Health care factors related to stage at diagnosis and survival among medicare patients with colorectal cancer

BACKGROUND. With the growth in enrollment of Medicare patients in HMOs the effectiveness of care received by Medicare/HMO patients continues to be of concern. By considering the relationship of insurance to stage at diagnosis, this study inquires whether HMOs emphasize early diagnosis of colorectal cancer to a greater extent than FFS plans, if particular HMO types (group/nongroup models) are more successful in doing so, and how this pertains to survival. METHODS. Data for 1329 Medicare patients with colorectal cancer, diagnosed 1987 to 1993, and residing in northern California, were acquired from a population-based cancer registry. Insurance included two types of Medicare HMOs (group and nongroup model) and three fee-for-service (FFS) categories: Medicare with private supplement, Medicare/Medicaid, and Medicare only. The relationships of insurance to AJCC stage at diagnosis and of insurance to survival following diagnosis were examined, respectively, with logistic regression models and survival analysis (controlling for age, ethnicity, tumor location, educational level, sex, and hospital type). RESULTS. Likelihood of early stage colorectal cancer was greater for Medicare patients in nongroup model HMOs or having private FFS supplements than for those in group model HMOs, Medicare/Medicaid, or Medicare alone. All-cause and colorectal cancer mortality did not differ significantly among Medicare patients with group model HMO, nongroup model HMO and private FFS supplements. Medicare/Medicaid patients experienced significantly greater all-cause mortality than private FFS patients. CONCLUSIONS. Differences within this study population in early stage diagnosis of colorectal cancer and breast cancer, respectively, by type of Medicare supplemental insurance may be attributable to which preventive screening measures are included in health plan report cards.