Correlating an 11-point verbal numeric rating scale to a 4-point verbal rating scale in the measurement of pruritus.

Pruritus, the subjective sensation of itch, can be a difficult symptom to assess and treat. Evaluating levels of patient discomfort across populations has proven to be challenging because of a lack of a standardized measurement tool to quantify levels of itch. The most widely used tool is the 4-point verbal rating scale (VRS-4), but others use an 11-point verbal numeric rating scale (VNRS-11). Therefore, the purpose of our study was to correlate a VNRS-11 to a VRS-4 for the assessment of pruritus. Fifty parturients were enrolled in this correlational study. Each subject's level of pruritus was measured at five specific intervals after administration of intrathecal opioids. The scales were administered one minute apart in random order. Data analysis demonstrated a strong correlation between these two scales, (r=.910 to .853) indicating that each verbal descriptor on the VRS-4 could readily be substituted with a quantifiable range on the VNRS-11.