Functioning in patients with schizophrenia: a systematic review of the literature using the International Classification of Functioning, Disability and Health (ICF) as a reference

To identify and quantify the main concepts included in published studies focusing on individuals with schizophrenia using the International Classification of Functioning, Disability and Health (ICF). Searches (limited to those published from 2008 to 2012) were performed in MEDLINE, PsycINFO and CINAHL. Included studies described participants with schizophrenia, were original articles and included only subjects who were at least 18 years of age at study entry. All concepts underlying the measures and the text of the articles were extracted, and they were linked to ICF categories using standardized rules. From the 3584 abstracts retrieved, 348 were randomly selected, and of these, 206 studies met the inclusion criteria. A total of 17,141 concepts were extracted, 84.8% of which could be linked to 491 ICF categories: 222 (45.21%) of the categories referred to Body Functions, 29 (5.91%) to Body Structures, 186 (37.88%) to Activities and Participation and 54 (11%) to Environmental Factors. Seventy second-level categories were reported in at least 5% of all studies: 30 of these categories referred to Body Functions, 2 to Body Structures, 34 to Activities and Participation and 4 to Environmental Factors. The study has allowed us to identify and quantify the main concepts included in studies focusing on people with schizophrenia using the ICF. The majority of the concepts refer to Body Functions and Activities and Participation, rather than to Body Structures and Environmental Factors.