Headache Medicine Connections

Abstract

Dear Readers

Belfast-born William Thomson (better known as Lord Kelvin) said ‘If you cannot measure it, you cannot improve it’ and this remains as true today as it was over 100 years ago. Measurement in headache medicine is challenged with a lack of gold standard testing for diagnoses, relying instead on symptom criteria much of the time rather than neurobiological features.

In this inaugural edition of Headache Medicine Connections Dr. Pravin Thomas and colleagues introduce the World Headache Society Classification of Headache Disorders, representing an exciting multidimensional user-friendly and up-to-date approach to the challenge of headache classification, an area in need of advancement. The reader will immediately notice the multi-axial construct, allowing separate axes for patient narrative, biomarkers and validated impairment scales which together gives a lot more information than diagnosis-based classification alone. The WHS classification is designed to be used by healthcare workers of any level of experience and the WHS classification committee endeavor to update the online classification document as needed enabling timely sculpting of their new classification. Users are encouraged to give feedback directly to the WHS.

Expunged are artificial constructs of treatment response defined disorders (treatment response as a sine qua non for diagnosis), acute/chronic designation and even primary/secondary headache. The reader will also notice the absence of diagnostic-like criteria in the classification, avoiding erroneously using the classification for diagnosis in practice which is a fundamental mistake. It is important to comment on the basic differences between a classification and diagnostic criteria. Classifications typically exhibit high specificity at the expense of sensitivity to identify a well-defined group, as this suits the clinical study of populations especially interventional studies. In this situation there is a desire to minimize false positive cases at the expense of missing some genuine cases (lower sensitivity) with a view to keeping non-cases out of a particular cohort. Classifications are focused then on populations, whereas diagnostic criteria involve the aggregation of symptoms, signs and testing found in clinical practice that allow formulation of a diagnosis for an individual patient. The WHS classification committee see a role for criteria that do not involve stipulating strict requirements, a position that will likely lead to criticism, however there is much that can be accomplished with this multi-axial and more user-friendly classification system nevertheless.

A lot has yet to be understood about the physiology of headache disorders and we still rely on symptom-based diagnoses. There is also a lot to learn yet about the impact of headache disorders on the individual, made more important with this new classification. The addition of patient narrative and impairment ratings gives more scope for epidemiologic study and presents a classification friendly to clinical practice. The WHS look forward to commentary on the new classification. While new classifications may draw criticism, this may be the disruptive innovation needed to move headache medicine forward.

Editor in Chief

Brian E McGeeney