How good are medical and death records for identifying dementia?

Introduction Retrospective studies using administrative data may be an efficient way to assess risk factors for dementia if diagnostic accuracy is known. Methods Within‐individual clinical diagnoses of Alzheimer's disease (AD) and all‐cause dementia in ambulatory (outpatient) surgery, inpatient, Medicare administrative records and death certificates were compared with research diagnoses among participants of Cache County Study on Memory, Health, and Aging (CCSMHA) (1995–2008, N = 5092). Results Combining all sources of clinical health data increased sensitivity for identifying all‐cause dementia (71%) and AD (48%), while maintaining relatively high specificity (81% and 93%, respectively). Medicare claims had the highest sensitivity for case identification (57% and 40%, respectively). Discussion Administrative health data may provide a less accurate method than a research evaluation for identifying individuals with dementing disease, but accuracy is improved by combining health data sources. Assessing all‐cause dementia versus a specific cause of dementia such as AD will result in increased sensitivity, but at a cost to specificity.