Incidence of Alzheimer’s disease (AD) dementia and mild cognitive impairment (MCI) in the United States Medicare population

Abstract

AbstractBackgroundAlzheimer’s disease (AD) is a chronic, neurodegenerative condition. Mild cognitive impairment (MCI) is characterized by cognitive decline, without dementia. We aimed to estimate the incidence of AD and MCI among Medicare beneficiaries.MethodPatients were identified from the US Center for Medicare and Medicaid Services (CMS) database using International Classification of Diseases (ICD) codes for AD (331.0, G30.9, G30.8, or G30.1,) and MCI (331.83 or G31.84). Both AD and MCI were identified using the search rule of 2 ICD codes ≥30 days apart ≤365 days from both Medicare fee‐for‐service (FFS: 2008‐2018) and Medicare Advantage (MA: 2015‐2018). US regions were derived using zip codes and categorized by National Center for Chronic Disease Prevention/Health Promotion regions. Yearly incidence was defined as the number of new cases of AD or MCI in each year divided by the population at risk in the year. Confidence intervals were not reported due to small intervals.ResultThe incidence of AD and MCI per 10,000 person‐years was 82.9 and 4.9, 80.3 and 7.4, 74.5 and 9.3, 69.8 and 10.9, 65.3 and 13.4, 62.8 and 15.8, 60.7 and 17.4, 65.5 and 20.7, 61.4 and 22.4, 56.0 and 22.9, and 52.2 and 23.2 spanning from 2008 through 2018, respectively. In 2018, the incidence of AD and MCI per 10,000 person‐years by demographic subgroups was: 43 and 21 for men and 59 and 25 for women; 16 and 10 among those aged 65‐69 years, 30 and 18 for ages 70‐74 years, 58 and 30 for ages 75‐79, 102 and 44 for ages 80‐84, 176 and 57 for age ≥85 years old; 56 and 26 for Whites, 38 and 13 for Blacks, and 43 and 15 for Asians. The incidence of AD and MCI per 10,000 person‐years in 2018 was highest in the US Northeast, especially in New Hampshire (77 and 39), Vermont (74 and 47), and New Jersey (73 and 33).ConclusionAmong Medicare beneficiaries from 2008 to 2018, AD incidence generally decreased while MCI increased. Women, older age, White race, and Northeast region were associated with higher incidence of AD and MCI in 2018.