Oral Bisphosphonates Do Not Increase the Risk of Severe Upper Gastrointestinal Complications

Competing interests
The authors declare that they have no competing interests.

Authors' contributions
AG and LS performed the statistical analyses, GDV was responsible for producing software assuring privacy, AG and GC wrote the paper, GC was responsible for designing the current study, GM was the main investigator of the AIFA-BEST project, LCDO, FL, FC, AC, AV, DG, RG, ARV and TS were the other investigators of the AIFA-BEST; they participated to the project's design and supplied data. All authors read and approved the final manuscript.

Acknowledgements
This study was almost entirely funded by a research grant from the AIFA - the Italian Medicines Agency – (AIFA grant FARM06R9YY), Rome, Italy. Data analyses were performed at the Unit of Biostatistics and Epidemiology, Dept. of Statistics, University of Milano-Bicocca with grants from the Italian Minister for University and Research ('Fondo d'Ateneo per la Ricerca' portion, year 2010).

Best investigators
Mazzaglia G, (main investigator): Regional Agency for Healthcare Services of Tuscany, Italy
Cipriani F (Head Unit), Lapi F, Sessa E: Regional Agency for Healthcare Services of Tuscany, Italy
Caputi AP (Head Unit), Arcoraci V: Department of Medicine and Pharmacology, University of Messina, Messina, Italy
Corrao G (Head Unit), Ghirardi A, Scotti L, Parodi A, Zambon A: Department of Statistics and quantitative methods, Unit of Biostatistics, epidemiology and public health, University of Milano-Bicocca, Milan, Italy
Montanaro N (Head Unit), Piccinni C, Suzzi C, Puccini A, Vaccheri A: Regional Centre for Drug Evaluation and Information (CREVIF), Department of Pharmacology, University of Bologna, Bologna, Italy.
Sturkenboom M (Head Unit): Departments of Epidemiology & Biostatistics and Medical Informatics, Pharmacoepidemiology Unit, Erasmus University Medical Center, The Netherlands
Geppetti P (Head Unit), Sati L, Di Bari M: Center of Pharmacoutilization, Pharmacoepidemiology, Pharmacovigilance and Pharmacoeconomics, University of Florence, Florence, Italy
Gregori D (Head Unit), Forlan F: Unit of Biostatistics, Epidemiology and Public Health, Department of Cardiac, Thoracic and Vascular Sciences, University of Padova
Carle F (Head Unit), Gesuita R: Center of Epidemiology, Biostatistics, and Medical Information Technology, Polytechnic University of Marche, Ancona, Italy. Provided data from Marche
Staniscia T (Head Unit), Menna A: Regional Agency of Healthcare services of Abruzzo, L'Aquila, Italy
Vestri A (Head Unit): Department of Public Health and Infectious Diseases, University "La Sapienza", Rome, Italy
Valenti M (Head Unit): Department of Clinical Sciences and Applied Biotechnology, University of L'Aquila, L'Aquila, Italy