IGA
Also written as: IGA — Investigator's Global Assessment
Abbreviation for Investigator's Global Assessment, a validated ordinal scale used in clinical trials to rate overall disease severity in skin conditions such as atopic dermatitis and psoriasis.
Full Definition
The Investigator's Global Assessment (IGA) is a widely used, standardised 5-point scale (0 = clear to 4 = severe) employed by investigators in dermatological clinical trials to assess overall disease severity at a single point in time. It is a co-primary or secondary endpoint in many pivotal trials for conditions including atopic dermatitis, psoriasis, and prurigo nodularis. The FDA and EMA reference IGA as an acceptable outcome measure. A clinically meaningful response is often defined as an IGA score of 0 or 1 with a ≥2-point improvement from baseline (IGA 0/1). Editors must define IGA at first use and not confuse it with EASI or PASI, which are lesion area and severity indices.
Usage
Usage note: Note the possessive apostrophe in 'Investigator's Global Assessment'. Some publications use 'vIGA' (validated IGA) for atopic dermatitis specifically; do not treat these as fully interchangeable without checking the clinical protocol.
In Context
- "The primary endpoint was achieved: 52% of patients in the active arm reached IGA 0/1 at week 16 compared with 7% on placebo." — Clinical trial results section
- "The editor standardised 'Investigator Global Assessment' to 'Investigator's Global Assessment (IGA)' per FDA guidance terminology throughout the document." — Regulatory document editing note