Reliability of pain scales in the assessment of literate and illiterate patients with rheumatoid arthritis.

The assessment of a measure of chronic pain, should be reliable, valid and sensitive to change. Our study evaluated the reliability of 3 pain scales, visual analogue scale (VAS), numerical rating scale (NRS) and verbal rating scale (VRS) in literate and illiterate patients with rheumatoid arthritis (RA). Patients with RA attending an outpatient rheumatology clinic were interviewed and asked to score their pain levels on the 3 pain scales. The scales were presented in random order, twice, before and just after a regular medical consultation. Ninety-one patients were studied (25 illiterate and 66 literate). The Pearson product moment correlation between first and second assessment was 0.937 for VAS, 0.963 for NRS and 0.901 for VRS in the literate patient group and 0.712 for VAS, 0.947 for NRS and 0.820 for VRS in the illiterate patient group. These results indicate that the NRS has the higher reliability in both groups of patients.