ICD 11 comes into force, with stroke reclassified as a neurological disorder

The International Classification of Diseases 11 (ICD 11) has come into effect on 1 January 2022. Among major changes in this new classifications, stroke has been moved from circulatory system diseases back to neurological disorders.

The ICD is maintained by WHO and distributed in countries across the globe. An ICD code is assigned to every disease. It can be found on patient paperwork, including hospital records, medical charts, visit summaries, and bills.

Coding has many practical implications. For instance, if you have a chronic illness, such as diabetes or Parkinson’s disease, your ICD code will typically follow your medical records. These codes ensure that you get proper treatment and are charged correctly for any medical services you receive. Insurance companies expect the codes to be consistent between a condition and the treatment rendered. The codes are followed in clinical trials to recruit and track subjects

ICD codes are also used globally to track health statistics such as morbidity (ill health) and mortality (causes of death). This is particularly helpful for gathering data on non-communicable diseases. Reporting of health statistics by the Member States to WHO using the new diagnostic system has now begun in 2022.

For many decades, cerebrovascular diseases including stroke were classified as circulatory system diseases in various ICD iterations. This was in contradiction to the pathophysiology and symptoms leading to mortality and morbidity, which are those of brain dysfunction. Moreover, the decision deviated from the principle of ischaemia of other organs (such as the intestines, kidneys, and the eye), which were listed under their respective organs in various iterations of ICD. For these reasons, the latest version of ICD – ICD 11put stroke back under the neurological heading.

Regarding another major neurological disorders group – dementias, in the 2016 ICD 11 draft, WHO moved the dementia categories from chapter 06- “Mental, behavioural or neurodevelopmental disorders” to chapter 08- “Diseases of the nervous system”. However, this generated written protest notes by many scientific associations, mainly from psychiatry, psychology and other mental health workforce. For this reason, in 2017, the dementia categories were moved back to chapter 06, reflecting clinical manifestations of dementia. At the same time, Alzheimer Disease sits in chapter 8, pointing to aetiology (the cause) of the disease.

The European Federation of Neurological Associations maintains that both Alzheimer’s and dementias are degenerative neurological (and not mental health) disorders due to their clear pathophysiology and hopes that in the future work on ICD these two categories will be united under one heading of diseases of the nervous system, i.e. neurological disorders.

When all neurological disorders are put in one category, as it was done in 2019 Lancet publication: “Global, regional, and national burden of neurological disorders” – we can better appreciate why neurological disorders are the leading cause of Disability Adjusted Life Years (DALYs) and the second leading cause of global deaths (both being third leading causes in the EU and WHO EU region).

While ICD11 officially came into effect on 1 January 2022, each country chooses when to adopt it, and WHO has acknowledged that “not many countries are likely to adapt that quickly”, i.e. begin using the ICD-11 by the time of its launch.

The WHO and national governments should accelerate efforts leading to the implementation of ICD11 – including full integration of stroke into neurological health – to align with the latest scientific evidence and clinical practice. This will help to prioritize and distribute limited public resources according to the latest and most robust scientific evidence.