Are preventable hospitalizations sensitive to changes in access to primary care? The case of the Oregon Health Plan
OBJECTIVE:To examine whether preventable hospitalization (PH) rates are sensitive to the impact of policies aimed at improving access, such as the Oregon Health Plan (OHP), which expanded Medicaid coverage to all adults with incomes under the federal poverty level. STUDY DESIGN/METHODS:We conducted a retrospective, time series analysis of PH rates in Oregon from 1990 to 2000. We calculated hospitalization rates for ambulatory-care sensitive conditions for the Medicaid + uninsured population and compared average annual rates from 1990 to 1993 (pre-OHP implementation) to those from 1995 to 2000 (post-OHP implementation). We compared changes in PH rates over time in the Medicaid + uninsured group to changes in the non-Medicaid insured population. We standardized rates by age and sex and used logistic regression models to compare rates. RESULTS:Contrary to our hypothesis, annual PH rates in the Medicaid + uninsured population increased after the eligibility expansion, from an average of 46.1 to 54.9 per 10,000 persons. This rise was significant compared with the non-Medicaid insured population, who experienced a slight decline in annual PH rates, from 26.9 to 26.1 per 10,000 (P < 0.001, after adjusting for age, sex, and rates of unpreventable hospitalizations). The increase in overall PH rates for the Medicaid + uninsured population can be explained by an increase in PH rates for the newly insured group. CONCLUSIONS:Our results suggest that PH rates may vary not only with access to primary care (inversely) but also with access to hospital care (directly). The use of PH rates as a marker of health care access should take into account these dual influences. Limitations in available data may also contribute to perceived variation in PH rates unrelated to health care access.
Emergency department visits for ambulatory care sensitive conditions: insights into preventable hospitalizations
OBJECTIVES: To explore whether differences in disease prevalence, disease severity, or emergency department (ED) admission thresholds explain why black persons, Medicaid, and uninsured patients have higher hospitalization rates for ambulatory care sensitive (ACS) conditions. MATERIALS AND METHODS: The National Hospital Ambulatory Care Survey was used to analyze the ED utilization, disease severity (assessed by triage category), hospitalization rates, and follow-up plans for adults with five chronic ACS conditions (asthma, chronic obstructive lung disease, congestive heart failure, diabetes mellitus, and hypertension). The National Health Interview Survey was used to estimate the prevalence of these conditions in similarly aged US adults. RESULTS: Black persons, Medicaid, and uninsured patients make up a disproportionate share of ED visits for these chronic ACS conditions. Cumulative prevalence of these conditions was higher in black persons (33%) compared with white persons (27%) and Hispanic persons (22%), but did not differ among the payment groups. All race or payment groups were assigned to similar triage categories and similar percentages of their ED visits resulted in hospitalization. Black persons and Hispanic persons (odds ratios for both = 0.7), were less likely than white persons, whereas Medicaid and uninsured patients (odds ratios for both = 0.8), were less likely than private patients to have follow-up with the physician who referred them to the ED. CONCLUSIONS: The disproportionate ED utilization for chronic ACS conditions by black persons and Medicaid patients does not appear to be explained by either differences in disease prevalence or disease severity. Follow-up arrangements for black persons, Medicaid, and uninsured patients suggest that they are less likely to have ongoing primary care. Barriers to primary care appear to contribute to the higher ED and hospital utilization rates seen in these groups