Validation of the eleven-point pain scale in the measurement of migraine headache pain

The four-point pain scale (none, mild, moderate, severe) and the 11-point pain scale (0 = no pain, 10 = pain as bad as it could be) have been used in migraine studies to assess treatment efficacy. The primary objective of this study was to investigate the validity and responsiveness of the 11-point pain scale using the four-point pain scale as a benchmark. Using data from 95 migraine patients recruited from headache clinics, this study found that 11-point pain scale scores were highly correlated with four-point pain scores. The correlations between the pain scales were significantly higher than the correlations with quality of life measures such as functional ability and emotional feelings. The 11-point pain scale was 55% more sensitive than the four-point pain scale in detecting clinically important differences. The strong linear relationship between the two pain scales allowed researchers to transform four-point pain scores to 11-point pain scores using regression weights.