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J66.0 ICD-10-CM Code: Byssinosis

J66.0 maps to CMS-HCC V28 280. A source-labeled RAF reference is available. Documentation must support MEAT. MEAT criteria · RAF Calculator · HCC Buddy coding tools

ICD-10-CM Code View

HCC Buddy Code Card

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FY 2026 Apr update / Diseases of the respiratory system (J00-J99) / Lung diseases due to external agents (J60-J70)

J66.0

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Byssinosis

A lung disease affecting textile workers exposed to cotton, flax, or hemp dust, causing airway obstruction and breathing difficulties. Symptoms often worsen on the first day back to work after time off.

Buddy the Bee presenting code insight

Buddy Insight

Byssinosis is an important occupational airway disease in textile workers that can progress from reversible Monday morning chest tightness to irreversible chronic obstructive pulmonary disease.

CMS-HCC V28

HCC 280

Code-level coefficient reference

CMS-HCC V24

Historical

Historical

Not used for CY2026 payment

ACA/HHS

HCC 162

Code-level coefficient reference

ESRD/PACE

HCC 112

Code-level coefficient reference

RXHCC

N/A

—

Not mapped

Code Book Path

Official
J66Airway disease due to specific organic dust
J66.0Byssinosis

Inclusion Terms

Official
  • Airway disease due to cotton dust

Excludes 2

Official
  • allergic alveolitis (J67.-)
  • asbestosis (J61)
  • bagassosis (J67.1)
  • farmer's lung (J67.0)
  • hypersensitivity pneumonitis due to organic dust (J67.-)

Related Child Codes

Official
J66.1Flax-dressers' disease
J66.2Cannabinosis
J66.8Airway disease due to other specific organic dusts

Includes

Official

ICD-10-CM does not list Includes notes for J66.0 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for J66.0 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for J66.0 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for J66.0 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for J66.0 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance
Documented occupational exposure to cotton, flax, or hemp dust in textile manufacturing
Clinical staging of byssinosis (Grade 0 through Grade 3) if documented
Characteristic symptom pattern — worsening on first day of work week ('Monday fever')
Pulmonary function test results, particularly pre- and post-shift spirometry

MEAT Support

HCC Buddy guidance
Documented occupational exposure to cotton, flax, or hemp dust in textile manufacturing
Clinical staging of byssinosis (Grade 0 through Grade 3) if documented
Characteristic symptom pattern — worsening on first day of work week ('Monday fever')
Pulmonary function test results, particularly pre- and post-shift spirometry

Audit Caution

HCC Buddy guidance
Miscoding byssinosis as generic occupational asthma when the textile dust exposure is documented
Not documenting the characteristic Monday symptom pattern that distinguishes byssinosis from other occupational lung diseases
Using a more general code (J66.8) when the specific textile dust (cotton, flax, hemp) is documented
Failing to capture progression to chronic irreversible disease, which may warrant additional COPD coding

Common Mistakes

HCC Buddy guidance
J66.1 (Flax-dressers' disease) — specific to flax processing; byssinosis is broader and includes cotton and hemp
J44.1 (Chronic obstructive pulmonary disease with acute exacerbation) — if byssinosis has progressed to COPD, code the COPD; but early byssinosis is distinct
J45.x (Asthma codes) — byssinosis can mimic occupational asthma but has distinct pathophysiology
J66.8 (Airway disease due to other specific organic dusts) — use J66.0 specifically for cotton/flax/hemp textile dust

Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →

Is J66.0 an HCC code?

Yes. J66.0 (Byssinosis) maps to HCC 280, Chronic Obstructive Pulmonary Disease, Interstitial Lung Disorders, and Other Chronic Lung Disorders under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 0.319. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes. It is billable for payment year 2026.

Coder answer: J66.0 is billable and maps to V28 HCC 280, Chronic Obstructive Pulmonary Disease, Interstitial Lung Disorders, and Other Chronic Lung Disorders. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.

Code
J66.0
Description
Byssinosis
HCC (V28)
HCC 280 — Chronic Obstructive Pulmonary Disease, Interstitial Lung Disorders, and Other Chronic Lung Disorders
RAF reference coefficient
0.319
Billable
Yes
Payment year
2026

HCC Category Mapping

V28HCC 280, Chronic Obstructive Pulmonary Disease, Interstitial Lung Disorders, and Other Chronic Lung Disorders
0.319
ESRDHCC 112, Fibrosis of Lung and Other Chronic Lung Disorders
Not separately weighted

These are source-labeled model coefficients, not member totals. A category may still be removed by hierarchy or model cleanup rules. Weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. Actual per-patient RAF contribution depends on member context, hierarchy and cleanup rules, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains available for historical review.

Work J66.0 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT Criteria for J66.0

For J66.0 to 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 J66.0 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

J66.0 is the ICD-10-CM diagnosis code for byssinosis. A lung disease affecting textile workers exposed to cotton, flax, or hemp dust, causing airway obstruction and breathing difficulties. Symptoms often worsen on the first day back to work after time off. J66.0 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, J66.0 maps to Chronic Obstructive Pulmonary Disease, Interstitial Lung Disorders, and Other Chronic Lung Disorders (HCC 280) with a source-labeled community, non-dual, aged reference coefficient of 0.319. No V24 mapping is shown for J66.0; use the applicable model and payment year when reviewing the V28 mapping. 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. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes.

Confirm occupational exposure to cotton, flax, or hemp dust in textile manufacturing or processing. Because J66.0 maps to an HCC category, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) before the diagnosis is used for risk adjustment. 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, source-labeled coefficient references, and MEAT documentation criteria for J66.0 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

  • •Confirm occupational exposure to cotton, flax, or hemp dust in textile manufacturing or processing
  • •Document the characteristic 'Monday fever' pattern if present, as it helps confirm the diagnosis

Clinical Significance

Byssinosis is an important occupational airway disease in textile workers that can progress from reversible Monday morning chest tightness to irreversible chronic obstructive pulmonary disease. It is significant for risk adjustment because it represents a chronic respiratory condition requiring ongoing management, workplace modification counseling, and pulmonary monitoring.

Documentation Requirements

  • ✓Documented occupational exposure to cotton, flax, or hemp dust in textile manufacturing
  • ✓Clinical staging of byssinosis (Grade 0 through Grade 3) if documented
  • ✓Characteristic symptom pattern — worsening on first day of work week ('Monday fever')
  • ✓Pulmonary function test results, particularly pre- and post-shift spirometry
  • ✓Duration of exposure and current work status
  • ✓Treatment plan and any work restrictions

Commonly Confused Codes

  • •J66.1 (Flax-dressers' disease): specific to flax processing; byssinosis is broader and includes cotton and hemp
  • •J44.1 (Chronic obstructive pulmonary disease with acute exacerbation): if byssinosis has progressed to COPD, code the COPD; but early byssinosis is distinct
  • •J45.x (Asthma codes): byssinosis can mimic occupational asthma but has distinct pathophysiology
  • •J66.8 (Airway disease due to other specific organic dusts): use J66.0 specifically for cotton/flax/hemp textile dust

Child Codes

J66.0Byssinosis
HCC 280
J66.1Flax-dressers' disease
HCC 280
J66.2Cannabinosis
HCC 280
J66.8Airway disease due to other specific organic dusts
HCC 280

Code Hierarchy

└J66Airway disease due to specific organic dust└J66.0Byssinosis
└J66.0Byssinosis

Because J66.0 maps to an HCC category, the documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) before the diagnosis is used for risk adjustment.

J66.0 maps to CMS-HCC V28 category 280, Chronic Obstructive Pulmonary Disease, Interstitial Lung Disorders, and Other Chronic Lung Disorders. See the ICD-10 to HCC mapping hub for how the V28 crosswalk works. The mapping identifies a payment HCC category for J66.0. Review its source-labeled HCC coefficient above, check the RAF Calculator with complete member context for CMS-HCC V28 PY2026, and confirm the documentation the chart needs before the code is submitted. HCC Buddy shows no RAF score unless every required source and calculation check passes.

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