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Table 2 Summary of proportion of concordance, simple kappa coefficient, κ, (95% confidence interval, CI), maximum attainable kappa, κmax, and prevalence-adjusted bias-adjusted kappa, PABAK (95% CI)

From: Development and validation of a telephone classification interview for common chronic headache disorders

Comparison Proportion of concordance κ 95% CI κmax PABAK 95% CI
Chronic migraine vs. othersa 0.76 0.31 (0.09 to 0.52) 0.79 0.51 (0.35 to 0.68)
Chronic migraine vs. chronic TTHb 0.96 0.38 (−0.18 to 0.94) 0.79 0.92 (0.83 to 1.00)
With MOH vs. without MOHc 0.76 0.40 (0.17 to 0.63) 0.93 0.51 (0.32 to 0.71)
  1. aChronic migraine = definite chronic migraine or probable chronic migraine; Others = chronic tension type, other chronic headaches or non-chronic headaches
  2. bChronic migraine = definite chronic migraine or probable chronic migraine; chronic TTH = chronic tension type headache
  3. cMOH, medication overuse headache
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