A randomized trial of elderly Medicaid beneficiaries found that enrollment in prepaid plans had no adverse effect on poor, elderly Medicaid beneficiaries during the year that the patients were evaluated. Although the enrollees in prepaid plans used significantly less care, there was no indication that they experienced poorer health as a result (Lurie et al., 1994).

Although the studies noted above are examples of evidence that HMOs have satisfactorily treated older or chronically ill patients, there is also evidence in the research literature that finds this model wanting with respect to vulnerable populations. The following describes several studies that point up concerns.

Safran and colleagues (1994) compared staff/group model HMOs, IPAs, and traditional fee-for-service plans to determine the extent to which each of five core dimensions of high-quality primary care (accessibility, continuity, comprehensiveness, coordination, and accountability) were received by chronically ill patients³ The results showed that neither prepaid systems nor fee-for-service plans provide primary care optimally. The prepaid plans (HMOs and IPAs) provided increased financial access and coordination and "reduced patient-physician continuity and comprehensiveness of care and, in many cases,… diminished organizational access and interpersonal treatment" (p. 1583).

The authors examined access from two perspectives, financial and organizational. Financial access was a greater barrier in fee-for-service plans because of requirements for higher out-of-pocket costs. However, organizational barriers were greater in some, although not all, HMOs studied. In the cases in which organizational access was a barrier, patients reported difficulties in receiving medical care on short notice and longer waits for emergency treatment. The authors observed that organizational barriers to access are disruptive to the continuity of care (which might be of particular significance to those with chronic