"Parallel" generally means that different groups of patients receive different treatments. The opposite is a within-patient study, where all patients get all tr

"Parallel" generally means that different groups of patients receive different treatments. The opposite is a within-patient study, where all patients get all treatments over time (possibly varying the order to prevent order effects). "Open-label" generally means "not blind at all." Basically, the patient knows what treatment is being administered. "Double-masked" is usually synonymous with "double-blind," because "masking" sounds less violent than "blinding." What did they actually do in the study? Well, §2.2.1 says the following: > 2.2.1. Randomization and Masking > > An electronically generated randomization 2:1 list was prepared by > independent statisticians. The list was accessible only to nonmasked > specialists in the study in an attempt to minimize observation bias. > The patients' data were recorded in the hospital's electronic > medical record, with blind access by the technical data collectors > and the statistician who carried out the study. My takeaway is that... the authors don't do a great job of describing who had access to what information. It sounds like those who analyzed the data didn't know which group was which, but in the case of unequal 2:1 group allocation it is typical for the larger group to be the treatment group. Why was unequal assignment used in the first place? The descriptor "open-label" suggests that someone knew which patients were in which groups: was it the people who administered the treatment, or the patients, or both? Unclear. The authors themselves write: "This pilot study has several limitations as it is not double-blind placebo controlled."