Will We Soon See a Low Cost, Small Portable Device for the Therapeutic Monitoring of Lithium? An Implementation Science Investigation

Lithium is a first-line medication for the treatment of bipolar disorder [1], and is included on the World Health Organization list of essential medicines [2]. Despite this, lithium use is declining in North America and Europe [3]. The need to achieve a narrow therapeutic range means that some clinicians and patients opt for other alternatives. Currently, lithium therapeutic drug monitoring (TDM) is a barrier for new patients, increases patient burden, is stigmatizing, and may contribute to treatment noncompliance. In some rural and remote locations, and outside of major urban centres in developing economies, lithium TDM may not be available and this essential medicine cannot be prescribed. Recent technological advances indicate the potential to develop a small portable device for the TDM of lithium [4]. Our research group is currently developing a portable device for the TDM of lithium and has conducted focus groups to understand where this device is needed and what design of device will best serve that need (Figure 1). This project bridges the gap between technological innovations and the consumer by using an implementation science framework to explore barriers and facilitators to adopting this new technology.

The Group 1 video (clinicians) was a 37-min recording, and the Group 2 video was 33 min, Group 3 was 54 min, and Group 4 was 50 min. The codes commonly mentioned were concerned with the design of the novel device, including cost, features, and what information the device would display. Codes referencing toxicity, adverse events, and being outside of the therapeutic window were also commonly mentioned.

A dissenting option was expressed by one of the participants with lived experience, who felt that the current system worked well for her and change was not required. Several participants also mentioned that they would like the device to also measure liver and thyroid function.

A small portable device for the TDM of lithium is expected to be developed in the near future and several separate research groups may be currently working on this tool. Our study has suggested some key design features that may maximize the usefulness of the device, aid in making lithium available to more patients, and make the lived experience of lithium treatment less of a burden. Firstly, everything possible should be done to minimize the cost of the device. Some participants may suggest an increased range of functions for the device, but any impact on cost for these functions may negate their benefit. For example, it is not necessary that the device should also measure liver and thyroid function, as changes in liver and thyroid health occur slowly and an annual test is sufficient, whereas blood lithium levels can change suddenly. Adding these extra functions may be an unnecessary increase in device costs, and receiving results from other variables may be confusing to patients and create more stress by not knowing what to do with that data.

A further design challenge is that the small device will need to meet or exceed the specifications of accuracy, specificity, and sensitivity established by lithium TDM procedures conducted in an accredited laboratory, which is a challenging benchmark to achieve.

From the clinician point of view, other advantages of point of care devices were the opportunities to discuss with patients the reasons for low adherence when there are findings of sub-therapeutic levels, as well as the possibility of making instant decisions when levels are supra-therapeutic.

Further important design features include device robustness and ease of use. A non-invasive device or one that uses a pin-prick to obtain a blood droplet would be preferred. Many people are familiar with small devices used to monitor glucose levels in diabetes, and these devices have set an expectation that something similar should be available for the monitoring of lithium.

A small device for the TDM of lithium is currently in development and will be an important tool for people being treated with lithium. The technology for this device already exists. This device is wanted by patients and clinicians and may improve clinical care and access to lithium treatment. Scientists developing this device need to be aware of which design features will best serve our patients, taking care to avoid developing an expensive device with many features and to instead focus on a low-cost device that will benefit a maximum number of patients.

The study was conducted in accordance with the Declaration of Helsinki and approved by the Human Research Ethics Committee of Barwon Health (approval number 92487, 26 June 2023).

The individual on whom this paper is written consented to participate in the research and has reviewed and approved this manuscript for publication.

The authors declare no conflicts of interest.