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UKCRC Health Research Classification System

Sequelae, consequences and side effects

Advice on health categories

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.

e.g. Cardiovascular disease in diabetic patients should be coded as 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.

e.g. A study into depression as a result of cancer should be coded 50% Mental Health and 50% Cancer.

e.g. Studies of post natal depression should be coded as 50% Mental Health and 50% Reproduction.


Studies of the direct side effects of a disease treatment are usually coded in the same way.

e.g. 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.

e.g. If a particular disease is being used as an exemplar for studying the side effects of a treatment, such as studies of generalisable anti-nausea drugs.


There is also additional guidance available for diseases used as case studies and co-morbidities.