Inter-observer reliability of the PASI in a clinical setting

With the evolving emphasis on evidence-based practice, the use of reliable clinical scales forms an important foundation for clinical assessment. The psoriasis area and severity index (PASI) is the most widely used tool for the measurement of psoriasis severity; however, there has been some debate over the potential reproducibility of PASI scoring.

To determine the inter-observer reliability of the PASI at a large tertiary hospital with a psoriasis treatment centre.

In total, 34 patients who were due for their 3-monthly follow up at a psoriasis treatment centre were independently evaluated by five clinical staff (observers) from the Department of Dermatology. Each observer independently determined the PASI score of each patient and the inter-observer reliability coefficient was determined by employing intra-class correlation coefficients (ICC).

There was a significant degree of concordance among the PASI scoring of observers (ICC = 0.804; CI 95%: 0.706-0.883).

Our cross-sectional study suggests that the PASI provides a reproducible method of assessing psoriasis severity among patients seen in a busy dermatology clinic at a large tertiary hospital.