Health care markets, the safety net, and utilization of care among the uninsured

Health Services Research, Feb, 2007 by Carole Roan Gresenz, Jeannette Rogowski, Jose J. Escarce

We also find that primary care physician supply is inversely related to ED visits, with greater availability of physicians associated with fewer ED visits (Table 5). This finding suggests that the timing of ED and physician visits affects their relationship. A physician visit may diminish the probability of a later ED visit (perhaps by preventing a medical condition from spiraling into a health emergency), whereas ED visits may result in a referral to a physician for follow-up care.

Finally, we find a relationship between distance to the nearest public hospital and nonphysician visits. Surprisingly, the results show that a longer distance to the nearest public hospital (or fewer number of public hospitals within a 10-mile radius) is associated with more nonphysician visits (Tables 5 and 7). Another unexpected finding in the rural results is that a greater number of BPHC providers within 10 miles is associated with a lower number of nonphysician visits (Table 7); by contrast, a longer distance to the nearest BPHC provider is associated with a fewer nonphysician visits (Table 5). The heterogeneity of nonphysician visits--which include visits to physician assistants and nurse practitioners but also to podiatrists, chiropractors, and psychologists--may underlie the unexpected results. Different types of nonphysician providers are typically available in different health care settings that may make the effect of availability on the use of these providers difficult to model. Moreover, while the results are significant at the conventionally used 0.05 level, they do not reach the more exacting 0.01 level attained by most of the other conceptually consistent results.

Urban Uninsured

In contrast to the rural uninsured, we find more limited associations between distances to safety-net providers and health care utilization among the urban uninsured. In the continuous-distance specification (Table 6), we find no association between distance to the closest ED and any type of utilization, and no association between distance to the closest BPHC provider and utilization (although the sensitivity analyses--Table 8--show a greater number of BPHC providers within a 5-mile radius is associated with a greater number of nonphysician visits). We find that a longer distance to the nearest public hospital is associated with more ED visits suggesting substitution of ED-based care for office-based visits received in clinics associated with the public hospital.

A key finding for the urban uninsured is the association between the level and structure of managed care in the local market and utilization among the uninsured (Table 6). The relationship appears across numerous types of utilization, including physician visits (the greater is HMO penetration, the fewer are visits), nonphysician visits (the greater is HMO penetration, the more such visits), and any medical expenditures or charges (greater HMO penetration associated with a lower probability of any expenditures or charges). Our results suggest that greater managed care presence shifts utilization among the uninsured away from office-based physician visits and towards nonphysician providers. One possibility is that the uninsured are less able to find charity or discounted care from physicians in areas where managed care limits their ability to set prices for insured patients. The uninsured in areas with greater HMO presence, facing relatively high prices for physician care, may substitute less expensive care from nonphysicians for physician care.