Risk Factors for Delirium Identified in Geriatric Patients Undergoing Abdominal Surgery

November 26, 2007 — In a subset of geriatric patients undergoing abdominal surgery who are at high risk for in-hospital delirium, adverse outcomes correlated with key clinical variables, such as hyperglycemia and poor nutritional and functional states, according to the results of a retrospective case series study published in the November issue of the Archives of Surgery. A high incidence of suboptimal care in several clinical areas suggested opportunities for intervention.
"Among patients undergoing cardiac, general, orthopedic, and vascular procedures, postoperative delirium has been found to correlate with a variety of preoperative, intraoperative, and postoperative clinical variables," write Sabha Ganai, MD, from Baystate Medical Center, Tufts University School of Medicine in Springfield, Massachusetts, and colleagues. "Evidence has suggested that strategies for reducing postoperative delirium may be different for patients at various risk levels. To our knowledge, no studies have evaluated geriatric patients undergoing major abdominal surgery who are identified at admission as high risk for postoperative delirium."
At a university-affiliated referral hospital, a total of 228 consecutive patients aged 70 years or older had major abdominal surgery from September 1, 2002, through December 31, 2003, and 89 of these patients with risk factors for delirium were studied. The primary endpoints were preoperative, intraoperative, and postoperative clinical factors predicting in-hospital delirium. These were tested with multivariate analysis for association with adverse outcomes of the incidence of delirium, mortality, and prolonged length of stay (LOS) of 14 days or longer.
Adverse outcomes included postoperative delirium in 60% of patients, death in 20%, and prolonged LOS in 32%. Poor preoperative functional and nutritional status were independent predictors of postoperative delirium and mortality; inadequate postoperative glycemic control also correlated with mortality. Correlates of prolonged LOS were complications in 2 or more organ systems and postoperative hypoalbuminemia (albumin level < 3.0 mg/dL [< .003 g/dL; to convert to grams per liter, multiply by 10]).
The investigators identified suboptimal care in the clinical areas of use of medications known to induce delirium, prolonged bed rest, uncontrolled pain, hypoxia, and glycemic control. Delay or neglect of nutritional support occurred in nearly one third of patients with poor nutritional status. Inadequate glycemic control was either not recognized or was undertreated in 56% of patients with glucose levels exceeding 150 mg/dL. Inadequate postoperative fluid hydration was managed suboptimally in 22% of affected patients.
"In a subset of geriatric patients undergoing abdominal surgery who are at high risk for in-hospital delirium, adverse outcomes correlated only with key clinical variables, such as hyperglycemia and poor nutritional and functional states," the study authors write. "A high incidence of suboptimal care was observed in several clinical areas, suggesting opportunities for intervention."
Limitations of the study include retrospective analysis rather than a prospective randomized trial; use of a narrowly defined, acutely ill patient population; small sample size; lack of a control group; reliance on the accuracy of documentation by caregivers; less than rigorous determination of poor preoperative functional and nutritional status; lack of standard assessment tools; inconsistency of the nurse and physician notes; possibly inadequate accuracy of the definition used for delirium; and questionable choice of high-risk inclusion criteria and criteria used to define suboptimal care.
"One may postulate that the surgical team in a university-affiliated teaching hospital is more educated, and therefore more aggressive, in the treatment of postoperative hypovolemia than hyperglycemia or nutritional deficit," the study authors conclude. "Clearly, opportunities exist for continuing education, improvement of care, and reduction of adverse outcomes when caring for high-risk geriatric patients undergoing major abdominal surgery."
The study authors have disclosed no relevant financial relationships.
Arch Surg. 2007;142:1072-1078.