Rate of conversion from mild cognitive impairment to dementia in a Thai hospital-based population: A retrospective cohort

Introduction Mild cognitive impairment (MCI) is the state between normal cognition and dementia. This study objective was to estimate an average 1-year rate of conversion from MCI to dementia and explore the associated factors of conversion in a hospital-based cohort. Methods A retrospective cohort study of participants with MCI was conducted in a tertiary care hospital in Thailand. Two hundred fifty participants, 50 years of age or older, were enrolled. Results An average 1-year conversion rate from MCI to dementia was 18.4%. MCI patients who converted to dementia were likely older (P < .001), predominantly female (P = .028), vitamin D deficient (P = .012), and associated with lower Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) scores during first assessments (P < .001, P < .001 respectively) and follow-up assessments (P < .045, P < .001 respectively). We conducted two models of multivariate analysis, using binary logistic regression. In the first model, adjusted for age, sex, education, vitamin D deficiency, and first assessment MMSE scores, we found that underlying vitamin D deficiency (odds ratio [OR] = 3.13, 95% confidence interval [CI] 1.04 to 9.44) and first assessment MMSE scores (OR = 0.83, 95% CI 0.73 to 0.93) were significantly associated with conversion to dementia. In the second model, adjusted for age, sex, education, vitamin D deficiency and first assessment MoCA scores, only first assessment MoCA scores (OR = 0.58, 95% CI 0.45 to 0.76) were significantly associated with conversion to dementia. Discussion The 1-year conversion rate from MCI to dementia was 18.4%. MMSE and MoCA were useful tools to assess baseline cognitive status in MCI patients and predict dementia progression. The association between vitamin D deficiency and risk of conversion from MCI to dementia requires further investigations.