Data extraction

Data will be extracted from the included studies using a structured data extraction form designed by the authors. Data extraction will be performed independently by two reviewers (MZ, AA).

The data extracted will include authors, publication year, study design, country of publication, time of assessment for PCAD, inclusion criteria for determination of cases, which will be defined as patients having PCAD, while controls will be defined as patients experiencing late-onset CAD or healthy controls (having no disease or without the disease of interest) (Appendix III, IV). To account for confounding, data on age, gender, and geographical settings will be extracted. All data will be extracted in alignment with the review questions. If a given study, fulfils the criteria of being included in more than one comparison group, the data extracted from that study will be analysed for each relevant comparison group. In addition, evaluation of duplicate published studies will be undertaken, the reviewers will identify the primary publication from the given set of studies from the same project. The primary study will be the one that has; the maximum sample size, maximum centres/countries involved, and maximum relevant outcomes reported.

Any disagreements that arise as a result of this appraisal will be resolved through discussion or in consensus with a third reviewer (RT, MA). Authors of the included studies will be contacted for any missing data if and when required.