Disease sequelae, consequences and side effects

Research aimed at investigating sequelae of a specific pre-existing disease should be assigned equal percentage weighting to the primary existing condition and to the condition under investigation.
Example: cardiovascular disease in diabetic patients is classified 50% Cardiovascular and 50% Metabolic and Endocrine.

Studies of the side effects of a disease, where the condition under study is a downstream consequence of an original condition, are treated similarly
Examples: A study into depression as a result of cancer would be coded 50% Mental Health and 50% Cancer. Post natal depression is coded 50% Mental Health 50% Reproduction

Studies of the direct side effects of a disease treatment are usually coded in the same way. Example: A study of bowel injury resulting from radiotherapy for cancer is coded 50% Cancer and 50% Oral and Gastrointestinal. In some cases, however, it may not be appropriate to code for the pre-existing disease if a particular disease is being used as an exemplar for studying the side effects of a treatment. Examples may include studies of generalisable anti-nausea drugs.