Did experimental and control groups retain a similar prognosis after the study started?
Blinding Since there is confusion about the terminology related to blinding (triple-blind, double-blind, and single-blind), it is useful to be explicit about who is blinded in the course of a trial24. Did investigators avoid effects of patient awareness of allocation: were patients blinded? The best way of avoiding the psychological impact of treatment (placebo effect) is to ensure that patients are unaware of whether they are receiving the experimental treatment. For instance, investigators conducting a trial to evaluate a new bone cement could blind patients by creating identicallooking incisions and packaging for the cement and the placebo. Were aspects of care that affect prognosis similar in the two groups: were clinicians blinded? Differences in patient care other than the intervention under study can bias the results. In the example of the calcium-phosphate cement trial, if patients in the treatment group received more intensive postoperative care than did those in the control g
