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. 2015 Mar 11;16(1):35. doi: 10.1186/s12931-015-0195-5

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© Cassano et al.; licensee BioMed Central. 2015

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

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Flow of participants included in FEV ₁ analysis by intervention group. ¹Participants lost to follow-up defined as deaths and participants not in contact for 2 years prior to the end of supplemented time period (March 1, 2009 was used in analyses to proxy the end of supplement). ²Refusals defined as withdrawals from SELECT and/or RAS.