Development of a novel computerised version of the Month Backwards Test: A comparison of performance in hospitalised elderly patients and final year medical students

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

BACKGROUND

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.

AIM

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

METHODS

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.

RESULTS

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).

DISCUSSION

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

CONCLUSIONS

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.

Attention, vigilance and visuospatial function in hospitalized elderly medical patients: Relationship to neurocognitive diagnosis

OBJECTIVE

Efficient detection of neurocognitive disorders is a key diagnostic challenge. We explored how simple bedside tests of attention, vigilance and visuospatial function might assist in identifying delirium in hospitalized patients.

METHODS

Performance on a battery of bedside cognitive tests was compared in elderly medical inpatients with DSM-IV delirium, dementia, comorbid delirium-dementia, and no neurocognitive disorder.

RESULTS

193 patients [mean age 79.9±7.3; 97 male] were assessed with delirium (n=45), dementia (n=33), comorbid delirium-dementia (n=65) and no neurocognitive disorder (NNCD) (n=50). The ability to meaningfully engage with the tests varied from 84% (Spatial Span Forwards) to 57% (Vigilance B test), and was especially problematic among the comorbid delirium-dementia group. The NNCD was distinguished from the delirium groups for most tests, and from the dementia group for the Vigilance B test and the Clock Drawing Test. The dementia group differed from delirium groups in respect of the Months Backward Test, Vigilance A and B tests, Global assessment of visuospatial ability and the Interlocking Pentagons Test. Overall, patients with delirium were best identified by three tests - the Months Backward Test, Vigilance A test and the Global Assessment of visuospatial function with failure to correctly complete any two of these predicting delirium status in 80% of cases.

CONCLUSION

Simple bedside tests of attention, vigilance and visuospatial ability can help to distinguish neurocognitive disorders, including delirium, from other presentations. There is a need to develop more accurate methods specifically designed to assess patients with neurocognitive disorder who are unable to engage with conventional tests.