Background: Professional boundaries between psychiatrists and other mental health professionals are difficult to set. Empirical evidence for the distribution of diagnostic and treatment tasks among professionals is lacking.
Aims: This study examines the 'collective sense of the profession' about the relationship between patient characteristics and the contribution of tasks by disciplines.
Method: An adapted RAND appropriateness method was used. Eighty-six professionals judged 77 case descriptions of psychiatric patients on the contribution to diagnostic and treatment tasks of eight selected disciplines.
Results: In two multi-level models the variance explained by the judges' characteristics was 3.7% for diagnostic tasks and 4.5% for treatment tasks. The variance explained by the patient characteristics was zero for diagnostic and 0.5% for treatment tasks. The variance explained by the indicated disciplines was 36.8% for diagnostic and 12.6% for treatment tasks.
Conclusions: The collective sense of the profession on the contribution of psychiatrists to mental healthcare is unambiguous but not related to patient characteristics. It seems to be based on an a priori ranking order of disciplines.