To our knowledge, no study has evaluated the quality of control groups in randomised controlled trials of multiple myeloma. We aimed to do a systematic review of randomised controlled trials of multiple myeloma to ascertain the quality of the control groups used. PubMed (MEDLINE), Embase, Cochrane Controlled Register of Trials, and CinicalTrials.gov were searched for articles of randomised controlled trials of multiple myeloma based in the USA that initiated participant enrolment between Jan 1, 2010, and June 30, 2020. A control group regimen was considered to be inferior if a previous randomised controlled trial had shown an improved progression-free survival versus the control group before enrolment. Of 49 identified randomised controlled trials, seven (14%) began enrolling patients into inferior control groups after an existing superior regimen to the control had already been published. Nine (18%) of the 49 trials continued enrolment on substandard control groups after data emerged during the study enrolment period. The median time that newer data emerged regarding inferiority of the control group from the time a trial first enrolled a patient was 13 months (IQR 8-29 months). 12 (75%) of these 16 randomised controlled trials are published, and nine (75%) of the 12 published trials had overlapping investigators with trials that had previously shown the inferiority of the control group being used. Greater scrutiny on the quality of control groups in randomised controlled trials of multiple myeloma is needed.
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