Data abstraction and quality assessment

Two authors independently assessed (BD and SS) and performed quality assessment independently, and any differences were resolved with the help of the third author (YN).

Data collection was recorded as number of reported events (n) out of the total number of patients (N) from each study. The collected data were treated akin to single group cohort studies, and therefore, we used the Newcastle–Ottawa scale (NOS) to assess the quality of studies.[10] This quality score is comprised of 3 categories and 8 questions, the details of which are provided in Supplementary Table 1.

Quality assessment of the study with Newcastle-Ottawa Scale

NOS score consists of 3 categories: 1) Selection-included 4 questions and maximum one star per question could be awarded 2) Comparability-included 1 question and maximum two stars could be awarded and, 3) Exposure- included 3 questions and maximum one star per question could be awarded. Good quality study was defined as 3 or 4 stars in selection domain and 1 or 2 stars in comparability domain and 2 or 3 stars in outcome domain. Fair quality study was defined as 2 stars in selection domain and 1 or 2 stars in comparability domain and 2 or 3 stars in outcome domain. Poor quality study was defined as 0 or 1 star in selection domain and 0 stars in comparability domain and 0 or 1 star in outcome domain.