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J4A.9 ICD-10-CM Code: Chronic lung allograft dysfunction, unspecified

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FY 2026 Apr update / Diseases of the respiratory system (J00-J99) / Chronic lower respiratory diseases (J40-J4A)

J4A.9

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

Chronic lung allograft dysfunction, unspecified

A general category for long-term dysfunction of a transplanted lung when the specific type of dysfunction is not specified.

Buddy the Bee presenting code insight

Buddy Insight

Chronic lung allograft dysfunction, unspecified is used when a lung transplant recipient develops chronic decline in graft function but the specific phenotype (restrictive vs.

CMS-HCC V28

HCC 276

RAF 0.193

CMS-HCC V24

HCC 186

RAF 0.910

ACA/HHS

0

0

RAF 0

ESRD/PACE

HCC 186

RAF 0.0

RXHCC

HCC 396

RAF 0.0

Code Trumping

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Code Book Path

Official
J4AChronic lung allograft dysfunction
J4A.9Chronic lung allograft dysfunction, unspecified

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for J4A.9 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for J4A.9 in this effective period.

Related Child Codes

Official
J4A.0Restrictive allograft syndrome
J4A.8Other chronic lung allograft dysfunction

Includes

Official

ICD-10-CM does not list Includes notes for J4A.9 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for J4A.9 in this effective period.

Code First

Official
  • , if applicable:
  • heart-lung transplant rejection (T86.31)
  • lung transplant rejection (T86.810)
  • other complications of heart-lung transplant (T86.39)
  • other complications of lung transplant (T86.818)

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for J4A.9 in this effective period.

Code Also

Official
  • , if applicable, bronchiolitis obliterans syndrome (J44.81)

Buddy Documentation Tip

HCC Buddy guidance
Lung transplant history and date of transplantation
Documentation of chronic decline in lung function post-transplant
Pulmonary function testing showing persistent decline from baseline
Documentation that specific CLAD phenotype has not been determined

MEAT Support

HCC Buddy guidance
Lung transplant history and date of transplantation
Documentation of chronic decline in lung function post-transplant
Pulmonary function testing showing persistent decline from baseline
Documentation that specific CLAD phenotype has not been determined

Audit Caution

HCC Buddy guidance
Using unspecified CLAD when the specific phenotype is documented — always code to highest specificity
Not querying the transplant pulmonologist for CLAD phenotyping when possible
Confusing CLAD with acute rejection — these are different clinical entities
Forgetting to code lung transplant status (Z94.2) as an additional diagnosis

Common Mistakes

HCC Buddy guidance
J4A.0 — Restrictive allograft syndrome: preferred when restrictive pattern is documented
J4A.8 — Other chronic lung allograft dysfunction: preferred when a specific non-RAS/BOS type is identified
J44.81 — Bronchiolitis obliterans syndrome: preferred when obstructive pattern is documented
T86.810 — Lung transplant rejection: different concept — acute rejection vs. chronic dysfunction

Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.

Is J4A.9 an HCC code?

Yes. J4A.9 maps to Lung Transplant Status/Complications under the CMS-HCC V28 risk adjustment model (and Major Organ Transplant or Replacement Status under V24).

HCC Category Mapping

V28HCC 276, Lung Transplant Status/Complications
0.193
V24HCC 186, Major Organ Transplant or Replacement Status
0.910
ESRDHCC 186, Major Organ Transplant or Replacement Status
0.000
RxHCCHCC 396, Allograft Complications
0.000

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 J4A.9

For J4A.9to 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 J4A.9 during that encounter, not just copy-forwarded from a problem list.

What This Code Means

J4A.9 is the ICD-10-CM diagnosis code for chronic lung allograft dysfunction, unspecified. A general category for long-term dysfunction of a transplanted lung when the specific type of dysfunction is not specified. J4A.9 sits in the ICD-10-CM chapter for diseases of the respiratory system (j00-j99), within the section covering chronic lower respiratory diseases (j40-j4a).

Under the CMS-HCC V28 risk adjustment model, J4A.9 maps to Lung Transplant Status/Complications (HCC 276) with a community, non-dual, aged base RAF weight of 0.193. Under the older CMS-HCC V24 model, J4A.9 maps to Major Organ Transplant or Replacement Status (HCC 186) with a community, non-dual, aged base RAF weight of 0.910. 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.

Use only when chronic lung allograft dysfunction is documented but the specific type is not identified. Because J4A.9 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 J4A.9 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

  • •Use only when chronic lung allograft dysfunction is documented but the specific type is not identified
  • •Query provider for more specific diagnosis if possible (restrictive vs. obstructive pattern)

Clinical Significance

Chronic lung allograft dysfunction, unspecified is used when a lung transplant recipient develops chronic decline in graft function but the specific phenotype (restrictive vs. obstructive vs. mixed) has not been determined or documented. This code still carries significant risk adjustment weight, reflecting the severity of post-transplant complications.

Documentation Requirements

  • ✓Lung transplant history and date of transplantation
  • ✓Documentation of chronic decline in lung function post-transplant
  • ✓Pulmonary function testing showing persistent decline from baseline
  • ✓Documentation that specific CLAD phenotype has not been determined
  • ✓Current immunosuppression and treatment adjustments
  • ✓Clinical rationale for why the dysfunction type is unspecified

Commonly Confused Codes

  • •J4A.0: Restrictive allograft syndrome: preferred when restrictive pattern is documented
  • •J4A.8: Other chronic lung allograft dysfunction: preferred when a specific non-RAS/BOS type is identified
  • •J44.81: Bronchiolitis obliterans syndrome: preferred when obstructive pattern is documented
  • •T86.810: Lung transplant rejection: different concept: acute rejection vs. chronic dysfunction
  • •Z94.2: Lung transplant status: code additionally

Child Codes

J4A.0Restrictive allograft syndrome
HCC 276
J4A.8Other chronic lung allograft dysfunction
HCC 276
J4A.9Chronic lung allograft dysfunction, unspecified
HCC 276

Code Hierarchy

└J4AChronic lung allograft dysfunction└J4A.9Chronic lung allograft dysfunction, unspecified
└J4A.9Chronic lung allograft dysfunction, unspecified

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