PATHWAYS Epidemiological Study



PATHWAYS is a two-tiered research study of patients with diabetes and depression, begun in 2001 by researchers at the University of Washington in collaboration with researchers at the Center for Health Studies at Group Health Cooperative in Seattle.

Epidemiological Study: The first aim of the study was to gather epidemiological data on approximately 5,000 patients with diabetes in nine primary care clinics. The purpose of this epidemiological study was to learn about the prevalence of depression in a population-based sample of patients with diabetes as well as to examine the impact of depression on: symptom burden, self-management (diet, exercise, taking medication), functioning, blood glucose levels, health and cardiac risk behaviors such as smoking and sedentary lifestyle, mortality and medical costs for patients with diabetes.


Intervention Study: The second aim of the PATHWAYS study was to enroll approximately 330 patients with diabetes and depression in a randomized trial comparing two different approaches to treating depression. Patients were randomized into groups receiving either collaborative care (a model in which a team approach is taken in treating the patient’s depression) or usual primary care. Researchers were then able to study which model had a greater positive impact on both depression, diabetes, and medical costs in these patients.

Research Methods: A 20-page survey was mailed to patients with diabetes from nine Group Health primary care clinics. The PHQ-9 was used to diagnose depression, and automated diagnostic, pharmacy, and laboratory data were used to measure diabetes treatment intensity, blood glucose levels, and diabetes complications. Data gathered from this survey was used in the epidemiological arm of the study. Eligible participants completing the survey were randomized into groups for the intervention.

PHQ-9 Depression Tool PHQ-9 Depression Tool
Diabetes Complications Measure Diabetes Complications Measure
Epidemiological Study Epidemiological Study
Intervention Study Intervention Study


Research Findings: The epidemiological data collected in the PATHWAYS study revealed the following key results:

  • The prevalence of Major Depression was 12% among the patients with diabetes
  • An additional 8.5% of patients met criteria for Minor Depression
  • Diabetic patients with minor and major depression had a more severe symptom burden, greater disability, a higher number of diabetes complications, increased mortality and higher medical costs than non-depressed patients
  • Depression was associated with lower adherence to medications and lower levels of
    self-care. This included higher rates of obesity and smoking, and less exercise and healthy eating
Slides of Research Findings Research Findings
Annotated Bibliography Annotated Bibliography: Epidemiological Study
Annotated Bibliography Annotated Bibliography: Intervention

1. Katon et al, Behavioral and clinical factors associated with depression among individuals with diabetes, Diabetes Care 27: 914-920, 2004