To explore bias in lupus erythematosus (LE) randomized clinical trials (RCTs) and to help the development of benchmarks for future trials and management. We searched systematically three databases and three registries to summarize the interventional randomized clinical trials (RCTs) and identify factors associated with participant loss. Trials which examined pharmacological interventions with control group were included and a meta-analysis was carried out by using fixed and random effects models to calculate risk ratio of participant loss in the intervention and control groups. A total of 481 trials with 68,582 participants met our inclusion criteria, organ specific interventional studies along with trials that address quality of life attributes and geopolitical disparities are missing or lagging behind. 90 trials were involved in the meta-analyses, the withdrawal ratio between intervention and control groups was distinctly influenced by national income of the trial-conducted country. In high income countries, the withdrawal ratio was relatively constant, while for trials conducted in low and middle income countries, the results were altered by trial registration, year of start, number of centers, number of participants, and primary outcome identification. Moreover, the comparability of participants was also worrying, trial location and registration status altered basal participant adherence. Our study reveals the unexpectedly huge heterogeneity brought by national income and trial registration in lupus RCTs worldwide. To maintain the fundamental repeatability and referenceability of LE RCTs, rigorously designed single-country trials with diverse inclusion criteria are needed.
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