J66.1
BillableFlax-dressers' disease
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is J66.1 an HCC code?
Yes. J66.1 maps to Chronic Obstructive Pulmonary Disease, Interstitial Lung Disorders, and Other Chronic Lung Disorders under the CMS-HCC V28 risk adjustment model (and Fibrosis of Lung and Other Chronic Lung Disorders under V24).
HCC Category Mapping
RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.
MEAT Criteria for J66.1
For J66.1to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically — it has to be re-documented and supported each calendar year.
- MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
- EEvaluate: test results, medication response, or physical findings reviewed by the provider
- AAssess: explicit mention in the assessment or plan with acknowledgment of status
- TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis
Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed J66.1 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
J66.1 is the ICD-10-CM diagnosis code for flax-dressers' disease. A respiratory disease that affects workers who process flax fibers, caused by inhaling flax dust and resulting in airway inflammation and breathing problems. J66.1 sits in the ICD-10-CM chapter for diseases of the respiratory system (j00-j99), within the section covering lung diseases due to external agents (j60-j70).
Under the CMS-HCC V28 risk adjustment model, J66.1 maps to Chronic Obstructive Pulmonary Disease, Interstitial Lung Disorders, and Other Chronic Lung Disorders (HCC 280) with a community, non-dual, aged base RAF weight of 0.319. Under the older CMS-HCC V24 model, J66.1 maps to Fibrosis of Lung and Other Chronic Lung Disorders (HCC 112) with a community, non-dual, aged base RAF weight of 0.219. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.
Verify occupational exposure specifically to flax dressing or processing operations. Because J66.1 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for J66.1 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Verify occupational exposure specifically to flax dressing or processing operations
- •This is a specific occupational disease; ensure documentation clearly indicates flax exposure rather than other textile dusts
Clinical Significance
Flax-dressers' disease is a specific occupational respiratory condition caused by flax fiber processing, representing a form of byssinosis with distinct exposure characteristics. It is relevant for risk adjustment as a chronic occupational lung disease requiring ongoing monitoring, treatment, and potential workplace restrictions.
Documentation Requirements
- ✓Documented occupational exposure specifically to flax dust during dressing or processing operations
- ✓Chest imaging and pulmonary function test results
- ✓Symptom description including temporal pattern related to work exposure
- ✓Duration of occupational exposure to flax processing
- ✓Current respiratory status and functional limitations
- ✓Treatment plan and work modification recommendations
Commonly Confused Codes
- •J66.0 (Byssinosis) — broader category including cotton and hemp; J66.1 is specific to flax processing
- •J66.2 (Cannabinosis) — hemp/cannabis dust, not flax
- •J66.8 (Airway disease due to other specific organic dusts) — residual category; use J66.1 when flax is identified
- •J67.8 (Hypersensitivity pneumonitis due to other organic dusts) — different mechanism than byssinosis-type disease