Common clinical tools to assess psoriasis severity may not capture full impact of disease

The IPC Disease Severity Working Group concluded that the objective measures of two commonly used clinical tools to determine psoriasis severity may not fully capture the impact of the disease on the individual in a new review published in the Journal of The Academy of Dermatology and Venerology (JEADV). 

Clinicians typically determine a patient’s psoriasis severity using quantitative and qualitative measures, including body surface area (BSA) involvement, the Psoriasis Area and Severity Index (PASI), and the Dermatology Life Quality Index (DLQI), a patient-reported questionnaire. Patients with a PASI score of 10 and higher are eligible for systemic and biologic psoriasis treatments. However, these assessment tools lack uniformity: some are not well validated and others are challenging to use in clinical settings.  Moreover, treatment decisions using artificially designated cut-offs based on quantitative measures may leave patients who are significantly affected by their disease undertreated.¹

In the new study, IPC researchers re-evaluated the validity of using a PASI score of 10-12 as a threshold to determine eligibility for systemic and biologic treatments when factoring in patient quality of life. The researchers conducted a systematic review of randomized control trial (RCT) data published between 2000-2017 to assess correlations between provider and patient-generated severity at baseline. The RCT data included information from patients with mild and moderate psoriasis. They found with that in subject groups with high impact on quality of life (DLQI >10), the mean weighted BSA was 7.6 (range: 7.1-8.4) and the mean weighted DLQI was 11 (range: 10.2-12.2). Similarly, the mean weighted PASI for patients with DLQI >10 was 8.7 (range: 7.1 – 10.1) and the mean weighted DLQI was 10.9 (range: 10.1 -12.2).

This study showed that the correlation between mean DLQI and mean BSA at baseline was high. However, BSA and DLQI were not well correlated at values of DLQI >10. Importantly, many patients with BSA <10 (range: 7.1-8.4) reported a significant impact on quality of life (DLQI range: 10.2-12.2). Similarly, patients with DLQIs >10 (range: 10.1-12.2) also reported PASI mostly below 10 (range: 7.1-10.1). In general, researchers concluded, the objective measures of BSA and PASI alone, when excluding DLQI, did not fully capture the impact of disease severity.