Potential bias due to outcome-related loss to follow-up in cohort studies on incidence of drug injection: systematic review and meta-analysis

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Funding Acknowledgements

The authors thank Patricia Spittal, Andrea M. Parriot and the members of the Amsterdam Study team (Maria Prins and Gerber Rienk) for their diligence and kindness in providing us with useful information. We are also grateful for the support of Mary Kumvaj, librarian from the National Drug and Alcohol Research Centre, University of New South Wales (Sydney) and the team of the National Library of Health Sciences, Carlos III Health Institute (Madrid). Thanks also to Mukesh Dherani and Daniel Pope (Division of Public Health, University of Liverpool, Liverpool, UK) for sharing with us the Liverpool Quality Assessment Tools (LQATs). Finally, we are grateful to Monica Ruiz for helping with the literature search and to Kathy Fitch for translation and comments. This work was supported by the Health Strategic Action grant (PI13/00183). Writing of the paper was also supported by Postdoctoral Sara Borrell Contract (CD10/00128) and Addictive Disorder Network (RTA in Spanish, RD12/0028/0018). Gregorio Barrio is supported by the RTA. Louisa Degenhardt is supported by an Australian National Health and Medical Research Council (NHMRC) Principal Research Fellowship. The National Drug and Alcohol Research Centre at the University of NSW is supported by funding from the Australian Government under the Substance Misuse Prevention and Service Improvements Grants Fund. The funders had no role in the study design, data collection and analysis, decision to publish or preparation of the manuscript.