Validation of a computerized Hong Kong – vigilance and memory test (HK-VMT) to detect early cognitive impairment in healthy older adults

Objectives: Hong Kong–Vigilance and Memory Test (HK-VMT) is developed to distinguish early cognitive impairment in the pre-symptomatic phase from normal cognitive ageing in older adults. The objectives were to validate HK-VMT to differentiate mild cognitive impairment (MCI) and healthy control (HC), and to explore the cut-off scores for different educational levels.

Method: A total of 606 older adults underwent the HK-VMT and conventional cognitive tests. HK-VMT is a 15 minutes cognitive battery that assesses episodic memory, attention, and visuospatial ability. The HK-VMT total is the sum of accuracy of all subtests with a range of 0 to 40. Differences in socio-demographic and clinical characteristics between groups were explored. Receiver operating characteristic (ROC) analyses were used to compare HK-VMT and Cantonese Mini Mental State Examination (CMMSE). A sample of 50 participants repeated the HK-VMT in 1 month to evaluate test-retest reliability.

Results: ROC analysis of Area Under Curve (AUC) demonstrated that HK-VMT (AUC 0.793) was comparable to CMMSE (AUC 0.748) in differentiating MCI from HC in a matched sample. A cutoff at 21/22 was chosen yielding a sensitivity of 86.1% and a specificity of 75.3% for differentiating MCI and HC. Test-retest reliability of HK-VMT total was 0.71 (p<.001) in a month time.

Conclusion: HK-VMT has demonstrated satisfactory validity in detecting cognitive impairment with good test-retest reliability in local older adults. It also performed favourably in the highly educated group when compared to CMMSE.