Fig. 1

Flowchart showing selection of studies. Total number of studies found were 9083 that include from PubMed (n = 58), Scopus (n = 1071) and Web of science (n = 5903).The additional studies found through other sources were (n = 2051). The Reference Management Software Package (Endnote X9) was used to check the duplication and 7013 studies were removed. Studies (n = 1569) conducted other than Pakistani population. The remaining (n = 501) was further screened and finally (n = 39) studies was selected for full text read. Of those (n = 7) articles did not reported prevalence and (n = 2) were a review articles. Finally, (n = 30) studies were matching the objective and was satisfying the inclusion criteria for this meta-analysis and were included