Matching resources to care: the acceptability, validity and inter-rater reliability of a new instrument to assess severe mental illness (MARC-1)

Background: Most definitions of severe mental illness (SMI) are categorical and assign the patient to either SMI or not-SMI. status. While this is useful for some purposes, it is a rather limited approach. The purpose of the present study is to develop a new method of addressing the issue of 'severity', and to develop a dimensional rather than a categorical approach. The paper reports on the acceptability, reliability and validity of a method developed to collect a standard set of data covering the majority of items specified in the academic and policy literature as characterising SMI. Method: A single page form, Matching Resources to Care (MARC-I), containing most of the items used in definitions of SMI was used to collect data from community mental health staff about their current open caseload, in four co-terminous health and social services settings during a census week (n = 2139). In addition to the data from the four pilot sites, we conducted a substudy(n = 91), in which two raters rated the same cases during the same week. Results: The MARC-1 scores were able to distinguish between patients in receipt, and those not in receipt, of specific types of community care (level of care, eligibility for care and statutory aftercare) (P <0.001). The MARC-1 score was modestly but significantly correlated (r = 0.28) with the Global Assessment Scale (P <0.001). The mean percentage interrater agreement for the MARC-I score items was 87%. Conclusion: It is possible to use a simple census form in both health and social services agencies. The completion rates were good in both services. The levels of reliability were good, and concurrent validity was established with specific types of care in the community.