IDENTIFYING FACTORS ASSOCIATED WITH STATE PSYCHIATRIC HOSPITAL USE TO INFORM ADMISSION, REFERRAL, AND POLICY DECISION-MAKING

Purpose: To use a large administrative dataset to identify factors associated with more intense patterns of state psychiatric hospital (SPH) use in a way that supports policy decision-making. 

Method: We held nine meetings (2008-2012) with SPH and local mental health agency stakeholders to determine what information about SPH use would be most useful in planning mental health crisis services for consumers with severe mental illness.  To address stakeholder priorities, we estimated two Cox proportional hazards models using admission and discharge data for non-forensic patients aged 18 to 64 who visited North Carolina SPHs between July 1, 2006 and December 31, 2011.  The first model estimated for admitted patients the association between patient-level and regional factors and the hazard of being discharged.  The second model focused on the hazard of readmission among discharged patients.  Time-dependent covariates were included in both models to analyze the effect of a statewide waitlist for SPH admission, which was implemented in 2007. We used a classification and regression tree (CART) model to classify SPH users based on length of stay and number of admissions during the study period. 

Result: Stakeholder priorities included identifying key characteristics associated with (1) both short and long lengths of stay, (2) more frequent readmission, and (3) distinct patterns of intense use (combining frequency and length of stay).  Among admitted patients, older age and having been declared incompetent had strong negative associations with the hazard of being discharged (i.e., these patients tended to have longer SPH stays).  Among discharged patients, the hazard of readmission was lower after the waitlist was implemented, but higher for patients declared incompetent or publicly insured.  The CART model identified several patient subgroups with unique patterns of SPH use.

Conclusion: Both the Cox and CART models were needed to address stakeholder questions.  While the Cox models were useful in identifying characteristics associated with hazards of discharge (i.e., length of stay) and readmission, the CART analysis complemented these models by offering an empirically-derived classification of SPH users.  Results highlight patient characteristics associated with increased SPH use and could be used by stakeholders in two ways: to distinguish patients most in need of SPH services from those who could be better served in the community and to develop supports needed to discharge stabilized patients sooner.