Analysing and reporting of observational data: a systematic review informing the EULAR points to consider when analysing and reporting comparative effectiveness research with observational data in rheumatology.

To evaluate the analysis and reporting of comparative effectiveness research with observational data in rheumatology, informing European Alliance of Associations for Rheumatology points to consider. We performed a systematic literature review searching Ovid MEDLINE for original articles comparing drug effectiveness in longitudinal observational studies, published in key rheumatology journals between 2008 and 2019. The extracted information focused on reporting and types of analyses. We evaluated if year of publication impacted results. From 9969 abstracts reviewed, 211 articles fulfilled the inclusion criteria. Ten per cent of studies did not adjust for confounding factors. Some studies did not explain how they chose covariates for adjustment (9%), used bivariate screening (21%) and/or stepwise selection procedures (18%). Only 33% studies reported the number of patients lost to follow-up and 25% acknowledged attrition (drop-out or treatment cessation). To account for attrition, studies used non-responder imputation, followed by last observation carried forward (LOCF) and complete case (CC) analyses. Most studies did not report the number of missing data on covariates (83%), and when addressed, 49% used CC and 11% LOCF. Date of publication did not influence the results. Most studies did not acknowledge missing data and attrition, and a tenth did not adjust for any confounding factors. When attempting to account for them, several studies used methods which potentially increase bias (LOCF, CC analysis, bivariate screening…). This study shows that there is no improvement over the last decade, highlighting the need for recommendations for the assessment and reporting of comparative drug effectiveness in observational data in rheumatology.

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© Author(s) (or their employer(s)) 2021. Re-use permitted under CC BY. Published by BMJ.

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Competing interests: KL received grant from AbbVie and speaker’s fees from Pfizer, Gilead-Galapagos, Viatris and Celltrion, outside this work. KLH received honoraria from Abbvie, grants from Pfizer and BMS outside this work. FI received a speaker’s fee and consultation grant from AbbVie, Actelion, BMS, Biogen, Lilly, MSD, Pfizer, Roche, Sanofi and UCB outside this work, PMM has received consulting/speaker’s fees from Abbvie, BMS, Celgene, Eli Lilly, Galapagos, Janssen, MSD, Novartis, Orphazyme, Pfizer, Roche and UCB outside this work, ZR has received speaker and consultancy fees from Abbvie, Amgen, Biogen, Boehringer, Eli Lilly, Janssen, Medias, Medis, MSD, Novartis, Pfizer, Roche, Sandoz, Sanofi, outside this work, TAS received grant/research support from AbbVie and Roche, has been a consultant for AbbVie and Sanofi Genzyme, and has been a paid speaker for AbbVie, Roche, Sanofi and Takeda outside this work. AF: speakers bureau from Pfizer, Eli-Lilly; and consultant of AbbVie, BMS, Gilead, Novartis, Pfizer, Viatris and grant/research support from Pfizer, BMS, outside this work.