GCA-VISION: Transparent Ocular Ischemia Risk-Context Stratification in Suspected Giant Cell Arteritis

Abstract

Visual ischemic complications of giant cell arteritis (GCA) are among the most time-sensitive emergencies in rheumatology and ophthalmology because permanent vision loss can occur before diagnostic certainty is complete. GCA-VISION is an executable dependency-free Python skill that converts this bedside problem into a transparent 0-100 ocular ischemia risk-context score. The model explicitly weights age context, new temporal headache, scalp tenderness, jaw claudication, temporal artery abnormality, polymyalgia rheumatica overlap, constitutional symptoms, inflammatory markers (ESR, CRP, thrombocytosis), and visual symptoms including transient visual loss, diplopia, persistent visual loss, and anterior ischemic optic neuropathy-pattern concern. It outputs a concern band, ocular red-flag status, ischemic-emergency status, component breakdown, and treatment-oriented recommendation statement. In demonstration scenarios, the tool separates a low-specificity older-headache presentation from a critical amaurosis-fugax pattern and a second critical scenario with established visual loss and optic-ischemic concern. GCA-VISION is deliberately heuristic, auditable, and reviewer-runnable. It is not a diagnostic model and does not replace urgent glucocorticoid-capable evaluation, ophthalmology assessment, vascular imaging, or biopsy, but it addresses a real clinical problem: deciding when suspected GCA should be treated as a same-day vision-protection emergency.

Clinical methodology

Problem being solved

Many suspected GCA encounters begin in outpatient settings where the clinician must judge urgency before complete workup returns. The major failure mode is not lack of knowledge that visual symptoms are dangerous; it is underestimating how dangerous the total pattern has become when age, cranial symptoms, inflammatory markers, and transient visual symptoms accumulate together.

Design principles

1. Older-age context matters. GCA is uncommon below age 50.
2. Specific cranial ischemic clues matter. Jaw claudication and temporal artery abnormalities receive strong weights.
3. Inflammatory context matters but is supportive. ESR, CRP, and thrombocytosis strengthen concern without replacing bedside symptoms.
4. Visual symptoms dominate urgency. Amaurosis fugax, diplopia, persistent visual loss, and AION-pattern concern strongly lower the threshold for emergency treatment.
5. Transparency matters. All feature weights are explicit and reviewer-runnable.

Output interpretation

GCA-VISION stratifies concern into:

• low ocular ischemia concern
• intermediate ocular ischemia concern
• high ocular ischemia concern
• very high ocular ischemia concern
• critical ocular ischemia concern

A separate emergency flag escalates persistent visual loss, AION-pattern concern, or transient visual loss within a strongly suggestive cranial GCA context.

Why this score exists

In suspected GCA, treatment delay can cost vision. A transparent escalation tool helps clinicians defend urgent action before confirmatory testing is finalized.

Demo output

Running python3 skills/gca-vision/gca_vision.py prints three scenarios:

1. older adult with nonspecific headache only → low concern
2. jaw claudication + PMR + temporal artery abnormality + amaurosis fugax → critical concern
3. persistent visual loss with AION-pattern context → critical concern

Limitations

• Not externally validated.
• Intended for transparent decision support, not autonomous diagnosis.
• Does not distinguish arteritic from non-arteritic optic neuropathy by itself.
• Does not replace urgent treatment, ophthalmology review, vascular imaging, or biopsy.
• Intended for adult suspected GCA only.

Authors

Dr. Erick Zamora-Tehozol (ORCID: 0000-0002-7888-3961), DNAI, RheumaAI

References

1. Maz M, Chung SA, Abril A, et al. 2021 American College of Rheumatology/Vasculitis Foundation Guideline for the Management of Giant Cell Arteritis and Takayasu Arteritis. Arthritis Rheumatol. 2021;73(8):1349-1365. DOI: 10.1002/art.41774
2. Hayreh SS, Podhajsky PA, Zimmerman B. Visual loss in giant cell arteritis. JAMA. 1998;280(4):385-391. DOI: 10.1001/jama.280.4.385
3. Liozon E, et al. The association of vascular risk factors with visual loss in giant cell arteritis. Rheumatology (Oxford). 2016. DOI: 10.1093/rheumatology/kew397
4. Czihal M, et al. Characteristics of patients with giant cell arteritis who experience visual symptoms. Rheumatol Int. 2019;39(12):2095-2102. DOI: 10.1007/s00296-019-04422-5

Executable Python Code

#!/usr/bin/env python3
"""
GCA-VISION: transparent ocular ischemia risk-context stratification in suspected
or established giant cell arteritis.

Authors: Dr. Erick Zamora-Tehozol (ORCID: 0000-0002-7888-3961), DNAI, RheumaAI
License: MIT
"""
from __future__ import annotations

from dataclasses import dataclass, asdict
from typing import Any, Dict, List, Optional


@dataclass
class GCAInput:
    label: str
    age: int
    new_temporal_headache: bool = False
    scalp_tenderness: bool = False
    jaw_claudication: bool = False
    temporal_artery_abnormality: bool = False
    polymyalgia_rheumatica: bool = False
    constitutional_symptoms: bool = False
    esr_mm_hr: Optional[int] = None
    crp_mg_l: Optional[float] = None
    platelets_k: Optional[int] = None
    transient_visual_loss: bool = False
    diplopia: bool = False
    persistent_visual_loss: bool = False
    anterior_ischemic_optic_neuropathy: bool = False


def clamp(x: float, lo: float = 0.0, hi: float = 100.0) -> float:
    return max(lo, min(hi, x))


def score_gca_vision(p: GCAInput) -> Dict[str, Any]:
    components: Dict[str, float] = {}
    components['age_ge_50'] = 8 if p.age >= 50 else 0
    components['new_temporal_headache'] = 8 if p.new_temporal_headache else 0
    components['scalp_tenderness'] = 6 if p.scalp_tenderness else 0
    components['jaw_claudication'] = 14 if p.jaw_claudication else 0
    components['temporal_artery_abnormality'] = 12 if p.temporal_artery_abnormality else 0
    components['pmr'] = 5 if p.polymyalgia_rheumatica else 0
    components['constitutional'] = 3 if p.constitutional_symptoms else 0

    if p.esr_mm_hr is not None:
        components['esr'] = 8 if p.esr_mm_hr >= 70 else 5 if p.esr_mm_hr >= 50 else 2 if p.esr_mm_hr >= 30 else 0
    else:
        components['esr'] = 0
    if p.crp_mg_l is not None:
        components['crp'] = 7 if p.crp_mg_l >= 30 else 4 if p.crp_mg_l >= 10 else 0
    else:
        components['crp'] = 0
    if p.platelets_k is not None:
        components['platelets'] = 6 if p.platelets_k >= 450 else 3 if p.platelets_k >= 350 else 0
    else:
        components['platelets'] = 0

    components['transient_visual_loss'] = 18 if p.transient_visual_loss else 0
    components['diplopia'] = 10 if p.diplopia else 0
    components['persistent_visual_loss'] = 24 if p.persistent_visual_loss else 0
    components['aion'] = 28 if p.anterior_ischemic_optic_neuropathy else 0

    raw = sum(components.values())
    score = round(clamp(raw), 1)

    ocular_red_flag = p.transient_visual_loss or p.diplopia or p.persistent_visual_loss or p.anterior_ischemic_optic_neuropathy
    ischemic_emergency = p.persistent_visual_loss or p.anterior_ischemic_optic_neuropathy or (p.transient_visual_loss and p.jaw_claudication and p.age >= 50)

    if ischemic_emergency:
        band = 'CRITICAL ocular ischemia concern'
    elif score >= 60:
        band = 'VERY HIGH ocular ischemia concern'
    elif score >= 40:
        band = 'HIGH ocular ischemia concern'
    elif score >= 20:
        band = 'INTERMEDIATE ocular ischemia concern'
    else:
        band = 'LOW ocular ischemia concern'

    if ischemic_emergency:
        recommendation = 'Treat as possible GCA-related ocular ischemic emergency now: immediate glucocorticoid-capable evaluation, urgent ophthalmology access, and confirmatory vascular workup should not delay vision-protection treatment.'
    elif ocular_red_flag and score >= 40:
        recommendation = 'Visual symptoms in a GCA-pattern context warrant same-day escalation, expedited inflammatory markers review, and urgent temporal-artery/vascular assessment.'
    elif score >= 40:
        recommendation = 'High-risk GCA pattern. Urgent specialist assessment and fast-track diagnostic workup are appropriate.'
    elif score >= 20:
        recommendation = 'Intermediate-risk GCA pattern. Reassess symptoms, inflammatory markers, and temporal artery findings promptly.'
    else:
        recommendation = 'No strong ocular ischemic GCA pattern detected from the supplied features.'

    notes: List[str] = []
    if p.jaw_claudication:
        notes.append('Jaw claudication is one of the more specific cranial ischemic clues for GCA')
    if p.transient_visual_loss or p.persistent_visual_loss:
        notes.append('Visual symptoms sharply lower the threshold for emergency treatment')
    if p.temporal_artery_abnormality:
        notes.append('Abnormal temporal artery exam strengthens pretest concern')
    if p.polymyalgia_rheumatica:
        notes.append('PMR overlap increases background suspicion for GCA')

    return {
        'label': p.label,
        'score': score,
        'band': band,
        'ischemic_emergency': ischemic_emergency,
        'ocular_red_flag': ocular_red_flag,
        'components': components,
        'notes': notes,
        'recommendation': recommendation,
        'input': asdict(p),
    }


def demo() -> List[Dict[str, Any]]:
    return [
        score_gca_vision(GCAInput(
            label='Older adult with nonspecific headache but no cranial ischemic features',
            age=58,
            new_temporal_headache=True,
            esr_mm_hr=28,
            crp_mg_l=6,
        )),
        score_gca_vision(GCAInput(
            label='Suspected cranial GCA with jaw claudication, PMR, and amaurosis fugax',
            age=74,
            new_temporal_headache=True,
            scalp_tenderness=True,
            jaw_claudication=True,
            temporal_artery_abnormality=True,
            polymyalgia_rheumatica=True,
            constitutional_symptoms=True,
            esr_mm_hr=88,
            crp_mg_l=46,
            platelets_k=498,
            transient_visual_loss=True,
        )),
        score_gca_vision(GCAInput(
            label='Established visual loss with AION-pattern concern in giant cell arteritis context',
            age=79,
            new_temporal_headache=True,
            scalp_tenderness=True,
            jaw_claudication=True,
            temporal_artery_abnormality=True,
            esr_mm_hr=102,
            crp_mg_l=61,
            platelets_k=522,
            persistent_visual_loss=True,
            anterior_ischemic_optic_neuropathy=True,
        )),
    ]


if __name__ == '__main__':
    print('=' * 82)
    print('GCA-VISION: Ocular Ischemia Risk-Context Stratification in Suspected GCA')
    print('=' * 82)
    for result in demo():
        print(f"\n{result['label']}")
        print(f"  Score: {result['score']}")
        print(f"  Band: {result['band']}")
        print(f"  Recommendation: {result['recommendation']}")
        if result['notes']:
            print('  Notes:')
            for note in result['notes']:
                print(f'    - {note}')
    print('\nReferences:')
    print('  1. Maz M, Chung SA, Abril A, et al. Arthritis Rheumatol. 2021;73(8):1349-1365. DOI: 10.1002/art.41774')
    print('  2. Hayreh SS, Podhajsky PA, Zimmerman B. JAMA. 1998;280(4):385-391. DOI: 10.1001/jama.280.4.385')
    print('  3. Liozon E, et al. Rheumatology (Oxford). 2016. DOI: 10.1093/rheumatology/kew397')
    print('  4. Czihal M, et al. Rheumatol Int. 2019;39(12):2095-2102. DOI: 10.1007/s00296-019-04422-5')
    print('=' * 82)

Skill Documentation

name: gca-vision description: Transparent ocular ischemia risk-context stratification in suspected giant cell arteritis.

GCA-VISION

GCA-VISION estimates how concerning ocular ischemic giant cell arteritis is when cranial symptoms, inflammatory markers, temporal artery findings, and visual symptoms cluster together.

Clinical problem

Permanent visual loss in giant cell arteritis is one of the most time-sensitive emergencies in outpatient rheumatology, internal medicine, and ophthalmology. The practical challenge is not whether jaw claudication or amaurosis fugax matter, but whether the bedside pattern is strong enough that treatment urgency should rise before confirmatory testing is complete.

What it outputs

• ocular ischemia risk-context score (0-100)
• concern band: low, intermediate, high, very high, or critical
• red-flag and ischemic-emergency flags
• transparent component breakdown
• recommendation summary

Intended use

• adults with suspected cranial giant cell arteritis
• triage framing when visual symptoms or jaw claudication appear
• bedside escalation support before biopsy or vascular imaging results are finalized

Run

python3 gca_vision.py

Clinical methodology

GCA-VISION is a transparent weighted heuristic, not a validated prediction model.

1. Age context matters — GCA is predominantly a disease of older adults.
2. Cranial ischemic symptoms matter — jaw claudication, scalp tenderness, and temporal artery abnormalities strengthen concern.
3. Inflammatory context matters — ESR, CRP, and thrombocytosis increase pretest concern but do not replace symptoms.
4. Visual symptoms matter most — transient visual loss, diplopia, persistent visual loss, or AION-pattern concern sharply increase urgency.
5. Transparency matters — every component is visible and reviewer-runnable.

Why this score exists

Visual complications of GCA are often catastrophic precisely because treatment decisions need to happen before all diagnostic certainty is available. A transparent escalation tool helps make that urgency explicit.

Demo output

Running python3 gca_vision.py prints three scenarios:

1. nonspecific older-headache case without major cranial ischemic features → low concern
2. jaw claudication + PMR + amaurosis fugax + inflammatory markers → critical concern
3. persistent visual loss with AION-pattern context → critical concern

Limitations

• Not externally validated.
• Not a substitute for immediate treatment decisions, ophthalmology assessment, vascular imaging, or biopsy.
• Does not distinguish arteritic from non-arteritic optic neuropathy by itself.
• Intended for adult suspected GCA only.

Authors

Dr. Erick Zamora-Tehozol (ORCID: 0000-0002-7888-3961), DNAI, RheumaAI

References

1. Maz M, Chung SA, Abril A, et al. 2021 American College of Rheumatology/Vasculitis Foundation Guideline for the Management of Giant Cell Arteritis and Takayasu Arteritis. Arthritis Rheumatol. 2021;73(8):1349-1365. DOI: 10.1002/art.41774
2. Hayreh SS, Podhajsky PA, Zimmerman B. Visual loss in giant cell arteritis. JAMA. 1998;280(4):385-391. DOI: 10.1001/jama.280.4.385
3. Liozon E, et al. The association of vascular risk factors with visual loss in giant cell arteritis. Rheumatology (Oxford). 2016. DOI: 10.1093/rheumatology/kew397
4. Czihal M, et al. Characteristics of patients with giant cell arteritis who experience visual symptoms. Rheumatol Int. 2019;39(12):2095-2102. DOI: 10.1007/s00296-019-04422-5

Minimal HTML Companion

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>GCA-VISION — RheumaScore Skills</title>
  <style>
    body { font-family: Arial, sans-serif; max-width: 860px; margin: 40px auto; padding: 0 16px; line-height: 1.6; color: #111827; }
    h1, h2 { color: #0f172a; }
    code, pre { background: #f3f4f6; border-radius: 6px; }
    code { padding: 2px 5px; }
    pre { padding: 14px; overflow-x: auto; }
    .muted { color: #4b5563; }
  </style>
</head>
<body>
  <h1>GCA-VISION</h1>
  <p class="muted">Transparent ocular ischemia risk-context stratification in suspected giant cell arteritis.</p>
  <h2>What it does</h2>
  <p>GCA-VISION makes bedside urgency explicit when cranial symptoms, inflammatory markers, and visual symptoms suggest possible giant cell arteritis-related ocular ischemia.</p>
  <h2>Inputs</h2>
  <ul>
    <li>Age, temporal headache, scalp tenderness, jaw claudication</li>
    <li>Temporal artery abnormality, PMR overlap, constitutional symptoms</li>
    <li>ESR, CRP, platelets</li>
    <li>Transient visual loss, diplopia, persistent visual loss, AION-pattern concern</li>
  </ul>
  <h2>Outputs</h2>
  <ul>
    <li>0-100 concern score</li>
    <li>concern band and emergency flags</li>
    <li>transparent component breakdown</li>
    <li>recommendation summary</li>
  </ul>
  <h2>Run</h2>
  <pre><code>python3 gca_vision.py</code></pre>
  <h2>References</h2>
  <ol>
    <li>Maz M, Chung SA, Abril A, et al. <em>Arthritis Rheumatol.</em> 2021;73(8):1349-1365. DOI: 10.1002/art.41774</li>
    <li>Hayreh SS, Podhajsky PA, Zimmerman B. <em>JAMA.</em> 1998;280(4):385-391. DOI: 10.1001/jama.280.4.385</li>
    <li>Liozon E, et al. <em>Rheumatology (Oxford).</em> 2016. DOI: 10.1093/rheumatology/kew397</li>
    <li>Czihal M, et al. <em>Rheumatol Int.</em> 2019;39(12):2095-2102. DOI: 10.1007/s00296-019-04422-5</li>
  </ol>
</body>
</html>

Demo Output

==================================================================================
GCA-VISION: Ocular Ischemia Risk-Context Stratification in Suspected GCA
==================================================================================

Older adult with nonspecific headache but no cranial ischemic features
  Score: 16
  Band: LOW ocular ischemia concern
  Recommendation: No strong ocular ischemic GCA pattern detected from the supplied features.

Suspected cranial GCA with jaw claudication, PMR, and amaurosis fugax
  Score: 95
  Band: CRITICAL ocular ischemia concern
  Recommendation: Treat as possible GCA-related ocular ischemic emergency now: immediate glucocorticoid-capable evaluation, urgent ophthalmology access, and confirmatory vascular workup should not delay vision-protection treatment.
  Notes:
    - Jaw claudication is one of the more specific cranial ischemic clues for GCA
    - Visual symptoms sharply lower the threshold for emergency treatment
    - Abnormal temporal artery exam strengthens pretest concern
    - PMR overlap increases background suspicion for GCA

Established visual loss with AION-pattern concern in giant cell arteritis context
  Score: 100.0
  Band: CRITICAL ocular ischemia concern
  Recommendation: Treat as possible GCA-related ocular ischemic emergency now: immediate glucocorticoid-capable evaluation, urgent ophthalmology access, and confirmatory vascular workup should not delay vision-protection treatment.
  Notes:
    - Jaw claudication is one of the more specific cranial ischemic clues for GCA
    - Visual symptoms sharply lower the threshold for emergency treatment
    - Abnormal temporal artery exam strengthens pretest concern

References:
  1. Maz M, Chung SA, Abril A, et al. Arthritis Rheumatol. 2021;73(8):1349-1365. DOI: 10.1002/art.41774
  2. Hayreh SS, Podhajsky PA, Zimmerman B. JAMA. 1998;280(4):385-391. DOI: 10.1001/jama.280.4.385
  3. Liozon E, et al. Rheumatology (Oxford). 2016. DOI: 10.1093/rheumatology/kew397
  4. Czihal M, et al. Rheumatol Int. 2019;39(12):2095-2102. DOI: 10.1007/s00296-019-04422-5
==================================================================================