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Interruptions in Medicaid Coverage and Risk for Hospitalization for Ambulatory Care–Sensitive Conditions

Andrew B. Bindman, MD; Arpita Chattopadhyay, PhD; and Glenna M. Auerback, MPH
[+] Article, Author, and Disclosure Information

From San Francisco General Hospital and University of California, San Francisco, San Francisco, California.

Disclaimer: The views presented here are those of the authors and are not necessarily those of The Commonwealth Fund, its director, officers, or staff.

Acknowledgment: The authors thank the California Department of Health Care Services and the California Office of Statewide Health Planning and Development, who provided the linked data set used in this analysis; Professor Eric Vittinghof in the Department of Epidemiology and Biostatistics at the University of California, San Francisco, for his helpful comments in reviewing our analytic plan; and Lauren Davidson for her assistance in preparing this manuscript for publication.

Grant Support: By The Commonwealth Fund, a national, private foundation that supports independent research on health and social issues.

Potential Financial Conflicts of Interest: None disclosed.

Reproducible Research Statement:Study protocol and statistical code: Available from Dr. Bindman (e-mail, abindman@medsfgh.ucsf.edu). Data set: Available by request from the California Department of Health Care Services.

Corresponding Author: Andrew B. Bindman, MD, Building 10, Ward 13, San Francisco General Hospital, 1001 Potrero Avenue, San Francisco, CA 94110; e-mail, abindman@medsfgh.ucsf.edu.

Current Author Addresses: Drs. Bindman and Chattopadhyay: San Francisco General Hospital, Building 10, Ward 13, 1001 Potrero Avenue, San Francisco, CA 94110.

Ms. Auerback: University of California, San Francisco, 1600 Divisadero Street, MZ Bldg B B-718, San Francisco, CA 94143-1297.

Author Contributions: Conception and design: A.B. Bindman, A. Chattopadhyay.

Analysis and interpretation of the data: A.B. Bindman, A. Chattopadhyay.

Drafting of the article: A.B. Bindman, A. Chattopadhyay, G.M. Auerback.

Critical revision of the article for important intellectual content: A.B. Bindman, A. Chattopadhyay.

Final approval of the article: A.B. Bindman, A. Chattopadhyay, G.M. Auerback.

Statistical expertise: A. Chattopadhyay.

Obtaining of funding: A.B. Bindman.

Administrative, technical, or logistic support: A. Chattopadhyay, G.M. Auerback.

Collection and assembly of data: A. Chattopadhyay, G.M. Auerback.

Ann Intern Med. 2008;149(12):854-860. doi:10.7326/0003-4819-149-12-200812160-00004
Text Size: A A A

Background: Many low-income U.S. citizens experience interruptions in health insurance coverage.

Objective: To determine the rate of hospitalization for ambulatory care–sensitive conditions among Medicaid beneficiaries with interruptions in coverage.

Design: Retrospective cohort study.

Setting: California Medicaid population.

Patients: 4 735 797 adults in California age 18 to 64 years who received a minimum of 1 month of Medicaid coverage between 1998 to 2002.

Measurement: Time to hospitalization for an ambulatory care–sensitive condition.

Results: Sixty-two percent of Medicaid beneficiaries experienced at least 1 interruption in coverage during the study period. The 3 most common ambulatory care–sensitive conditions resulting in a hospitalization were heart failure, diabetes, and chronic obstructive pulmonary disease. Interruptions in coverage were associated with a higher risk for hospitalization for an ambulatory care–sensitive condition (adjusted hazard ratio, 3.66 [95% CI, 3.59 to 3.72]; P < 0.001). In subgroup analyses, the association between interrupted coverage and hospitalization was stronger for beneficiaries eligible through the Temporary Aid to Needy Families program (adjusted hazard ratio, 8.56 [CI, 8.06 to 9.08]) than for beneficiaries eligible through the Supplemental Security Income program (adjusted hazard ratio, 1.72 [CI, 1.67 to 1.76]), who typically retain Medicare coverage even when their Medicaid coverage is interrupted.

Limitation: The study lacked information on why interruptions occurred and whether beneficiaries with interruptions transitioned to other insurance coverage.

Conclusion: Interruptions in Medicaid coverage are associated with a higher rate of hospitalization for ambulatory care–sensitive conditions. Policies that reduce the frequency of interruptions in Medicaid coverage might prevent some of the health events that trigger hospitalization and high-cost health care spending.


Grahic Jump Location
Appendix Figure.
Diagrammatic representation of repeatable events with time-varying covariates.

The exposure time starts on the first month of eligibility or at the beginning of the study period (1 January 1998) for beneficiaries who were already enrolled in the program. An exposure period ends with a hospitalization for an ambulatory care–sensitive condition, at the end of the study period (31 December 2002), with a person turning 65 years of age, or with an interruption in coverage. A new exposure time begins after an interruption in Medicaid eligibility or hospitalization for an ambulatory care–sensitive condition.

Grahic Jump Location
Grahic Jump Location
Probability of hospitalization for an ambulatory care–sensitive condition over time, by Medicaid coverage status, 1998 to 2002.

Hazard ratio2, 7.99 (95% CI, 7.88–8.11).

Grahic Jump Location




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