Pain perception among Emergency Department patients with headache: responses to standardized painful stimuli

Perception of pain varies significantly across groups of patients. The primary objective of this study was to measure perceived pain among Emergency Department (ED) patients with headache in response to standardized painful stimuli, including blood pressure (BP) cuff inflation and intravenous catheterization (IVC). In this prospective, case-control series, ED patients undergoing IVC and with a headache were compared to those undergoing IVC but without a headache. Medical care of participants was not altered. Data were collected by trained research assistants, including demographic and historical characteristics, and perceived pain scores. Using a 10-point verbal numeric rating scale (0 = no pain ... 10 = worst imaginable pain), participants rated their perceived pain of BP measurement and IVC. Ninety-five percent confidence intervals (CI) constructed around means and proportions were used to assess group differences. One hundred participants had headache; 100 participants with no headache served as controls. There were no differences between groups with regard to gender, ethnicity, or insurance status. Intravenous catheterization was successful in all 200 participants, with a median intravenous catheter gauge of 20 (range 18-24). There were no differences between groups in difficulty of insertion of intravenous catheter or number of intravenous catheterization attempts. Participants with headache reported significantly higher pain scores from BP cuff inflation (mean score 2.9) compared to participants without headache (mean 1.4; mean difference between groups 1.5, 95% CI 0.7-2.3). Participants with headache reported slightly higher pain scores from IVC (mean 4.6) compared to participants without headache (mean 3.9; mean difference between groups 0.7, 95% CI -0.2-1.6), but this difference was not significant. Among participants with headache, there were no statistically significant differences between single headache, acute headache (<10/past 30 days), and chronic headache (>or=10/past 30 days) for reported pain scores of BP cuff inflation or IVC. ED participants with headache reported significantly higher pain scores secondary to BP cuff inflation when compared to control participants without headache.