Assessing the severity of functional impairment of psychiatric disorders: Equipercentile linking the mini-ICF-APP and CGI

Abstract

Background: The assessment of functioning and impairment due to psychiatric illness has been acknowledged to be crucial for research and practice. This led to the development of the mini-ICF-APP, which provides a reliable and time-efficient measure of functioning and impairment. Although its use is increasing, it remains unclear how it reflects severity and how change might be interpreted from a clinical perspective. Methods: In a clinical sample of 3067 individuals hospitalized for mental health treatment, we used an equipercentile approach to link the mini-ICF-APP with the Clinical Global Impression scale (CGI) at admission and discharge. We linked the mini-ICF-APP sum score to the CGI-S scale and the mini-ICF-APP proportional change between admission and discharge to the CGI-I scale. Results: The mini-ICF-APP and CGI scales showed a Spearman correlation of 0.50 (p.000); "no-change" in the CGI-I corresponded to an increase or decrease of 2%; "minimally-improved" to a mini-ICF-APP reduction of 3-30%; "much-improved" to a reduction of 31-63%; "very-much-improved" to a reduction of ≥64% "minimally-worse" to an increase of 3-34% "much-worse" to an increase of 35-67%; and finally "very-much-worse" with an increase of ≥68%. Conclusions: Our findings improve understanding of the clinical meaning of the mini-ICF-APP sum score and percentage change in patients hospitalized for treatment.