It may soon be possible to monitor adherence to antiretroviral therapy or tuberculosis treatment using a simple breath test which has been developed by researchers at the University of Florida and Xhale Inc. It is hoped that the device could be particularly useful in clinical trial settings, and it could also have potential to act as an adjunct or replacement to directly observed therapy, a cornerstone of tuberculosis treatment programmes in many settings.
Antiretroviral therapy for HIV and combination antibiotic treatment for tuberculosis demand high levels of long-term adherence. Poor adherence risks the development of drug-resistant stains of HIV or tuberculosis. Patients who are committed to their therapy are most likely to achieve good levels of adherence, but there can be times when individuals require adherence support. Recall about pill taking is often not a reliable guide.
Clinical trials also require accurate information about adherence. There are a number of methods of encouraging and monitoring adherence, but many tuberculosis treatment programmes and some for HIV (particularly for drug users and other patients with a high risk of poor adherence), as well as many trials, rely upon directly observed therapy.
This can help monitor adherence and increase compliance to treatment regimens, but it is costly, labour intensive, and often unpopular with patients.
Researchers at the University of Florida are therefore hopeful that an instrument they have developed will prove to be an accurate measure of adherence. The device can monitor adherence using a breath test is about the size of a shoe box and is taken home by patients.
It also sounds an alarm when it is time to take medication, and this alarm gets louder if treatment is not taken and will alert a trial (or, potentially, a treatment programme) coordinator to indicate that a patient has missed a dose of medication.
The results of each breath test are recorded by the device and these results can be downloaded onto a memory card or USB stick which can be brought to the clinic for a print out to monitor adherence. The investigators are hopeful that they can reduce the size of the device to fit inside a mobile phone.
To have their adherence monitored by the breath test, patients take a gel capsule that includes a tiny amount of alcohol. When this is metabolised by the stomach and liver, it is converted into a gas that can be measured by the breath test.
A trial involving six healthy volunteers showed that five to ten minutes after swallowing the capsule, a gas was produced that could be monitored using the detector.
“If we have a good way of doing directly observed therapy that’s realistic, instead of having someone come to your house or you going to the clinic every day of your life, the we would know whether these people stopped taking their medication and why. Right now, nobody knows any of that”, said Prof Richard Melker. “The implications of being able to understand what normal human behavior is in a clinical trial and, of course, in the real world, are huge.”