An overview of the common methods used to measure treatment adherence

Background and aims The success of a treatment depends on the effectiveness of the medication regimen, provided that patients take the medicines as prescribed. A low rate of adherence in chronic conditions is associated with poor outcome and decreased quality of life, which constitutes an additional burden for the healthcare systems. To correctly identify the dimension of this problem may be a challenge, as there are numerous methods, definitions, patient settings and factors, each with their specific roles. Our aim was to give an appropriate overview of the most common validated methods that can be used to identify non-adherent patients. Methods This overview is based on an online search of PubMed database and includes the relevant articles in this field. Results We included both direct and indirect methods for measuring treatment adherence and presented concise information that can help researchers and clinicians when choosing an appropriate method. Both subjective and objective methods have advantages and disadvantages that should be fully understood and taken into consideration. Conclusions Choosing a simple, accurate and inexpensive method that can give supplementary information about the patterns, beliefs and barriers of adherence would be desirable. But because this perfect method to measure treatment adherence does not exist, the best solution seems to be the combined use of at least two methods.