Schizophrenia spectrum disorders (SSD): an empirical benchmark study of real-world diagnostic accuracy and reliability among leading international psychiatrists

Assigning a psychiatric diagnosis in real-world situations is often difficult, given that the clinical presentation does not usually conform to the list of condensed, simplified behavioral descriptors of mainstream operational taxonomies (MOT) (e.g. ICD-11 and DSM-5). The goal of this study was to benchmark diagnostic accuracy and reliability on a central and severe spectrum of psychopathology (i.e., the schizophrenia spectrum disorders [SSD]), adopting a pragmatic approach as close as possible to real-world clinical settings. We examined the diagnostic performance of 30 international psychiatrists expert in SSD. The clinicians were asked to make their clinical best diagnostic estimate for two written clinical vignettes excerpted from real-world SSD cases. In the first vignette, 22 out of the 30 clinicians (73.5%) indicated a schizophrenia spectrum disorder as their main diagnostic hypothesis. In the second vignette, 12 clinicians (40%) chose SSD as their main diagnostic hypothesis. Only 10 of the 30 clinicians (33%) correctly identified both vignettes as cases of SSD. The level of inter-rater diagnostic agreement (Fleiss’ Kappa) was but statistically significant (KFleiss = 0.08, p = 0.01). The results suggest that, even in a sample of influential international psychiatrists, the diagnostic accuracy and reliability on SSD presentations is poor and substantially inferior to those obtained in reliability studies using structured or semi-structured interviews. The widespread adoption of MOT systems in the last decades may have inadvertently eroded ability of clinicians to detect a typical pattern of psychiatric illnesses.