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UKCRC Health Research Classification System

Systematic reviews

Advice on research activities

Systematic reviews are increasing in importance for evidence-based medicine. Systematic reviews tend to involve meta-analysis of a given set or sub-set of treatments for purposes of evaluation, and as such will normally be coded in 6 Treatment Evaluation, using appropriate sub-code(s) for the particular treatments being assessed. If the review involves such a range of treatments that more than four sub-codes (the maximum allowed under HRCS) is required, use 100% 6.9 Resources and Infrastructure.

However some systematic reviews have a scope beyond treatment comparisons and may involve an assessment of delivery of 8 Health Services. Such broad, organisational systematic reviews should be coded as 8.1 Organisation and delivery of services.


Advice on health categories

Both smoking and alcohol have their own specific guidance topics relating to misuse and addiction.

Other substances should be classified depending on the nature of the research.

  • All studies of addiction are treated as psychological conditions and should be coded as Mental Health.
  • Any study of substance abuse / misuse that relates to a specific disease or condition should be coded to the appropriate health category:
    • e.g. intravenous drug use and risk of infection should be coded Infection.
  • The Disputed Aetiology and Other health category also includes some types of social services research for specific ‘healthy’ at risk groups that is not relevant to the general population, e.g. young people or minorities at risk of developing substance misuse problems. Note that in these cases Other should only be used if there is no other disease/condition of focus presented.


Advice on research activities

Substance misuse is considered a risk factor for other diseases. Therefore, interventions to reduce substance misuse should be coded as 3 Prevention, even if the person is already misusing. Use 5 Treatment Development or 6 Treatment Evaluation for studies focussed on treatment of an existing substance-misuse-related disease and in cases of secondary prevention.

Additional guidance on differentiating secondary and primary prevention is also available.


Advice on research activities

Classification of research is context dependent and the coding guidance for assigning research activities is to identify the appropriate main code group first, then assigning a sub-code within it.

If the work relates to diagnostic or prognostic testing to inform treatment decisions, it would be more appropriate to code to 4 Detection and Diagnosis; in most cases using 4.1 Discovery for pre-clinical development and 4.2 Evaluation for clinical use.

If the work is development of new treatments in a pre-clinical or model setting, it would be more appropriate to code to 5 Treatment Development. This includes studies of pharmacogenetics for new therapeutics, which shold be coded as 5.1 Pharmaceuticals.

If it is clinical research using a precision medicine approach then it would be more appropriate to code to 6 Treatment Evaluation for the intervention being evaluated.


Advice on health categories

Studies of sleep follow the same guidance as neuropsychology:

  • Studies mapping normal behaviour or cognitive processes to brain regions should be coded 50% Neurological and 50% Mental Health.
  • Studies of abnormal behaviour and psychology will generally be coded as Mental Health.
  • Studies of abnormal brain and neural structures will generally be coded as Neurological.
  • Studies of circadian rhythm are often but not always Neurological.

Sleep disorders refer to studies which investigate sleep disturbances.  They are divided into six main categories:

  • Insomnia – should be coded as Neurological.
  • Sleep related breathing disorders – e.g. sleep apnoea – should be coded as Respiratory.
  • Hypersomnias – e.g. narcolepsy – should be coded as Neurological.
  • Circadian rhythm sleep disorders – should be coded as Neurological.
  • Parasomnias – e.g. sleepwalking – usually involve motor and verbal elements and should be coded as Neurological.
  • Sleep related movement disorders – e.g. restless leg syndrome – should be coded as 50% Neurological and 50% Musculoskeletal.


Advice on health categories

In general, normal function and conditions affecting the liver (e.g. cirrhosis) should be coded as Oral and Gastrointestinal. Otherwise follow the guidance associated with other health categories appropriately.

e.g. Studies of liver cancer should be coded as 100% Cancer and neoplasms.

e.g. Studies of liver infections (e.g. infectious hepatitis) should be coded as 100% Infection.

e.g. Conditions relating to blood vessels of the liver, such as hepatic vein thrombosis, should be coded as 100% Cardiovascular.

Many conditions of the liver are associated with an inflammatory or metabolic response, e.g. non-infectious hepatitis. However only the disease under investigation should be coded and not to the accompanying inflammatory/metabolic response.

Studies focused on alcohol should follow the separate guidance on alcohol consumption, and use the standardised breakdown only where there is no other indication of disease area.


Advice on research activities

‘Bioinformatics’ is a relatively new interdisciplinary field focusing on interpretation of complex biological data. Studies using bioinformatics will therefore be usually coded in:

Evidence obtained via bioinformatics research may also lead to biomarkers for diagnostic applications (4 Detection and Diagnosis), and development of new therapeutics (5 Treatment Development). However these are often potential future applications and not the main objective of the current research.

The wider topic of ‘Informatics’ – the science of processing, interpretation and storing of vast quantities of data – can often refer to significant resources with wide-reaching applications in health research. As such the guidance for Resources and Infrastructure should be followed when awards support the creation of ‘big data’ repositories. However, the onward use of informatics data should be treated as any other database or resource used in research, with awards coded based on the main research objective.


Advice on health categories

Co-morbidities – the incidence of two or more diseases simultaneously – is common in medicine and has impact on treatments depending on whether they are coincidental, synergistic or one is clinically dominate.

Studies of co- or multi-morbidities should be coded to reflect all contributory diseases/conditions with the appropriate health categories, in alignment with the guidance on sequelae, consequences and side effects. If this were to exceed the limit of five health categories, use 100% Generic Health Relevance instead.

There is also additional guidance for diseases used as case studies and tracer examples for wider health conditions, which is a common theme in co-morbidity studies.


Advice on health categories

Cachexia is the term used for the weight loss, muscle wastage (atrophy), and fatigue associated with late stage, long term and/or chronic conditions (e.g. Cancer, HIV/AIDS, muscular sclerosis). Cachexia is also used in association with the effects of chemotherapy medication in cancer treatment.

Studies of patients with cachexia should be coded based on the underlying causal condition, but follow the rules for sequelae and side effects as appropriate.

e.g. Assessment of cancer patients with cachexia should be coded as 100% Cancer and neoplasms.

e.g. Assessment of depression in cancer patients with cachexia should be coded as 50% Mental Health, 50% Cancer.


Advice on health categories

Vasculitis is a group of diseases featuring inflammation of the wall of blood vessels which can affect several organ systems and have widespread systemic effects.

Studies of vasculitis will usually focus on the inflammation and damage to blood vessels and hence should be coded as 100% Cardiovascular.

Where vasculitis is a secondary condition that arises as a consequence of a specific immune condition it may be appropriate to code 50% Inflammatory and Immune System and 50% Cardiovascular.


Advice on research activities

Trials are not just in 6 Treatment Evaluation – there can be trials in 4 Detection and Diagnosis, 3 Prevention and 8 Health Services.

There are a number of research topics (e.g. Policy, Education, Trial) that are repeated in different parts of the Research Activity codes. Classification of research is context dependent and the coding guidance for assigning research activity codes is to identify the appropriate main code group first, then assign a sub-code within it.