The numeric rating scale and labor epidural analgesia

A verbal numeric 0-10 rating scale (NRS) is widely used to evaluate pain in research studies, but its usefulness to the clinician is not well established. In this study, we define desire for additional analgesic medication as a clinically relevant outcome in research studies about pain and compare it with the results of the NRS. A post hoc analysis of three studies that we previously conducted concerning labor epidural analgesia was performed. In all three studies, a verbal NRS score was obtained before and 15 min after labor epidural analgesia. At 15 min, the woman was also asked if she wanted more pain medication. We found that very few patients (2%) with a NRS score of 0-1 wanted more medication. When the NRS score was 2 or 3, 51% of the patients wanted more medication, and when the NRS score was >3, almost all patients (93%) wanted more medication. Grouping the final NRS scores into 3 categories (0 or 1, 2 or 3, and >3) is more useful to the clinician than using individual NRS scores.