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

Ann Intern Med. 2008 Jul 1;149(1):11-9. doi: 10.7326/0003-4819-149-1-200807010-00005.

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 A1c [HbA1c] level of 7.0) versus moderate glucose control (HbA1c 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.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Aged
  • Aged, 80 and over
  • Blood Glucose / metabolism*
  • Decision Support Techniques
  • Diabetes Complications* / mortality
  • Diabetes Mellitus, Type 2 / blood*
  • Diabetes Mellitus, Type 2 / drug therapy*
  • Diabetes Mellitus, Type 2 / mortality
  • Female
  • Glycated Hemoglobin A / metabolism
  • Humans
  • Life Expectancy
  • Male
  • Middle Aged
  • Quality of Life
  • Sensitivity and Specificity

Substances

  • Blood Glucose
  • Glycated Hemoglobin A