A revised version of Diabetes Quality of Life Instrument maintaining domains for satisfaction, impact, and worry

Background: Diabetes quality of life (DQoL) instrument has been widely used to measure quality of life among diabetes patients. This study aimed to develop a revised version of DQoL instrument that incorporated issues of redundancies in the items and strengthen the basis of validity of the instrument.

Methods: This was a cross-sectional study where diabetes patients were recruited from December 1, 2014, until end of March 2015 at a public health clinic in Peninsular Malaysia. A questionnaire that included patients' information and DQoL instrument was distributed to patients. Item selection of DQoL instrument was conducted to screen and finalize the items based on issues of missing values and redundancy. Validity testing was conducted for the revised DQoL instrument based on exploratory factor analysis, confirmatory factor analysis, and Rasch analysis.

Results: The pattern structure matrix yielded three domains similar to the original version with 18 items. The minimum factor loading from the structure matrix was 0.358. The item's and person's reliability was excellent with 0.92 and 0.84 for "satisfaction" domain, 0.98 and 0.60 for "impact" domain, and 0.99 and 0.57 for "worry" domain, respectively. Confirmatory factor analysis has dropped 5 items and the revised version of DQoL contained 13 items. Composite reliability of the revised version was computed for "satisfaction" domain (0.922; 95% CI: 0.909-0.936), "impact" domain (0.781; 95% CI: 0.745-0.818), and "worry" domain (0.794; 95% CI: 0.755-0.832).

Conclusion: A revised version of DQoL that maintains the conceptualization of "satisfaction," "impact," and "worry" with 13 items was successfully developed.