Contribution to authorship:
All authors accept responsibility for this paper.
E. van Barneveld : search, review of articles, meta-analysis,
interpretation of data, writing of article.
J. Manders : review of articles, writing of article.
F. van Osch : statistics, meta-analysis.
M. van Poll : review of articles.
L. Visser : providing study protocol, identifying relevant
search terms, third opinion in review of articles.
N. van Hanegem : study protocol, interpretation of data for
clinical practice, contribution to writing of article.
A.C. Lim : study protocol, interpretation of data for clinical
practice, contribution to writing of article.
M.Y. Bongers : study protocol, interpretation of data for
clinical practice, contribution to writing of article.
C. Leue : study protocol, third opinion in review of articles,
interpretation of data for clinical practice, contribution to writing of
article.