The delirium screening tool 4AT in routine clinical practice: prediction of mortality, sensitivity and specificity

Purpose: Delirium is common and associated with poor outcomes, partly due to underdetection. We investigated if the delirium screening tool 4 A's test (4AT) score predicts 1 year mortality and explored the sensitivity and specificity of the 4AT when applied as part of a clinical routine.

Methods: Secondary analyses of a prospective study of 228 patients acutely admitted to a Medical Geriatric Ward. Physicians without formal training conducted the index test (the 4AT); a predefined cut-off ≥ 4 suggested delirium. Reference standard was delirium diagnosed by two geriatricians using the Diagnostic and Statistical Manual of Mental Disorders 5 (DSM-5). We calculated hazard ratios (HR) using Cox regression based on the groups 4AT = 0, 1-3, 4-7 and ≥ 8, first unadjusted, then adjusted for the covariates age, comorbidity, and personal activities of daily living. We calculated sensitivity, specificity, and the area under the receiver operating curve (AUC).

Results: Mean age of patients was 86.6 years, 139 (61.0%) were female, 78 (34.2%) had DSM-5 delirium; of these, 56 had 4AT-delirium. 1 year mortality was 27.6% (63 patients). Compared to 4AT score 0, the group 4AT ≥ 8 had increased 1 year mortality (HR 2.86, 95% confidence interval 1.28-6.37, p = 0.010). The effect was reduced in multiadjusted analyses (HR 1.69, 95% confidence interval 0.70-4.07, p = 0.24). Sensitivity, specificity, and AUC were 0.72, 0.84, and 0.88, respectively.

Conclusions: 4AT ≥ 8 indicates increased mortality, but the effect was reduced in multiadjusted analyses. 4AT had acceptable sensitivity and specificity when applied as a clinical routine.