Exploration of the Product of the 5-Point Investigator’s Global Assessment and Body Surface Area (IGA × BSA) as a Practical Minimal Disease Activity Goal in Patients with Moderate-to-Severe Psoriasis

Background/Aims: In the treat-to-target era, psoriasis disease activity measures that can be easily performed in routine clinical practice are needed. This retrospective pooled analysis explored cutoff values of the product of the 5-point Investigator’s Global Assessment and percentage of affected body surface area (IGA × BSA) correlating with achievement of minimal disease activity (MDA). Methods: Post hoc analysis of the phase 3 clinical trials ERASURE, FIXTURE, FEATURE, and JUNCTURE was conducted to determine associations between IGA × BSA and 2 MDA definitions (Psoriasis Area and Severity Index [PASI] 90 and Dermatology Life Quality Index [DLQI] 0/1, or PASI score ≤1 or BSA <3%) in patients with moderate-to-severe psoriasis receiving secukinumab 300 mg. For each definition of MDA, a range of possible cutoff values of IGA × BSA was examined at each time point. The optimal cutoff value was determined using Youden index (YI), calculated as (sensitivity + specificity – 1). Results: For MDA defined as PASI 90 and DLQI 0/1, optimal IGA × BSA cutoffs were 2.10 at week 12 (YI, 0.60; sensitivity, 0.78; specificity, 0.82), 1.02 at week 24 (YI, 0.55; sensitivity, 0.73; specificity, 0.82), and 1.00 at week 52 (YI, 0.65; sensitivity, 0.79; specificity, 0.86). For MDA defined as PASI score ≤1 or BSA <3%, optimal IGA × BSA cutoffs were 2.98 at week 12 (YI, 0.91; sensitivity, 0.99; specificity, 0.92), 2.80 at week 24 (YI, 0.94; sensitivity, 0.99; specificity, 0.95), and 3.00 at week 52 (YI, 0.96; sensitivity, 1.00; specificity, 0.96). Conclusion: IGA × BSA could be a valid measure highly associated with achievement of MDA.