[Severity scores for childhood psoriasis: A systematic literature review]

Psoriasis affects 0.5 to 1 % of children in Europe. It has a significant impact on quality of life. Recently, systemic treatments have been licensed for children with moderate-to-severe psoriasis. While scores to assess the severity of the disease are thus important for the management of these children, there is no standardization or consensus concerning their use in childhood psoriasis. The aim of this study was to examine the use of clinical severity scores and quality of life in children with psoriasis.

A systematic literature review was conducted on PubMed and Embase. Further research was carried out using the bibliographic references in selected articles. The following keywords were used: "psoriasis" with "pediatric", "childhood", "infant", "child" or "adolescent", and "Severity of Illness Index", "sickness impact profile", "quality of life", "index", "measure" or "score". A first selection was made from the titles and abstracts of the selected articles.

After evaluating 1712 articles on Medline and 233 on Embase, 78 were finally selected. The Psoriasis Area Severity Index (PASI: 74.4 %) was the most frequently found score followed by the Body Surface Area (BSA: 48.7 %) and the Physician's Global Assessment (PGA: 29.5 %). Recourse to systemic therapies and failure of topical treatments were also used as severity criteria. Over half the studies did not define a severity threshold. We also observed extensive heterogeneity in the definition of psoriasis severity. The same scores were often used regardless of psoriasis type or patient age. Regarding quality of life, most studies used the Children's Dermatology Life Quality Index (CDLQI: 23.1 %) and DLQI (5.1 %). Non-specific quality-of-life scores for psoriasis were also used, such as the Pediatric Quality of Life Inventory (Peds-QL: 6.4 %) and Skindex (2.6 %). Here again, no severity threshold was defined for these scores.

Severity scores are chiefly used by analogy with adults but without validation in the pediatric population. They do not consider pediatric specificities such as progression of BSA according to age, clinical aspect, clinical types, etc. Severity thresholds are rarely defined in children, whether in terms of clinical score or quality of life. This can constitute a limitation in terms of both prescription of systemic treatments and comparison between different studies. Our study demonstrates the need to validate severity and quality-of-life scores and to define child-specific thresholds.