Author Contributions: Dr Hempel had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
Study concept and design: Hempel, Newberry, Maher, Wang, Shekelle.
Acquisition of data: Hempel, Newberry, Maher, Wang, Shanman, Johnsen.
Analysis and interpretation of data: Hempel, Newberry, Maher, Wang, Miles, Johnsen, Shekelle.
Drafting of the manuscript: Hempel, Johnsen.
Critical revision of the manuscript for important intellectual content: Hempel, Newberry, Maher, Wang, Miles, Shanman, Johnsen, Shekelle.
Statistical analysis: Miles.
Obtained funding: Shekelle.
Administrative, technical, or material support: Johnsen.
Study supervision: Shekelle.
Conflict of Interest Disclosures: All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest and none were reported.
Funding/Support: The RAND Corporation internally funded this review, building on the literature database established for contract HHSA 290-2007-10062-I, an evidence report on the safety of probiotics commissioned by the Agency for Healthcare Research and Quality and funded jointly by the National Institutes of Health (NIH) Office of Dietary Supplements, the NIH National Center for Complementary and Alternative Medicine, and the US Food and Drug Administration (USFDA) Center for Food Safety and Applied Nutrition. Dr Shekelle reports support from the Department of Veterans Affairs.
Role of the Sponsor: The sponsors had no role in the conduct of this review; collection, management, analysis, and interpretation of the data for this review topic; or in the preparation, review, or approval of this manuscript.
Additional Contributions: Alexandria Smith, MPH, and Ning Fu, MA, provided assistance with the database, and Tanja Perry, BHM, provided administrative assistance for the manuscript. All of these individuals are employees of RAND and received no additional compensation in association with their contributions to this article.