April 2008

Document Type


Degree Name



Dept. of Public Health and Preventive Medicine


Oregon Health & Science University


Introduction: The Oregon Medical Insurance Pool (OMIP) is a high-risk health insurance pool that provides health insurance to Oregonians who cannot obtain health insurance through other mechanisms. On January 1, 2006, premiums increased by 16.5%. On that date, 860 (6.0%) of OMIP’s 14,336 enrollees discontinued their coverage. We used this natural experiment to determine the association between the decision to cease OMIP coverage and two enrollee characteristics of interest: chronic medical condition status and income level. Methods: This was a retrospective cohort study using data collected by OMIP to track enrollment and utilization of services. After exclusions, our study population consisted of 10,586 members, of whom 545 (5.1%) discontinued their OMIP coverage effective January 1, 2006. We performed a backwards stepwise logistic regression for our analysis with a primary outcome of discontinuation of OMIP enrollment on January 1, 2006. Results: In multivariate models, presence of a




School of Medicine



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