Cohort Definition Name : Earliest event of Dementia
Contributor name : Azza Shoaibi’
Contributor OrcId : 0000-0002-6976-2594’
Logic Description : Occurrences of dementia indexed on diagnosis or observation date with no required prior continuous enrollment subset to earliest observation where the patient was 18 years or older cohort exit is the end of continuous observation.
Recommended study application : target
Assertion statement : This cohort definition was executed on at least one real person-level observational health data source and resulted in a cohort with at least 1 person.
Target Clinical Description : Dementia is the loss of cognitive functioning — thinking, remembering, and reasoning — to such an extent that it interferes with a person’s daily life and activities. We are targettimng any genereal dementia in this deffinition.
"Evaluation conclusion : • Code selection
• This cohort target any kind of dementia including including concepts corresponding to drug-induced, alcohol-related, and psychoactive substance-induced dementia.
• Based on clinical expertise and also a brief review of literature (The Accuracy of Medicare Claims as an Epidemiological Tool: The Case of Dementia Revisited - PMC) we decided to include concepts corresponding to ““Senility””, ““Dementia co-occurrent with HIV infection””, and ““Diffuse Lewy body disease””
• Consider Include ““H/O: dementia”” code for the prevalent cohort definition concept sets but not for the incident cohort definitions
• We excluded all concepts corresponding to Niemann-Pick disease, but kept concepts for Pick’s disease
• We included Amnestic disorder (conceptId=372608) and all of its descendants in the concept set.
• We added a requirement that age>= 18 after initial data inspection indicated that all cohort definitions were selecting children (to varying degrees). While this is possible in cases of certain auto-genetic disorders (e.g. liposomal disorders), they are not of interest for this cohort definition.
• Observations from cohort diagnostics
• After developing concept sets, we compared a cohort identifying incident dementia, requiring two diagnosis codes within a year or a single diagnosis code in the ER/IP setting against the simple single-diagnosis cohort definition.
• Inspecting cohort counts, the two-diagnosis/one-diagnosis in ER/IP cohort selects a cohort that is about half the size of the single-diagnosis cohort.
• Inspecting baseline variables, the two-diagnosis/one-diagnosis in ER/IP cohort selects patients who are generally sicker relative to the single-diagnosis cohort in IBM-CCAE but we see no StdzDiff > 0.10 when we look in MDCR. Differences are similarly small in JMDC.
• Inspecting the Index Event Breakdown, we observed that the single-diagnosis cohort includes many people who enter the cohort with ““degenerative brain disorder”” which is not the case for the cohort entries in the two-diagnosis/one-diagnosis in ER/IP cohort. This indicates that many people who are diagnosed with degenerative brain disorder, never receive the diagnosis again in their data.
• The group did not believe this was sufficient reason to not choose the simple definition. Given that this was the only meaningful difference we observed between the definitions, we selected to maximize sensitivity and recommend the simple, single diagnosis cohort.
"
Imported to the OHDSI Phenotype Library. It may be expected to be found with id = 864 in the next release. Thank you