A systematic literature review of existing tools used to assess medication adherence in connective tissue diseases: the state of the art for the future development of co-designed measurement tools

Lack of medication adherence is frequent in chronic connective tissue diseases and is associated with poorer health outcomes, low quality of life and economic loss. This research is based on a systematic literature search and aims to identify the surveys and tools used for the assessment of medication adherence in patients with connective tissue diseases (CTDs) and in particular the tools co-designed with patients. A systematic literature review was performed in PubMed and Embase databases searching for studies concerning the application of surveys or tools designed for medication adherence assessment. A specific analysis was also performed to identify which of these existing tools were developed in co-design with patients affected by CTDs. 1958 references were identified, and 31 studies were finally included. Systemic lupus erythematosus was the most investigated disease, followed by the Behçet's disease. The tools used to assess adherence in CTDs were, in most cases, valid and useful. However, the results showed a certain degree of heterogeneity among the studies and the medication adherence assessment and measurement tools adopted, which were mostly based on selfreported questionnaire. No co-designed tools with patients were found. Low- and non-adherence were explored in some CTDs with valid and useful tools, while other CTDs still need to be assessed. Therefore, more efforts should be made to better understand the specific reasons for the low- and non-adherence in CTDs patients.