Original sentence: Wessely and his colleagues also developed a rehabilitation strategy for patients that involved cognitive behavioral and graded exercise therapy; research using randomised controlled trials and follow-up studies, which have by his own studies been demonstrated as effective at reducing symptoms of the condition in ambulant (non-severely affected) patients, which otherwise lacks a cure or unequivocally successful treatment
Edited sentence: Wessely and his colleagues also developed a rehabilitation strategy for patients that involved cognitive behavioral and graded exercise therapy; research using randomised controlled trials and follow-up studies, which have been demonstrated as effective at reducing symptoms of the condition in ambulant (non-severely affected) patients, which otherwise lacks a cure or unequivocally successful treatment