. 2009 Sep 2;9:308. doi: 10.1186/1471-2407-9-308
Copyright ©2009 Beier et al; licensee BioMed Central Ltd.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Figure 1.
CONSORT flow diagram.