Why Your Medication Adherence Looks Good but Blood Pressure Control Is Flat

The bottom line

• An 80% PDC confirms a member picked up their medication, but it doesn't confirm their blood pressure is controlled.
• "CBP non-compliant" is two groups with different fixes: members with no reading on file (an engagement problem) and members above 140/90 (a behavior problem).
• Consistency decides control, and pharmacy claims can't see it.
• The fix is making daily behavior visible, not collecting one more reading in December.

Most plans read a strong Proportion of Days Covered (PDC) as reassurance. As a cardiologist, I've spent years watching members clear every adherence benchmark and still walk into my office dangerously uncontrolled.

When PDC is within benchmark but Controlling Blood Pressure (CBP) stays flat, the prescription is being filled. The real gap is whether the medication is being taken consistently enough to improve blood pressure. 

High blood pressure is a silent killer. A member can feel fine even as arterial pressure climbs, and a health plan can’t clearly see the risk of unmanaged high blood pressure in a claims file. 

Although health plans are doing plenty to be member-centered, blood pressure can be uncontrolled in the weeks between visits—the critical moment when a member decides whether to measure their blood pressure and take their medication. 

For a health plan, that disconnect has a real cost. A member who looks adherent on paper may be heading toward a preventable stroke, heart attack, or heart failure episode. Those events mean lengthy hospital stays, measurable impact on quality of life, and rising costs the plan absorbs.

Why do members with good PDC still have uncontrolled blood pressure?

Filling a prescription is not the same as taking a blood pressure medication, and taking the medication doesn’t guarantee blood pressure control. 

PDC indicates whether a member had access to their medication, based on pharmacy refill data. It doesn’t prove the medication was taken correctly, consistently, and appropriately dosed, tolerated, or clinically effective for that person.

Blood pressure control is clinically complex and varies from patient to patient. Some members need a dose adjustment or a second medication. Others run into side effects, cost barriers, or daily habits like sleep and diet that pull the number in the wrong direction. For a plan, the point is that none of this shows up in a refill record.

Quality measures aimed at controlling blood pressure can mask two very different problems. 

On the one hand, a member without a recent blood pressure reading is primarily an engagement and measurement problem who needs to be reached out to, have an accurate reading taken, and the data gap closed. 

On the other hand, a member with a documented blood pressure above goal is a clinical problem that usually requires repeated measurements, medication optimization, behavior change, and follow up over time. 

If we treat both groups the same, we may improve documentation but fail to improve blood pressure control. 

What do pharmacy claims miss about how members take their medication?

Claims data can indicate whether a prescription was filled. It can’t tell us what happened after the medication reached the member. 

PDC is useful but incomplete, as it reflects medication availability primarily based on refill history. Additionally, PDC doesn’t prove the medication was taken correctly, tolerated, or sufficient to control blood pressure for that specific patient. 

When pharmacy data suggests good adherence, but blood pressure remains elevated, I think about and try to answer the following three questions:

• First, is the member actually taking the medication consistently? Refill data does not confirm daily use, correct timing, missed doses, or whether the member stopped and restarted therapy.
• Second, is the regimen clinically appropriate for that member? Some patients need dose titration. Others need combination therapy. Some may not respond adequately to a specific medication, or may have side effects that limit consistent use.
• Third, what is happening in the member’s daily life? Blood pressure control is influenced by many factors, including, but not limited to, diet, sleep, medication interactions, and comorbidities such as diabetes and chronic kidney disease. 

The major limitation of claims data is that it can show medication access but not medication behavior, treatment fit, or clinical response. To improve blood pressure control, we need to understand the patient behind the refill.

How does seeing their own blood pressure data change member behavior?

Seeing their own blood pressure data tends to shift member behavior in three ways: 

1. Members start to understand which daily choices affect their numbers
2. They begin to trust the treatment plan
3. They become more likely to stay consistent

One reading in the exam room captures a single moment. Home monitoring works more like a dashboard, giving a clearer view of what is happening between visits.

For many individuals, blood pressure is invisible. They might feel fine even if it's uncontrolled, making it difficult to grasp why daily habits and medications are important. 

Fortunately, home blood pressure data changes that by making members aware of how their choices connect to their numbers, and three things start to shift:

1. They understand what daily behaviors affect their blood pressure and how
2. They begin to trust the treatment plan
3. They’re more likely to stay consistent

A refill reminder can help people remember to take their medication, but home blood pressure feedback goes further. It shows how taking medication regularly and maintaining daily habits can lead to better numbers over time. 

This kind of feedback helps medication feel less like “Take this because your doctor said so” and more like “I can see this is helping me.”

Hello Heart is built to support what happens between visits. Not just whether a prescription was refilled, but whether members understand their numbers, build consistent habits, and stay connected to their cardiovascular health over time.

Does digital blood pressure monitoring improve outcomes?

In peer-reviewed research, including studies of Medicare Advantage members, Hello Heart has been associated with clinically meaningful reductions in blood pressure among members with hypertension:

• One analysis examined nearly 1,000 Medicare Advantage members who used Hello Heart. Members who began with uncontrolled blood pressure lowered their systolic blood pressure by an average of 14.5 mmHg after three months. The percentage with controlled blood pressure rose from 60.3% to 70.7%.
• A peer-reviewed JAHA study followed over 100,000 people with hypertension. Participants who started with systolic blood pressure of 140 mmHg or higher lowered it by an average of 21 mmHg after two years.
• In a JAMA Network Open study of more than 28,000 adults, participants with baseline systolic blood pressure at or above 140 mmHg and 3-year follow-up data experienced an average reduction of ~21 mmHg.

These results highlight the importance of supporting the parts of blood pressure management that claims data often miss, including daily monitoring, medication routines, and sustained healthy habits. That is why Hello Heart developed a suite of tools aimed at supporting medication adherence:

• Hello Meds: Helps members manage complex medication routines, especially when multiple prescriptions, different schedules, or changing instructions make consistency harder.
• Nia: Hello Heart’s AI heart health assistant helps members navigate everyday questions about prescriptions, potential side effects, and possible interactions, with medication content reviewed by Hello Heart’s clinical team.
• Connected Pill Box: Adds practical support to the daily medication routine by helping members stay organized and on track over time.

Together, these tools are designed to support what happens between fills, not just whether a prescription was picked up

What should a health plan do when PDC is high but CBP is flat?

Keep claims data as your benchmark, but stop managing adherence from claims alone, and add visibility into the daily behaviors that influence adherence. When PDC is strong but CBP won't move, the issue is rarely medication access. It's whether the medication is being taken consistently enough to bring the number down, and that happens in the weeks between visits, where claims can't see it.

CBP is triple-weighted for a reason. The plans that treat it as everyday disease management, rather than a fourth-quarter reading scramble, are the ones that protect both their members and their Stars revenue. Get the behavior between visits right, and you can change where a member's heart health is headed before it becomes more costly and harder to undo.

The behavior between visits is where CBP is won or lost. Get your copy of our latest guide to see what missed doses are really costing Medicare Advantage plans, and how to close the gap before it reaches your claims or your Stars rating.

Frequently asked questions

Does an 80% PDC score mean a member's blood pressure is under control? No. PDC only shows a member had medication on hand during the measurement period, based on pharmacy claims. It can't tell you whether they took it consistently, tolerated it, or got the right dose. A member can hit 80% PDC and still sit above 140/90, which is how PDC and CBP end up moving in opposite directions.

Why is CBP harder to move than PDC? PDC reflects a transaction at the pharmacy. CBP reflects what's happening in the body, which only changes through consistent medication-taking, habit change, and follow-up over time. Getting a reading on file can happen fast. Actually bringing the pressure down takes weeks of daily behavior a refill alone can't drive.

What's the difference between filling a prescription and taking a medication? Filling a prescription is a one-time step that tells you the medication made it home. Taking it is a daily habit that has to fit into someone's real life. A pharmacy claim confirms the first. Only seeing the behavior between visits confirms the second, and that's what determines whether blood pressure comes down.

How does Hello Heart help close the gap between adherence and control? Hello Heart is a digital platform that helps members track their blood pressure, understand their readings, and stay consistent between visits. Tools like Hello Meds, the Connected Pill Box, and Nia, its AI heart health assistant, take friction out of daily medication routines and give members the feedback that builds lasting habits, the behavior pharmacy claims can't see.

The gap between a good PDC and a flat CBP is a behavior problem, and behavior is something you can change. If your adherence numbers look strong but your control numbers won't budge, let's look at what's happening between your members' visits.