The clinical characteristics of schizophrenic patients consenting or not consenting to a placebo controlled trial of antipsychotic medication

Sixty‐seven patients meeting DSM‐III‐R criteria for schizophrenia who had been eligible for a placebo controlled trial of an antipsychotic preparation were followed up at 9 months to examine whether a variety of socio‐demographic, illness, treatment and compliance variables were associated with consent to participate in the treatment trial. A survey of subjective appraisals concerning the trial and attitudes to medication of trial participants was also carried out. The data revealed that the non‐consenting patients had similar lengths of illness histories to those consenting but had experienced fewer previous psychiatric hospital admissions. The non‐consenting group had been less compliant with their overall treatment in the follow‐up period. More consenting patients were inpatients or day patients (rather than outpatients) at follow‐up and as a group, they were receiving significantly more medication than non‐consenting patients. They also exhibited more extrapyramidal and abnormal involuntary movements than the non‐consenting group. Our results do not support a direct relationship between severity of illness and the likelihood to consent to this type of research. The highly selective nature of samples of patients entering research is highlighted and the generalizability of results of similar drug studies may therefore be questioned.