Selection process 
The outcome of the study was screened and selected using an open-source machine learning (ML)-aided pipeline applying active learning: ASReview, Active learning for Systematic Reviews (Van de Schoot et al., 2021). ASReview is a tool that increases the efficiency of screening titles and abstracts by determining prioritization with active learning. The ASReview tool is extensively tested and validated and has shown to achieve better performance in SR’s than manually evaluation titles and abstracts (Van de Schoot et al., 2021). The tool was initially trained for the current study with 10 relevant and 10 irrelevant publications selected by two independent researchers (ARU & KvH). After feeding the tool with the training publications, the tool returned the set of hits ordered according to relevance priority. These results were checked by the same two independent researchers. In case of several irrelevant results among the top priority hits, the tool was further trained by manually screening at least 1% of the total number of publications in the whole set. Publications selected for further full-text review (n=99) were those prioritized by ASReview. For each assigned publication, authors checked each criterion and assessed the inclusion of only those publications that met all criteria. Each publication was reviewed by a second independent author following concordant and stratified criteria. The full list of studies included for full-text review as well as the inclusion and exclusion criteria can be consulted in Supplementary Material; Table S2. For the selected publications (n=47), authors annotated some additional publication details (e.g., country of the study, participants included, disease area, factors affecting adherence considered, study design, type of experimental design, etc.). The total number of records after each screening round was documented using the PRISMA flow diagram template (see Figure 1 below). 
–Figure 1 should come around here –
Subsequently, the data related to the effect of interventions to increase adherence were extracted from each study. These effects were grouped according to the following dimensions: Socioeconomic, Treatment, Condition, Personal, and Healthcare-related factors, which were based on WHO’s 5 dimensions of treatment adherence (Sabaté, 2003). For each adherence factor, both the inclusion and exclusion in each of the reviewed studies were reported, as well as evidence of a significant association of that specific factor with treatment adherence. Variables related to the characteristics of the study, study sample, and study intervention were also extracted.