Clinical research study
Independent Vascular and Cognitive Risk Factors for Postoperative Delirium

https://doi.org/10.1016/j.amjmed.2007.02.026Get rights and content

Abstract

Background

Delirium is a common, morbid, and costly syndrome that occurs frequently after surgery for atherosclerosis. We hypothesized that vascular risk factors and mildly impaired cognitive performance would independently predispose nondemented patients to develop delirium after noncardiac surgery.

Methods

The International Study of Postoperative Cognitive Dysfunction recruited patients undergoing noncardiac surgery from 8 countries. Subjects provided detailed medical history and underwent preoperative testing of multiple cognitive domains with a neuropsychologic battery. Postoperatively, subjects (n = 1161) were assessed daily for delirium.

Results

Ninety-nine subjects (8%) developed delirium. In bivariable analysis, several vascular risk factors were significantly associated with the likelihood of delirium, including male sex, exposure to tobacco, previous myocardial infarction, and vascular surgery. After adjustment for age, tobacco exposure and vascular surgery were independent vascular risk factors for delirium (adjusted relative risk [RR] 3.2, 95% confidence interval [CI], 2.1-4.9). In addition, mildly impaired cognitive performance, defined as performance 1.5 standard deviation below the mean on either of 2 neuropsychologic tests, was independently associated with delirium (adjusted RR 2.2, 95% CI, 1.4-3.6). Subjects with both vascular risk factors and mildly impaired cognitive performance were at double the risk of delirium (RR 2.2, 95% CI, 1.2-4.2) compared with those with either of these risk factors alone.

Conclusions

Vascular risk and mildly impaired cognitive performance independently predispose patients to delirium after noncardiac surgery. These factors will help to identify high-risk patients for delirium and to design and target future intervention strategies.

Section snippets

Recruitment

The International Study of Postoperative Cognitive Dysfunction (ISPOCD) recruited 1218 patients aged 60 years or more at 13 hospitals in 8 countries (Denmark, France, Germany, Great Britain, Greece, The Netherlands, Spain, and United States) undergoing noncardiac surgery between November 1, 1994, and May 31, 1996. This study has been described in detail.16 Eligible surgical procedures included orthopedic, abdominal, thoracic, vascular, or other noncardiac procedures with anticipated general

Results

The characteristics of the sample are summarized in Table 1. The resultant sample had a mean age of 68.9 (SD ± 5.9) years and a slight preponderance of males (53%). The mean preoperative MMSE score was 27.8 (±1.6). The cohort included subjects with vascular risk factors, such as a history of tobacco use in 685 (59%), diabetes in 86 (7%), hypertension in 398 (34%), previous myocardial infarction in 102 (9%), congestive heart failure in 132 (11%), and angina pectoris in 100 (9%). The sample

Discussion

In this study assessing preoperative risk factors for delirium in patients undergoing noncardiac surgery, tobacco exposure, the need for vascular surgery, and mildly impaired cognitive performance on 2 measures of executive function contributed independently to delirium risk.

Many studies have identified individual vascular risk factors for delirium,1, 3, 9, 10 but our study is unique in examining multiple vascular risk factors in a broad spectrum of noncardiac surgery patients. We identified

Conclusions

Delirium has been well recognized to pose a major risk in postoperative patients and is associated with substantial morbidity and mortality. The identification of vascular risk factors and mildly impaired cognitive performance as independent risk factors for delirium holds substantial clinical implications. Use of these risk factors will help to identify patients at high risk for postoperative delirium, who may benefit from interventions to prevent delirium and its attendant complications.

Acknowledgments

We thank the ISPOCD group for access to their data.

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  • Cited by (0)

    These data were collected as a result of funding from multiple sources.16 The authors were supported in part by National Institute of Health grants: 5 K12 AG00294-18 (Dr Rudolph), 5 P60 AG08812-14 (Drs Marcantonio and Jones), RO1AG018772-04 (Dr Silverstein), and R21AG025193 and K24AG000949 (Dr Inouye).

    1

    Dr Rasmussen is supported in part by ongoing research studies on postoperative complications.

    2

    Dr Marcantonio is a Paul Beeson Physician Faculty Scholar in Aging Research.

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