Focusing on Inattention: The Diagnostic Accuracy of Brief Measures of Inattention for Detecting Delirium

BACKGROUND: Delirium is frequently missed in most clinical settings. Brief delirium assessments are needed.

OBJECTIVE: To determine the diagnostic accuracy of reciting the months of year backwards (MOTYB) from December to July (MOTYB-6) and December to January (MOTYB-12) for delirium as diagnosed by a psychiatrist and to explore the diagnostic accuracies of the following other brief attention tasks: (1) spell the word “LUNCH” backwards, (2) recite the days of the week backwards, (3) 10-letter vigilance “A” task, and (4) 5 picture recognition task.

DESIGN: Preplanned secondary analysis of a prospective observational study.

SETTING: Emergency department located within an academic, tertiary care hospital.

PARTICIPANTS: 234 acutely ill patients who were ≥65 years old.

MEASUREMENTS: The inattention tasks were administered by a physician. The reference standard for delirium was a comprehensive psychiatrist assessment using Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision criteria. Sensitivities and specificities were calculated.

RESULTS: Making any error on the MOTYB-6 task had a sensitivity of 80.0% (95% confidence interval [CI], 60.9%-91.1%) and specificity of 57.1% (95% CI, 50.4%-63.7%). Making any error on the MOTYB-12 task had a sensitivity of 84.0% (95% CI, 65.4%-93.6%) and specificity of 51.9% (95% CI, 45.2%-58.5%). The best combination of sensitivity and specificity was reciting the days of the week backwards task; if the patient made any error, this was 84.0% (95% CI, 65.4%-93.6%) sensitive and 81.9% (95% CI, 76.1%-86.5%) specific.

CONCLUSION: MOTYB-6 and MOTYB-12 had very good sensitivities but had modest specificities for delirium, limiting their use as a standalone assessment. Reciting the days of the week backwards appeared to have the best combination of sensitivity and specificity for delirium.