Managed Care and Cancer Outcomes for Medicare Beneficiaries With Disabilities

Objective: To determine if the type of insurance arrangement, specifically health maintenance organization (HMO) vs fee-for-service (FFS), affects cancer outcomes for Medicare beneficiaries with disabilities.

Study Design

: Retrospective cohort.

Methods: We used the Surveillance, Epidemiology, and End Results–Medicare linked dataset to identify beneficiaries older and younger than 65 years entitled to Medicare benefits because of disability (Social Security Disability Insurance) who subsequently were diagnosed as having breast cancer (n = 6839) or non–small cell lung cancer (n = 10,229) from 1988 through 1999. We categorized persons according to Medicare insurance arrangement (continuous FFS, continuous HMO, or mixed FFS/HMO) during the periods 12 months before diagnosis and 6 months after diagnosis. Using a retrospective cohort design, we examined stage at diagnosis, cancer-directed treatments, and survival.

Results

: Women with continuous HMO insurance had earlier-stage breast cancer diagnosis (adjusted relative risk, 0.77; 95% confidence interval, 0.65-0.91) and were more likely to receive radiation therapy following breast-conserving surgery (adjusted relative risk, 1.11; 95% confidence interval, 1.03-1.19). Women having continuous HMO insurance had better breast cancer survival, primarily resulting from earlier-stage diagnosis. Among persons with non–small cell lung cancer, those having mixed FFS/HMO insurance were more likely to receive definitive surgery for early-stage disease (adjusted odds ratio, 1.23; 95% confidence interval, 1.02-1.49) and to have better overall survival but not significantly better lung cancer survival.

Conclusion

: When diagnosed as having breast cancer or non–small cell lung cancer, some Medicare beneficiaries with disabilities fare better with managed care compared with FFS insurance plans.

(Am J Manag Care. 2008;14(5):287-296)

It is unknown whether the type of Medicare insurance arrangement, specifically health maintenance organization (HMO) vs fee-for-service (FFS), affects cancer outcomes for Medicare beneficiaries with disabilities, a vulnerable population. We found that Medicare beneficiaries with disabilities had better breast cancer outcomes if they were continuously enrolled in HMOs.

• The HMO vs FFS insurance arrangement had little effect on the care and outcomes of lung cancer among Medicare beneficiaries with disabilities.

In 2005, 1 in 6 Medicare beneficiaries (6.5 million persons) was entitled to receive Medicare benefits because of disability.¹ Medicare beneficiaries with disabilities seem to be at risk for increased cancer mortality,² even when diagnosed at the same stage or at an earlier stage, compared with persons without disabilities.³ In addition, persons with disabilities may receive different cancer treatment than persons without disabilities.^2,4

Medicare beneficiaries may receive care within a health maintenance organization (HMO) or within the fee-for-service (FFS) sector. It is uncertain whether the type of health insurance arrangement (HMO vs FFS) affects the quality of care for Medicare beneficiaries with disabilities.⁵ In some studies,^6,7 beneficiaries with disabilities were less satisfied with managed care plan performance and were more likely to disenroll. However, other evidence indicates that beneficiaries with disabilities receiving care in HMO plans perceive better access to primary care services and greater affordability of health services than those with traditional Medicare coverage.⁸ Medicare beneficiaries who are enrolled in HMO plans are more likely to undergo cancer screening,^9-12 generally have cancers diagnosed at an earlier stage,^13-16 and may have improved survival.¹⁴

The Surveillance, Epidemiology, and End Results (SEER) cancer registries merged with Medicare data have been used to study health disparities among persons with disabilities.^2,3 We used merged SEER-Medicare data to evaluate whether the type of Medicare insurance arrangement (HMO or FFS) affects cancer outcomes for Medicare beneficiaries with disabilities. We studied 2 high-volume cancers, breast cancer and lung cancer. We chose breast cancer because it is amenable to screening and because experiences of these patients would capture potential disparities in early detection and treatment. In contrast, screening is not recommended to detect lung cancer, although surgery and radiation treatment may improve survival.^17,18

METHODS

We used the SEER-Medicare dataset, which links SEER registry information to Medicare claims data.^19,20 SEER consists of 11 population-based tumor registries representing approximately 14% of the US population.²⁰ SEER collects patient information on demographic characteristics, primary tumor site, stage at diagnosis, tumor size, histologic findings, tumor grade, hormone receptor status, initial course of treatment, and vital status. SEER tracks vital status annually, and death certificates are used to capture underlying cause of death.

Study SampleWe identified all persons 21 years and older within the SEER-Medicare dataset having a pathologically confirmed first diagnosis of breast cancer (n = 62,315) or non&#8211;small cell lung cancer (n = 55,770) from January 1, 1988, through December 31, 1999. We then restricted our sample to those persons who originally qualified for Medicare coverage because of Social Security Disability Insurance (6839 with breast cancer and 10,229 with lung cancer). Therefore, our sample includes persons younger than 65 years who have Social Security Disability Insurance and persons 65 years and older whose Social Security Disability Insurance has been automatically converted to Old Age Survivors Insurance. As described elsewhere, we focused exclusively on individuals with Medicare when newly diagnosed with cancer, eliminating persons disabled by cancer.³Medicare data indicate for each month whether persons were eligible for Part A and Part B and whether they were enrolled in an HMO insurance arrangement. To examine possible effects of insurance structure on early detection of cancer, we constructed a variable that defined insurance arrangement before diagnosis. We determined the type of insurance arrangement during the month of diagnosis and the previous 12 months. For this period, we assigned cases to 1 of the following 3 insurance categories: FFS for persons continuously enrolled in traditional FFS Medicare, HMO for persons continuously enrolled in HMO plans, and mixed FFS/HMO for persons enrolled in both FFS and HMO plans during the period. To examine treatments following diagnosis, we designated similar postdiagnosis insurance variables for persons continuously eligible for Medicare Part A and Part B during the month of diagnosis and the 6 months after diagnosis (or until death if survival was <6 months). For analyses of survival, we assigned cases to similar insurance categories covering the prediagnosis and postdiagnosis periods combined.

Stage at DiagnosisSEER determines stage at diagnosis based on a combination of pathologic surgical and clinical assessments available within 2 months of diagnosis.²¹ Stage at diagnosis is recorded using the American Joint Committee on Cancer (AJCC) staging system (stage 0, I, II, III, or IV). In our analysis of stage at diagnosis, we excluded persons whose cancers were unstaged (346 with breast cancer and 1182 with lung cancer).

Cancer-directed Treatments

We examined survival (all-cause and cancer-specific mortality) following diagnosis. We measured survival time as the number of days from diagnosis until death or December 31, 2001, whichever came first. For all-cause mortality analyses, we censored observations of persons alive at the end of followup. We studied breast cancer&#8211;specific and lung cancer&#8211;specific deaths, censoring observations of subjects alive at the end of follow-up or who died from causes other than breast cancer or lung cancer.

Statistical Analysis

Table 1 lists the characteristics of our sample. Persons having HMO insurance at diagnosis tended to be older and more likely to reside in census tracts having higher median household income. Consistent with market penetration of HMOs, patients having HMO insurance were more likely to originate from SEER registries in California and in Seattle, Washington. Among patients with breast cancer, those having FFS insurance were more likely to have missing information on tumor grade and on estrogen receptor status and progesterone receptor status.

Insurance type was sometimes statistically significantly associated with cancer-directed treatments for breast cancer and for lung cancer (Table 3). Women having HMO insurance were more likely to receive radiation therapy following breast-conserving surgery. There was a statistically nonsignificant trend for women having HMO insurance to receive breast-conserving surgery rather than mastectomy. Insurance status had no effect on the likelihood of axillary lymph node dissection. Among persons diagnosed as having non&#8211;small cell lung cancer, those having mixed FFS/HMO insurance were more likely to receive definitive surgery for early-stage tumors.

Results were similar when subjects having missing information on tumor characteristics were excluded from the sample and multivariate analysis was repeated (data not shown). To examine the possibility that the effects of HMO insurance varied over time, we repeated our analyses separately for 2 periods, persons diagnosed from 1989 through 1994 and persons diagnosed from 1995 through 1999. Results were similar for both periods. We calculated an attributable fraction for the 831 breast cancer deaths observed in the cohort (769 with FFS insurance and 62 with HMO insurance). We estimated that 17% (144 deaths) would theoretically have been prevented if patients having FFS insurance had a mortality experience comparable to that of patients having HMO insurance.

DISCUSSION

associations for patients with disabilities diagnosed as having lung cancer (eg, no association with stage).

Among Medicare beneficiaries, patients belonging to HMOs are more likely to be screened for cancer^9-12 and are more likely to have cancers diagnosed at an earlier stage.^13-16 This may in part explain our finding of earlier breast cancer diagnosis and improved survival. Higher rates of cancer screening within HMOs may result from greater emphasis on delivery of preventive care32 and from increased focus on primary care rather than on subspecialty care.³³ In some studies, beneficiaries with disabilities in HMOs perceived better access to primary care services8 and were more likely to undergo cancer screening tests.³⁴ Greater use of preventive services in HMOs may be the result in part of favorable selection in which healthier patients are differentially enrolled in HMOs.³⁵

There was some evidence that Medicare beneficiaries with disabilities enrolled in HMOs were more frequently treated with breast-conserving surgery as shown by a statistically significant odds ratio in the unadjusted model but not in the adjusted model. These HMO enrollees were more often treated with radiation therapy following breast-conserving surgery (the treatment combination recommended by National Institutes of Health consensus panels) and had better breast cancer survival. Persons having HMO insurance were more likely to have tumor grade and hormone receptor status documented for their cancers. Findings from previous studies suggest that in general Medicare beneficiaries belonging to HMOs are more likely to undergo breast-conserving surgery,³⁶ to receive adjuvant radiation therapy following breast-conserving surgery,¹⁶ and to have improved breast cancer survival.^36,37 Our study extends these findings to Medicare beneficiaries with disabilities.

The reasons for treatment differences among patients having HMO insurance vs FFS insurance could not be ascertained in this study but may result from variations in practice structure. Health maintenance organizations, especially staff-model and group-model forms, have resources and organizational structures that can disseminate standards of care and ensure that current practice patterns are consistent with these standards.^38,39 Improved breast cancer survival among HMO recipients seemed to be primarily the result of earlier stage at diagnosis.

While HMO insurance vs FFS insurance arrangement was statistically significantly associated with breast cancer outcomes, lung cancer outcomes showed few effects. The subset of persons changing between HMO and FFS plans seemed to have better lung cancer outcomes. Among 137 patients with lung cancer who changed insurance type between diagnosis and 6-month follow-up, most (65%) changed from HMO insurance to FFS insurance. This group had a greater likelihood of undergoing surgery for early-stage disease and had better overall survival, with a statistically nonsignificant trend toward better lung cancer survival.

Changing between HMO and FFS Medicare plans might indicate problems in accessing care or dissatisfaction with care. Patients having disabilities are generally more likely to report dissatisfaction or problems with their healthcare plan^6,7,40-42 and are more likely to disenroll from their HMO, often changing to an FFS plan.⁴³ Forced disenrollment from a Medicare HMO plan has been associated with problems in accessing needed care.^44-46

In our study, Medicare beneficiaries with disabilities had remarkably stable HMO and FFS insurance status during their follow-up, similar to other studies.^47,48 Among persons continuously eligible for Medicare and followed up until their death, 95% of persons with lung cancer and 92% of persons with breast cancer had continuous coverage within FFS or HMO arrangements from the 12 months before diagnosis until their death. In addition, patients who changed between HMO and FFS plans generally had similar or better outcomes compared with persons continuously enrolled in FFS.

Our study had several important limitations. We did not have Medicare claims data for persons enrolled in HMOs and were unable to examine cancer screening or to supplement SEER information on treatment using Medicare claims. Our lack of Medicare claims for persons in HMOs prevented us from assessing comorbidity. SEER does not release data on chemotherapy, so we were unable to evaluate this aspect of cancer treatment, which is especially critical in breast cancer. Medicare data did not include details about the specific HMO plan, so we were unable to assess the particular financial arrangements for the HMO plan, nor could we capture patient movement between HMO plans. Our sample was restricted to persons who originally qualified for Medicare coverage because of Social Security Disability Insurance, and our results may not generalize to the greater population of persons having disabilities. We studied persons who were diagnosed as having cancer through the end of 1999, and it is possible that trends may have changed since that time. Finally, this was an observational study that did not randomize subjects to insurance types. Statistical methods, such as propensity scores, can only adjust for measured characteristics within the cohort. As a result, it is possible that our results were in part due to unmeasured patient characteristics that differed between HMO patients and FFS patients and not because of the specific insurance arrangement.

In conclusion, Medicare beneficiaries with disabilities diagnosed as having breast cancer generally had more favorable outcomes within HMO arrangements. Health maintenance organization vs FFS insurance status had little effect on lung cancer outcomes. Changes between HMO and FFS insurance types were not associated with poor cancer outcomes.³²

AcknowledgmentsThis study used the linked SEER-Medicare database. The interpretation and reporting of these data are the sole responsibility of the authors. The authors acknowledge the efforts of several groups responsible for the creation and dissemination of the linked database, including the Applied Research Branch, Division of Cancer Control and Population Sciences, National Cancer Institute; the Office of Information Services and the Office of Strategic Planning, Centers for Medicare and Medicaid Services; Information Management Services, Inc; and the SEER Program Tumor Registries.

Author Affiliations: Department of Family Medicine, University of South Florida (RGR), and H. Lee Moffitt Cancer Center & Research Institute (RGR, TNC, KJW), Tampa; and Divisions of General Medicine and Primary Care (EPM, LHN, DL) and Hematology and Oncology (RED), Beth Israel Deaconess Medical Center, Department of Medicine, Harvard Medical School (EPM, LHN, RED, LII), and Institute for Health Policy, Division of General Medicine, Massachusetts General Hospital (LII), Boston.

Funding Source: This study was supported by grant R01 CA100029 from the National Cancer Institute.

Author Disclosures: The authors (RGR, TNC, KJW, EPM, LHN, DL, RED, LII) report no relationship or financial interest with any entity that would pose a conflict of interest with the subject matter of this article.

Authorship Information: Concept and design (RGR, TNC, EPM); acquisition of data (TNC, EPM, DL, LII); analysis and interpretation of data (RGR, TNC, KJW, EPM, DL, RED, LII); drafting of the manuscript (RGR, TNC, KJW, RED); critical revision of the manuscript for important intellectual content (RGR, TNC, EPM, RED, LII); statistical analysis (RGR, TNC, KJW, LHN, DL); and obtaining funding (TNC, LII).

Address correspondence to: Richard G. Roetzheim, MD, MSPH, Department of Family Medicine, University of South Florida, 12901 Bruce B. Downs Blvd, MDC 13, Tampa, FL 33612. E-mail: rroetzhe@hsc.usf.edu.1. Centers for Medicare and Medicaid Services Web site. Medicare enrollment: disabled beneficiaries: as of July 2005. http://www.cms.hhs.gov/MedicareEnRpts/Downloads/05Disabled.pdf. Accessed January 21, 2008.

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