Pain medicine : the official journal of the American Academy of Pain Medicine
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The present study sought to derive an algorithm using factor analysis and structural equation modeling (SEM) to describe headache and orofacial pain patients using measures of behavioral and psychological functioning. This investigation further examined whether the underlying factor structure differed in 3 presumed distinct diagnostic categories: myofascial, neuropathic, and neurovascular pain. ⋯ Analysis derived a 3-factor solution. The factors were Pain Impact, Illness Conviction, and Depression. SEM revealed the critical causal pathway showing that Depression determined Illness Conviction and Pain Impact. We conclude that the main target for pain treatment is depression. No differences in factor structure were found for the 3 diagnostic categories of myofascial, neuropathic, or neurovascular pain. This suggests that psychological processes are similar in chronic headache and orofacial pain patients despite their presumed distinct underlying pathophysiological mechanisms. SME is a powerful methodology to construct causal models that has been underutilized in the pain literature.