BCS, HMO enrollees were significantly more likely than those in FFS plans to receive radiation therapy (69 versus 64 percent). Analyses of treatment patterns were controlled for age, race, cancer history, year of diagnosis, stage at diagnosis, tumor size, county of residence, and education at the census tract level. Investigators found aggregate comparisons of the experiences of HMO and FFS populations to obscure important variation among HMO plans. Among BCS cases, for example, radiation therapy was more commonly received by HMO enrollees overall but the pattern varied by HMO. Enrollees in some HMOs were significantly more likely than those in FFS plans to have had radiation therapy, and in other HMOs, the opposite was true. The authors conclude that variation among HMOs is likely attributable to differences in both plan and market characteristics. Plans differ in their structure, organization, benefit packages, payment policies, practice protocols, and provider relationships. Market characteristics vary along many dimensions, such as degree of competition, managed care penetration, and availability of radiation facilities. These findings illustrate how difficult it is to generalize about managed care.

In an earlier study, Potosky et al. (1997) compared HMO to FFS care among 13,358 Medicare beneficiaries diagnosed with breast cancer from 1985 to 1992 in the Seattle-Puget Sound and San Francisco Bay areas. Cancer registry data (i.e., SEER) were linked to Medicare administrative files to assess aspects of care and survival (Potosky et al., 1997). In San Francisco-Oakland, the 10-year adjusted risk of death due to breast cancer was 29 percent lower, and the overall adjusted risk of death 30 percent lower, among women belonging to an HMO (i.e., Kaiser Permanente of Northern California) compared to women insured by FFS plans (Table 5.13). A significant HMO mortality advantage was not found in the Seattle-Puget Sound area (i.e., Group Health of Puget Sound).

Women enrolled in HMOs in both areas were more likely than those covered by FFS plans to have received breast conserving surgery (BCS) and, among those having BCS, were more likely to have had radiation therapy following surgery (Table 5.13). The authors conclude that long-term survival outcomes in the two prepaid group practice HMOs were at least equal to, and possibly better than, outcomes in the FFS system. In addition, the use of recommended therapy for early-stage breast cancer was more frequent in the two HMOs. Medicare patients with breast cancer in these two established nonprofit staff-and group-model HMOs appeared to receive better quality of care than Medicare enrollees in FFS.

Strengths of this study were the large sample size; adjustments for sociodemographic (i.e., age, race, area-level educational status); and clinical factors (i.e., stage, whether the diagnosis was a single or first primary cancer, comorbidity); and the length of follow-up (10 years). The authors speculate that the observed HMO survival advantage is, in part, due to more frequent screening. HMO compared to FFS care was associated with earlier stage at diagnosis and within stage, with smaller tumors. Some of the HMO survival advantage could be artifactual if higher rates of screening within HMOs are identifying biologically less aggressive tumors, including those that would never have been detected via symptoms. The analysis controlled for stage, but not for the within-stage shift in tumor size. The findings from this study may not be generalizable to other areas or types of managed care plans (e.g., for profit, independent practice associations). The two HMOs included in the study embody core features of traditional managed care, which include an emphasis on creating long-standing relationships between patient and providers, preventive care, the practice of evidence-based medicine, less stringent utilization review with greater physician autonomy, and greater coordination of specialty care (Clancy and Brody, 1995).

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