A Checklist for the Diagnosis of Schizophrenia

Despite extensive research and a vast literature, the diagnosis of schizophrenia remains primarily a clinical decision based upon the presence of some agreed-upon symptom complex. Laboratory studies and special testing procedures have not yet demonstrated their utility in establishing diagnosis in this syndrome. While it is easy to cite studies of diagnostic difficulty (Beck, 1962), it is also apparent that when clinicians state they are ‘certain of the diagnosis' or agree to utilize pre-established diagnostic stereotypes, the diagnostic agreement frequently achieves an 80 per cent reliability (Beck, 1962; Hordern et al. , 1968). Clinicians the world over tend to identify gross symptoms in similar ways. However, they may ascribe varying significance to similar symptom complexes and may even use similar symptom constellations to arrive at different diagnoses (Saenger, 1968; Sandifer et al. , 1968). There seems to be general agreement on the major symptoms found in schizophrenia (Cooper, 1967; Beck et al. , 1962; Hordem et al. , 1968); however, diagnostic agreement on subtypes, and on admixtures of paranoid symptoms and depression is much more difficult to achieve (Cooper, 1967; Morgan et al. , 1968; Lorr and Klett, 1968; Hordem et al. , 1968). The present study attempts to formalize the apparent commonality of clinical features which together establish a diagnosis of schizophrenia through the development of a valid and reliable checklist of symptoms.