Estimating a preference-based single index measuring the quality of life impact of self-management for diabetes

D Rowen, A Labeit, K Stevens, J Elliott, B Mulhern, J Carlton, H Basarir, J Brazier

ABSTRACT

Objective:
Self-management is becoming increasingly important in diabetes, but is neglected in conventional preference-based measures. The objective of this paper is to generate health state utility values for a novel classification system measuring the quality of life impact of self-management for diabetes, that can be used to generate Quality Adjusted Life Years (QALYs).

Methods:
A large online survey was conducted using a discrete choice experiment (DCE) with duration as an additional attribute on members of the UK general population (n=1,493) to elicit values for health (social limitations, mood, vitality, hypoglycaemia) and non-health (stress, hassle, control, support) aspects of self-management in diabetes. The data was modelled using a conditional fixed-effects logit model and utility estimates were anchored on the 1-0 full health-dead scale. Robustness analyses were conducted excluding very quick responses.

Results:
The model produced significant and consistent coefficients, with one logical inconsistency and three insignificant coefficients for the milder levels of some attributes. The anchored utilities range from 1 for the best state to -0.029 for the worst state (meaning worse than dead) defined by the classification system. The results were largely robust.

Conclusion:
Health and self-management can be valued in a single classification system and both can be represented using a single utility value to generate quality adjusted life years (QALYs). The results presented here can be used in economic models of the cost-effectiveness of new interventions to value the day to day impact of the interventions for health and self-management of diabetes.