WHO, Neuro Experts Clash Over ICD-11 Stroke Classification

October 21, 2016

Leading neurology experts have criticized the World Health Organization (WHO) over how stroke is classified in its new draft revision of the International Statistical Classification of Diseases and Related Health Problems (ICD).

The WHO is updating the current ICD-10, which is based on medical knowledge from the 1980s, and the new ICD-11 has been under discussion since 2009.

An expert advisory group, led by Raad Shakir, MD, Imperial College London, United Kingdom, and president of the World Federation of Neurology, was appointed by the WHO to make recommendations on the classification of various neurologic conditions, including stroke.

The current issue of disagreement concerns the fact that stroke, which is part of a newly created cerebrovascular thematic block, has been classified as a "circulatory disease," not as a neurologic condition.

In a letter to The Lancet, Professor Shakir and colleagues call the medical rationale for stroke being a disease of the brain "overwhelming.… All manifestations of cerebrovascular disease are related to brain dysfunction. The relationship with dementia and particularly Alzheimer’s disease is becoming clearer."

However, they write, "On Sept 9, 2016, WHO classification staff unilaterally decided to break their agreed decision made 5 years earlier and move the newly created cerebrovascular block from neurology to circulatory disease."

They called its classification as a circulatory disease a "backward step" that "did not follow the expected transparency and openness of WHO decision-making."

The decision "came totally out of the blue and even the WHO departments that are responsible for neurosciences and non-communicable diseases, as well as the Neurosciences TAG (Topic Advisory Group), were not informed, let alone consulted," the authors write.

Other signatories to the letter include leading stroke experts Steve Davis, MD, Melbourne Brain Centre, Royal Melbourne Hospital and University of Melbourne, Parkville, Australia; Bo Norrving, MD, Lund University, Sweden; Wolfgang Grisold, MD, Kaiser Franz Josef Hospital, Vienna, Austria; William M. Carroll, MD, Department of Neurology, Sir Charles Gairdner Hospital, Perth, Australia, Centre for Neuromuscular and Neurological Disorders, Western Australian Neuromuscular Research Institute, University of Western Australia; Valery Feigin, MD, National Institute for Stroke and Applied Neurosciences, Auckland University of Technology, New Zealand; and Vladimir Hachinski, MD, University of Western Ontario, London, Ontario, Canada.

"We as an advisory group nominated by the WHO 7 years ago have spent many hours of our time, meeting twice year, and exchanging thousands of emails discussing the issues of classification of various neurological conditions, including stroke," Professor Shakir commented to Medscape Medical News. "We advised that the new ICD-11 should have a new classification of stroke — as a neurological condition — but they have left it classified as cardiovascular.

"Transient ischemic attack (TIA) is also not considered to be a neurological condition, but is classified as an 'acute episodic condition.' That’s completely wrong too," he said.

"Why did they bother asking a team of international specialists with many years of expertise and experience to do this if they take no notice of our recommendations?" he added.

It is "far too simplistic just to describe stroke as a disease of the blood vessels," Professor Shakir said. "If it is classified as a cardiovascular condition, then it is lumped in with heart disease and peripheral vascular disease, and this makes the statistics very difficult to understand. These ICD classifications are only updated every 20 to 30 years, so now again for the next quarter of a century we will be lumbered with incorrect classification of one of the major killer conditions in the world."

He says the classification system is important because it affects how governments allocate funding to various conditions and how research and treatment decisions are made.

"Because stroke has been classified as a cardiovascular condition, this will make it more difficult to get funding to promote educational programs specific to stroke such as the FAST campaign, and to understand more about the condition — for example, how many people develop vascular dementia," he said. "If the numbers are not entered correctly, then it’s very difficult to know what you’re dealing with and how to move forward. If you put rubbish in you’ll get rubbish out.

"If it was classified correctly, the numbers of people affected would be more accurately assessed and the condition would get better attention."

Professor Shakir believes the WHO is reluctant to change stroke to be classified as a neurologic condition for logistic rather than medical reasons. "The people in the WHO making these decisions are statisticians — not medical professionals. They are reluctant to change the status quo."

The "main purpose of any enduring classification should be to serve the interests of patients, which is not the case unless stroke is acknowledged as being a brain disease," the authors of the comment cautioned. "The latest classification decision with respect to stroke needs to be reversed in order to safeguard patient care and provide correct figures and funding for health care provision."

In a response, also published in The Lancet, representatives from the WHO Joint Task Force on ICD-11 write: "Production of a classification that is taxonomically sound and practicable for users has required appraisal and integration of a vast amount of advice, which was sometimes contradictory.

"Continuity of mortality statistics remained the priority for the ICD, which is essentially an aetiological classification, and some of the proposals of expert groups with a clinical focus were revised or rejected," they add. "For instance, although the sequelae of a cerebrovascular condition may largely be related to the nervous system, the acute phase and aetiology are clearly vascular."

They add: "‘Vascular lesions affecting central nervous system’ have been in the diseases of the vascular system chapter since ICD-7."

The WHO task force notes that decisions were made available on the ICD web platform in August 2016, and the WHO was to release the 2016 version of the ICD-11 for country comments during the ICD revision conference in Tokyo, Japan, held October 12–14, 2016. The results of country field testing and further refinements should result in the release of the ICD-11 for country implementation in 2018.

Lancet. Published online October 13/14, 2016. Letter, Response

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