The Effect of Comorbid Illness and Functional Status on the Expected Benefits of Intensive Glucose Control in Older Patients with Type 2 Diabetes: A Decision Analysis

The Effect of Comorbid Illness and Functional Status on the Expected Benefits of Intensive Glucose Control in Older Patients with Type 2 Diabetes: A Decision Analysis

Elbert S. Huang, MD, MPH;
Qi Zhang, PhD;
Niren Gandra, BA;
Marshall H. Chin, MD, MPH; and
David O. Meltzer, MD, PhD

From the University of Chicago, Chicago, Illinois; Old Dominion University, Norfolk, Virginia; and Boston University School of Medicine, Boston, Massachusetts.

Abstract

Background: Physicians are uncertain about when to pursue intensive glucose control among older patients with diabetes.

Objective: To assess the effect of comorbid illnesses and functional status, mediated through background mortality, on the expected benefits of intensive glucose control.

Design: Decision analysis.

Data Sources: Major clinical studies in diabetes and geriatrics.

Target Population: Patients 60 to 80 years of age who have type 2 diabetes and varied life expectancies estimated from a mortality index that was validated at the population level.

Time Horizon: Patient lifetime.

Perspective: Health care system.

Intervention: Intensive glucose control (hemoglobin A_1c [HbA_1c] level of 7.0) versus moderate glucose control (HbA_1c level of 7.9).

Outcome Measures: Lifetime differences in incidence of complications and average quality-adjusted days.

Results of Base-Case Analysis: Healthy older patients of different age groups had expected benefits of intensive glucose control ranging from 51 to 116 quality-adjusted days. Within each age group, the expected benefits of intensive control steadily declined as the level of comorbid illness and functional impairment increased (mortality index score, 1 to 26 points). For patients 60 to 64 years of age with new-onset diabetes, the benefits declined from 106 days at baseline good health (life expectancy, 14.6 years) to 44 days with 3 additional index points (life expectancy, 9.7 years) and 8 days with 7 additional index points (life expectancy, 4.8 years). A similar decline in benefits occurred among patients with prolonged duration of diabetes.

Results of Sensitivity Analysis: With alternative model assumptions (such as Framingham models), expected benefits of intensive control declined as mortality index scores increased.

Limitations: Diabetes clinical trial data were lacking for frail, older patients. The mortality index was not validated for use in predicting individual-level life expectancies. Adverse effects of intensive control were not taken into account.

Conclusion: Among older diabetic patients, the presence of multiple comorbid illnesses or functional impairments is a more important predictor of limited life expectancy and diminishing expected benefits of intensive glucose control than is age alone.

Article and Author Information

Acknowledgment: The authors thank Priya John, MPH, for her assistance in preparing this manuscript.
Grant Support: By a National Institute on Aging Career Development Award (K23 AG021963 [Dr. Huang]), a National Institute of Diabetes and Digestive and Kidney Diseases Diabetes Research and Training Center (P60 DK20595 [Drs. Huang, Zhang, Chin, and Meltzer]), the Chicago Center of Excellence in Health Promotion Economics (Drs. Huang, Chin, and Meltzer), a National Institute of Child Health and Human Development Small Grant (R03 HD056073 [Dr. Zhang]), and a National Institute of Diabetes and Digestive and Kidney Diseases Midcareer Investigator Award in Patient-Oriented Research (K24 DK071933 [Dr. Chin]).
Potential Financial Conflicts of Interest: None disclosed.
Reproducible Research Statement:Study protocol: Not available. Statistical code: Readers with questions about the simulation model used in this analysis may contact Dr. Huang (ehuang{at}medicine.bsd.uchicago.edu). The model is not available without establishing written agreements with the authors. Data set: Not available.
Requests for Single Reprints: Elbert S. Huang, MD, MPH, The University of Chicago, 5841 South Maryland Avenue, MC 2007, Chicago, IL 60637; e-mail, ehuang{at}medicine.bsd.uchicago.edu.
Current Author Addresses: Drs. Huang, Chin, and Meltzer: The University of Chicago, 5841 South Maryland Avenue, MC 2007, Chicago, IL 60637.
Dr. Zhang: 3138 Health Sciences Building, School of Community and Environmental Health, Old Dominion University, Norfolk, VA 23529.
Mr. Gandra: 10 Buick Street, Box 8298, Boston, MA 02215.
Author Contributions: Conception and design: E.S. Huang, Q. Zhang, M.H. Chin, D.O. Meltzer.
Analysis and interpretation of the data: E.S. Huang, Q. Zhang, N. Gandra, D.O. Meltzer.
Drafting of the article: E.S. Huang.
Critical revision of the article for important intellectual content: E.S. Huang, Q. Zhang, M.H. Chin, D.O. Meltzer.
Final approval of the article: E.S. Huang, Q. Zhang, N. Gandra, M.H. Chin, D.O. Meltzer.
Provision of study materials or patients: D.O. Meltzer.
Statistical expertise: E.S. Huang, Q. Zhang.
Obtaining of funding: E.S. Huang.
Administrative, technical, or logistic support: N. Gandra.