Interstitial Lung Disease — Written Clinical Reasoning

SAQ 1 — Integrated Management (20 marks, 30 minutes)

Prompt: Outline your integrated management plan for this patient, including the diagnostic conclusion, pharmacological therapy, non-pharmacological measures, prognostic assessment, and surveillance plan. Justify each decision with reference to evidence. [1]

Model Answer

Diagnostic conclusion (2 marks): [1]

The diagnosis is idiopathic pulmonary fibrosis (IPF) based on a definite UIP pattern on HRCT with exclusion of known causes of ILD (negative autoimmune screen, no occupational or drug cause, no CTD symptoms). Per the ATS/ERS/JRS/ALAT 2018 diagnostic criteria, a definite UIP on HRCT with exclusion of known causes is diagnostic of IPF — no biopsy is required. The MDT should confirm this diagnosis. [1]

Problem list (3 marks): [1]

1. Idiopathic pulmonary fibrosis — definite UIP, moderate-severe physiological impairment (FVC 58%, DLCO 36%), progressive
2. Exertional desaturation (6MWT desaturation to 86%) — meets criteria for ambulatory oxygen assessment
3. Possible mild pulmonary hypertension (estimated RVSP 42 mmHg) — needs monitoring
4. GERD — aspiration micro-injury may contribute to disease progression
5. Hypertension — cardiovascular comorbidity management
6. Former smoker (50 pack-years) — increased lung cancer risk; surveillance discussion needed [1]

Pharmacological management (5 marks): [1]

Choice between nintedanib and pirfenidone is driven by tolerability and patient preference — there is no head-to-head superiority trial. Both are equivalent in efficacy. [1]

Key teaching point: Corticosteroids are contraindicated. The PANTHER-IPF trial demonstrated harm with triple therapy (prednisone + azathioprine + NAC). Do not prescribe corticosteroids for IPF. [1]

Non-pharmacological management (4 marks): [1]

• Oxygen therapy: Assess for long-term oxygen therapy with formal arterial blood gas. If PaO2 is less than 55 mmHg at rest, prescribe supplemental oxygen at 2-4 L/min to maintain SpO2 at 92 percent or above. For exertional desaturation (6MWT desaturation to 86 percent), prescribe ambulatory oxygen. LTOT is the only therapy besides transplantation that improves survival in ILD with severe hypoxaemia.
• Pulmonary rehabilitation: Refer to a structured pulmonary rehabilitation programme — improves exercise capacity, dyspnoea, and quality of life.
• Vaccinations: Annual influenza, pneumococcal (Prevenar 13 then Pneumovax 23), COVID-19 boosters, and pertussis booster. Prevent infections that could trigger acute exacerbations.
• Smoking cessation: Even as a former smoker, reinforce complete abstinence. [1]

Prognostic assessment (2 marks): [1]

Calculate the GAP score (Gender-Age-Physiology, PMID 22586007):

• Gender: Male = 1 point
• Age: 69 years = 2 points (over 65)
• FVC: 58 percent predicted = 1 point (50-75)
• DLCO: 36 percent predicted = 1 point (36-55)
• Total: 5 points = GAP Stage II (1-year mortality approximately 11 percent; 3-year mortality approximately 29 percent) [1]

This confirms moderate-severity disease. Antifibrotic therapy is clearly indicated. [1]

Transplant referral (2 marks): [1]

Refer for lung transplant assessment now. Indications for early referral include FVC less than 80 percent predicted or DLCO less than 40 percent predicted — both criteria are met. Transplant workup takes months; early referral preserves the option. Bilateral sequential lung transplant is the preferred procedure for IPF. [1]

Surveillance and follow-up (2 marks): [1]

• PFTs every 3-6 months (FVC trajectory is the primary disease activity marker)
• Annual HRCT to assess progression
• Annual 6-minute walk test
• Echocardiography every 1-2 years to monitor for pulmonary hypertension
• ILD nurse coordinator for education, adherence monitoring, and symptom assessment
• Early advance care planning discussion [1]

SAQ 2 — CTD-ILD Problem-Solving (20 marks, 30 minutes)

Prompt: A 45-year-old woman presents with progressive dyspnoea over 6 months. She has a 2-year history of Raynaud phenomenon and has noticed skin thickening of her fingers over the past year. PFTs show FVC 68 percent predicted, DLCO 48 percent predicted (disproportionately reduced). HRCT shows NSIP pattern (bilateral symmetric basal ground-glass and reticulation). ANA is positive (1:1280, nucleolar pattern), anti-Scl-70 is positive. Echocardiography shows estimated RVSP 48 mmHg. Outline the integrated management plan. [1]

Model Answer

Problem list: [1]

1. Systemic sclerosis-associated ILD (SSc-ILD) — NSIP pattern, FVC 68 percent, progressive
2. Disproportionate DLCO reduction (48 percent) with possible overlapping pulmonary arterial hypertension (PAH) — needs right heart catheterisation
3. Raynaud phenomenon — digital vascular disease
4. Skin thickening (sclerodactyly) — diffuse cutaneous SSc
5. GERD risk — oesophageal dysmotility nearly universal in SSc
6. Scleroderma renal crisis risk — blood pressure surveillance critical [1]

Pharmacological management: [1]

• Mycophenolate mofetil 1-1.5 g BID — first-line immunosuppressant for SSc-ILD. The Scleroderma Lung Study II showed equivalence to cyclophosphamide with better tolerability and longer-term maintenance of lung function. Monitor FBC, LFTs monthly.
• Nintedanib 150 mg BID — add if fibrosis is progressive (FVC decline despite immunosuppression). INBUILD (PMID 31566307) demonstrated benefit in progressive fibrosing ILDs including SSc-ILD.
• PPI (omeprazole 20-40 mg OD) — GERD prophylaxis given near-universal oesophageal involvement
• Calcium channel blocker (amlodipine 10 mg OD) — Raynaud management, blood pressure control, and renal crisis prophylaxis (ACE inhibitor if renal crisis develops)
• Avoid high-dose corticosteroids (greater than 15 mg/day prednisolone equivalent) — increases scleroderma renal crisis risk [1]

Pulmonary hypertension assessment: [1]

The disproportionate DLCO reduction (48 percent) relative to FVC (68 percent) raises suspicion for overlapping PAH (WHO Group 1) or pulmonary hypertension due to ILD (WHO Group 3). Estimated RVSP 48 mmHg on echo is borderline. Refer for right heart catheterisation to define the pulmonary haemodynamics and guide therapy. If PAH confirmed, initiate pulmonary vasodilator therapy (ambrisentan, sildenafil, or riociguat) per PH specialist. [1]

Surveillance: [1]

• PFTs every 3-6 months
• Annual HRCT
• Annual echocardiography (or sooner if symptoms change)
• Blood pressure monitoring twice weekly for renal crisis surveillance — any rise in creatinine or new hypertension requires urgent ACE inhibitor initiation
• ILD and rheumatology co-management [1]