3.1 Study selection:
The flowchart represents the search and selection strategy for the
study. The initial search resulted total 1361 studies, PubMed (n=65),
Cochrane Library (n=276), Google Scholar (n=1000) and articles
identified through forward/backward search (n=20). 29 articles were
excluded as duplicate and 1270 articles were excluded from title and
abstract screening. From remaining articles, 24 articles were excluded
due to lacking of mortality data in screening full-text content. A total
38 studies were considered in the systematic review (Figure-1).