Atrial fibrillation phenotype
Name phenotype_af
Chapter Circulatory disease/Atrial fibrillation
The case definition for AF has three categories:

1.	Historical: first recorded AF code indicates monitoring of an existing condition, or reference to a previous AF diagnosis.

2.	Diagnosed: first record is a diagnosis code for AF; preference given to the earliest dated record rather than diagnosis source (i.e. no preference for primary versus secondary care).

3.	Inferred: no diagnosis code is present, but the patient record includes a warfarin prescription in the absence of prior DVT or PE, or a digoxin prescription in the absence of HF.

The phenotype algorithm incorporates these definitions in a hierarchical, mutually exclusive manner (see FIGURE).  If the earliest recorded AF codes relate to a historical diagnosis or monitoring, the patient is in category 1 which precludes inclusion in other categories.  If these codes are absent, then the presence of a coded diagnosis from primary or secondary care places a patient in category 2.  Finally, in the absence of a coded diagnosis, a patient may be allocated to category 3, depending on the combination of prescriptions and diagnoses in their record.  Otherwise a participant is treated as undiagnosed.
Data sources GPRD, HES
Dictionaries Read, Multilex, OPCS 4, ICD 10
Repeated No
Agreed 23/11/2013 (Revision 1)
Phenotype components
Variable TitleCategories
af_gprd Atrial fibrillation diagnosis (primary care)
af_gprdprod AF Related medication
af_hes Atrial fibrillation diagnosis (secondary care)
af_proc_gprd Atrial fibrillation procedures (primary care)
af_proc_opcs Atrial fibrillation procedures (secondary care)
af_warfarin_digoxin_gprdprod Warfarin or Digoxin prescription
cardiac_surgery_associated_with_af_gprd AF-related cardiac surgery (primary care)
cardiac_surgery_associated_with_af_opcs AF-related cardiac surgery procedures (secondary care)
heartvalve_gprd Heart valve replacement (primary care)
heartvalve_opcs Heart valve replacement procedure (secondary care)
Codelist version
Codelist authors
Creation date
Warning! Unless explicitly noted otherwise, three-digit ICD10/OPCS4 codes also include all codes below them.
Category (code) Read code Read term CPRD Medcode
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