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Improved measures of adherence: How HealthBeacon’s ICMS™ enhances confidence in medication adherence rates

Medication Event Monitoring Systems Provide Improved Measures of Adherence: How HealthBeacon’s Injection Care Management System™ can Enhance Confidence in Adherence Rates. September 2020.

By Dr.Sharifah Sarhan, MB, BCh, BAO, Medical Science Liaison Officer & Sean Glynn, MSc, Director of HEOR

The ability to provide patients and their healthcare practitioners with individualised and real-time medication adherence data is a powerful tool in the management of chronic disease, and a key offering in our Injection Care Management System™ (ICMS). In this piece, HealthBeacon explores the different methods traditionally used to calculate medication adherence and how we offer an innovative approach for a more reliable measure.

Accurately and reliably measuring medication adherence can be challenging. There are both direct and indirect measures which can offer us insight into patient adherence rates. Direct measures, including measuring serum drug levels can be invasive and time-consuming. Therefore, it is largely indirect measures which are employed, the most common of which are Medication Possession Ratios (MPRs) and Proportion of Days Covered (PDC). These indirect measures can be calculated easily from pharmacy-based data; however, this convenience comes at the cost of reliability.


What are MPR and PDC?

Medication Possession Ratio (MPR) has been used for several decades as an indirect measure of medication adherence. MPR is a calculation of the number of days of supplied medication divided by the number of days between the first and last prescription refill. A fundamental flaw with MPR is that it can overestimate adherence; if a patient gets their prescription filled early, the number of days of supplied medication can be greater than the number of days in the time period, and hence can result in a score of greater than 100%.
The MPR’s successor is Proportion of Days Covered (PDC). PDC addresses the MPR calculation shortfall by considering the number of days supplied divided by the number of days in the refill period. In this way, the ratio can never be greater than 1, making PDC more accurate. Both MPR and PDC can be relatively easily calculated from inexpensive data acquired from pharmacy refill records, however they are not without their shortcomings.

How accurate are MPR and PDC as measures of adherence?

When it comes to mail-order and specialty pharmacy data, MPR and PDC are more reflections of an organization’s quality of shipping and logistics, than true measures of patient medication adherence. They inform us that medications have been shipped and are in the patient’s possession, but not whether they have been taken by patients or not. As such, they become financial measures passed back to manufacturers and lose their clinical focus. Further, they over-estimate adherence as they do not account for doses not taken and/or doses not taken on time. A leading Paediatric Endocrinologist told us of a patient under his care who was coming off injectable medication after almost twelve years of treatment. The patient’s mother was delighted her son was due to finish his treatment and enquired as to what she should do with the unused injections she had at home. These however were doses that the child had been scheduled to take during his treatment period. Indeed, although MPR and PDC can give us an indication of a patient’s access to and possession of medication, they do not provide us with insight into the medication taking behaviours of patients.


HealthBeacon’s Measure of Adherence

At HealthBeacon, our measure of adherence is based off real-time data, customized to both individual patients and the pharmacokinetics of each product. The HealthBeacon Smart Sharps Bin records (to the minute) each time a patient drops a used syringe/needle/auto-injector into the unit. Each drop is then reconciled with the patient’s customized dosing schedule. To calculate a Personal Adherence Score, the number of drops made into the Smart Sharps Bin within the product-specific window of time is divided by the number of scheduled drops. Using this method, HealthBeacon can provide a more clinically meaningful adherence score for any injectable medication, ranging from daily growth hormone to a bi-weekly anti-TNF inhibitor.

As part of HealthBeacon’s ICMS™, patients can self-report doses taken at times when they may not have access to their Smart Sharps Bin, such as when on vacation. Patients can self-report by calling or emailing our Customer Care Team or through the HealthBeacon Companion App. This allows us to minimize any under-estimation that may occur if patients were otherwise unable to log their medication as taken.


Clinicians and researches are recognizing devices that are classified as Medication Event Monitoring Systems (MEMS) as the new “gold standard” for tracking medication adherence, due to greater reliability and validity of the data they produce. MEMS have the capability to capture dose-to-dose medication taking behaviour and to get that data out of the patient’s home. The HealthBeacon Smart Sharps Bin does this by simply recording the disposal of the waste, requiring no additional work by the patient. Therefore, this real-time data capture, with analysis tied to product specifics and injection frequencies, provides far more accurate and insightful adherence data than traditional pharmacy refill records.


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