Complex sentence: Also prior to the study, the self-reported quality of life was higher among participants receiving standard therapies exclusively though Cassileth said that researchers tried to match equally sick groups of patients as fairly as possible.
Split into simpler sentences: Also prior to the study, the self-reported quality of life was higher among participants who received the standard treatments exclusively. However according to Cassileth, researchers tried to study equally sick groups of patients as fairly matched as possible.