Nurses' recognition of delirium and its symptoms: comparison of nurse and researcher ratings.

BACKGROUND: Nurses play a key role in recognition of delirium, yet delirium is often unrecognized by nurses. Our goals were to compare nurse ratings for delirium using the Confusion Assessment Method based on routine clinical observations with researcher ratings based on cognitive testing and to identify factors associated with underrecognition by nurses.
METHODS: In a prospective study, 797 patients 70 years and older underwent 2721 paired delirium ratings by nurses and researchers. Patient-related factors associated with underrecognition of delirium by nurses were examined.
RESULTS: Delirium occurred in 239 (9%) of 2721 observations or 131 (16%) of 797 patients. Nurses identified delirium in only 19% of observations and 31% of patients compared with researchers. Sensitivities of nurses' ratings for delirium and its key features were generally low (15%-31%); however, specificities were high (91%-99%). Nearly all disagreements between nurse and researcher ratings were because of underrecognition of delirium by the nurses. Four independent risk factors for underrecognition by nurses were identified: hypoactive delirium (adjusted odds ratio [OR], 7.4; 95% confidence interval [CI], 4.2-12.9), age 80 years and older (OR, 2.8; 95% CI, 1.7-4.7), vision impairment (OR, 2.2; 95% CI, 1.2-4.0), and dementia (OR, 2.1; 95% CI, 1.2-3.7). The risk for underrecognition by nurses increased with the number of risk factors present from 2% (0 risk factors) to 6% (1 risk factor), 15% (2 risk factors), and 44% (3 or 4 risk factors; P(trend)<.001). Patients with 3 or 4 risk factors had a 20-fold risk for underrecognition of delirium by nurses.
CONCLUSIONS: Nurses often missed delirium when present, but rarely identified delirium when absent. Recognition of delirium can be enhanced with education of nurses in delirium features, cognitive assessment, and factors associated with poor recognition.