A Trial To Assess Risk of Delirium in Older Adults Undergoing Hip Fracture Surgery With Spinal or General Anesthesia

This pilot project will address the gaps in knowledge regarding the effect of anesthetic technique on the risk of delirium through an adequately-powered trial employing standardized regimens for treatment and outcome assessment to test the hypothesis that use of spinal versus general anesthesia decreases the risk of delirium after hip fracture surgery.

Objectives Overall objectives Overall Objectives Specific Aims

1. To compare the effect of spinal versus general anesthesia on rates of postoperative delirium after hip fracture surgery. We hypothesize that rates of delirium after hip fracture surgery will be lower among patients receiving spinal versus general anesthesia.
2. To develop, field-test, and conduct a qualitative evaluation of protocols and procedures for a planned multicenter trial to test the association of anesthesia technique with survival and recovery of function in activities of daily living ambulatory ability at six months after hip fracture.

Primary outcome variable(s) The primary outcome variable is the rate of delirium after hip fracture surgery.

Background Delirium, or a disturbance of consciousness and a change in cognition that develop over a short period of time, (1) complicates 2.6 million hospitalizations among U.S. adults aged 65 or older each year. (2,3) Patients who experience delirium during hospitalization face increased risks morbidity, mortality, and functional disability. (4) Each year, delirium accounts for $6.9 billion in Medicare hospital expenditures. (5) Delirium occurs in 35% to 65% of the 320,000 older U.S. adults hospitalized for hip fracture each year. (6) While adverse survival and functional outcomes are common after hip fracture, (7) a single episode of delirium doubles the odds of both new functional dependence and new ambulatory disability at six months after fracture, and triples the odds of death or new nursing home placement. (8) Compared to general endotracheal anesthesia, spinal anesthesia may decrease the incidence of postoperative delirium after hip fracture surgery. Small randomized trials of anesthesia type for hip fracture have suggested a 50% lower risk of acute confusion after hip fracture surgery with spinal anesthesia, (9) but the heterogeneity of outcome definitions and measurement strategies employed by past trials, along with their use of historical anesthesia practices limit their applicability to current practice.

As a result of these limitations, clinical equipoise continues to exist regarding the optimal anesthetic technique for hip fracture care. Compared to general anesthesia, spinal anesthesia may offer potential benefits not limited to decreased delirium. These may include decreased intraoperative blood loss, and decreased risks of postoperative thromboembolic events, respiratory infections and malignant hyperthermia. At the same time, spinal anesthesia may be associated with greater hypotension than general anesthesia, and may carry small risks of bleeding and infection at the site of the spinal injection and discomfort during block placement. Relative to spinal anesthesia, general anesthesia may offer benefits of hemodynamic stability. At present, while spinal anesthesia has been demonstrated in a retrospective observational study to be associated with lower in-hospital mortality after hip fracture (10), a meta-analysis of randomized trials was inconclusive with regard to mortality differences. (9) Reflecting this state of clinical equipoise patterns of anesthesia care differ widely by country and by provider, reflecting a large role of provider practice style in determining anesthesia care for hip fracture. For example, in a recent survey of UK anesthesiologists, 76% indicated that they routinely performed hip fracture surgeries with spinal anesthesia (11). In contrast, recent U.S. data suggest that approximately 80% of hip fracture surgeries are performed with general anesthesia, with wide variability in practice across hospitals.(10) While these variations may in part reflect differences in patient preferences, the current state of knowledge regarding the risks and benefits of differing types of anesthesia is inadequate to support appropriately informed medical decision-making by either patients or health care providers. The UKs national institute for Health and Care Excellence (NICE) strongly recommend further clinical trials to provide additional information regarding the clinical and cost effectiveness of differing anesthesia types for hip fracture, stating that they were unable to identify any recent randomised controlled trialsthat fully address this question and that the \[available\] evidence is old and does not reflect current practice.

Study Design Phase II

Design This is a randomized, controlled trial of spinal versus general anesthesia to test the effect of anesthesia type on rates of postoperative delirium after hip fracture surgery.

Study duration It is expected that this study will begin enrollment in June 2013. The enrollment of all subjects is projected to be completed in May 2014 with data analysis to follow. The study will hope to be completed by June 2015.

The length of participation for each subject will be about 5 days.

Eligibility Criteria:
Inclusion Criteria:

1. Subject is aged 18 and older.
2. Subject is scheduled to undergo surgical treatment of an acute femoral neck or pertrochanteric hip fracture.
3. Subject can speak English
4. Subject has ability to sign informed consent

Exclusion Criteria:

1. Subject has a pathological or periprosthetic fracture.
2. Subject has concurrent conditions anticipated at the time of admission to require surgical treatment (e.g. multiple trauma, acute cholecystitis).
3. Subject has severe cognitive impairment, as evidenced by a Montreal Cognitive Assessment Score (MOCA) of 15 or less.
4. Subject has clinical findings of delirium prior to surgery, as evidenced by a positive Confusion Assessment Method (CAM) evaluation;
5. Subject has contraindications to spinal anesthesia or volatile general anesthetics.