Adjustment for continuous confounders: an example of how to prevent residual confounding - 28/03/13

Doi : 10.1503/cmaj.120592

Rolf H.H. Groenwold, MD PhD ^a,^b,^⁎ , Olaf H. Klungel, PharmD PhD ^a,^b, Douglas G. Altman, DSc ^c, Yolanda van der Graaf, MD PhD ^b, Arno W. Hoes, MD PhD ^b, Karel G.M. Moons, PhD ^b

on behalf of PROTECT WP2 (Pharmacoepidemiological Research on Outcomes of Therapeutics by a European Consortium, Work Programme 2 [Framework for pharmacoepidemiology studies])

^a Division of Pharmacoepidemiology and Clinical Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, the Netherlands

^b Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, the Netherlands

^c Centre for Statistics in Medicine, University of Oxford, Oxford, UK

^* Correspondence to: Rolf H.H. Groenwold

Contributors: All of the authors contributed to the conception and design of the study. Rolf Groenwold performed the data analysis and interpretation of the data. Rolf Groenwold, Olaf Klungel and Karel Moons drafted the article, which all of the authors critically reviewed for important intellectual content. All of the authors approved the final version submitted for publication.

Plan

Systematic revierw of the reporting of confounding adjustment

Controlling for continuous confounders

Competing interests: Olaf Klungel’s nnstitutioi has received unrestricted research funding from Top Institute Pharma, GlaxoSmithKline and Pfizer. Karel Moons’ institution has received unrestricted research grants from GlaxoSmithKline, Bayer and Boehringer Ingelheim. No other competing interests were declared.
This article has been peer reviewed.
Funding: ehT research leading to this analysis was conducted as part of the PROTECT (Pharmacoepidemiological Research on Outcomes of Therapeutics by a European Consortium, www.imi-protect.eu) project, which is a public–private partnership coordinated by the European Medicines Agency. The PROTECT project has received support from the Innovative Medicine Initiative (www.imi.europa.eu) under grant agreement no. 115004, supported by the European Union’s Seventh Framework Programme (FP7/2007–2013) and in-kind contributions from members of the European Federation of Pharmaceutical Industries and Associations. In the context of the Innovative Medicine Initiative, the Division of Pharmacoepidemiology and Clinical Pharmacology, Utrecht University, received a direct financial contribution from Pfizer. The views expressed are those of the authors only and not of their respective affiliation.
Members of PROTECT WP2 (Pharmacoepidemiological Research on Outcomes of Therapeutics by a European Consortium, Work Programme 2 [Framework for pharmacoepidemiology studies]): Yolanda Alvarez, Jim Slattery, Xavier Kurz (European Medicines Agency); Marietta Rottenkolber, Jorg Hasford, Alexandra Sassenfeld (Ludwig–Maximilians–Universität München); Francisco J. de Abajo Iglesias, Miguel Gil, Consuela Huerta, Dolores Montero (Agencia Española de Medicamentos y Productos Sanitarios); Luis A. Garcia-Rodriguez, Ana Ruigomez (Fundación Centro Español de Investigación Farmacoepidemiológica); Patrick Souverein, Dinny de Bakker, Anthonius de Boer, Rolf Groenwold, Svetlana Belitser, Wiebe Pestman, Kit Roes, Arno Hoes, Victoria Abbing-Karahagopian, Frank de Vries, Tjeerd van Staa, Antoine C.G. Egberts, Hubertus G.M. Leufkens, Liset van Dijk, Olaf Klungel (Utrecht University, The Netherlands); Arlene Gallagher, Deven Patel (The UK General Practice Research Database); Per Helboe, Jytte Lyngvig, Anne Marie Clemensen, Tina Engraff, Ulrik Hesse, Jan Poulsen (Lægemiddelstyrelsen, Danish Medicines Agency); John Weil (GlaxoSmithKline, Research and Development); Lamiae Bensouda-Grimaldi, Lucien Abenhaim (L.A. Sante Epidemiologie Evaluation Recherche); Robert F. Reynolds, Nicolle Gatto, Andrew Bate (Pfizer); Gerry F. Downey, Ruth Brauer, Sam Yeboa, Kah L. Goh, Maurille F. Tepie, Andrew Roddam (Amgen NV); Erica Velthuis (Genzyme Europe); Montserrat Miret (Merck KGaA); Saga Johansson (AstraZeneca AB); Paolo Primatesta, Raymond Schlienger, Joan Fortuny, Elena Rivero (Novartis); George Quartey, Hans Petri, Marcus Schuerch, Jamie Robinson (F. Hoffmann–La Roche AG); Joan-Ramon Laporte, Luisa Ibañez, Monica Sabaté, Elena Ballarin, Paula Solari (Fundació Institut Català de Farmacologia)