The search did not address all sources of grey literature.
Data will be sourced from a range of electronic databases and sources of grey literature.
The sources of data searched included 12 electronic bibliographic databases and five sources of grey literature.
The search strategy involved identification of keywords (medical subjects' headings), synonyms, relevant theses and dissertations, and sources of grey literature.
In addition, we looked for current and closed clinical trials, practice guidelines, meeting abstracts and dissertations, and searched other sources of grey literature using the Grey Matters Checklist created by the 2011 Canadian Agency for Drugs and Technology in Health.
The major strength of our study was the comprehensive searching of a range of electronic databases to capture relevant research publications, including databases which contain sources of grey literature.
Given the multidisciplinary nature of this topic, databases from the fields of medicine, health, social science, and economics, and sources of grey literature (i.e., IDEAS, BLDS) were selected.
A total of 2646 patients in 36 papers and eight sources of grey literature including three conference abstracts and data in non-peer-reviewed journals or the internet, published between 1966 and 2003, were identified.
This review has the following limitations: It consulted a limited number of databases and sources of grey literature, possibly limiting the number of studies identified and included in the review.
For example, the subactions of searching for research include searching academic literature databases or libraries and searching sources of grey literature (see Table 1 for definitions of key terms and examples).
