Static Physician Global Assessment of Psoriasis (sPGA)

Clinical Tools

DESCRIPTION:
The 5-point Static Physician Global Assessment scale is used to assess the overall severity of psoriasis at a given point in time. The score ranges from 0 (clear) to 4 (severe). The assessment is considered “static” because it refers to the subject's disease state at the time of the assessment without comparison to any of the subject's previous disease states, whether at baseline or at a previous visit.1-3

DISEASE STATES: 
Psoriasis

VALIDATED USES: 
Treatment monitoring in clinical trials/research in conjunction with PASI, guiding treatment decisions in clinical practice

ADMINISTRATION METHOD:
Physician, clinician, HCP representative

COMMONLY USED IN:
Clinical trials, research, clinical practice

DETAILED DESCRIPTION:
The sPGA is based on the Physician Global Assessment (PGA) and/or the Investigator's Global Assessment (IGA). The PGA/IGA may use 5-point or 6-point assessment scales and differ in that they can be used to determine change over time. The 5-point sPGA involves a visual evaluation of the skin by a physician, clinician, or an appropriate HCP representative who then assigns a score to the patient’s psoriatic lesions. The psoriatic lesions are graded for erythema (e), induration (i), and scaling (s) based on a scale that ranges from 0 to 4.2-4

The final sPGA is a composite score that is generated from an average of the 3 domain scores (final sPGA score = e+i+s/3). A lower average score indicates less severity, with 0 being clear and 1 being almost clear.2,4 In moderate-to-severe psoriasis studies, there is a correlation between PGA scores and the proportion of subjects achieving a percent reduction of disease severity represented by PASI percent score.1

Common endpoint in clinical trials for the sPGA is 0/1 and/or a ≥2 point reduction from baseline when using the non-static PGA/IGA.

sPGA RATING SCALE FOR OVERALL PSORIATIC DISEASE2,4

Average Scoring Assessment Psoriasis Description
0 Clear
  • No signs of psoriasis/scaling
  • Postinflammatory hyperpigmentation may be present
1 Almost clear
  • Normal to pink coloration
  • No thickening
  • No to minimal focal scaling
2 Mild
  • Pink to light red coloration
  • Just detectable to mild thickening
  • Predominantly fine scaling
3 Moderate
  • Dull to bright red coloration
  • Clearly distinguishable to moderate thickening
  • Moderate scaling
4 Severe
  • Bright to deep dark red coloration
  • Severe thickening with hard edges
  • Severe coarse scaling covering almost all or all lesions

Note: Clear requires a “0” for all 3 domains (e, i, s). The total score average is rounded to nearest whole number score; e.g., if the total is ≤2.49, the score is 2; if the total is ≥2.50, score is 3.

VALIDITY:
The 5-point scale was developed based on guidance from clinical trial investigators and regulatory authorities for use in Phase 3 clinical trials in conjunction with PASI.1 The 3-item PGA scale to assess erythema, induration, and scaling demonstrates good reliability with test-retest variability of 1% to 3%.5 It demonstrates good stability (intraclass correlation coefficient [ICC] = 0.852) and good internal consistency (Cronbach’s alpha > 0.8 consistently from Week 2).4 The sPGA is further validated by its relationship to QoL and may be used to monitor change induced by placebo or active therapy in a clinical trial setting.2,3

LIMITATIONS:
Limited ability to quantify individual elements of plaque morphology and body surface area (BSA) involvement.5,6 The lack of BSA in the 5-point sPGA scoring may attribute to poorer pretherapy correlations with PASI.2-4 When measuring the extent of disease activity across both clinical trials and clinical practice, a BSA tool needs to be included with the 5-point sPGA scale.1

This resource is intended for educational purposes only and is intended for US healthcare professionals. Healthcare professionals should use independent medical judgment. All decisions regarding patient care must be handled by a healthcare professional and be made based on the unique needs of each patient.

References: 1. Langley RGB, Feldman SR, Nyirady J, van de Kerkhof P, Papavassilis C. The 5-point Investigator's Global Assessment (IGA) Scale: a modified tool for evaluating plaque psoriasis severity in clinical trials. J Dermatolog Treat. 2015;26(1):23-31. doi:10.3109/09546634.2013.865009 2. Chow C, Simpson MJ, Luger TA, Chubb H, Ellis CN. 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. J Eur Acad Dermatol Venereol. 2015;29(7):1406-1414. doi:10.1111/jdv.13132 3. Simpson MJ, Chow C, Morgenstern H, Luger TA, Ellis CN. Comparison of three methods for measuring psoriasis severity in clinical studies (Part 2 of 2): use of quality of life to assess construct validity of the Lattice System Physician's Global Assessment, Psoriasis Area and Severity Index and Static Physician's Global Assessment. J Eur Acad Dermatol Venereol. 2015;29(7):1415-1420. doi:10.1111/jdv.12861 4. Cappelleri JC, Bushmakin AG, Harness J, Mamolo C. Psychometric validation of the physician global assessment scale for assessing severity of psoriasis disease activity. Qual Life Res. 2013;22(9):2489-2499. doi:10.1007/s11136-013-0384-y 5. Weisman S, Pollack CR, Gottschalk RW. Psoriasis disease severity measures: comparing efficacy of treatments for severe psoriasis. J Dermatolog Treat. 2003;14(3):158-165. doi:10.1080/09546630310013360 6. Feldman SR, Menter A, Koo JY. Improved health-related quality of life following a randomized controlled trial of alefacept treatment in patients with chronic plaque psoriasis. Br J Dermatol. 2004;150(2):317-326. doi:10.1111/j.1365-2133.2004.05697.x

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