Development of the PREMIUM computerized adaptive testing for measuring the access and care coordination for patients with severe mental illness.

Severe mental illness (SMI) patients often have complex health needs, which makes it difficult to access and coordinate their care. This study aimed to develop a computerized adaptive testing (CAT) tool, PREMIUM CAT-ACC, to measure SMI patients' experience with access and care coordination. This multicenter and cross-sectional study included 496 adult in- and out-patients with SMI (i.e., schizophrenia, bipolar disorder, or major depressive disorder). Psychometric analysis of the 13-item bank showed adequate properties, with preliminary evidence of external validity and no substantial differential item functioning for sex, age, care setting, and diagnosis, making it suitable for CAT administration. A post-hoc CAT simulation demonstrated that the tool was efficient and accurate, with an average of seven items, compared to the full item bank administration. Its use by clinicians can contribute to optimizing patient care pathways and transitioning towards more person-centered healthcare.