title: Are migraine and tension-type headache diagnostic types or points on a severity continuum? An exploration of the latent taxometric structure of headache.
abstract: The objective of this study was to assess whether migraine and tension-type headache (TTH) are best viewed as discrete entities or points on a severity continuum using taxometric analysis. Historically, classification systems have conceptualized the primary headache disorders of migraine and TTH as fundamentally different disorders that are differentiated by their characteristic symptom profiles and, as such, imply differing pathophysiologies and required treatments. Despite this categorical nosology, findings continue to emerge suggesting that migraine and TTH instead reflect dimensions of severity within the same headache construct. However, few studies have assessed this issue using taxometric statistical analyses or investigated how this taxonomic structure varies as a function of age and headache frequency. We conducted a latent-mode factor analysis of headache symptomatology obtained from 3449 individuals with headache from 2 previous, large-scale cross-sectional studies of primary headache sufferers (Martin et al., 2005, and Smitherman and Kolivas, 2013). Stratified taxometric analyses suggest that the validity of a categorical vs dimensional classification varies as a function of sample characteristics. Specifically, graphical results revealed that high headache frequency (>15 d/mo) and younger age (<24 years old) were associated with unimodal distributions suggestive of a dimensional construct of primary headache, whereas lower headache frequency and older age were associated with bimodal distributions characteristic of discrete diagnostic entities. Conceptualizing primary headache as a severity continuum was supported for young adults and those with frequent headaches. The distinctions of a categorical classification system were supported for adults (>24 years old) and those with infrequent headache.
authors.affiliation: Department of Anesthesiology, Wake Forest School of Medicine, Winston-Salem, NC, USA Department of Psychology, University of Mississippi, Oxford, MS, USA Advance Neurology and Pain, Advance, NC, USA Northshore Integrative Healthcare, Chicago, IL, USA Department of Neurology, Wake Forest School of Medicine, Winston-Salem, NC, USA.
authors.forename: Dana P
authors.initials: DP
authors.lastname: Turner
authors.forename: Todd A
authors.initials: TA
authors.lastname: Smitherman
authors.forename: Anna Katherine
authors.initials: AK
authors.lastname: Black
authors.forename: Donald B
authors.initials: DB
authors.lastname: Penzien
authors.forename: John A H
authors.initials: JAH
authors.lastname: Porter
authors.forename: Kenneth R
authors.initials: KR
authors.lastname: Lofland
authors.forename: Timothy T
authors.initials: TT
authors.lastname: Houle
mesh_terms: D000293:Adolescent; D000328:Adult; D003430:Cross-Sectional Studies; D016208:Databases, Factual / Q000639:trends; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008881:Migraine Disorders / Q000145:classification* / Q000175:diagnosis*; D012720:Severity of Illness Index; D018781:Tension-Type Headache / Q000145:classification* / Q000175:diagnosis*; D055815:Young Adult