🛡️ Chronic GVHD Organ Involvement Assessment Simulator

Chronic GVHD — A Systemic, Multi-Organ Syndrome Distinct From Acute GVHD

Chronic graft-versus-host disease typically emerges months to years after allogeneic hematopoietic stem cell transplant, well beyond the classic 100-day window used to define acute GVHD. Where acute GVHD centers on inflammatory damage to three organs — skin, liver, and gastrointestinal tract — chronic GVHD behaves more like an acquired autoimmune disease, with donor-derived immune cells mediating fibrosis, sclerosis, and chronic inflammation across a much wider organ spectrum. This shift in pathophysiology, from acute alloreactive cytotoxicity to chronic dysregulated immune tolerance, is why chronic GVHD assessment requires a fundamentally different organ-scoring framework.

• 8: Organs assessed (NIH) (skin, mouth, eyes, GI, liver, lung, joints, genital)
• >100 days: Typical onset (post-transplant, often 4–24 months)
• 30–70%: Incidence (of long-term allo-HSCT survivors)
• Fibrotic/autoimmune: Pathophysiology (vs. acute cytotoxic inflammation)

Why chronic GVHD needs its own organ framework

Acute GVHD staging (skin rash %BSA, bilirubin level, diarrhea volume) is time-bound and organ-limited because it reflects direct donor T-cell cytotoxic attack on rapidly dividing epithelium in three tissues during early engraftment.

Chronic GVHD instead reflects: • Thymic damage impairing negative selection of autoreactive T-cells • Dysregulated B-cell activation producing autoantibodies • Fibroblast activation and TGF-β driven collagen deposition (sclerosis/fibrosis) • Loss of regulatory T-cell homeostasis

Because these mechanisms operate systemically rather than in a fixed set of rapidly-dividing tissues, chronic GVHD can present in almost any organ system — hence the NIH consensus criteria (2005, revised 2014) formally score 8 organs plus additional "other" manifestations, rather than the 3 organs staged in acute GVHD.

Diagnostic vs. distinctive features: • Diagnostic (sufficient alone): sclerosis, esophageal web, bronchiolitis obliterans, certain nail/oral/genital findings • Distinctive (needs biopsy/confirmation): most skin, mouth, eye, joint, GI, liver, and lung findings

This stage maps out the full breadth of organs the clinician must systematically examine — a far broader canvas than acute GVHD's three-organ checklist.

Sclerotic Skin, Oral Lichenoid Change, and Sicca Syndrome — the Earliest Clues

Skin, mouth, and eye involvement are frequently the first signs clinicians and patients notice, making them the most common entry point to a chronic GVHD diagnosis. Skin manifestations range from superficial lichen planus-like papules to deep sclerotic, scleroderma-like fibrosis that can restrict joint mobility. Oral disease presents as lacy white lichenoid striae, mucosal atrophy, ulcers, and mucoceles. Ocular disease manifests predominantly as dry eye (keratoconjunctivitis sicca) from lacrimal gland damage.

• ~75%: Skin involvement (of chronic GVHD patients, any severity)
• ~50–70%: Oral involvement (lichenoid change most common pattern)
• ~40–60%: Dry eye (sicca) (Schirmer test <5mm diagnostic aid)
• Diagnostic: Sclerotic skin (sufficient alone per NIH criteria)

Scoring skin, mouth, and eye severity

Skin (0–3 score): • 0: no involvement • 1: <18% body surface area (BSA), no sclerotic features • 2: 19–50% BSA or superficial sclerotic features (can pinch skin) • 3: >50% BSA or deep sclerotic features (cannot pinch), impaired mobility, ulceration

Mouth (0–3 score, using modified Oral Mucositis Rating Scale or NIH oral score): • Lichenoid changes, mucoceles, ulcers, mucosal atrophy scored by extent and symptom burden (pain with spicy food, xerostomia)

Eyes (0–3 score): • Based on symptom score (dry eye questionnaire), Schirmer test (tear production), and impact on daily activity • 3: unable to function due to eye symptoms, or requiring punctal plugs/surgery

These three domains are often the earliest and most visible signs, prompting biopsy confirmation and formal NIH organ scoring even before deeper organ involvement (lung, GI, liver) becomes clinically apparent.

Bronchiolitis Obliterans Syndrome — the Most Feared Chronic GVHD Complication

Pulmonary chronic GVHD, principally bronchiolitis obliterans syndrome (BOS), is a fibrotic obliteration of small airways that produces progressive, largely irreversible airflow obstruction. Unlike skin or mouth disease, which often responds to topical or systemic immunosuppression, established BOS causes fixed lung damage. Because early BOS can be asymptomatic, current guidelines recommend routine spirometry surveillance in long-term transplant survivors so treatment can begin before FEV1 decline becomes severe.

• ~6–20%: BOS incidence (of chronic GVHD patients)
• FEV1 <75%: Diagnostic criterion (predicted, with obstructive pattern)
• Largely irreversible: Reversibility (goal is to halt progression, not reverse)
• Reduced: 5-yr survival if severe BOS (major driver of late non-relapse mortality)

Detecting and scoring lung involvement

Lung scoring relies on pulmonary function testing (PFTs) rather than physical exam alone:

NIH lung score (0–3), based on FEV1 % predicted and symptoms: • 0: FEV1 ≥80%, asymptomatic • 1: FEV1 60–79%, mild symptoms • 2: FEV1 40–59%, or moderate symptoms limiting activity • 3: FEV1 <40%, or severe symptoms requiring oxygen

BOS-specific diagnostic criteria (2014 NIH revision): • FEV1/FVC ratio <0.7 • FEV1 <75% predicted with ≥10% decline over 2 years • Air trapping on expiratory CT or RV/TLC >120% • Absence of active pulmonary infection

Why lung involvement is weighted heavily in overall risk: • Once fibrotic airway obliteration is established, it rarely reverses with immunosuppression • Progressive BOS is a leading cause of late non-relapse mortality in long-term survivors • Early detection via surveillance spirometry (every 3 months in the first 2 years) allows treatment initiation while airflow limitation may still be modifiable

Because of this asymmetric risk of irreversible harm, any degree of confirmed lung involvement should escalate global severity classification and prompt pulmonology involvement, even when other organs show only mild disease.

From Organ-Specific Scores to a Global Severity Grade

Each of the eight organs is independently scored 0 (none) to 3 (severe) using organ-specific criteria. These individual scores are then combined — not simply averaged, but weighted by clinical impact, with lung and any single severe-organ score carrying outsized influence — into an overall global severity grade of mild, moderate, or severe. This global grade, formalized by the 2005/2014 NIH Consensus Conference, is the primary variable used to guide treatment intensity and estimate prognosis.

• 8: Organs scored (0–3 scale each, per NIH criteria)
• 3: Global grades (mild / moderate / severe)
• Any organ = 3: Severe-defining criterion (or lung score ≥2)
• 1–2 organs, score ≤1: Mild-defining criterion (no lung or GI involvement)

How the NIH global severity composite is derived

Simplified NIH global severity logic:

Mild: • 1–2 organs involved, each with a score of 1 (no lung involvement)

Moderate: • ≥3 organs involved with a score of 1, OR • any single organ scored 2, OR • lung score of 1

Severe: • any single organ scored 3, OR • lung score of 2 or 3

Why weighting matters: • A patient with mild skin, mild mouth, and mild eye disease (3 organs, all score 1) is classified moderate — breadth of involvement alone escalates severity • A patient with only lung score 2 and no other organ involved is still classified severe — a single organ's irreversibility can dominate the overall picture • This composite structure is why the simulator above weights lung involvement heavily even when few organs are affected

Clinical use of the global score: • Drives first-line vs. second-line systemic therapy decisions • Stratifies patients in clinical trials • Correlates with non-relapse mortality and quality-of-life outcomes • Re-assessed longitudinally at each follow-up to track response to therapy

Coordinating Care Across Specialties for a Multi-Organ Disease

Because chronic GVHD can involve nearly any organ system, effective management increasingly depends on coordinated, multidisciplinary care rather than management by the transplant team alone. Dedicated chronic GVHD clinics bring together hematology/transplant medicine with dermatology, ophthalmology, pulmonology, gastroenterology, oral medicine/dentistry, gynecology, and physical/occupational therapy — each addressing organ-specific disease while the transplant team manages systemic immunosuppression and overall risk-benefit balance.

• 6+: Specialties commonly involved (derm, pulm, ophtho, GI, OB/GYN, PT)
• ≥3 organs: Referral threshold (this model) (triggers multidisciplinary recommendation)
• Improves outcomes: Dedicated clinic model (vs. fragmented single-specialty care)
• Q3 months: Follow-up frequency (typical in first 2 years post-diagnosis)

The multidisciplinary chronic GVHD clinic model

Typical specialty roles in coordinated chronic GVHD care:

• Transplant/hematology: overall immunosuppression strategy, systemic and second-line therapy selection, infection prophylaxis, relapse surveillance • Dermatology: sclerotic skin assessment, photopheresis coordination, topical regimens, skin cancer surveillance (chronic immunosuppression raises risk) • Ophthalmology: sicca management (punctal plugs, scleral lenses), scarring conjunctivitis monitoring • Pulmonology: spirometry surveillance, BOS diagnosis and management, azithromycin/FAM regimens • Gastroenterology: esophageal web/stricture management, nutrition support • Oral medicine/dentistry: lichenoid lesion biopsy, xerostomia management, oral cancer surveillance • Gynecology: genital tract sclerosis, vaginal stenosis prevention and treatment • Physical/occupational therapy: joint and fascial mobility preservation, especially with sclerotic disease

Why this matters for outcomes: • Single-organ specialists may under-recognize that a finding is part of a systemic chronic GVHD process • Coordinated clinics enable synchronized visits, reducing burden on patients already managing a complex chronic illness • Early referral (e.g., to pulmonology at first spirometric decline, or ophthalmology at first sicca symptoms) can preserve organ function before damage becomes irreversible

A widely used practical rule: any patient with three or more organs involved, or any organ scored severe, or any degree of confirmed lung involvement, warrants coordinated multidisciplinary evaluation rather than management by the transplant team in isolation — mirroring the referral logic modeled in this simulator.