If your pharmacy boss won’t stop talking about “adherence,” there’s a reason. Medicare’s Star Ratings are built to reward plans that keep members taking certain chronic meds on time. Plans push pharmacy benefit managers (PBMs). PBMs push pharmacies. The result: your day-to-day refill work can push real dollars—up or down—through your store’s reimbursement. Here’s how the system works, why adherence dominates the conversation, and what you can do that actually moves the needle.
What Star Ratings Are—and Who Cares
Medicare Star Ratings score health and drug plans on quality and outcomes. For drug coverage (Part D), the measures include adherence to three chronic medication classes and a handful of safety and medication-related measures. The ratings are public and affect plan enrollment, marketing, and—in Medicare Advantage with drug coverage (MA-PD)—bonus payments.
Why plans obsess: A 4-star or higher MA-PD rating earns a quality bonus payment (QBP). That bonus can be worth roughly 5% of the plan’s local benchmark. Multiply that by tens of thousands of members and 12 months, and you get real money that funds richer benefits and lower premiums. Better benefits draw more members, which brings even more revenue the next year.
Why pharmacies feel it: Plans can’t fix adherence alone. They rely on PBMs and pharmacy networks to move refills. PBMs respond by tying pharmacy reimbursement to “performance” on adherence and related measures. Miss targets and you pay fees or lose preferred network status. Hit targets and you keep more reimbursement, sometimes with bonuses. That’s why your boss keeps asking about PDC.
Why Adherence Is the Boss’s Obsession
Not all measures are created equal. CMS “weights” measures by importance. The three Part D adherence measures—statins, diabetes meds, and RAS antagonists (ACEIs/ARBs)—are treated as intermediate outcome measures. They carry a heavy weight compared with simple process checks.
What that means in practice:
- There are usually a dozen or so Part D measures. Each adherence measure is triple-weighted.
- Together, the three adherence measures often account for roughly one-third of a plan’s Part D summary rating.
- They’re also the measures a retail pharmacy can influence today—by filling meds on time—without waiting on a doctor visit or a lab result.
Adherence matters clinically too. Better statin and antihypertensive adherence lowers heart attacks and strokes. Better diabetes adherence reduces complications and hospitalizations. CMS weights adherence because it predicts outcomes that drive total Medicare costs. That’s the “why” behind the rulebook—and the pressure.
How Adherence Is Actually Measured
Star Ratings use Proportion of Days Covered (PDC) for each drug class:
- Statins (hyperlipidemia)
- RAS antagonists (ACE inhibitors and ARBs, for hypertension)
- Diabetes medications (oral/non-insulin classes such as metformin, sulfonylureas, DPP-4s, SGLT2s, TZDs, and combos; insulin is not included)
PDC basics:
- Denominator: Calendar days the patient is eligible and “on therapy” during the year.
- Numerator: Days the patient actually has medication on hand (based on paid claims) for that class.
- Threshold: A patient counts as adherent if PDC is ≥80%.
- Therapeutic class logic: Switching within the class (e.g., lisinopril to losartan) keeps coverage continuous. Gaps, short fills, and late refills drive PDC down.
Example: A patient is on a statin all year (365 days). They receive 4 x 90-day refills on time = 360 days covered. PDC = 360/365 = 98.6% (adherent). If one refill is 20 days late, coverage drops to about 340 days. PDC ≈ 93% (still adherent). Two late refills could push PDC below 80%—now they count against the plan’s measure.
Important nuance: Stockpiling doesn’t help because PDC caps at 100%. A 180-day fill does not give credit beyond the days covered. Missing days early in the year are hard to recover from because you can’t “overfill” to make up lost time.
Timing matters: The Star Rating you see in a given year reflects performance from two years earlier (e.g., 2025 stars largely use 2023 data). That lag is why plans and PBMs push adherence every single month; today’s refills are next year’s score.
The Money Trail: From CMS to Plan to PBM to Pharmacy
Follow the dollars to understand the pressure:
- CMS → Plan: Higher Star Ratings bring MA-PD quality bonuses and better marketing power. A 5% bonus on a $1,000 monthly benchmark equals ~$50 per member per month. For 50,000 members, that’s ~$30 million a year.
- Plan → PBM: Plans contract with PBMs to improve Part D performance. Contracts include adherence targets and penalties if targets are missed.
- PBM → Pharmacy: PBMs build “performance networks.” If your pharmacy hits adherence benchmarks, you keep base reimbursement or earn a bonus. Miss benchmarks, and you pay a performance fee per claim or lose preferred cost-sharing status in that network next year.
What changed in 2024: CMS required nearly all pharmacy price concessions to be reflected at the point of sale. The old retroactive “DIR fee surprise” largely went away, but PBMs still use performance adjustments, holdbacks, and reconciliation. The mechanism changed, not the incentive. Your fill behavior still affects your net pay.
How Star Ratings Control Your Pharmacy’s Reimbursement
PBMs translate plan targets into pharmacy-level scorecards, often via platforms like EQuIPP. Typical components:
- Adherence tiers: Your store’s statin, RAS, and diabetes PDC rates put you in a tier. Higher tiers mean fewer fees or a bonus; lower tiers mean per-claim fees.
- Preferred network status: Plans steer members to “preferred” pharmacies. Preferred status depends partly on performance. Lose it, and you lose traffic and better cost-sharing placement.
- Reconciliation math: You may see a base reimbursement close to acquisition cost and a later adjustment. For example, a $75 claim could carry a $2.50 performance fee if your tier is low. Across thousands of claims, small fees become big dollars.
Concrete scenario: Suppose your pharmacy fills 4,000 Part D claims monthly. A $1.50 per-claim performance adjustment equals $6,000/month. Improving adherence enough to move up one tier could cut that in half or flip it to a small bonus. That’s why your boss wants 90-days and med sync on every eligible chronic med.
What Actually Moves Adherence in a Pharmacy
Adherence is about removing refill friction and fixing claim issues quickly. Tactics that reliably work:
- Enroll eligible patients in med sync for the three classes. Synchronization reduces late refills by batching and scheduling. Target patients on 2+ chronic meds first.
- Convert to 90-day supplies when allowed. Fewer trips mean fewer chances to miss. Use clear scripts: “Because this is a year-round medicine, a 90-day supply helps you stay on track and saves you time.”
- Use opt-in auto-refill with reminders. CMS allows automatic refills with patient consent. Confirm pickup method and contact preferences and reschedule actively if they don’t pick up.
- Fix days’ supply coding. Wrong days’ supply can sink PDC (e.g., coding 30 when the sig is BID for 15 days). Train staff to check SIG-to-day-supply math on chronic meds.
- Proactively resolve rejections. PA denials, NDC not covered, or step therapy can create multi-week gaps. Call prescribers same day with a covered alternative.
- Bridge short gaps. If a prior authorization is pending or the prescriber is unreachable, ask about a documented short “loaner” fill when your policy allows. Every day counts toward PDC.
- Delivery and curbside options. Transportation is a top barrier. Offer delivery windows aligned with med sync cycles.
- Adherence packaging (multi-dose blister packs) helps patients with complex regimens. Start with high-risk, high-ROI classes (statin + RAS + diabetes).
- Targeted conversations: Have a simple script for the three classes: what the med prevents, why daily use matters, and what to do when side effects show up. The “why” increases refill motivation.
- Use your performance dashboard weekly. Pull the “at-risk” list (patients hovering near 80% PDC) and call them first. Late-December rescues rarely work; monthly maintenance does.
Pitfalls and Myths That Kill PDC
- “Early fills will fix low PDC.” No. PDC caps at 100%. You can’t prepay future days beyond actual coverage.
- “One December refill erases a bad year.” It doesn’t. Missing 60 days in spring can’t be undone with one on-time fill in winter.
- “Switching meds restarts PDC.” Switching within class (ACEI → ARB) maintains coverage. Switching out of class (statin → ezetimibe alone) ends eligible days and can hurt unless clinically documented.
- “Partial fills are harmless.” Short fills reduce covered days if not completed quickly. Out-of-stock on chronic meds is a PDC leak.
- “Mail order will fix everything.” Mail can help some patients, but missed deliveries or address problems create big gaps. Local delivery with confirmed handoff can outperform.
- “Auto-refill without consent is fine.” It isn’t. Confirm consent and refresh it periodically. Unwanted refills that sit on the shelf do not improve PDC.
How Cut Points and “Guardrails” Affect You
Plans are graded against national cut points that shift each year. CMS now limits how fast those cut points can move to avoid big swings. You can’t control cut points, but you can control your store’s consistency. Consistent high PDC keeps you above the moving target, regardless of small year-to-year shifts.
What to Tell Your Team
- Our work on three classes—statins, RAS, diabetes—drives plan Stars and our pay.
- Goal: PDC ≥80% for as many patients as possible. Med sync + 90-day + quick problem solving gets us there.
- Every late refill is a revenue leak. Five phone calls today can prevent dozens of dollars in performance fees next month.
- Check the dashboard weekly. Rescue the “near 80%” patients before they fall off.
The Bottom Line
Star Ratings don’t measure your pharmacy directly, but they absolutely shape your reimbursement. Adherence dominates because it is heavily weighted, clinically meaningful, and something pharmacies can change today. When you turn late refills into on-time 90-day fills, you aren’t just helping patients—you’re protecting your store from performance fees, keeping preferred status, and supporting the plan’s Star Rating that funds better benefits. That’s why your boss is obsessed with adherence—and why your daily workflow should be, too.
I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.
Mail- Sachin@pharmacyfreak.com