Selection of studies
The titles and abstracts of all studies were screened independently by
two authors (AT/MDW) against the inclusion and exclusion criteria. Where
there was uncertainty regarding eligibility, or there was disagreement
between authors, the full texts of articles were obtained and reviewed.
There were no differences of opinion that were not resolved through
discussion. Where title and abstracts were identified in English
language, but the main report was in a foreign language, they were
subsequently excluded from analysis.