Access to the Indian Health Service Care System Is Not Associated with Early Enrollment in Medicaid for American Indian and Alaska Natives with Cancer

Health insurance is one of the most important factors influencing access to healthcare in the United States (1). However, only 41% of American Indians and Alaskan Natives (AIAN) have private health insurance (2). AIANs who are federally recognized are eligible for primary healthcare from Indian Health Service, Tribal, and Urban facilities of the Indian Health Service Care System (IHSCS). However, insurance coverage may be needed for specialty care, like cancer treatment. For many AIANs diagnosed with cancer, obtaining publicly sponsored Medicaid insurance is their only way to cover treatment-related expenses and gain access to care (3).

We hypothesized that the IHSCS, through its delivery of primary care and cancer screening, may play an important role in supporting rapid Medicaid enrollment for uninsured AIANs. No study has yet investigated time to Medicaid enrollment specifically for AIANs with cancer. This is important because delays in enrollment may create delays in access to lifesaving treatments. Accordingly, the objective of this study was to determine the association between IHSCS eligibility and timely Medicaid enrollment (enrollment ≤1 month following diagnosis) in AIANs with cancer.

Washington, Oregon, and California State Cancer Registries are members of the North American Association of Central Cancer Registries (NAACCR; ref. 4). These registries collect data on incident cancers among their residents and conduct regular links to registries of tribal health programs and the IHSCS (5). We used these NAACCR sites to identify AIAN individuals with and without IHSCS eligibility diagnosed with their first invasive cancer between January 1, 2001 and December 31, 2007 who were 21 years or older and had one of the following cancers: breast, cervical, colorectal, lung, ovarian, prostate, or stomach. These data were linked to Medicaid enrollment records, and cases were excluded if they: (i) were diagnosed at death or (ii) had a Medicaid enrollment date that was >60 days before diagnosis or >365 days after diagnosis.

Approval for the study was granted by the Institutional Review Boards of the Fred Hutchinson Cancer Research Center (Seattle, WA), Oregon Department of Public Health (Portland, OR), Oregon Department of Health Services (Portland, OR), California Rural Indian Health Board, Inc. (Sacramento, CA), Northwest Portland Area Indian Health Board (Portland, OR), California Committee for the Protection of Human Subjects (Sacramento, CA), and the California Department of Health Care Services (Sacramento, CA).

The number of days between diagnosis and Medicaid enrollment was calculated by comparing the Medicaid date of enrollment and cancer registry date of diagnosis. Some Medicaid programs allow individuals with cancer to enroll retrospectively and record their enrollment date up to 2 months before their application. To account for this, we considered patients with dates of enrollment between 2 months before diagnosis and 1 month after diagnosis to be enrolled ≤1 month following their cancer diagnosis. Patients enrolled >1 month but ≤6 months after diagnosis and those enrolled >6 months but ≤12 months after diagnosis were also categorized into two separate groups.

We used a multivariable polytomous logistic regression model to estimate odds ratios (OR) and 95% confidence intervals (CI) for moderately late Medicaid enrollment (>1 to ≤6 months after cancer diagnosis) and for very late Medicaid enrollment (>6 to 12 months after cancer diagnosis) relative to early Medicaid enrollment (≤1 month after cancer diagnosis), comparing those without IHSCS eligibility to those with IHSCS eligibility at diagnosis. Regression models included the following covariates, selected a priori: gender, anatomic site of cancer, age at diagnosis, stage, year of diagnosis, state of residency, and type of residence.

Using Power (version 3.0, 1999, National Cancer Institute, Bethesda, MD), we calculated that, given our sample size and α = 0.05, our study had 80% power to detect an OR ≥ 1.8.

Among AIANs who enrolled in Medicaid during the year following their cancer diagnosis, those without IHSCS eligibility were more likely than those with IHSCS eligibility to have distant stage cancer, reside in California, and live in an urban area (Table 1). Approximately, 32% of AIANs enrolled in Medicaid >1 month following diagnosis (Table 2). Comparing those without IHSCS eligibility to those with IHSCS eligibility at diagnosis, the adjusted OR for the association between moderately late Medicaid enrollment and no IHSCS eligibility was 1.10 (CI, 0.62–1.95) and for very late Medicaid enrollment, OR was 1.14 (CI, 0.54–2.43).

Our results suggest that nearly one third of AIANs with cancer who enroll in Medicaid wait for more than 1 month before enrolling, and that IHSCS eligibility does not impact the likelihood of delay. Because many AIANs rely on Medicaid as a primary insurer for their cancer treatment expenses (3), initiation of treatment may be delayed if time to enrollment in Medicaid is delayed. Delays in access to timely treatment, perhaps exacerbated by delays in Medicaid enrollment, may explain in part why AIANs have among the lowest 5-year survival rates of any racial group (6–8). Therefore, additional research is needed to identify factors that lead to delays in Medicaid enrollment and to develop interventions that can increase timely access to care in AIAN populations.

No potential conflicts of interest were disclosed.

The contents of this article are the sole responsibility of the authors and do not necessarily represent the official views of the National Cancer Institute (NCI) or the Indian Health Service Care System.

Conception and design: A.N. Burnett-Hartman, M.E. Bensink, C. Korenbrot, S.D. Ramsey

Development of methodology: M.E. Bensink, K. Berry, C. Korenbrot, S.D. Ramsey

Acquisition of data (provided animals, acquired and managed patients, provided facilities, etc.): M.E. Bensink, C. Korenbrot, S.D. Ramsey

Analysis and interpretation of data (e.g., statistical analysis, biostatistics, computational analysis): A.N. Burnett-Hartman, M.E. Bensink, K. Berry, D.G. Mummy, C. Korenbrot, S.D. Ramsey

Writing, review, and/or revision of the manuscript: A.N. Burnett-Hartman, M.E. Bensink, D.G. Mummy, V. Warren-Mears, C. Korenbrot, S.D. Ramsey

Administrative, technical, or material support (i.e., reporting or organizing data, constructing databases): D.G. Mummy, C. Korenbrot, S.D. Ramsey

Study supervision: C. Korenbrot, S.D. Ramsey

This research was supported by grants from the NIH NCI (R01CA125231 to S.D. Ramsey) and the National Center for Advancing Translational Sciences (KL2 TR000421 to A.N. Burnett-Hartman).