Assessment of severity score in patients with psoriasis

Clinical evaluation of a more rapid and sensitive Psoriasis Assessment Severity Score (PASS), and its comparison with the classic method of Psoriasis Area and Severity Index (PASI), before and after climatotherapy at the Dead-Sea

BACKGROUND

The Psoriasis Area and Severity Index (PASI) is used to quantify the extent of the disease, and to evaluate its improvement with treatment. It is considered to be a slow, rough, nonsensitive, and complex tool, with high interobserver variability and low reproducibility.

OBJECTIVES AND METHODS

To develop a simpler, more sensitive, and more rapid end-point determination for evaluating the psoriatic condition, and to compare its sensitivity with that of the classic PASI score in psoriatic patients undergoing 4-week climatotherapy at the Dead-Sea (Israel).

RESULTS

This study describes a new, rapid, and simple Psoriasis Assessment Severity Score (PASS), whose readings are spread over a longer scale, making the test more sensitive than PASI, and allow better differentiation.

CONCLUSIONS

The comparison between the classic PASI and our new PASS emphasizes the weight of the "sensitivity to change" (responsivity) in selecting a better evaluation method for psoriatic patients.

The Salford Psoriasis Index: an holistic measure of psoriasis severity

We have developed, tested and validated a new scoring system for psoriasis: the Salford Psoriasis Index (SPI). The SPI incorporates the current clinical extent of psoriasis based on the Psoriasis Area and Severity Index (PASI), a score indicating psychosocial disability, and past severity based on treatment history. The resultant three-figure SPI (signs, psychosocial disability, interventions) is a similar paradigm to the TNM (tumour, nodes, metastasis) classification used for cancer staging. The first figure transforms the PASI into a number from 0 to 10 reflecting extent of psoriasis. The second assesses the psychosocial impact of psoriasis on each patient using a 0-10 visual analogue scale. The third figure reflects historical severity of disease as judged by the need for systemic treatment, admission to hospital and number of episodes of erythroderma. The SPI was prospectively employed in assessing 150 consecutive patients with psoriasis. Furthermore, in a separate cohort of 100 patients we tested the Psychosocial Impact Score against a recognized self-report psoriasis-specific measure, the Psoriasis Disability Index. There was a strong correlation between the two (r = 0.59, P < 0.001). However, the Psychosocial Impact Score correlated poorly with clinical extent scores such as the PASI (r = 0.28, P < 0.05) and the Self-administered PASI in 72 patients tested (r = 0.19, P = 0.1). There was a high correlation between all six observers in 20 patients for both PASI (r = 0.71; 95% confidence interval, CI 0.51-0.86) and the Extent Score (r = 0.70; 95% CI 0. 56-0.89). We believe that the SPI will be more relevant to real-life categorization of psoriasis severity in that it takes an holistic approach based not only on physician assessment but also psychological disability and treatment resistance.

Clinical measures of disease severity and outcome in psoriasis: a critical appraisal of their quality

In clinical trials, a wide range of outcome measures has been used to evaluate the severity of psoriasis and its response to treatment. Despite their widespread use, many measures have received little attention with regards to their reliability and validity. Selecting an appropriately developed measurement tool is therefore of critical importance. We conducted a literature survey to examine the status of clinical outcome measures used in psoriasis research. The measures most commonly used were individual sign scores, e.g. for erythema, plaque thickness or scaling, and pooled indices, e.g. the Psoriasis Area and Severity Index. None of these, however, systematically fulfilled all the requirements of a validated instrument for disease assessment. Ideally, a core set of reliable and validated outcome measures for use in all psoriasis clinical trials is needed. Objective instrumental methods should minimise observer variation, but unless a simple non-invasive method can be developed, the uptake of such technology will probably be limited by cost and lack of practicality. Moreover, the translation of instrumental readings into clinically relevant measures is always a major problem, and for none of the methods has there been a robust mapping of instrumental readings on to a clinically meaningful scale. Further research is needed to determine the most appropriate and sensitive parameters to use as surrogate measures for capturing the distress which psoriatic patients feel but which is not measured with sufficient sensitivity or precision with current quality of life or distress questionnaires.