PGA Score — SCE Dermatology MCQ
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Correct answer: D — An overall clinician assessment of disease severity on a 5-point scale from 0 (clear) to 4 (severe) — a simple global measure increasingly used in clinical trials
Explanation lettering: D = shown as A · A = shown as B · E = shown as C · C = shown as D · B = shown as E
C is correct: an overall clinician assessment of disease severity on a 5-point scale from 0 (clear) to 4 (severe), a simple global measure increasingly used in clinical trials. PGA is a static, whole-body clinician-rated impression that averages erythema, induration and scaling across all lesions to give a single category (clear, almost clear, mild, moderate, severe). It is deliberately simpler and quicker to perform than PASI, which is why it has become a common co-primary trial endpoint (PGA 0/1) and why UK real-world data from BADBIR show it correlates strongly with PASI in routine biologic monitoring. Unlike PASI it does not quantify body surface area or produce a numeric severity score; it is a global gestalt rating, not a component or patient-reported measure. Why the other options are wrong: A. Histological severity: PGA is a clinical, bedside visual assessment; it does not involve skin biopsy or histopathological grading. B. Patient-reported quality of life: quality of life impact is captured by DLQI, a patient-completed questionnaire, not by PGA, which is scored entirely by the clinician. D. Exact body surface area: BSA (percentage of skin affected) is a separate, distinct metric; PGA gives a severity impression, not an area measurement, though PGA x BSA composites exist as an alternative index. E. Number of plaques: PGA does not count discrete lesions; it rates average morphological severity (erythema, induration, scaling) across the whole body, not lesion quantity. Key point: PGA is a rapid 0 to 4 clinician global severity rating (clear to severe) based on average erythema, induration and scaling, distinct from PASI (numeric score), BSA (extent) and DLQI (patient-reported quality of life).
Reference: British Journal of Dermatology (BADBIR study), Mahil SK et al., 'Psoriasis treat to target: defining outcomes in psoriasis using data from a real-world, population-based cohort study (BADBIR)', 2020, https://onlinelibrary.wiley.com/doi/full/10.1111/bjd.18333