Proteus Digital Health, the ingestible sensor company that raised $45 million in May -- the largest funding raise in digital health this year so far -- has published the results of a small clinical trial in a peer-reviewed journal. The study of 27 adults with bipolar disorder or schizophrenia found that the addition of an ingestible sensor to their regiment led to 67 percent of patients taking their medication within 2 hours of their designated time. The mean adherence rate was 74 percent.

The study, which was published recently in the Journal of Clinical Psychiatry as an online exclusive, was conducted over four weeks in May 2011. Along with Proteus, Massachusetts General Hospital and the Zucker Hillside Hospital were collaborators.

The main purpose of the study was to test the accuracy of Proteus's digital health feedback system, which includes the ingestible sensor pill, a patch and a mobile app. Compared to tracking adherence by observation, the ingestible sensors tracked adherence with 94 percent accuracy.

The feedback system also tracked other statistics about the users including activity and sleep. Activity among the participants ranged from 847 to 15,930 steps per day and subjects slept between 3.2 and 15.2 hours per day. The system also tracked sleep disruption -- the amount patients wake up during the night -- a number that could be very useful in assessing the effectiveness of medication for a condition like schizophrenia, according to the researchers. Mean sleep disruption varied from 5 percent to 43 percent over the course of the study period.

The study affirmed that Proteus's FDA-cleared ingestible pill had few-to-no adverse affects on participants. No subjects had a worsened psychosis because of the pills. Five experienced mild skin irritation due to the patch that transmits the data from the sensor to collection devices, but none dropped out of the study because of it.

Finally, study participants were asked some questions about the digital health feedback system. Nineteen of the 27 participants (70 percent) found the system easy to understand and 24 (89 percent) thought it could be useful to them. Twenty-one (78 percent) expressed interest in having the system send reminders to them via text message if they forgot to take their medication.