[Adherence: definitions and measurement methods: characteristics of adherence to topical treatments]

Taking into account topical treatment compliance is extremely important given its fundamental place in the dermatologist's armamentarium. After reviewing the definition of compliance, adherence, alliance, and clinical inertia, the direct methods used to measure compliance with a topical treatment (counting tubes administered, MEMS system performance, measuring circulating blood or urine rate of a medication or its metabolite, and observation of medication intake by a third party) and indirect methods (questioning the patient, the dermatologist's opinion) will be reviewed. The question of frequency, more important than compliance in cases of topical treatments compared to systemic treatments, has given rise to controversial opinions. Six factors related to topical treatment that play a role in therapeutic compliance can be cited: the perception of efficacy, the feeling of harmlessness, the treatment's simplicity, the treatment's duration, the galenic formulation, and the cost.