To investigate how the use of pharmacologic concomitant medications (CMs) is planned and reported in rheumatology randomized controlled trials (RCTs).
We searched PubMed for RCTs on rheumatic diseases published in leading medical journals in the past 2 years. CMs potentially influencing primary outcome(s) were identified by a panel of experts and included in the analysis. Information on trial characteristics, how the use of CMs was planned and conducted throughout the trial were extracted. Data were summarized as number (%) for qualitative, and median (range) for continuous variables.
The 109 RCTs were mainly international (65%), industry-funded (81%) studies, including 267 CMs potentially influencing primary outcome(s). Forty-one RCTs (38%) did not provide any data about the dosages of CMs allowed. Information on whether the intake of a permitted CM could have been modified during the study was missing in 24 (22%) or incompletely reported in 23 (21%) RCTs. As regards CMs use throughout the study, the baseline number of patients on CMs per arm and the mean baseline dosage was lacking in 20 (18%) and 57 (52%) trials, respectively. Ninety-five percent of RCTs did not provide any information on cumulative/mean exposure to CMs. Two of 109 trials described how many patients had modified CM dosage for reasons permitted by the protocol, and 3 reported the number of patients violating protocol because of an incorrect CM intake.
The use of CMs potentially impacting on primary outcome is poorly reported in rheumatology RCTs.