Understanding the utility of MPR
Kevin Cast, vice president, Curascript, explains how medication possession ratios (MPR) can improve forecasting and compliance
By on Aug 3, 2010Kevin Cast, vice president, Curascript, explains how medication possession ratios (MPR) can improve forecasting and compliance
Medication possession ratio (MPR) has become a standard statistical measurement for medication adherence via pharmacy claims.
It can be used to generate significant data about forecasting as well as compliance.
A study initiated by Express Scripts, for example, suggests that financial incentives are not enough to encourage greater compliance with medication for chronic conditions.
Researchers found that decreasing co-payments resulted in only a modest 2.5 percentage point increase in patients' compliance with their medication.
The study focused on examining the effect on medication compliance of a decrease in patient co-payments and demand for statins after the simvastatin patent expiration in 2006.
Statins are prescription drugs used to lower cholesterol and triglycerides.
Patient compliance was measured using MPRthe proportion of days patients took prescribed medications compared to all days after the first prescription was filled.
Compliance was defined as an MPR of 80% or greater.
An almost identical percentage of intervention patients (10.5%) compared with control patients (10.0%) increased their MPR from less than 80% in the pre-period to greater than 80% in the post-period. (For more background on MPR, see Why metrics matter in patient adherence.)
Impacting MPR
Our ability to impact MPR, where appropriate, has increased in many disease states, yet possibly diminished in others, says Kevin Cast, vice president, Curascript.
Older products in open distribution models (i.e., products available at both retail and Specialty outlets) may actually be harder to significantly impact, since the patient has many references upon which to draw.
While this is positive, an SPs ability to clinically interface with a patient at times can be challenging.
Competition exists among primary healthcare professions, the pharmacist, and their friendscall center hubs and even SP compliance programs.
The end result may be a very compliant patient or a very frustrated patient, Cast says.
That said, even in an open distribution program, MPR can vary greatly between retail, specialty, and even within an SP. For products focused on SP [not available at retail], MPR is often easier to impact, as the controls are in place to have the SP work as a key caregiver and thus impact outcomes.
Measuring MPR
MPR is the number of eligible days in the measurement period during which the member possessed any medication in the class.
This number is divided by the number of days in the period.
The key factor, according to Cast, is related to determining an appropriate measurement period.
He says chronic products (MS, HepC) are typically calculated using longer periods (365 days, or at least 180 days), while other products, like oral oncology drugs, will typically use shorter periods.
A study released earlier this year used several statistical methods to assess patient data and examine the relationship between the timing of drug exposure and long-term outcomes.
The study, sponsored by Bayer HealthCare Pharmaceuticals, featured longitudinal data from 372 patients collected 16 years after the start of the registration trial.
The study set out to investigate the relationship between timing of drug initiation and exposure and long-term outcomes.
Drug exposure was measured as MPR, defined as the actual time the patient received therapy divided by the total time possible before a negative outcome was reached (or at data censor).
A statistical method called recursive partitioning was then used to divide treatment groups into high or low exposure and to determine the relationship between length of drug exposure and long-term outcomes.
The use of MPR was said to reduce the bias introduced in long-term trials by the tendency of patients who are doing well on therapy to stay on therapy and for patients who are doing poorly to stop.
MPR and disease states
MPR can vary greatly in any disease state, according to Cast.
An MS self-injectable product is a case in point: retail MPR is 76%; SP core program MPR is 90%; and SP customized P&C program MPR is 94%.
The difference lies in the number of patient contacts.
Retail has the fewest patient contacts; an SP core program may only have a proactive monthly refill reminder; a customized P&C program at an SP has scheduled clinical interventions with each patient who has opted in to the program.
An oral oncology product is another case in point.
MPR for an oral oncology product in open distribution is as follows: Retail MPR is 51.3%; core SP MPR is 60.5%.
Compared to MS, the MPR rates are low, but the therapy is completely different, thus clinically appropriate.
Cast is not sure if MPR is currently used as a forecasting tool for compliance and production.
But if a manufacturing professional can understand MPR and how it affects forecasting and compliance, then this can feed into production schedules and overall profitability.
This may not be as important for a mass-market product, but in specialty markets it is critical to understand. (For more on specialty markets, see Patient compliance and specialty pharmacy products.)
Even a 5% to 15% MPR change can dramatically affect the number of units demanded.
Learn more about MPR at the Pharma Forecasting Excellence Summit in Boston from October 5-6, 2010.