Study selection
The following criteria were considered essential for an
article to qualify for inclusion in this review:
i) Proper study design of survey, case–control and
cohort studies, and clinical trials.
ii) Review articles by prominent scholars if the
authors had at least four articles of their own in
the list of references of review papers.
Reviewers were not blinded to the study authors’
names. This resulted from the fact that we wanted to
include all pertinent studies, and it was an exposure to
the articles and the study authors. A deliberate strategy
to limit bias was, therefore, developed. All articles were
initially potential candidates for inclusion; an article
was excluded if it lacked appropriate study design.