The Cause of Delirium in Patients With Hip Fracture

Abstract

DELIRIUM OCCURS in 11% to 42% of the hospitalized elderly^1-5 and is associated with increased mortality, delayed rehabilitation efforts, prolonged length of hospital stay, poorer functional outcomes, and increased risk of nursing home placement.⁶ Several studies have identified specific patient characteristics, medical conditions, and iatrogenic interventions that place patients at increased risk for the development of delirium,^4,5 and it is now possible to identify high-risk patients and to correct or avoid modifiable risk factors.⁷ Once delirium develops, the cornerstone for its management is the treatment of the underlying cause. Surprisingly, there have been few studies that have systematically described the frequency of different causes of the delirium syndrome, and the current recommended diagnostic approach is thus largely empirical and based on expert opinion. The data that are available are drawn from 3 relatively small studies. Moses and Kaden⁸ reported a case series involving 105 patients with delirium. In their study, no single cause was found in 47% of cases, a medication was implicated in 17%, a fluid or electrolyte abnormality in 12%, and hypoxia or hypotension in 10%. Another series of 56 patients with delirium reported that the "discharge diagnoses" were related to toxic diagnoses in 39% of cases, fluid and electrolyte problems in 11%, alcohol withdrawal in 11%, and other diagnoses less commonly.⁹ The most systematic classification of cause was in a study of 229 elderly patients, 50 of whom developed delirium during hospitalization.¹⁰ Fluid and electrolyte abnormalities had a possible role in 40% of cases, infection in 40%, drug toxicity in 30%, metabolic disorders in 26%, sensory and environmental problems in 24%, and low perfusion in 14%. In summary, the studies that have systematically examined causes have been few in number, relatively small in size, and have focused primarily on medically ill patients.