CALIBER Alzheimers disease phenotype

person Phenotype Alzheimers disease
person Type Disease or syndrome
person Data sources Primary care (CPRD), hospital admission data (HES)
person Clinical Terminologies Read, ICD-9, ICD-10
person Valid event date range 01/01/1999 - 01/07/2016
person Sex Female/Male
person Agreed 23.11.2012 (Revision 2)
person Authors Mar Pujades-Rodriguez, Valentina Assi, Arturo Gonzalez-Izquierdo, Tim Wilkinson, Christian Schnier, Cathie Sudlow, Harry Hemingway, William N. Whiteley

Primary Care (incident and prevalent)

In the Clinical Practice Research Datalink (CPRD, primary care data) we ascertained cases by searching for Read terms related to:

Diagnoses
Eu00012	[X]Primary degen dementia, Alzheimer's type, presenile onset
Eu00013	[X]Alzheimer's disease type 2
Fyu3000	[X]Other Alzheimer's disease
Eu00111	[X]Alzheimer's disease type 1
Eu01111	[X]Predominantly cortical dementia
Eu00113	[X]Primary degen dementia of Alzheimer's type, senile onset
Eu00011	[X]Presenile dementia,Alzheimer's type
Eu00000	[X]Dementia in Alzheimer's disease with early onset
Eu00z00	[X]Dementia in Alzheimer's disease, unspecified
Eu00100	[X]Dementia in Alzheimer's disease with late onset
F110100	Alzheimer's disease with late onset
F110000	Alzheimer's disease with early onset
Eu00200	[X]Dementia in Alzheimer's dis, atypical or mixed type
Eu00112	[X]Senile dementia,Alzheimer's type
Eu00z11	[X]Alzheimer's dementia unspec
Eu00.00	[X]Dementia in Alzheimer's disease
F110.00	Alzheimer's disease      
Read terms are hierarhically organized in top-level chapters i.e. chapter G....00 is related to Circulatory System Diseases and sub-headings i.e. heading G2...00 is related to Hypertensive Heart Disease while G3...00 is related to Ischaemic Heart Disease.

Secondary Care (incident and prevalent)

In Hospital Episode Statistics (HES, hospital admission data) we used ICD-10 terms (see below) for diagnosis when marked as the primary diagnosis i.e. the main condition treated or investigated during the relevant episode of healthcare. We used the date of admission to hospital as the date of the event. We additionally searched for OPCS-4 terms indicating releted procedures.

Diagnoses
F00	Dementia in Alzheimer's disease
F000A	Dementia in Alzheimer's disease with early onset
F001A	Dementia in Alzheimer's disease with late onset
F002A	Dementia in Alzheimer's disease, atypical or mixed type
F009A	Dementia in Alzheimer's disease, unspecified
G30	Alzheimer’s disease
G30.0	Alzheimer’s disease with early onset
G30.1	Alzheimer’s disease with late onset
G30.8	Other Alzheimer disease, unspecified
G30.9	Alzheimer's disease unspecified
331.0	Alzheimer's disease        

Mortality data

In mortality data, we used ICD-9 and ICD-10 terms (see below) at any position (underlying or not):

F00	Dementia in Alzheimer's disease
F000A	Dementia in Alzheimer's disease with early onset
F001A	Dementia in Alzheimer's disease with late onset
F002A	Dementia in Alzheimer's disease, atypical or mixed type
F009A	Dementia in Alzheimer's disease, unspecified
G30	Alzheimer’s disease
G30.0	Alzheimer’s disease with early onset
G30.1	Alzheimer’s disease with late onset
G30.8	Other Alzheimer disease, unspecified
G30.9	Alzheimer's disease unspecified
331.0	Alzheimer's disease        

Combining evidence across sources to define and date phenotypes

We defined dementia as the record of one or more diagnostic codes in any of the three data sources at any time and in any position (i.e. dementia was any of the recorded diagnosis in hospital admission or death record). We defined people with corroborating evidence of diagnosis if they had dementia with: (i) more than one record of dementia in the same data source, on different dates; or (ii) a record of dementia in 2 or 3 data sources; or (iii) a record of falls, confusion, memory problems or nursing home admission; or (iv) dementia monitoring codes in primary care; or (v) a referral to a dementia speciality (geriatrics, care of the elderly, psychiatry); or (v) more than one prescription of rivastigmine, galantamine, donepezil, memantine, which are typically used to treat patients with Alzheimer’s disease and sometimes patients with dementia in Parkinson’s disease and dementia with Lewy bodies.
Pujades-Rodriguez, Mar, Valentina Assi, Arturo Gonzalez-Izquierdo, Tim Wilkinson, Christian Schnier, Cathie Sudlow, Harry Hemingway, and William N. Whiteley. "The diagnosis, burden and prognosis of dementia: A record-linkage cohort study in England." PloS one 13, no. 6 (2018): e0199026.
Pujades-Rodriguez, Mar, Valentina Assi, Arturo Gonzalez-Izquierdo, Tim Wilkinson, Christian Schnier, Cathie Sudlow, Harry Hemingway, and William N. Whiteley. "The diagnosis, burden and prognosis of dementia: A record-linkage cohort study in England." PloS one 13, no. 6 (2018): e0199026.
Pujades-Rodriguez, Mar, Valentina Assi, Arturo Gonzalez-Izquierdo, Tim Wilkinson, Christian Schnier, Cathie Sudlow, Harry Hemingway, and William N. Whiteley. "The diagnosis, burden and prognosis of dementia: A record-linkage cohort study in England." PloS one 13, no. 6 (2018): e0199026.