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IM7.1-22 | Rheumatologic Problems — PBL Case

CLINICAL SETTING

Dr Ananya Krishnan is a medical intern posted in the general medicine OPD at a 900-bed teaching hospital in Puducherry. It is a busy Monday morning. Her next patient is Mrs Kavitha Selvam, a 30-year-old school teacher, who has been referred from the primary health centre with a letter that reads: 'Joint pain, 6 months, not responding to analgesics. Please advise.' Kavitha enters the room walking slowly, both hands slightly swollen. She is visibly tired. Her husband has come with her and immediately asks: 'Doctor, is this serious? She has a 4-month-old baby at home and she is still breastfeeding.' Dr Ananya opens her history sheet and starts the clinical encounter.

Trigger 1: The Clinical History — Patterns Emerge

Kavitha describes her joint pain: it started insidiously about 6 months ago, initially in both wrists and then spreading to involve the small joints of both hands — the knuckles nearest the palm (MCPs) and the middle knuckles (PIPs). The feet are also involved. She reports marked stiffness every morning that takes nearly 2 hours to ease. The stiffness improves as the day goes on and worsens after rest. She has not noticed any swelling of the larger joints. She has mild fatigue and occasional low-grade fever. She does not have any skin rash, mouth ulcers, hair loss, or eye symptoms. She delivered a healthy baby 4 months ago after a full-term uncomplicated pregnancy. Her family history is notable: her mother has 'some kind of joint disease' and has been on tablets for many years. On examination: both MCP joints (2nd-4th) and PIP joints bilaterally are swollen, warm, and tender. Wrists are swollen bilaterally. DIP joints are normal. There is no skin rash. MCP squeeze test is positive bilaterally. No lymphadenopathy. Temperature 37.8°C. Dr Ananya notes the joint pattern and reviews her initial assessment.

DISCUSSION POINTS

  • Using the clinical history alone, how do you classify this joint disease as inflammatory versus mechanical? Which specific features in the history support each criterion of the inflammatory pattern?
  • What is the significance of the joint pattern described — symmetric, small joints, MCPs and PIPs involved, DIP spared? Which diagnoses does this distribution suggest, and which does it make less likely?
  • The MCP squeeze test was positive. What is the clinical significance of transverse compression tenderness across the MCP heads, and at what stage of disease is it most useful?
  • What additional history would you specifically ask to narrow the differential diagnosis at this point?
Click to reveal Trigger 2: Investigation Results — Confirming the Diagnosis (discuss previous trigger first!)

Trigger 2: Investigation Results — Confirming the Diagnosis

Dr Ananya orders investigations after her clinical assessment. Results return 3 days later. Haemoglobin: 9.8 g/dL (normocytic). Platelet count: 420,000/mm3. ESR: 72 mm/hour. CRP: 48 mg/L (normal <5). RF: positive at 128 IU/mL (upper limit of normal 20 IU/mL). Anti-CCP antibody: strongly positive (>3x upper limit of normal). ANA: negative. Serum uric acid: 3.8 mg/dL. Liver function and renal function: normal. X-ray of both hands: periarticular osteoporosis at the MCPs and PIPs bilaterally; no erosions yet; joint spaces preserved. Dr Ananya calls Kavitha back and presents the results to the medical unit consultant, Dr Suresh, who says: 'Good. Now use the ACR/EULAR 2010 criteria and tell me her score. Then tell me your treatment plan — she is breastfeeding. What does that change?'

DISCUSSION POINTS

  • Apply the ACR/EULAR 2010 classification criteria for rheumatoid arthritis to Kavitha's case. Calculate her score and state whether she meets the criteria for definite RA. Which domain contributes the most points?
  • Interpret the serological results: what do the RF and anti-CCP results tell you about the specificity, sensitivity, and prognostic implications for this patient? Why is a strongly positive anti-CCP result clinically more significant than a weakly positive RF?
  • What do the plain X-ray findings of periarticular osteoporosis with preserved joint spaces indicate about disease stage? What early radiographic change would indicate the onset of erosive disease?
  • Kavitha is breastfeeding. Which DMARDs are safe, contraindicated, or require dose adjustment during breastfeeding? How does this change your treatment choice?
Click to reveal Trigger 3: The Treatment Challenge — First-Line DMARD and Safety (discuss previous trigger first!)

Trigger 3: The Treatment Challenge — First-Line DMARD and Safety

Dr Suresh confirms the diagnosis: seropositive rheumatoid arthritis, early non-erosive stage. He prescribes methotrexate 7.5 mg once weekly and asks Ananya to counsel Kavitha. Kavitha listens carefully and then asks three questions: 'Doctor, my baby is 4 months old and I'm still breastfeeding — is this medicine safe for my baby? Can I ever stop this medicine if my joints get better? And my mother has been on similar tablets for over 15 years — will I end up the same way?' Ananya also notes from the prescription that Dr Suresh has written: 'Folic acid 5 mg weekly.' A colleague standing nearby whispers to Ananya: 'That folic acid tablet — do you know why it's given separately?' Later that afternoon, Dr Suresh tells Ananya that if Kavitha's disease remains active at 3 months (DAS28 >5.1 despite methotrexate), he will consider adding a biologic. He says: 'Before we ever start a TNF-inhibitor, there is one test we cannot skip. What is it and why?'

DISCUSSION POINTS

  • What is the pharmacological basis of co-prescribing folic acid with methotrexate? What toxicities does folic acid prevent, and which toxicity does it NOT prevent?
  • Methotrexate is classified as contraindicated during breastfeeding. What alternative DMARD could be used safely in a breastfeeding mother with early RA, and what monitoring would it require?
  • Explain the treat-to-target strategy in RA: what is the target (DAS28 score, remission definition), at what time points is the target assessed, and what constitutes a DMARD failure that triggers escalation?
  • Why is tuberculosis screening mandatory before starting a TNF-alpha inhibitor? What is the physiological basis for this risk, and what specific investigations constitute adequate TB screening in an Indian patient (consider BCG vaccination background)?
Click to reveal Trigger 4: Three Months Later — A New Symptom, A New Concern (discuss previous trigger first!)

Trigger 4: Three Months Later — A New Symptom, A New Concern

Kavitha returns at 3 months. She has stopped breastfeeding at 6 weeks. She has been taking methotrexate 15 mg weekly (dose was increased at week 8) and folic acid. Her DAS28 score has improved from 6.1 to 4.2 (still above remission threshold of <2.6 but no longer in high disease activity). She reports her joint pain is 60% better. However, she now brings a new complaint: over the past 4 weeks she has developed increasing fatigue, shortness of breath on climbing two flights of stairs, and a dry cough. She is afebrile. Chest examination reveals fine bilateral basal crackles. Chest X-ray: bilateral lower zone interstitial infiltrates. SpO2 at rest: 94%. Her rheumatoid disease is improving — but something new has developed. Dr Suresh looks at the chest X-ray and says to Ananya: 'This is the most important safety concern with this drug. Tell me the two most likely causes of these chest findings in this patient — and tell me what you are going to do right now.'

DISCUSSION POINTS

  • What are the two most important diagnoses to consider in a patient on methotrexate who develops progressive dyspnoea, dry cough, and bilateral interstitial infiltrates? How would you distinguish between them clinically and radiologically?
  • If this is methotrexate-induced pneumonitis, what is the immediate management? Is it safe to restart methotrexate once she recovers, and what factors would influence this decision?
  • RA itself can cause interstitial lung disease. What features would make you suspect RA-ILD rather than drug toxicity in this case, and how would the management differ?
  • Kavitha is now considering switching to a biologic for her RA. Given the new lung complication, which biologics would be preferred and which should be avoided? Explain the basis for your choice.

Group Task Assignments

  • Construct the complete ACR/EULAR 2010 RA classification criteria scorecard for Kavitha, domain by domain. Discuss which single domain would have contributed most to earlier diagnosis had it been identified at the first visit to the PHC.
  • Develop a structured drug counselling card for a patient newly started on methotrexate: include the weekly dose schedule, the importance of NOT taking daily, the folic acid co-prescription, five side effects to report immediately, pregnancy and breastfeeding advice, and monitoring plan.
  • Debate the clinical scenario: 'If Kavitha's DAS28 does not reach the target of <2.6 at 6 months despite two DMARDs, should the team escalate to a biologic without a rheumatology referral, or is this the mandatory referral trigger?' Defend your position with clinical guidelines.
  • Design the pre-biologic screening protocol for an Indian patient with RA: which tuberculosis screening test is preferred (TST vs IGRA) given BCG vaccination, what constitutes a positive result, what is the next step if latent TB is detected, and when can the biologic be safely started?

Learning Issues

Research these questions and bring your findings to the discussion.

  1. [IM7.5] What are the distinguishing clinical features of inflammatory versus mechanical joint disease, and how does each feature (morning stiffness duration, response to activity, joint distribution, systemic symptoms) arise from the underlying pathophysiology?
  2. [IM7.11] What are the ACR/EULAR 2010 classification criteria for rheumatoid arthritis? What is the sensitivity and specificity of RF and anti-CCP antibody for RA, and what prognostic information does a strongly positive anti-CCP result provide?
  3. [IM7.17] What is the first-line DMARD for rheumatoid arthritis, and what are the dose, monitoring requirements, contraindications, and key drug interactions? Which DMARDs are safe during breastfeeding?
  4. [IM7.18] What is the pathophysiological basis for using TNF-alpha inhibitors in RA? Why does TNF-alpha inhibition increase the risk of tuberculosis reactivation, and what pre-treatment screening is mandatory?
  5. [IM7.20] What is the treat-to-target strategy in RA? Define DAS28 and its cut-off scores for remission, low, moderate, and high disease activity. At what intervals should disease activity be assessed, and what constitutes an inadequate treatment response triggering escalation?
  6. [IM7.22] What are the indications for specialist rheumatology referral in a patient with inflammatory arthritis? At what stage of disease management should the GP/internist refer versus manage independently?