Validation of the ICF Core Sets for schizophrenia from the perspective of psychiatrists: An international Delphi study.

Schizophrenia is a chronic mental illness associated with several functional impairments. The International Classification of Functioning, Disability and Health (ICF) Core Sets for schizophrenia are shortlists of ICF categories that are relevant for describing the functioning and disability of people suffering from schizophrenia. The aims of this study were to explore the content validity of these Core Sets from the perspective of psychiatrists and to identify - from this perspective and using the ICF framework - the most common problems of patients with schizophrenia. In a three-round survey using the Delphi technique, psychiatrists experienced in schizophrenia treatment were asked about the problems they commonly encounter in these patients. A total of 352 psychiatrists from 63 countries representing all six WHO regions responded to the first-round questionnaire, and 303 completed all three rounds (86% response rate). From the first-round responses, 7133 concepts were extracted and linked to 387 ICF categories and 35 personal factors. Of these, consensus (≥75% agreement) was reached for 91 ICF categories and 31 personal factors. Eighty-seven of the 97 ICF categories that form the Comprehensive ICF Core Set for schizophrenia were represented in this list. Only four of the categories for which consensus was reached do not feature in the Comprehensive Core Set. From the perspective of psychiatrists the content validity of the ICF Core Sets for schizophrenia was largely supported. This suggests that these Core Sets offer an effective framework for describing functioning and disability in individuals with schizophrenia.