Patients’ Preferences for Insulin Injection Devices

Abstract

In this issue, Pohlmeier et al report on a device assessment study in insulin-naïve patients with type 2 diabetes, to investigate the ease of use/learning and patient preference of the new prefilled U300 insulin glargine injection pen. Human factor studies are required by regulatory agencies and should ensure the proper use of the device in the context of the provided instructions. The patients found the device easy to learn/use and had a stable treatment satisfaction despite introduction of injection treatment. The lack of a control arm, the short duration, and the small sample size make it difficult to translate these results into clinical practice. It is encouraging to know, however, that the new pen is accepted by one of the intended patient populations.

Performance of human factor studies has become a regulatory requirement for medical technology products for patient use, such as blood glucose meters or insulin injection devices. When using medical devices for administration of insulin or other drugs into the subcutaneous tissue, it is important to understand use-related hazards. It is therefore necessary to have an accurate and complete understanding of how a device will be used. Understanding and optimizing how people interact with technology is the subject of human factors engineering and usability engineering. These considerations are important to the development of medical devices and include three major components of the device-user system: (1) device users, (2) device use environments, and (3) device user interfaces. ¹ The purpose of human factor studies is to identify issues that may not be detected through application of analytical techniques, for example, if aspects of the device are inconsistent with user expectations or intuition, if the demands associated with device use exceed the user’s capabilities, if the device can be used in unexpected ways, and so on. Another purpose is to assess the clarity and effectiveness of all labeling (eg, instructions for use, other documentation, packaging, etc) and to determine the level and nature of training that will be necessary for proper device use.

During the development of insulin injection pens, the above-mentioned requirements usually lead so called “ease of use/ease of learning” studies, where the necessity of training activities for proper device use are being investigated. Another aspect of human-factor studies is to explore patient preference and the treatment satisfaction that is associated with the use of the new device. A first study of this kind has been performed and published in 1989 comparing insulin injections with vial and syringe vs the NovoPen I device. ² Many more published reports have followed since this time. The results of a recent investigation with an adapted version of the well-known SoloSTAR device, which is to be used with the U300 formulation of insulin glargine, and which was performed with forty insulin-naïve type 2 diabetes over a period of four weeks, are reported by Pohlmeier et al in this issue of the journal. ³

The authors conclude that the new pen is a reliable device that is easy to use (and easy to learn to use) and provides patients with high treatment satisfaction despite introduction of injection treatment. These results are in line with prior publications regarding the dosing accuracy of this device and its usability in comparison to other commercialized disposable insulin pen injection devices,^4,5 previously published by the same group. The study has several limitations, which are correctly mentioned and discussed in the discussions section, including but not limited to the small samples size, the open-label nature of the trial, and the short study duration. Not mentioned limitations, however, are the lack of a comparator group, which would allow for understanding the ranking of the obtained results in comparison to other devices, and the limited possibility to associate any of the observed and reported results regarding glycemic control to the device functionality and acceptance.

When interpreting such results, it is in any case important to understand that this particular type of studies is subject to a major publication bias. First, manufacturers have it in their own control to publish the results of these human factor assessment studies or not. Second, the design of the study is frequently specifically set-up to favor a particular design feature of the investigative new device. It is important to understand that there is yet no standardization of the questionnaires and other assessment tools used in these trials. Usually, there is a final and conclusive ultimate question, such as “which device do you prefer for use in your treatment.” By careful selection of the prior questions, it is possible to induce a kind of “question-guided” bias of the patients to finally prefer a specific device. The outcome of the published data is usually favorable for the manufacturer of the new investigational device or the sponsor of the study. It is therefore possible that similar studies published about comparisons of the same competitive devices but by different sponsors can come to quite opposite conclusions.^6-10 In order to avoid this situation, the manufacturers often perform comparisons amongst devices of their own product portfolio^11,12 or against vial and syringe^13-15 so that no dispute about competitive product comparisons can come up in the scientific community.

From a patient perspective, factors driving patient preference include ease of use, ease of learning, pen functionality (redialing option, injection force requirements, injection automation, time requirements, dosing accuracy, etc), pen appearance (size, shape, color, material, etc), and pen features enabling use by patients with impaired dexterity. ¹¹ From a health care provider perspective, this is completed by information about ease and time requirements of teaching and any other associated instructions. This part may become more complicated, when future pens will be Bluetooth enabled and will become an integrated part of online treatment diary systems.

For future human factor studies, it would be desirable to have standardized designs, defined patient populations, standardized assessment tools, questionnaires, and metrics, for example, for patient preference, in order to be able to compare results between different human factor studies and to draw conclusions between different device developments, which is not possible to date.

It is in any case encouraging to know however from this study report that the prefilled pen that comes along with the U300 glargine formulation is accepted and efficiently used by one of the intended patient populations.