Methodological issues in meta-analyses of real-world clinical data to infer causality

Note: Funding Information: LHL reports personal fees from Merck, personal fees from Sanofi, grants and personal fees from Vifor-Fresenius , grants and personal fees from AstraZeneca , grants and personal fees from Relypsa , personal fees from Bayer, grants from Boston Scientific , personal fees from Pharmacosmos, personal fees from Abbott, grants and personal fees from Mundipharma , personal fees from Medscape, personal fees from Myokardia, grants and personal fees from Boehringer Ingelheim , grants and personal fees from Novartis , outside the submitted work. Funding Information: FWA is supported by UCL Hospitals NIHR Biomedical Research Centre . Funding Information: LHL reports personal fees from Merck, personal fees from Sanofi, grants and personal fees from Vifor-Fresenius, grants and personal fees from AstraZeneca, grants and personal fees from Relypsa, personal fees from Bayer, grants from Boston Scientific, personal fees from Pharmacosmos, personal fees from Abbott, grants and personal fees from Mundipharma, personal fees from Medscape, personal fees from Myokardia, grants and personal fees from Boehringer Ingelheim, grants and personal fees from Novartis, outside the submitted work.FWA is supported by UCL Hospitals NIHR Biomedical Research Centre.GS reports grants and personal fees from Vifor, grants and non-financial support from Boehringer Ingelheim, personal fees from Societa? Prodotti Antibiotici, grants and personal fees from AstraZeneca, personal fees from Roche, personal fees from Servier, grants from Novartis, personal fees from GENESIS, personal fees from Cytokinetics, personal fees from Medtronic, grants from Boston Scientific, grants from PHARMACOSMOS, grants from Merck, outside the submitted work. Funding Information: GS reports grants and personal fees from Vifor , grants and non-financial support from Boehringer Ingelheim , personal fees from Societa´ Prodotti Antibiotici, grants and personal fees from AstraZeneca , personal fees from Roche, personal fees from Servier, grants from Novartis , personal fees from GENESIS, personal fees from Cytokinetics, personal fees from Medtronic, grants from Boston Scientific , grants from PHARMACOSMOS , grants from Merck , outside the submitted work.