Abstract
The first edition of the ‘International classification of headache, cranial neuralgias and facial pain’, in short often named ‘The IHS classification’, was published in 1988 and is thus 12 years old. We created the first edition virtually from scratch, and therefore expected that a revision would be necessary soon, but it subsequently became clear that we had produced a lasting document.
There are several reasons for its longevity. First, the document represented novel thinking and it took a long time before neurologists and other headache doctors understood the new system and started using it in scientific studies. The document also had to find its way to users throughout the world and this required multiple translations. Currently more than 20 translations have been published. The document proved excellent in virtually all population-based epidemiological studies, and it was only felt to be inadequate by some working in tertiary referral centres. Finally, it took a very long time before evidence was published on which revisions could be based.
The accumulated scientific data are however, now sufficient to make a revision meaningful. Disease classifications should only be changed when there is a real need, because changes have profound effects. Most importantly, major changes make it difficult to use previous research because that research was done with previous diagnostic criteria. This pertains not only to drug trials but also to epidemiological and pathophysiological studies. On the other hand, a classification should be changed when there is a good evidence base for doing so, otherwise it becomes a hindrance to scientific progress.
These then are the rules under which a new committee of the IHS, The International Headache Classification Committee, has begun its work. Each member is the chairperson of a subcommittee which deals with a particular type of headache disorders. I chaired the first classification and I also chair the revision. The other members of the second International Headache Classification Committee are: Richard Lipton, USA, migraine; Jean Schoenen, Belgium, tension-type headache; Peter Goadsby, UK, cluster headache and allied disorders; Giuseppe Nappi, Italy, miscellaneous primary headaches; Miguel Lainez, Spain, headache attributed to head trauma; Marie-Germaine, France, headache attributed to vascular disorders; Michel Ferrari, The Netherlands, headache attributed to non-vascular, non-infectious intracranial disorders; Stephen Silberstein, USA, headache attributed to substance use; Fumihiko Sakai, Japan, headache attributed to infectious disorders; Tim Steiner, UK, headache attributed to metabolic and other systemic disorders; Hartmuth Goebel, Germany, headache attributed to diseases in cranium, eyes, ears and spine; Michael First, USA, headache attributed to psychiatric disorders; James W. Lance, Australia, cranial nerve pain and atypical facial pain.
The new committee had its first meeting in New York in December 1999 and the next in San Diego in May 2000. Further meetings are scheduled for London, September 2000, Copenhagen, December 2000, and one more in the spring of 2001. Preliminary results will be presented in New York at the IHS congress and the work is expected to be finished at the end of 2001 with the publication coming out in 2002.
Throughout this work we welcome comments and there will be a possibility for all IHS members and for sponsors to sit in during the sessions of the classification committee. Results of the deliberations of the committee will be available on the IHS web site, including minutes from the meetings. We welcome comments and plan to have a discussion forum on the web site. Please be active, but remember that the revision will be entirely evidence based. Unfounded opinions or beliefs should not be presented and all comments should be referenced.
All the other members of the committee look forward to utilizing this new methodology in our communication with the headache community. We believe that it will help us not to forget any important information that has been published. Please address your comments directly to the relevant chairperson or, if it does not pertain to the topic of a particular subcommittee, then to me.