Law, ethics, and psychiatryPreoperative risk factors for postoperative delirium
Introduction
Delirium, a clinical syndrome characterized by an acute disruption of attention and cognition [1], is a common postoperative complication for many elderly patients [2], [3], [4], [5], [6], [7], [8], [9]. As an older, sicker population is admitted to medical and surgical hospital services and as surgical techniques are performed on more debilitated patients, the incidence of delirium is likely to increase. Because of a strong association with higher morbidity rates, longer hospital stays, higher costs of care, and more frequent discharge to long-term care facilities [2], [3], [4], [10], detection of delirium will assume even greater importance as pressure mounts to contain medical costs.
Although a common, but potentially life-threatening event on surgical floors, delirium often goes unrecognized [11]. Paradoxically, guidelines stressing the importance of enhanced vigilance in delirium recognition [8], [12], [13], [14], as well as reports describing factors that predispose [5], [6], [7], [8], [9] or precipitate this condition are currently available in the medical literature [13], [14], [15].
Delirium management guidelines alone, however, may not be adequate to reduce longer hospital stays and greater costs. Specialized delirium teams, for example, may be more effective in shortening lengths of stay and reducing the associated costs of care [16]. Such teams, however, come with their own costs and might be better used for patients with characteristics associated with greater delirium risk.
Similarly, the value of earlier reports describing factors related to postoperative delirium, although useful in raising awareness about delirium, is limited by differing methods of assessment and subsequent under-detection or recognition of important associations with key factors [7], [17], [18], [19]. More recent prospective reports address these issues through the use of standardized evaluations on successive postoperative days with brief, clinically applicable instruments to maximize the speed and accuracy of detection [8], [12], [13], [14], [20], [21]. Building further on these reports, a scored assessment system stratifying preoperative risk for postoperative delirium has been described in a sample of surgical patients by Marcantonio et al. [12]. The components of this scoring system, age≥70 years, self-reported alcohol abuse, a measure of cognitive status, functional status, preoperative laboratory results and surgery type, are ones commonly reviewed by physicians at most preoperative medical evaluations, but their utility and generalizability to other settings has not been established.
In this prospective, descriptive study, therefore, we sought to accomplish three objectives; 1) estimate the incidence of postoperative delirium in a sample of patients served at our institution; 2) apply and establish the validity of a previously reported risk assessment system based on preoperative factors [12]; and 3) evaluate through a similar approach whether other preoperative factors might better reflect postoperative risks for delirium in a large, consecutive sample of patients undergoing elective major surgery.
Section snippets
Materials and methods
All patients scheduled to undergo major elective surgery over a ten month period at the Cleveland Clinic were considered for this study approved by our Institutional Review Board. Patients were excluded if they were less than 50 years old or were non-English speaking. Patients meeting DSM-IV diagnostic criteria for delirium or those with an abnormal screening assessment for delirium using the Confusion Assessment Method (CAM) [22] at the preoperative medical consultation were excluded from
Characteristics of the study sample
A total of 563 consecutive patients met criteria to participate in this study, however 63 (11%) chose not to participate or were unavailable for evaluation following surgery. No differences were noted between participants and nonparticipants in the distribution of age, gender, race, or hospital length stay. The study sample consisted predominantly of women (61%) and Caucasians (90%) with a mean age of 67 (±9.0) years. Greater than half were admitted for elective orthopedic surgery (54%) and the
Discussion
Traditionally, physicians have used the preoperative medical evaluation to assess risk for complications, such as delirium, which may threaten life or lead to significant morbidity. The sensitivity and specificity of the CCC scoring system indicates its potential use for predicting postoperative delirium during the preoperative evaluation.
In validating the BWD scoring system, we approached eligible individuals consecutively, rather than by invitations based “on the availability of study
Acknowledgements
The authors express their gratitude to Dr. Robert Palmer for his careful review of this manuscript, to Lisa Rybicki, M.Sc for her assistance with the statistical analyses, and to Joy Frame RN, Alan Brockhurst, Howard Widmann, PA, David Shearer, and Eric Challgren for their invaluable assistance in the successful completion of this study.
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