Summary & Overview
HCPCS Level II G9810: Asthma Controller Medication Adherence (PDC ≥75%)
HCPCS Level II code G9810 denotes that a patient achieved a proportion of days covered (PDC) of at least 75% for their asthma controller medication. This code represents a medication-adherence quality measure tied to chronic asthma management and population health efforts; it is used across outpatient settings to document adherence performance for care teams, payers, and quality programs. Nationally, measuring controller medication adherence is significant because higher adherence is associated with fewer exacerbations, emergency visits, and hospitalizations, and it informs value-based contracts and quality reporting.
Key payers included in this overview are Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find context on clinical meaning and expected use cases, typical sites of service, common modifiers applicable to HCPCS Level II billing, and where this code fits in quality measurement and reporting workflows. The publication also summarizes benchmarking and reporting considerations, coding relationships, and operational implications for ambulatory practices and population-health teams.
This summary is intended for national audiences including clinicians, billing managers, and policy analysts seeking concise guidance on the purpose and relevance of G9810 within asthma care quality measurement and outpatient service delivery.
Billing Code Overview
HCPCS Level II code G9810 indicates that a patient achieved a proportion of days covered (PDC) of at least 75% for their asthma controller medication. This measure captures medication adherence to prescribed long-term controller therapy intended to reduce asthma symptoms and exacerbations.
Service Type: Medication adherence measurement / quality reporting
Typical Site of Service: Outpatient ambulatory care, primary care clinics, specialty pulmonology or allergy clinics, and population health/quality reporting programs
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Clinical & Coding Specifications
Clinical Context
A 34-year-old patient with persistent asthma attends a primary care or pulmonary follow-up visit for routine chronic disease management. The clinician reviews prescription refill history and pharmacy claims to calculate the proportion of days covered (PDC) for the patient’s prescribed asthma controller medication (for example, inhaled corticosteroid or ICS/long-acting beta-agonist combination). During the visit, the clinician documents medication adherence counseling, verifies inhaler technique, and records that the patient achieved a PDC of at least 75% over the measurement period. The clinical workflow includes: medication reconciliation, review of pharmacy fill data (electronic health record and pharmacy benefit manager), calculation or confirmation of PDC, counseling or care plan adjustments as indicated, and coding the encounter with the appropriate HCPCS Level II code G9810 to indicate the adherence threshold was met. Typical sites of service include outpatient primary care offices, pulmonary or allergy specialty clinics, and ambulatory care centers. Common patient scenarios include routine asthma control visits, annual chronic care management encounters, and post-hospitalization follow-up where adherence assessment is part of quality reporting or value-based contract requirements.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
22 | Increased procedural services | Use if additional work beyond usual services was documented for adherence assessment (rare for this non-procedural code). |