Assessing headache severity. New directions.

Headache is a heterogeneous condition that varies widely in global severity and in severity of individual attacks. Whereas recent efforts have focused on improving the diagnostic criteria for classifying headache, less effort has been directed toward developing reliable, valid, and clinically useful methods of assessing the impact or severity of headache. Existing measures of severity include one or more of the following weaknesses: (1) only pain intensity is assessed or the measure is incomplete in other ways, (2) measures have little or no prognostic value for relevant outcomes, (3) the reliability or the validity of the measure has not been assessed, or (4) the measure is too cumbersome for clinical practice or field research. We describe a brief, simple method for grading the severity of headache, the Chronic Pain Index, which assumes that a continuum of pain intensity and disability is the underlying dimension of severity. Along this continuum, lower levels of severity are differentiated by pain intensity and higher levels by interference with function. The prognostic value of the results from a seven-item questionnaire for grading headache severity is compared with that of alternative measures. The Chronic Pain Index showed the strongest independent cross-sectional and prospective correlation with measures of headache impact, depression, and use of healthcare services. These results support the potential utility of brief methods of assessing headache severity and exemplify the importance of including measures of interference with function when assessing severity.