Table I.

Levels of measurement

	Definition	Example
Generic	Instrument can be used across therapeutic areas, e.g. dermatology, diabetes or cancer.	Short Form-36, EuroQOL 5D, Nottingham Health Profile
Dermatology-specific	Instrument is specific to dermatology and can be used across skin conditions.	Dermatology Life Quality Index, Skindex, Patient Benefit Index
Disease-specific	Instrument is to be used only with a certain skin condition.	Patient Oriented Eczema Measure, Rosacea Quality of Life Index, Comprehensive Appraisal of Life Impact of Psoriasis