Objective: The objective of this study was to develop a valid and reliable health-related quality of life (HRQOL) questionnaire for use in multinational clinical trials of patients with type I and type II diabetes.
Methods: Through patient focus groups and expert clinician panels in the United States (US) and France, relevant HRQOL domains for patients with type I and type II diabetes were identified. A draft questionnaire was developed by including validated, widely used generic and diabetes-specific domains and by developing original questions as required. A pilot study (n = 123) was conducted to evaluate the psychometric properties of the draft questionnaire with revisions being subsequently made. Data collected from two multinational clinical trials of patients with type I and type II diabetes were used to further validate and enhance the questionnaire (DQLCTQ).
Results: A total of 942 patients were recruited in the clinical trials from Canada, France, Germany, and the United States. The mean age was 33.8 years for patients with type I diabetes (n = 468) and 58.2 years for patients with type II diabetes (n = 474). The mean HbAlc level at baseline was 8.6. The revised version of the questionnaire (DQLCTQ-R) contains a total of 57 questions comprising 8 generic and disease-specific domains, as follows: Physical Function; Energy/Fatigue; Health Distress; Mental Health; Satisfaction; Treatment Satisfaction; Treatment Flexibility; and Frequency of Symptoms. Intraclass correlation coefficients range from 0.74 to 0.90 and Cronbach's alphas range from 0.77 to 0.90. With very few exceptions, all eight domains were able to discriminate between type I and type II diabetes, tight and poor metabolic control, male and female, and good and poor self perceived control of diabetes. Four domains (Treatment Satisfaction, Health/Distress, Mental Health, and Satisfaction) were responsive to clinical change in metabolic control.
Conclusion: The DQLCTQ-R is a reliable, valid, and comprehensive HRQOL instrument. It is suitable in multinational clinical trials to evaluate new or alternative treatments for patients with type I and type II diabetes.