Summary & Overview
HCPCS G9811: Asthma Controller Medication Non‑adherence (PDC <75%)
HCPCS Level II code G9811 denotes that a patient did not achieve a proportion of days covered (PDC) of at least 75% for their asthma controller medication. As a performance measure and reporting element, this code is used in quality monitoring and care management workflows to identify patients with suboptimal adherence to maintenance inhaled therapies. Nationally, tracking adherence for asthma controller medications is important because poor controller use is associated with increased exacerbations, avoidable acute care, and higher total cost of care.
Key payers covered in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will gain an overview of the clinical context behind the code, typical sites of service where the measure is captured (outpatient primary care and pharmacy-managed programs), and the role of the code in quality reporting and care management. The publication outlines common modifiers and implementation considerations, summarizes how payers incorporate adherence metrics into value-based contracts and quality programs, and highlights reporting and billing implications for providers and health systems.
What readers will learn: the operational meaning of G9811, where it applies in clinical workflows, how it relates to adherence-focused quality initiatives, and practical considerations for documentation and claims reporting. Data not available in the input.
Billing Code Overview
HCPCS Level II code G9811 indicates that a patient did not achieve a proportion of days covered (PDC) of at least 75% for their asthma controller medication. This measure reflects medication adherence for patients prescribed maintenance therapy for asthma.
Service Type: Medication adherence assessment / quality measure
Typical Site of Service: Outpatient clinic, primary care, or pharmacy-managed care programs
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Clinical & Coding Specifications
Clinical Context
A 14-year-old patient with persistent asthma presents for a routine follow-up at a pediatric primary care clinic after recent emergency department treatment for an exacerbation. The clinic team reviews pharmacy fill history and electronic medication adherence data and determines the patient’s proportion of days covered (PDC) for the prescribed inhaled corticosteroid controller medication is 60%, below the required 75% threshold. The clinician documents counseling on adherence barriers, updates the asthma action plan, and communicates with the family’s community pharmacy to coordinate a 90-day refill with adherence supports. The visit is coded with the quality measure billing code G9811 to indicate the patient did not achieve a PDC ≥75% for their asthma controller medication.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
22 | Increased procedural services | Use when work required to address adherence issues or complex counseling is substantially greater than typical for the visit and documentation supports extra work. |
23 | Unusual anesthesia |