Longitudinal Follow-Up of a Population with MCI: Predictive Value of the MIS Test with Delayed Recall for Progression to Dementia

摘要

Background: Early detection of dementia is currently of great interest and of crucial importance for the implementation of preventive measures and treatment of the disease. Impairment in verbal episodic memory, and in particular in a delayed recall phase, is considered one of the early markers of progression from mild cognitive impairment (MCI) to dementia. Therefore, having cognitive screening instruments with predictive value for progression is of utmost importance. Objective: The purpose of this work is to show the predictive value, sensitivity and specificity of the Memory Impairment Screen with delayed recall (MIS-DR) to predict conversion to dementia in patients with MCI. Methods: In retrospective study 502 patients over 60 years old, evaluated in the Older Adult Functional Evaluation Unit of our hospital for cognitive complaint, were diagnosed with MCI. They were followed up to assess conversion to dementia. Results: During follow up, 144 participants developed dementia (28.6%, 95% CI 24.76 - 32.85) and the average time of progression to dementia were 23 months (SD 13.2). The cut-off point was established below 6 for MIS-DR and it showed a sensitivity of 76% (95% CI 68.77 - 77.84) and a specificity of 56% (95% CI 50.44 - 61.58), with a positive predictive value of 41% (95% CI 34.78 - 47.6) and a negative predictive value of 85% (95% CI 80.53 - 91.11) for predicting progression to dementia. Of those patients who obtained a MIS-DR score below 6, 41% developed dementia, in contrast to 14.53% of those with a score above or equal to 6, OR 4.09 (95% CI 2.64 - 6.34), p 0.00001. There were no significant differences in terms of gender, education level or vascular risk factors among patients who converted and those who did not convert to dementia. Conclusion: We believe that MIS-DR is a useful and valid test to detect episodic memory impairment and to identify patients at risk of progression to dementia.