Comparison of three methods for measuring psoriasis severity in clinical studies (Part 1 of 2): change during therapy in Psoriasis Area and Severity Index, Static Physician's Global Assessment and Lattice System Physician's Global Assessment.
BACKGROUND
Accurate and reliable assessment of changes in psoriasis severity is critical in clinical trials of therapies.


OBJECTIVE
To compare Psoriasis Area and Severity Index (PASI), static Physician's Global Assessment (sPGA), and the Lattice System Physician's Global Assessment (LS-PGA) in a trial of systemic treatments for plaque psoriasis vulgaris and to assess whether they measure change in psoriasis induced by therapy.


METHODS
Patients were randomized to voclosporin or cyclosporine for 24 weeks (the '24-week-treatment' group, n = 366), or placebo for 12 weeks followed by voclosporin for 12 weeks (the 'initial-placebo' group, n = 89).


RESULTS
All scoring systems changed in concert and were sensitive enough to detect reductions in severity during placebo therapy as well as with active therapy (P < 0.01 for each measurement). At study onset, there were poorer correlations of sPGA with PASI (r = 0.45) and LS-PGA (r = 0.39) than between PASI and LS-PGA (r = 0.68). After therapy, all correlations were stronger, but sPGA continued to be less well correlated (with PASI, r = 0.85; with LS-PGA, r = 0.79) than LS-PGA with PASI (r = 0.90). Two- or three-step improvements in LS-PGA showed very good to excellent accuracy in corresponding to PASI-50 and PASI-75, respectively, and were more accurate than comparable changes in sPGA.


CONCLUSIONS
PASI, sPGA and LS-PGA are responsive to the varying degrees of improvement in psoriasis induced by either placebo or active therapy. While the three systems capture similar information, each has different reasons for use in a clinical trial.
Department of Dermatology, University of Michigan Medical School, Ann Arbor, Michigan, USA.
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Chow
Department of Dermatology, University of Michigan Medical School, Ann Arbor, Michigan, USA.|Department of Epidemiology, School of Public Health, University of Michigan, Ann Arbor, Michigan, USA.
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Simpson
Department of Dermatology, University of Münster, Münster, Germany.
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Luger
Department of Dermatology, University of Michigan Medical School, Ann Arbor, Michigan, USA.
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Chubb
Department of Dermatology, University of Michigan Medical School, Ann Arbor, Michigan, USA.
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Ellis
D000328:Adult; D002983:Clinical Competence; D016572:Cyclosporine / Q000627:therapeutic use*; D004311:Double-Blind Method; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007166:Immunosuppressive Agents / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D010820:Physicians / Q000592:standards*; D011565:Psoriasis / Q000175:diagnosis* / Q000188:drug therapy; D012720:Severity of Illness Index; D013997:Time Factors; D016896:Treatment Outcome
D007166:Immunosuppressive Agents; C484071:voclosporin; D016572:Cyclosporine