Pain measurement in cancer patients: a comparison of six methods.

A consecutive sample of 53 chronic cancer pain patients were administered 5 different pain intensity scales: a visual analogue scale (VAS), a numerical rating scale from 0 to 10 (NRS), a verbal rating scale (VRS), the Italian Pain Questionnaire (Italian version of the McGill Pain Questionnaire) (PRI), and the Integrated Pain Score (IPS) which is an instrument designed at the Pain Therapy and Palliative Care Division of the National Cancer Institute of Milan to integrate pain intensity and duration in a single measure. These scales were administered before and after a definite therapy change. At the time of the second evaluation the patients were also administered a pain relief scale (IRS). A factor analysis of the scoring properties of these instruments revealed a high degree of association between the variables. A single factor clearly emerged explaining most of the different scales variability. A logistic regression analysis showed that VAS, NRS, VRS were more strongly associated with IRS than PRI and IPS.