- A comparative assessment of itch assessment scales (visual analog scale [VAS], numeric rating scale [NRS], verbal rating scale [VRS], and itch severity scale [ISS]) for chronic pruritus finds that the ISS has the best retest reliability.
Why this matters
- Chronic pruritus affects many dermatology patients, necessitating valid and reliable measurement tools.
- VAS, NRS, and VRS were strongly correlated at initial visit (Spearman’s correlation coefficient, 0.86 for VAS vs NRS, 0.81 for NRS vs VRS, 0.72 for VAS vs VRS) and follow-up (0.92 for VAS vs NRS, 0.83 for NRS vs VRS, 0.80 for VAS vs VRS).
- ISS showed low intercorrelation validity with these tools at initial visit (0.54 vs VAS, 0.60 vs NRS, 0.62 vs VRS) and follow-up (0.63 vs VAS, 0.66 vs NRS, 0.64 vs VRS).
- ISS had a higher intraclass coefficient at retest (0.89) compared with VAS (0.77), NRS (0.77), and VRS (0.75).
- ISS had the best correlation with the Itchy Quality of Life tool at initial visit (0.73 and 0.70, respectively).
- 419 patients with chronic pruritus were included.
- Funding: Ministry of Health & Welfare, Republic of Korea.
- Patient heterogeneity.
- Potential recall bias.