Searching other resources. It is also
planned to manually retrieve articles considered relevant in non-indexed
literature in the cited databases, such as dissertations or theses,
using the Gray Matters-Canada‘s Drug and Health Technology Agency
(CADTH) gray literature registry
(https://www.cadth.ca ) and Grey
Source
(http://greynet.org/greysourceindex.html). In addition, it was planned to maintain contact with relevant people
and organizations to obtain information on unpublished or ongoing
studies. We also hand-searched the reference lists of included studies
and any current relevant systematic
reviews