Comparison of verbal and computerised months backwards tests in a hospitalized older population

Delirium is extremely prevalent, yet underdiagnosed, in older patients and is associated with prolonged length of hospital stay and higher mortality rates. Impaired attention is the cardinal deficit in delirium and is a required feature in diagnostic criteria. The verbal months backwards test (MBT) is the most sensitive bedside test of attention, however, hospital staff occasionally have difficulty with its administration and interpretation. We hypothesise that the MBT on an electronic tablet may be easier and more consistent to use for both experienced and unexperienced medical professionals and, if the diagnostic efficacy was similar, aid delirium diagnosis.

We aim to investigate the correlation of the verbal MBT with a computerised MBT application.

Participants recruited (age > 65, n = 75) were allocated to different cohorts (Dementia and Delirium (DMDL), Dementia (DM), Delirium (DL), No Neurocognitive Disorder (NNCD)) and were administered both the verbal and electronic versions.

Correlation between measurements were: overall Spearman's rho = 0.772 (p < 0.0001); DMDL rho = 0.666 (p < 0.0001); DL rho = 0.778 (p = 0.039); DM rho = 0.378 (p = 0.203); NNCD rho = 0.143 (p = 0.559).

Overall, and for the delirious subset, statistically significant agreement was present. Poor inter-test correlation existed in the groups without delirium (DM, NNCD).

The MBTc correlates well with the MBTv in patients who are clinically suspected to have delirium but has poor correlation in patients without delirium. Visuospatial cognition and psychomotor deficits in a dementia cohort and mechanical factors (such as tremor, poor fingernail hygiene and visual impairment) in a group with no neurocognitive disorder may limit the utility of the MBTc in a hospitalised older population.