Rheumatoid Arthritis — Written Clinical Reasoning

SAQ 1 — Integrated Management of Newly Diagnosed Seropositive RA (20 marks, 30 minutes)

Prompt: Outline your integrated management plan for this patient with newly diagnosed, active, seropositive erosive rheumatoid arthritis, including: (a) the classification criteria confirming the diagnosis; (b) the treatment strategy and first-line pharmacological therapy with exact drug, dose, route, frequency and monitoring; (c) the treat-to-target framework and the evidence supporting it; (d) the role of glucocorticoids; (e) comorbidity management at diagnosis; and (f) the principles of escalation if the target is not met. [1]

Model Answer

(a) Diagnosis confirmation — the 2010 ACR/EULAR criteria (3 marks): [1]

This patient meets the 2010 ACR/EULAR classification criteria for definite RA [1]. The prerequisite (confirmed synovitis in at least one joint, not better explained by another disease) is met. The score: joint involvement — 16 joints with at least 1 small joint = 5 points; serology — anti-CCP above 3 times ULN (high-positive) = 3 points; acute-phase reactants — CRP abnormal = 1 point; symptom duration — 4 months (above 6 weeks) = 1 point. Total: 10 out of 10. A score of 6 or more classifies definite RA. The strongly positive anti-CCP confirms a seropositive subset with a high risk of erosive progression [2], and the early marginal erosions on X-ray confirm that structural damage has already begun. This patient needs urgent, aggressive disease-modifying therapy to prevent further irreversible joint damage.

(b) Treatment strategy and first-line pharmacological therapy (4 marks): [1]

Methotrexate is the anchor DMARD and first-line therapy for this patient, per EULAR and ACR recommendations [3]. Dose: 15 mg orally once weekly, titrating up by 5 mg every 2 to 4 weeks to a target of 20 to 25 mg weekly. If oral absorption is poor or gastrointestinal side effects limit oral tolerance, switch to subcutaneous methotrexate. Prescribe folic acid 5 mg once weekly (given on a different day to methotrexate, or 1 to 2 mg daily) to reduce mucosal, hepatic and gastrointestinal toxicity.

Monitoring: full blood count, liver function tests and creatinine every 2 to 4 weeks for the first 3 months, then every 8 to 12 weeks. Counsel the patient: methotrexate is taken once weekly (daily dosing is dangerous), alcohol intake should be low-risk, she must use reliable contraception (methotrexate is teratogenic — she is a 42-year-old woman of childbearing potential), and she should report immediately any mouth ulcers, sore throat, fever, or new respiratory symptoms (possible methotrexate pneumonitis). [1]

Add an NSAID (e.g., naproxen 500 mg twice daily) for symptomatic control of pain and stiffness while waiting for methotrexate to take effect (4 to 8 weeks). Check renal function, blood pressure and gastrointestinal risk before prescribing NSAIDs. [1]

(c) Treat-to-target framework and evidence (4 marks): [1]

The treatment strategy follows the treat-to-target paradigm [3]:

• Target: remission (DAS28 below 2.6) or, if remission is not achievable, low disease activity (DAS28 2.6 to 3.2). Given her young age, early disease and seropositive erosive subset, aim for remission.
• Assessment frequency: every 1 to 3 months during active disease, using a composite measure that includes joint counts (DAS28 with ESR or CRP, or the CDAI/SDAI which do not require laboratory data).
• Escalation window: if the target is not reached within 3 months, or low disease activity within a maximum of 6 months, escalate therapy.

The TICORA trial (Grigor et al., 2004) is the landmark evidence [4]: patients managed with intensive, protocolised tight control — monthly assessment with DAS and escalation of DMARD therapy if DAS remained above 2.4 — had significantly more remission, less radiographic damage and better function than patients managed with routine, unstructured care. The strategy matters as much as the drugs.

(d) Role of glucocorticoids — bridging therapy (3 marks): [1]

This patient has high disease activity and is at risk of rapid erosive progression in the weeks before methotrexate takes full effect. Bridging glucocorticoids are appropriate to rapidly suppress inflammation while the methotrexate works. Options:

• Intramuscular depot methylprednisolone 120 mg — single injection, provides 4 to 6 weeks of suppression.
• Oral prednisolone 10 to 15 mg daily, tapered over 4 to 8 weeks as methotrexate takes effect. [1]

The goal is to stop glucocorticoids as soon as the DMARD achieves control — glucocorticoids are not disease-modifying, and long-term use causes osteoporosis, diabetes, hypertension, cataracts and increased infection risk. The EULAR recommendation is to use the lowest dose for the shortest duration possible, aiming for glucocorticoid-free remission. [1]

(e) Comorbidity management at diagnosis (3 marks): [1]

1. Cardiovascular risk: RA is a coronary risk equivalent (48 per cent increased risk of incident cardiovascular events) [6]. Calculate her cardiovascular risk (using QRISK which incorporates RA, or the Australian Absolute Cardiovascular Risk calculator with clinical upward adjustment). Manage lipids, blood pressure and weight. Counsel smoking cessation (she is a non-smoker, but document this).

2. Osteoporosis: If glucocorticoids are used for 3 months or more, prescribe calcium 1000 mg daily and vitamin D 800 to 1000 IU daily, assess FRAX with glucocorticoid adjustment, and arrange a baseline DEXA scan. Consider a bisphosphonate if at moderate or high fracture risk. [1]

3. Vaccinations: Ensure influenza (annually), pneumococcal (23-valent polysaccharide plus 13-valent conjugate) and COVID-19 boosters are up to date before starting immunosuppressive therapy. Check hepatitis B immunity. Offer recombinant zoster vaccine (Shingrix) if she is above 50 or if JAK inhibitor therapy is anticipated. [1]

4. Psychological health: Screen for depression and anxiety (PHQ-9, GAD-7) — 2 to 3 times more common in RA than in the general population. [1]

5. Occupational therapy and physiotherapy: Early referral for joint protection education, splinting if needed, and exercise programme. Address her work capacity and ergonomic adaptations. [1]

(f) Principles of escalation if target not met (3 marks): [1]

If DAS28 remains above the target after 3 to 6 months of optimised methotrexate monotherapy, escalation options include [3][7]:

1. Triple therapy: add sulfasalazine (2 to 3 g daily) and hydroxychloroquine (200 to 400 mg daily) to methotrexate. Supported by the TEAR and RACAT trials showing non-inferiority to anti-TNF plus methotrexate in many patients, though onset is slower. [1]

2. Biologic DMARD: add an anti-TNF agent (adalimumab 40 mg subcutaneously every 2 weeks, etanercept 50 mg weekly, or certolizumab — preferred if pregnancy is planned as it does not cross the placenta). Screen for latent TB (IGRA), hepatitis B and C before starting. The ATTRACT trial established the efficacy of anti-TNF plus methotrexate [7].

3. JAK inhibitor (tofacitinib, baricitinib, upadacitinib): oral, rapid-acting. However, in patients above 50 with cardiovascular or malignancy risk factors, the ORAL Surveillance study showed higher MACE and malignancy with tofacitinib than with anti-TNF [5] — prefer anti-TNF in that group. At 42 years old, this patient would not yet fall into the high-risk group, but the caveat should be remembered.

Before any biologic, perform the full pre-biologic screen (IGRA, HBV/HCV serology, HIV, FBC, U&E, LFTs, vaccination review). [1]

SAQ 2 — RA Interstitial Lung Disease and Comorbidity Management (10 marks)

Prompt: A 65-year-old man with a 12-year history of seropositive rheumatoid arthritis (currently on methotrexate 20 mg weekly and adalimumab 40 mg every 2 weeks) presents with a 3-month history of progressive exertional dyspnoea and dry cough. He has smoked 30 pack-years. Examination reveals bilateral basal fine inspiratory crackles. Spirometry shows a restrictive pattern. HRCT demonstrates basal-predominant reticulation with honeycombing and traction bronchiectasis, consistent with a usual interstitial pneumonia (UIP) pattern. His DAS28 is 2.8 (in low disease activity). Discuss your approach to the interstitial lung disease, including differentiation from methotrexate pneumonitis, treatment, and the broader comorbidity management this patient requires. [1]

Model Answer

(a) Diagnosis and differentiation (3 marks): [1]

This patient has rheumatoid arthritis-associated interstitial lung disease (RA-ILD) with a UIP pattern on HRCT. The UIP pattern — basal-predominant reticulation, honeycombing and traction bronchiectasis — is the most common pattern in RA-ILD and is radiologically identical to idiopathic pulmonary fibrosis. Risk factors for RA-ILD include male sex, smoking history, older age, long disease duration and anti-CCP positivity — this patient has all of these. [1]

Critical differential — methotrexate pneumonitis: Methotrexate can cause an idiosyncratic interstitial pneumonitis that is clinically and radiologically similar to RA-ILD but differs in onset (acute to subacute, within weeks to months of starting or dose escalation), association with eosinophilia and fever, and ground-glass opacity on HRCT rather than established fibrosis. His methotrexate has been stable for years and his HRCT shows established fibrosis (honeycombing) rather than acute ground-glass changes — favouring RA-ILD over methotrexate pneumonitis. However, if there is any diagnostic uncertainty, temporarily stopping methotrexate and observing for improvement is appropriate. Bronchoalveolar lavage may show lymphocytic predominance in methotrexate pneumonitis. [1]

(b) Management of RA-ILD (3 marks): [1]

1. Refer to a respiratory physician for shared care. Serial pulmonary function tests (FVC, DLCO) every 3 to 6 months to monitor progression. A decline in FVC of 10 per cent or more or DLCO of 15 per cent or more indicates progressive disease. [1]

2. Immunosuppression: For progressive RA-ILD, immunosuppressive therapy is indicated. Rituximab (anti-CD20) is the preferred biologic in RA-ILD — it depletes B cells and has evidence for efficacy in connective tissue disease-associated ILD. If he is already on adalimumab, consider switching to rituximab. Mycophenolate mofetil or azathioprine are alternative immunosuppressants. Antifibrotic therapy (nintedanib) is now approved for progressive fibrotic ILD, including RA-ILD, based on the INBUILD trial showing it slows FVC decline. [1]

3. Smoking cessation is essential — smoking accelerates RA-ILD progression. Provide nicotine replacement therapy, varenicline or bupropion. [1]

4. Oxygen therapy if hypoxaemic (resting SpO2 below 88 per cent or exertional desaturation). Assess for pulmonary hypertension with echocardiography. [1]

(c) Broader comorbidity management (4 marks): [1]

1. Cardiovascular risk: RA is a coronary risk equivalent [6]. This man is 65, a heavy smoker, on anti-TNF. Calculate his cardiovascular risk (likely very high). Start a high-intensity statin (atorvastatin 40 to 80 mg), optimise blood pressure to target (130/80 or below), and enforce smoking cessation. Minimise NSAID exposure (cardiovascular risk).

2. Methotrexate and ILD: Given the RA-ILD, consider whether methotrexate should be continued. The evidence is nuanced — methotrexate does not clearly worsen established RA-ILD, but many rheumatologists switch to a non-methotrexate regimen (e.g., rituximab with or without mycophenolate) in significant RA-ILD. Discuss in multidisciplinary meeting. [1]

3. Infection risk: On anti-TNF and methotrexate, he is at increased risk of respiratory infections. Ensure pneumococcal, influenza and recombinant zoster (Shingrix) vaccinations are current. Have a low threshold for investigating new respiratory symptoms — RA-ILD patients can decompensate quickly with infection. [1]

4. Glucocorticoid-induced osteoporosis: If glucocorticoids are used for the ILD, ensure bone protection (calcium, vitamin D, DEXA, bisphosphonate or denosumab if indicated). [1]

5. Screening for pulmonary hypertension and lung cancer: RA-ILD patients are at increased risk of both. Monitor with echocardiography and have a low threshold for investigating new or changing respiratory symptoms. [1]