Were measures objective or were the patients and clinicians kept “blind” to which treatment was being received?
It is ideal if the study is ‘double-blinded’ – that is, both patients and investigators are unaware of treatment allocation. If the outcome is objective (eg., death) then blinding is less critical. If the outcome is subjective (eg., symptoms or function) then blinding of the outcome assessor is critical.
First, look in the Methods section to see if there is some mention of masking of treatments, eg., placebos with the same appearance or sham therapy. Second, the Methods section should describe how the outcome was assessed and whether the assessor/s were aware of the patients' treatment.