Prospective study of cognitive decline assessed using the mini-mental state examination and the risk of incident long-term care insurance among community-dwelling older Japanese

Abstract

Aim: We examined the longitudinal association between the change in the Mini-Mental State Examination (MMSE) score per year and the incidence of a certified need for care in the long-term care insurance system among community-dwelling older Japanese subjects. Methods: A total of 773 adults 65 years of age or older who participated in a baseline survey (2002 to 2007) underwent MMSE reevaluation at least once until Wave-1 (2003 to 2008). The incidence of a certified need for care in the long-term care insurance system until Wave-2(Wave-1 to 2013) was examined in all subjects. Results: During an average follow-up of 1,195 days (baseline survey to Wave-1), the change in the MMSE score per year was greater than 0 in 511 (66.1%) participants, 0 to - 0.5 in 94 (12.2%) participants, - 0.5 to -1 in 66 (8.5%) participants, -1 to -2 in 56 (7.2%) participants, and less than -2 in 46 (6.0%) participants. During an average follow-up of 1,802 days (Wave-1 to Wave-2) , 104 participants (13.5%) were newly certified with a need for care in the long-term care insurance system. After controlling for important confounders, elders with a change in the MMSE score of 0 to - 0.5, -0.5 to -1, -1 to -2 and less than - 2 per year were 1.73 (95% confidence interval, 0.93-3.23), 1.94 (1.01-3.45), 1.95 (1.02-3.76) and 3.16 (1.68-5.98) times as likely to be newly certified with a need for care in the long-term care insurance system, respectively, compared those with a change in the score greater than 0. Conclusions: The extent of change in the MMSE score per year independently predicted the incident certified need for care in the long-term care insurance system in a general population of older Japanese subjects. A decrease of greater than 0.5 points per year may be a useful cutoff value for clinically evaluating elders.