The conditions (disease) mappings are provided in the 'Conditions Data Mappings' Appendices for each clinical system. Please select your clinical system on this page and then use the relevant mapping page: Data Mapping
Note that some conditions are flagged as true for a patient if the patient has ever had the condition ie. the condition forms part of the patient history but is not currently listed as active (eg. heart disease). Check the appendix for your clinical system for details about how different conditions are collected.