• The ability of six different operational definitions of schizophrenia to identify prospectively patients whose eventual prognosis would be poor was studied using data from a six-year follow-up of a series of 134 patients with functional psychoses. All six definitions were more successful at predicting a poor symptomatic outcome than a poor social outcome. Spitzer's Research Diagnostic Criteria, Carpenter's flexible criteria, and Langfeldt's criteria predicted a poor outcome as well as the original clinical diagnoses and were considerably better than the New Haven criteria, Schneider's first rank symptoms, or the computer program Catego.
Kendell RE, Brockington IF, Leff JP. Prognostic Implications of Six Alternative Definitions of Schizophrenia. Arch Gen Psychiatry. 1979;36(1):25-31. doi:10.1001/archpsyc.1979.01780010031002