How representative of everyday clinical populations are schizophrenia patients enrolled in clinical trials?

INTRODUCTION: There has been considerable discussion whether clinical trials accurately depict everyday practice. Restrictive inclusion/exclusion criteria, ethical considerations, differences in the severity of psychopathology between clinical and trial patients, or safety issues may bias results, which in turn may rather represent outcome for the "ideal" than for the "average"patient. Therefore, translation into psychiatric practice may be difficult.
METHODS: A retrospective case-control study was performed. Schizophrenia inpatients at the LMU Department of Psychiatry, Munich, Germany, who had participated in clinical trials were compared to regular patients serving as controls. Probands and controls were matched by DSM-IV diagnosis, gender and age. The AMDP module, CGI and GAF were used to compare psychopathology. In addition, charts were reviewed for medication dosages, concurrent medical and neurological illness, and clinical history such as age of onset or family history.
RESULTS: A total of 200 probands (100/100) were enrolled in the study. With respect to psychopathology, formally thought disordered or suicidal patients were significantly less likely to be study participants (n = 3) than controls (n = 22; p < or = 0.05). Similarly, negative schizophrenia symptoms were significantly less often present in study participants (n = 17) than in controls (n = 38; p < or = 0.05). Study participants were also medically and neurologically healthier than controls. (p = 0.05 respectively). No differences in overall illness severity as depicted by CGI and GAF were observed.
CONCLUSION: We found the patients included in our clinical trials representative of the patient encountered in routine clinical practice. Adherence to inclusion and exclusion criteria prevents inclusion of severely ill (e. g. suicidal) patients requiring a more intensive treatment setting. Illness severity was found to be similar in trial participants and controls, and indicates an overall comparably severe psychopathology. The more chronic, rather treatment refractory patients were also not reflected in the trial participant pool; this population may arguably not represent the average clinical patient either. A more careful administration of antipsychotic medication was found in trial participants and may effectively be considered "good clinical practice".