The Development of an Instrument for Assessing the Quality of Life of People with Diabetes

Abstract

The aim of this 2-year research project was to develop an instrument specifically designed to assess the quality of life of people with diabetes. The project was divided into two phases. In the first phase, information from a detailed literature review, from existing quality-of-life instruments, and from interviews with health professionals and people with diabetes was used to develop an initial instrument of 92 items considered to address important aspects of patients' lives. This questionnaire was mailed to 1,000 people with diabetes, and data from the 516 respondents were used to select the most important and useful items. Fifty items were excluded, leaving 42 items that constituted the pilot instrument. During phase 2, the pilot instrument was used to assess the quality of life of 427 diabetic patients who completed the revised questionnaire. After analyzing this data, three additional items were dropped. The final instrument consists of 39 items and covers five dimensions of patients' lives: Energy and Mobility, Diabetes Control, Anxiety and Worry, Social Burden, and Sexual Functioning. The results of validity and reliability tests conducted to date testify to the relevance of the 39-item questionnaire (Diabetes-39) as a valid discriminative instrument, one which shows significant correlations with an overall quality-of-life assessment, the pattern of diabetes severity, and comorbidity. Further, the results from Diabetes-39 correlate well with the results from the established generic quality-of-life instrument, the Medical Outcomes Study 36-Item Short-Form Health Survey. Validation of a quality-of-life instrument, however, is an ongoing process. Further research is required to corroborate these early findings and to ensure that this is an instrument that can capture data of greatest relevance to the diabetic patient and that is responsive to change in quality of life.