Preferences of Patients with Diabetes Mellitus for Inhaled versus Injectable Insulin Regimens
In clinical trials, patients have expressed greater satisfaction with inhaled human insulin (EXUBERA®, Pfizer) than with injectable insulin. No studies to date have attempted to quantify the strength of preferences for these alternative routes of administration.
To elicit health state preference values from people with diabetes mellitus for treatment with inhaled human insulin compared with injectable insulin.
A patient preference study.
Written descriptions were developed for five clinical scenarios: two for type 1 diabetes and three for type 2 diabetes. Each scenario required adjustment or initiation of insulin treatment because of poor glycaemic control. Two alternative insulin regimens were described for each scenario: injectable-only or inhaled human insulin to replace or reduce the number of daily injections. Equal efficacy was assumed within each of these scenario pairs.
A total of 344 UK adults (66% male), 132 (mean age 49 years) with type 1 diabetes and 212 (mean age 63 years) with type 2 diabetes, rated scenario pairs corresponding to their own type of diabetes and rated their own health by time trade-off (TTO), by correspondence with EQ-5D health descriptions and on the EQ-5D visual analogue scale. Respondents stated their preference for, or indifference between, the injection-only or inhalation variant comprising each scenario pair. TTO utilities and EQ-5D utilities by UK community tariff were compared within each scenario pair, for the total sample rating, each scenario pair, and by subgroups of stated preference for each variant.
A majority, ranging from 63% to 81% across the scenarios, preferred inhalation. Mean differences in TTO scores were 0.074, 0.076, 0.088, 0.053 and 0.043 for the five scenarios, respectively (p < 0.005 for all). Mean EQ-5D differences were 0.043, 0.029, 0.037, 0.020 and 0.021 for the five scenarios, respectively (p < 0.05 for scenarios 1 and 3), driven mainly by differences on the pain/discomfort dimension of the EQ-5D. Differences in favour of inhalation among those preferring inhalation, were greater than differences in favour of injections among those preferring injections. Mean self-rated health was similar between respondents with type 1 and type 2 diabetes, at 0.83 (TTO) and 0.75 (EQ-5D). The TTO was more sensitive than EQ-5D. Self-rated health by EQ-5D compared closely with reported values from the UK Prospective Diabetes Study (UKPDS).
This study highlights the utility differences that people with diabetes perceive between the prospect of inhaled and injected routes of insulin administration, even under the assumption of no difference in efficacy. These differences are magnified when the comparison in utility scores is between the majority who prefer the inhaled route and the minority who prefer the injectable route.
KeywordsHuman Insulin Utility Score Injectable Insulin Treatment Scenario Perfect Health
J. Chancellor, S. Aballéa and S. Cure are employees of i3 Innovus (formerly Innovus); A. Lawrence and R. Sheldon are Directors of Accent. N. Marchant is an employee of Pfizer and J. Plun-Favreau was an employee of Pfizer when the study was conducted. i3 Innovus and Accent conducted this research under a research grant from Pfizer and Sanofi-Aventis. The sponsors were involved in defining the research questions, piloting of the questionnaire and reviewing the manuscript, as reflected in the authorship. However, the sponsors had no role in the main study implementation, analysis or reporting of results.
J. Chancellor directed the study, contributed to its design, developed the scenarios and drafted the manuscript. S. Aballéa designed the chained time trade-off, wrote the statistical analysis plan and supervized the analysis. A. Lawrence developed the questionnaires, and managed recruitment and fieldwork. R. Sheldon contributed to the study design, developed the fieldwork plan and directed the development of the computer-assisted personal interview procedures and the database creation and validation. S. Cure performed the statistical analyses and prepared the statistical reports. J. Plun-Favreau helped define the study objectives, recruited respondents for the pre-pilot exercise and facilitated recruitment for the main study. N. Marchant helped define the study objectives and clinical indications. All co-authors read, commented on and approved the final manuscript.
The authors would like to acknowledge the expert technical advice on preference measurement provided by Professor John Brazier of the University of Sheffield and Professor Martin Buxton of Brunel University, England.
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