Lee-Feldstein et al. (1994), using cancer registry data, found significantly worse five-year survival among women with localized breast cancer treated at HMO hospitals in Orange County, California, in 1984-1990, compared to women treated at teaching hospitals, small community hospitals, and large community hospitals. Patients treated at an HMO facility had a 63 percent increased risk of dying, compared with the reference group treated in small hospitals, when age, tumor size, number of positive lymph nodes, and type of treatment (e.g., breast conserving surgery with radiation versus no radiation) were controlled for. The excess deaths among HMO patients with localized disease were limited to 1984 through 1987. Only 380 HMO patients with localized disease were available for analysis, and the confidence interval around the point estimate (i.e., OR = 1.63) ranges from 1.16 to 2.30. No HMO mortality disadvantage for women with regional disease was found. The unexpected finding of a 45 percent increased risk of death for patients having a total mastectomy compared to those having BCS, when no difference is expected, has raised questions about the validity of this study (Hillner et al., 1998b). Furthermore, survival comparisons between HMO and non-HMO hospitals did not control for comorbidity, race, and socioeconomic status. Clinical and socioeconomic variables are likely to differ by type of hospital and are strongly related to survival of women with breast cancer (Charlson et al., 1987; Eley et al., 1994; Greenwald, 1992). Methodologic flaws of this study limit its interpretation.
Retchin and Brown (1990) assessed the effect of being insured by an HMO in two different studies related to care for colorectal cancer in the elderly. The first study examined pre-and postoperative care processes for 330 patients diagnosed from 1983 to 1986 as part of an evaluation of the Medicare demonstrations in prepaid care. Some differences in use of diagnostics tests were observed, but findings are difficult to interpret because analyses were largely descriptive in nature, with few controls for clinical or sociodemographic characteristics. A more recent study of 813 patients diagnosed in 1989 compared perioperative care and outcomes within 19 geographically dispersed HMOs to FFS care (Retchin et al., 1997). There were some differences in processes of care; for example, compared to those covered by FFS plans, HMO enrollees had shorter lengths of stay and received fewer tests and services. There was no evidence that HMO members experienced different outcomes (e.g., hospital readmissions, in-hospital deaths, admissions within one year of discharge). A limitation of this study is the lack of control in some comparisons for sociodemographic characteristics, stage, and other clinical factors.
Greenwald and Henke (1992) compared care and outcomes by HMO status among Medicare beneficiaries with prostate cancer diagnosed from 1980 to 1982 in the Seattle area. Patients in Group Health of Puget Sound (n = 131) relative to 1,032 FFS patients had less surgery, more radiation therapy, and—after adjustment for stage, urban location, and age—better survival. The relatively small sample from one HMO, the age of the data, and a lack of adjustment for clinical prognostic factors in the analysis limit the value of this study.
Vernon and colleagues (1992) evaluated the effect of insurance status on the care of 330 patients with colorectal cancer diagnosed from 1984 to 1989 and seen by the same set of providers in one group practice in Houston, Texas. No systematic differences were found in the care offered to HMO and FFS patients (e.g., type of primary treatment). Limitations of this study include the small sample size and a lack of adjustments for differences in the HMO and FFS study populations (e.g., HMO members were younger).
In summary, relatively few studies have compared cancer care under managed care and FFS financing and delivery arrangements. Most of these studies have involved comparisons of