The impact on utilities of differences in body weight among Canadian patients with type 2 diabetes

Abstract

Objective:

The objective of this study was to estimate utility values for hypothetical health states that describe differences in weight and quality of life associated with type 2 diabetes mellitus (DM) from Canadians with type 2 DM. The impact on utility values was examined separately for participants with a body mass index (BMI) of 18 to less than 25 kg/m² (‘healthy’), 25 to less than 30 (‘overweight’), and 30 or more (‘obese’).

Methods:

The health state descriptions were modified from a published diabetes utility study. Health states included a base-case type 2 DM health state (at participants’ current weight), and six health states where the weight and attendant quality of life impact varied (base case ±3%, ±5%, and ±7% weight). Utilities were elicited using the time trade-off technique. Linear regression modeling was used to estimate the utility increment or decrement associated with a one unit difference in BMI.

Results:

Among 96 participants, the mean age was 55 years and 51% were men. The mean BMI was 32 kg/m² and 84% wanted to lose weight. The mean (SD) utility for the base-case state was 0.911 (0.013). Mean utilities (utility decrements) were 0.907 (−0.004), 0.865 (−0.046) and 0.806 (−0.105) for the health states describing an increased weight of 3%, 5% and 7%, respectively; and 0.923 (+0.012), 0.940 (+0.029) and 0.949 (+0.038) for the health states describing a decreased weight of 3%, 5% and 7%, respectively. For every increase of 1 kg/m² BMI there was an associated decrease in utility of 0.0472 (95% CI: 0.0375, 0.0569) and for every decrease of 1 kg/m² BMI there was an associated increase in utility of 0.0171 (95% CI: 0.0103, 0.0238).

Conclusions:

The preferences of Canadian patients with type 2 DM for diabetes-related health states varied according to the weight, and quality of life impact, associated with that health state. Increased weight had a greater effect on utilities than decreased weight.

Keywords::

• Quality of life
• Time trade-off
• Type 2 diabetes
• Utility
• Weight change

Transparency

Declaration of funding

This study was funded by Bristol-Myers Squibb and AstraZeneca.

Declaration of financial/other relationships

S.L. is, and J.S. was, an employee of Oxford Outcomes Ltd/ICON PLC. A.R.L. is a Senior Scientific Adviser to Oxford Outcomes Ltd/ICON PLC. H.T. was an unpaid consultant to Oxford Outcomes on this project. J.M. is an employee of BMS and has stock options.

CMRO peer reviewers on this manuscript have received an honorarium from CMRO for their review work, but have no other relevant financial relationships to disclose.

Acknowledgments

The authors thank the BMS clinical team including Dr. Nayyar Iqbal and Dr. Afshin Salsali for their clinical input. The authors thank Endocrine Research Inc., specifically Jessica Aydin and Dr. Hugh Tildesley; LMC Endrocrinology Centre, specifically Dr. Ronnie Aronson, Natalie Gibbs and Aryn Gatto; and Angelo Iezzi for assistance with data collection. The authors thank Sarah Goring (Oxford Outcomes) for her statistical analysis support.

Previous presentation: Presented as a poster at the ISPOR 2012 conference. Lane S, Levy A, Sambrook J et al. The impact on utilities of weight loss and weight gain among Canadian patients with type 2 diabetes. International Society for Pharmacoeconomics and Outcomes Research, Washington DC, June 2012.