Objective: The INTERMED Self-Assessment questionnaire (IMSA) was developed as an alternative to the observer-rated INTERMED (IM) to assess biopsychosocial complexity and health care needs. We studied feasibility, reliability, and validity of the IMSA within a large and heterogeneous international sample of adult hospital inpatients and outpatients as well as its predictive value for health care use (HCU) and quality of life (QoL).
Methods: A total of 850 participants aged 17 to 90 years from five countries completed the IMSA and were evaluated with the IM. The following measurement properties were determined: feasibility by percentages of missing values; reliability by Cronbach α; interrater agreement by intraclass correlation coefficients; convergent validity of IMSA scores with mental health (Short Form 36 emotional well-being subscale and Hospital Anxiety and Depression Scale), medical health (Cumulative Illness Rating Scale) and QoL (Euroqol-5D) by Spearman rank correlations; and predictive validity of IMSA scores with HCU and QoL by (generalized) linear mixed models.
Results: Feasibility, face validity, and reliability (Cronbach α = 0.80) were satisfactory. Intraclass correlation coefficient between IMSA and IM total scores was .78 (95% CI = .75-.81). Correlations of the IMSA with the Short Form 36, Hospital Anxiety and Depression Scale, Cumulative Illness Rating Scale, and Euroqol-5D (convergent validity) were -.65, .15, .28, and -.59, respectively. The IMSA significantly predicted QoL and also HCU (emergency department visits, hospitalization, outpatient visits, and diagnostic examinations) after 3- and 6-month follow-up. Results were comparable between hospital sites, inpatients and outpatients, as well as age groups.
Conclusions: The IMSA is a generic and time-efficient method to assess biopsychosocial complexity and to provide guidance for multidisciplinary care trajectories in adult patients, with good reliability and validity across different cultures.