Q&A: Wireless sensor can track scratching for pruritus management

Itch can have a substantial impact on quality of life, but is difficult to quantify, according to a research article in Science Advances.

As a result, it is hard to track how well treatments work in patients with conditions such as atopic dermatitis. Therefore, researchers at Northwestern University developed the ADvanced Acousto-Mechanic (ADAM) sensor, a wireless device that measures itch objectively by capturing motion and other low-frequency signals along with acousto-mechanic, high-frequency signals. It is the first sensor that can capture scratching related to finger, wrist and elbow motion, according to a press release.

Researchers validated the device in a cohort of 11 participants aged 4 to 24 years who had moderate to severe atopic dermatitis over 46 sleep-nights, for a total of 378.4 hours. For each participant, clinical research personnel completed an eczema area and severity index and investigator’s global assessment. Participants received training on the ADAM sensor and set up infrared video cameras at home. The researchers then compared video data with ADAM data. The results showed that the ADAM sensor performed with 84.3% sensitivity and 99.3% specificity compared with visual observation, according to the researchers.

To learn more about the sensor, Healio Primary Care spoke with study coauthor Shuai Xu, MD, MSc, an assistant professor of dermatology and pediatrics at the Feinberg School of Medicine, assistant professor of biomedical engineering at the McCormick School of Engineering and Applied Science, and medical director of the Querrey Simpson Institute of Bioelectronics at Northwestern University.

Healio Primary Care: What prompted you to develop this technology?

Xu: As a dermatologist, I have seen firsthand how devastating itch can be on the quality of life for my patients. Itch is not limited to just skin disease; it’s a highly debilitating symptom that affects up to one in five adults worldwide. Nearly every patient with atopic dermatitis (or eczema) suffers from itch; it is the hallmark symptom of the disease.

One of the biggest problems we face in the management of itch is measuring it. If you can't measure it, you can't manage it. Thus, the ability to objectively quantify itch by accurately measuring scratching behavior (a reflex for itch) helps all patients suffering from itch. With an objective tool, we can help drugs get approved by showing objectively their benefit. It can help individuals track their own treatment response at home. In addition, it may help identify subtle worsening of disease by increased scratching that you as a patient may not even notice. This may allow for early intervention before a full-on flare happens.

Healio Primary Care: How does it work?

Xu: The sensor is really unique — it looks like a [bandage]. The soft, flexible, wireless and miniaturized nature of the sensor allows it to couple gently to the dorsum of the hand on even a child. The sensor measures both motion and acousto-mechanic signatures of scratching (both the “motion” of scratching AND the “sound” of scratching). By placing it on the hand, it can capture fine finger scratching as well as wrist bound scratching. By having both motion and acousto-mechanic data, the sensor is not tricked by hand waving or even scratching in the air — something that wristwatch systems struggle with. There is a mobile application that allows data transfer from the sensor, and real time streaming of scratching. Everything gets sent to the cloud so it's ready for home use and clinical trial use.

Healio Primary Care: Which patients would benefit most from using the device?

Xu: When you think of itch and human disease, it’s usually atopic dermatitis or eczema. The hallmark of atopic dermatitis is itch. On average, children with eczema lose one night of sleep per week from the itching. One of the biggest challenges we face is how do we know how well we are managing the condition if we can't quantify itch? This is particularly hard in children where surveys and scales are not as trustworthy. It is an exciting time for atopic dermatitis in that there are many new drugs in development. Thus, this sensor can play a key role in helping objectively measure the benefit (or lack thereof) of new drugs in clinical trials.

As another point, eczema is not just itchy skin. It is a devastating condition that dramatically reduces a patient's quality of life. Many people don’t know this, but people with eczema are 44% more likely to have suicidal thoughts, and 36% are more likely to attempt suicide compared to the general population.

But beyond atopic dermatitis, there are many human diseases that lead to itch. Chronic itch is a major problem, particularly in older adults. Both kidney disease and liver disease can lead to debilitating itch. This sensor could be helpful across any condition that leads to itch.

Healio Primary Care: What are the costs associated with it? Will it be affordable to middle- and lower-income patients?

Xu: At scale, these devices will cost less than a FitBit with the goal of being available to all patients no matter their socioeconomic background.

Healio Primary Care: When do you predict this technology will be widely available to patients?

Xu: Later this year. We’re already a part of the FDA’s Drug Discovery Tool program. We’re also seeking FDA clearance later this year as well for this.

Healio Primary Care: What is your take-home message for primary care providers?

Xu: There are many exciting things happening in digital health; this is an example of a sensor that measures an important symptom that is often ignored, undertreated and underrecognized. In many ways, itch is just as important to manage as pain. They are two of the core nociceptive outputs of the human nervous symptoms. This tool can be wielded much like blood sugar in diabetes or blood pressure in hypertension to track treatment response, disease control and the potential need to change therapeutic strategies, all in a wearable format.

References:

• Northwestern University. How much does it itch? Accessed May 10, 2020. Available at: https://www.eurekalert.org/pub_releases/2021-04/nu-hmd042521.php.
• Xu S, et al. Sci Adv. 2021;doi:10.1126/sciadv.abf9405.