Development and validation of a new instrument for the assessment patient-defined benefit in the treatment of acne vulgaris

Background: Benefit assessment of drugs and medical products has become a legally established feature of medical research. A standardised assessment of benefits using scientifically sound and valid methods is essential. Objective: Development, validation and practical evaluation of an instrument to record patient benefit in treatment of acne. Patients and Methods: In open interviews with n = 50 patients, possible benefits of the therapy from the patients' point of view were recorded. The item pool thus generated was reviewed by a panel of dermatologists, psychologists and patients and transferred to a 23-item questionnaire. This is used prior to therapy to assess patients' desired benefits and after therapy to record the perceived benefits. The therapy goals and the resulting benefits are then used to generate a weighted 'Patient Benefit Index' (PBI). The procedure has been tested for its validity and feasibility in n = 923 patients with acne. Results: Patients accepted the instrument and deemed it to be easily understandable. Additionally, the method proved itself to be internally consistent, constructively valid and sensitive to changes. Conclusions:The Patient Benefit Index (PBI) is a valid and highly accepted practical instrument for recording patient benefit. The PBI permits an individualised, patient-weighted assessment of the benefits of acne therapy.