Data extraction and quality assessment

The primary online search for the review was conducted between February 16 to May 21 2020. We have included studies irrespective of their publication date through May 21 2020. The review followed PRISMA flow chart to identify and select relevant studies for this analysis. Primarily, duplicated retrievals were removed. Then, studies whose titles were irrelevant for this study were excluded. After that, the abstracts were assessed and screened based on the outcome variables. At this stage, studies that were not relevant for this study were excluded. For the remaining articles, the full text was assessed. The eligibility of these articles was assessed based on the pre-set inclusion criteria. When articles did not have sufficient data, corresponding authors of the research articles were contacted.

Then, the two reviewers (YGY and MDA) independently assessed or extracted the articles for overall quality and or inclusion in the review using a standardized data extraction format. The third author (GMK) reconciled any disagreements that occurred among the two authors. From each study, we extracted data on the study location, region, publication year, study design, sample size, and author name for the overall practice of breast self-examination (Table 1).

Key: CR:-Cross-sectional, HEW:—health extension workers, RAW-: reproductive age women, SNNPR:- Southern Nations, Nationalities, and People's Region.

The quality of included studies was assessed in accordance with the relevant critical Joanna Brigs Institute (JBI) appraisal checklist (JBI). Two independent reviewers (YGY & MDA) did a full-text quality assessment. Then, a combined quality score ranging from 0 to 9 was assigned to each included article (S2 File). Finally, studies with the scale of ≥ 6 out of 9 were categorized as high quality [32].