirium, and did not have dementia before the fracture, AA was associated with delirium severity. Neopterin (a marker of inflammation) was higher in CSF and serum in patients with delirium. This supports a theory of inflammation being important in the pathogenesis of delirium.

Conclusion The orthogeriatic model tested in this study was not effective in reducing delirium or long term cognitive decline. There was, however, a trend that the intervention had a positive effect on mobility in patients not admitted from nursing homes. Delirium is very common among hip fracture patients, and in our study 50 % of the patients were affected. We found that delirium was associated with acceleration of cognitive decline in patients that had dementia before the fracture. Analyses of CSF and blood taken from the hip fracture patients in our study have given important new knowledge regarding the pathophysiology in delirium. Yet, much more research is needed to increase our understanding of this common, dramatic and serious condition.