biostudies-literatureBhattacharyya JNational Institute on Aging at the National Institutes of HealthNIA NIH HHSe70200https://www.ebi.ac.uk/biostudies/studies/S-EPMC12069012biostudies-literatureUnknown21(5)<h4>Introduction</h4>US Medicare claims can be used to identify dementia cases for research. Our objective was to evaluate the performance of International Classification of Diseases, 10th Revision (ICD-10) code definitions versus research-based dementia ascertainment.<h4>Methods</h4>Participants of five Rush Alzheimer's Disease Center (RADC) cohorts with study visits between October 2015 and December 2019 and fee-for-service Medicare contributed observations. For each observation, we compared research-based dementia status to dementia status based on six ICD-10 code definitions.<h4>Results</h4>A total of 1869 participants contributed 5309 observations (mean age 82.9 years, 21.0% Black, 9.3% met research-based dementia criteria). The accuracy of ICD-10 code definitions was high (87%-90%); five of six code definitions favored specificity over sensitivity. All ICD-10 code definitions were less accurate among subgroups defined by older age, minoritized race, increased depressive symptoms, and history of stroke.<h4>Discussion</h4>Performance of ICD-10 code definitions mirrored that of ICD-9 code definitions. Awareness of differential performance by participant characteristics can improve the robustness of research.<h4>Highlights</h4>We report the performance of the International Classification of Diseases, 10th Revision (ICD-10) code versus research-based dementia ascertainment. ICD-10 performed worse with age, depressive symptoms, minoritized race, and stroke. Awareness of accuracy and differential performance can improve research robustness.Alzheimer's & dementia : the journal of the Alzheimer's AssociationEvaluating linked ICD-10 Medicare claims data as a method of dementia case ascertainment in research settings.PMC12069012P30AG72975P30 AG072975R01 AG079226R01 AG072559RO1AG0757305R01AG072559R01 AG022018R01AG22018R01AG79226R01 AG017917R01 AG075730R01AG17917Barnes LLGianattasio KZPrather CMarquez DXJames BDGrodstein FBhattacharyya JRein DBMoghtaderi AShah RCPower MCChen YStapp EKfalseEvaluating linked ICD-10 Medicare claims data as a method of dementia case ascertainment in research settings.<h4>Introduction</h4>US Medicare claims can be used to identify dementia cases for research. Our objective was to evaluate the performance of International Classification of Diseases, 10th Revision (ICD-10) code definitions versus research-based dementia ascertainment.<h4>Methods</h4>Participants of five Rush Alzheimer's Disease Center (RADC) cohorts with study visits between October 2015 and December 2019 and fee-for-service Medicare contributed observations. For each observation, we compared research-based dementia status to dementia status based on six ICD-10 code definitions.<h4>Results</h4>A total of 1869 participants contributed 5309 observations (mean age 82.9 years, 21.0% Black, 9.3% met research-based dementia criteria). The accuracy of ICD-10 code definitions was high (87%-90%); five of six code definitions favored specificity over sensitivity. All ICD-10 code definitions were less accurate among subgroups defined by older age, minoritized race, increased depressive symptoms, and history of stroke.<h4>Discussion</h4>Performance of ICD-10 code definitions mirrored that of ICD-9 code definitions. Awareness of differential performance by participant characteristics can improve the robustness of research.<h4>Highlights</h4>We report the performance of the International Classification of Diseases, 10th Revision (ICD-10) code versus research-based dementia ascertainment. ICD-10 performed worse with age, depressive symptoms, minoritized race, and stroke. Awareness of accuracy and differential performance can improve research robustness.2025-01-01T00:00:00Z2025 May2026-06-06T23:40:24.218Z2026-06-06T03:11:00.73ZS-EPMC120690124035603710.1002/alz.70200