Renata Yang


May 2009

Document Type


Degree Name



Dept. of Public Health and Preventive Medicine


Oregon Health & Science University


CONTEXT: Most individuals with schizophrenia and substance use disorders depend heavily on Medicaid benefits to fund the provision of mental health and addiction services. The Oregon Health Plan is an important health care program that provides outpatient mental health and chemical dependency benefits to the majority of persons diagnosed with schizophrenia. OBJECTIVES: The purpose of this study was to investigate whether there was an increase in the number of acute care hospitalizations for persons diagnosed with schizophrenia, who were enrolled in OHP Standard between August of 2003 and August of 2004 when, due to changes in OHP policy, access to mental health and addiction services was lost and increased barriers to care occurred to this population. METHODS: The project was a retrospective cohort study of 8,489 patients diagnosed with schizophrenia, who were between the ages of 18 and 65, and enrolled in either OHP Plus or OHP Standard between 2002 and 2004. Data files maintained by the State Addictions and Mental Health (AMH) Division were constructed to include patients’ demographic, enrollment and claims information for acute care hospitalization stays. Negative binomial regression was used to determine whether changes to OHP policy had a significant impact in the rates of acute care hospitalization by comparing data one year before and after policy changes. MAIN OUTCOME MEASURES: Rate of acute care hospitalization in the one-year period before and after changes to OHP policy. RESULTS: The rate of acute care hospitalization was significantly less in the period after changes to OHP policy for both insurance groups. The rate of acute care hospitalization decreased by 34.6% and 58.4%, respectively for OHP Plus and OHP Standard. The magnitude of change in the rate of acute care hospitalization was significantly larger at 36% for the group enrolled in OHP Standard. Other significant predictors of rate of acute care hospitalization included time period of enrollment, age, gender, a co-occurring substance use diagnosis and number of previous hospitalizations. CONCLUSION: Between 2002 and 2004, the rates of acute care hospitalization declined for persons enrolled in both OHP Plus and OHP Standard. The magnitude of change was greater for OHP Standard, but it is uncertain whether this difference was secondary to policy changes which affected this group or to other unaccounted factors.




School of Medicine



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