Study designs of evaluations included in the review
Single-case studies were excluded, but otherwise there were no restrictions on study design. The review classified studies as: pre-experimental including pre-test post-test studies; quasi-experimental including case-control and cohort studies; and experimental including randomised controlled trials (RCTs).
Specific interventions included in the review
Studies of interventions aimed at weight loss were eligible for inclusion. The included studies used pharmacological interventions and behavioural and diet interventions. The pharmacological interventions comprised chlorphentermine, phenmetrazine, metformin, D-fenfluramine, phenylpropanolamine, olanzapine, fluoxetine, nizatidine, amantadine and metformin, either alone or in combination. The behavioural and diet interventions were behaviour modification, cognitive-behavioural therapy, therapy group, tokens reinforcement, nutrition education, Weight Watchers, education and diet restriction alone. The pharmacological interventions lasted from 7 to 21 weeks (mean 13.5), while the behavioural interventions lasted from 8 to 72 weeks (mean 23.5). Most of the studies were conducted in in-patient or long-stay residential settings. The authors pointed out that some of the drugs used in the studies have since been withdrawn, or are being considered for withdrawal.
Participants included in the review
Studies in which most patients had been diagnosed as having schizophrenia using criterion-based classification systems were eligible for inclusion. The mean age of the participants was 42 years in the studies of pharmacological interventions and 38 years in those of behavioural interventions. Only one study explicitly stated that the participants were having a first episode of schizophrenia.
Outcomes assessed in the review
Studies that assessed weight loss were eligible for inclusion if they used measures such as body weight, body mass index (BMI), waist circumference, waist-to-hip circumference ratio, or percentage body fat.
How were decisions on the relevance of primary studies made?
Two reviewers selected the studies and reached consensus through discussion.