Psoriasis Area and Severity Index (PASI) percentage change is dependent upon baseline PASI before a switch in treatment. However, in clinical practice, patients with psoriasis often lack baseline PASI values, thereby making goals such as PASI 90 unsuitable to inform treatment guidelines or follow-up, according to a study published in the British Journal of Dermatology. Instead, the dermatology community would be better served focusing on skin clearance end points rather than relative reductions in psoriasis lesions.

Randomized clinical trials (RCTs) of biologics and psoriasis treatment guidelines often base treatment goals on percentage improvement using PASI 75 or PASI 90, and few assess factors that may be associated with higher rates of skin clearance or improvements in health-related quality of life associated with different degrees of skin clearance.

This study was designed to investigate these associations in a real-world setting with patients who had not been exposed to treatment with biologics. PASI, Dermatology Life Quality Index (DLQI), and EuroQol-5D (EQ-5D) outcomes were assessed before (6 months maximum) and after (ranging from 3 to 12 months) a switch to biologics. The 515 patients ultimately included were identified using the Swedish Registry for Systemic Treatment of Psoriasis.

Regression analyses were used to investigate patient characteristics associated with higher treatment response, and absolute PASI, DLQI, and EQ-5D before and after switch were assessed in different PASI percentage response subgroups including: no response or worsened (PASI ≤0), low responders (PASI 1 to <50 and PASI 50 to <75), responders (PASI 75 to <90 and PASI 90 to <100), and high responders with complete skin clearance (CSC). 

High PASI percentage response was associated with higher baseline PASI and lower body mass index. EQ-5D and DLQI improved within all responder groups (P <.001), but the magnitude of improvement in DLQI (P =.02) differed between groups.

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The mean (SD) PASI improvement for PASI 75 to <90 was 11.1 (5.4) compared with 14.5 (7.8) for PASI 90 to <100 and 9.6 (5.6) for patients who achieved CSC (P <.001). The mean (SD) DLQI improvement for PASI 75 to <90 was 9.9 (7.4), compared with 11.5 (7.0) for PASI 90 to <100, and 8.0 (6.1) for patients achieving CSC (P =.02). Improvements in EQ-5D were not statistically significant (P =.403).

Patients achieving CSC had, on average, a lower absolute baseline PASI (P =.004) and lower DLQI improvement compared with the PASI 90 to <100 responder group (P =.05). Differences in EQ-5D improvements between the CSC and PASI 90 to <100 responder groups were not statistically significant (P =.313).

The study investigators concluded that PASI percentage change is largely dependent on absolute PASI before a switch to biologics. The researchers suggested that “future RCTs should report absolute PASI at follow up, in order to improve the transferability between trial data and real-world data. This would support reimbursement decision-making which require information on whether treatments work, not only in the pre-marketing experimental RCT setting, but also post-marketing, under real-world conditions.”

Disclosure: This clinical trial was supported by AbbVie, Eli Lilly, Janssen Cilag, Leo Pharma, and Novartis.

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Reference

Norlin JM, Nilsson K, Persson U, Schmitt-Egenolf M. Complete skin clearance and PASI response rates in clinical practice: predictors, health related quality of life improvements and implications for treatment goals [published online July 20, 2019]. Br J Dermatol. doi:10.1111/bjd.18361