Figure 1. Headache-day frequency by noncephalic pain region.

The frequency of headache days by (A) presence of pain most/all of the time or (B) severe pain intensity. Pain frequency at each location was assessed with the Total Pain Index. Response options included none of the time, a slight bit of time, some of the time, most of the time, and all of the time. Pain severity was assessed by the Total Pain Index. Respondents were asked to rate pain severity on a scale from 0 (no pain) to 10 (worst pain you have had), and severe pain intensity was defined as a score ≥8. *p < 0.05; p < 0.001 for all other comparisons.