This review was performed systematically in an unbiased manner by
using a pre-specified protocol and an explicit, reproducible plan for
literature search and synthesis. Study designs such as RCTs, prospective
cohort studies, and retrospective study designs were included in
this review. Searches to identify RCTs were of literature published
from 1960 to 7 March 2012; searches to identify observational
studies were of literature published from January 1990 to 7 March
2012, as observational clinical data published before 1990 are unlikely
to be relevant to current treatment practices and resource patterns.
No limitations on publication language or geographical perspective
were applied. Translation of the articles to English was done asrequired.