Systemic Lupus Erythematosus

📋 Key Information Summary

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Diagnosis: Based on 2019 EULAR/ACR criteria (ANA titre ≥1:80 is an entry criterion). No single pathognomonic test.
Key Antibodies: Anti-dsDNA (disease activity, nephritis risk), Anti-Smith (highly specific), Anti-Ro/La (neonatal lupus, photosensitivity), Anti-RNP (mixed connective tissue disease overlap).
Lupus Nephritis (LN): Occurs in ~50% of patients. Biopsy is gold standard for classification (ISN/RPS) and guides therapy. Class III/IV (±V) require aggressive immunosuppression.
Induction Therapy for Active LN: Mycophenolate mofetil (MMF) or low-dose Euro-Lupus IV cyclophosphamide, PLUS glucocorticoids. Belimumab is an add-on option for active LN.
Maintenance for LN: MMF or azathioprine for at least 3–5 years post-induction.
Cutaneous Lupus: First-line is photoprotection (broad-spectrum SPF 50+). Topical calcineurin inhibitors or corticosteroids for localised disease. Hydroxychloroquine is first-line systemic agent.
Pregnancy: Hydroxychloroquine should be continued. Plan pregnancy during stable remission (≥6 months). Avoid MMF, cyclophosphamide, methotrexate. Screen for anti-Ro/La antibodies (risk of congenital heart block).
CV Risk: Accelerated atherosclerosis is a major cause of late mortality. Aggressive management of traditional risk factors (BP, lipids, smoking) is essential.
Immunosuppression Backbone: Hydroxychloroquine for all patients unless contraindicated. Reduces flares, organ damage, thrombosis, and mortality.
Biologics: Belimumab (anti-BLyS) for active disease despite standard therapy. Anifrolumab (anti-IFNAR) for moderate-severe non-renal lupus. Rituximab (off-label) for refractory cases.
ATSI Considerations: Higher incidence and severity, particularly in younger patients. Barriers include remote access to specialist care and lower rates of renoprotective therapy.
Vaccination: All patients should receive influenza and pneumococcal vaccines. Live vaccines are contraindicated on immunosuppression.

Introduction & Australian Epidemiology

Systemic Lupus Erythematosus (SLE) is a chronic, multisystem autoimmune disease characterised by the production of pathogenic autoantibodies and immune complex deposition, leading to inflammation and tissue damage. It follows a relapsing-remitting course with considerable heterogeneity in presentation and prognosis.

In Australia, the estimated prevalence is approximately 45–100 per 100,000 people. It disproportionately affects women (female:male ratio ~9:1) and individuals of non-European ancestry. Aboriginal and Torres Strait Islander peoples experience a higher incidence, earlier onset, more severe organ involvement (especially renal), and increased mortality compared to non-Indigenous Australians. The disease has a significant impact on quality of life and life expectancy, primarily due to active disease flares, infections from immunosuppression, and accelerated cardiovascular disease.

ANA & Autoantibody Patterns

A positive antinuclear antibody (ANA) test at a titre of ≥1:80 on HEp-2 cells is an entry criterion for the 2019 EULAR/ACR classification. However, ANA can be positive in other conditions and in ~15% of healthy individuals, so it is not diagnostic alone. Specific autoantibody profiling is crucial for diagnosis, prognostication, and monitoring.

Antibody	Prevalence in SLE	Clinical Significance
Anti-dsDNA	60–70%	Highly specific. Titres often correlate with disease activity, especially lupus nephritis. Can be used for monitoring.
Anti-Smith (Sm)	20–30%	Most specific for SLE (>99%). Not associated with a particular manifestation but confirms diagnosis.
Anti-Ro (SSA) / Anti-La (SSB)	30–40% / 10–15%	Associated with photosensitive cutaneous lupus, neonatal lupus, and congenital heart block. Can be present in ANA-negative SLE.
Anti-RNP	25–40%	High titres associated with Mixed Connective Tissue Disease (MCTD) overlap (Raynaud's, swollen hands, myositis).
Anti-ribosomal P	10–20%	Associated with lupus psychosis and depression.
Antiphospholipid Antibodies (aPL)	30–40%	Lupus anticoagulant, anti-cardiolipin, anti-β2 glycoprotein I. Confers risk of arterial/venous thrombosis and obstetric complications.

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Key Point: A positive ANA alone does not diagnose SLE. The clinical context and specific autoantibody profile are essential. A negative ANA makes SLE very unlikely, but rare ANA-negative SLE exists (often with anti-Ro antibodies).

Lupus Nephritis (LN)

LN is a major cause of morbidity and mortality. It occurs in approximately 50% of SLE patients within 10 years of diagnosis. Early detection and aggressive treatment are critical to prevent end-stage kidney disease (ESKD).

Diagnosis & Classification

Screen with urine microscopy, urine protein:creatinine ratio (uPCR) and serum creatinine/eGFR at diagnosis and regularly thereafter. A renal biopsy is indicated for persistent proteinuria (uPCR >50 mg/mmol), active urinary sediment, or unexplained rise in creatinine. Biopsy is classified using the ISN/RPS system:

ISN/RPS Class	Description	General Treatment Approach
I, II	Minimal mesangial / Mesangial proliferative	Treat systemic symptoms; usually no specific nephritis therapy needed.
III	Focal proliferative	Requires induction immunosuppression.
IV	Diffuse proliferative (most severe)	Requires intensive induction immunosuppression.
V	Membranous	Treat if nephrotic-range proteinuria. Often combined with III or IV.
VI	Advanced sclerosing	ESKD likely; immunosuppression usually futile. Supportive care.

Management of Proliferative LN (Class III/IV)

Induction Therapy (3–6 months): Aim to control active inflammation.

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Mycophenolate Mofetil (MMF)

CellCept® · Generic · Antiproliferative

Adult Induction Dose Target 2–3 g/day PO in divided doses (BD). Start low (500 mg BD) and titrate up over 2–4 weeks.

Renal Adjustment Dose reduce if eGFR <25 mL/min. Avoid with allopurinol.

PBS Status ✔ PBS General Benefit (Authority Required for LN)

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Cyclophosphamide (IV)

Endoxan® · Alkylating agent

Adult Dose (Euro-Lupus) 500 mg IV fortnightly x 6 doses. Pre-hydrate with Mesna to prevent haemorrhagic cystitis.

Paediatric Dose 500–750 mg/m² IV monthly. Adjust for gonadotoxicity risk.

PBS Status ✔ PBS General Benefit

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First-line induction is MMF or low-dose IV cyclophosphamide. High-dose NIH cyclophosphamide regimens are rarely used due to toxicity. Glucocorticoids (e.g., methylprednisolone 500mg IV x 3 days then oral prednisone 0.5–1 mg/kg/day, tapering to ≤7.5 mg/day by 3 months) are used alongside.

Add-on Biologic: Belimumab can be added to standard therapy (MMF or azathioprine) for active LN to improve renal response and reduce flares.

Maintenance Therapy (≥3–5 years): After successful induction, switch to lower-dose oral therapy to prevent relapse.

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Mycophenolate Mofetil

Maintenance Dose

Adult Dose 1–2 g/day PO. Often preferred over azathioprine for efficacy.

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Azathioprine

Imuran® · Purine analogue

Adult Dose 2–2.5 mg/kg/day PO. Check TPMT/NUDT15 genotype before starting.

PBS Status ✔ PBS General Benefit

Supportive Care in LN

Hydroxychloroquine: Continue for all LN patients (reduces flares, thrombosis, and improves survival).
Renin-Angiotensin System Blockade: ACE inhibitor or ARB for proteinuria >0.5 g/day, regardless of blood pressure.
Cardiovascular Risk Reduction: Statin therapy, BP control (<130/80 mmHg).
Infection Prophylaxis: Consider PJP prophylaxis (e.g., trimethoprim-sulfamethoxazole) during intensive immunosuppression, especially with cyclophosphamide.

Cutaneous Lupus

Cutaneous manifestations occur in >80% of SLE patients. They are broadly categorised as acute (e.g., malar rash), subacute (photosensitive, annular polycyclic lesions), or chronic (discoid lupus).

General Principles

Photoprotection: Cornerstone of management. Broad-spectrum SPF 50+ sunscreen, protective clothing, and sun avoidance. Reapply sunscreen every 2 hours.
Smoking Cessation: Smoking worsens cutaneous lupus and reduces response to hydroxychloroquine.

Pharmacological Therapy

First-line Systemic:

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Hydroxychloroquine

Plaquenil® · Generic · Antimalarial

Adult Dose 200–400 mg/day PO (max 5 mg/kg/day actual weight). Takes 2–3 months for full effect.

Monitoring Baseline and annual ophthalmological screening after 5 years (sooner if high-risk).

PBS Status ✔ PBS General Benefit

Second-line Systemic (if inadequate response to HCQ):

Methotrexate: 7.5–25 mg once weekly PO/SC, with folic acid. Effective for inflammatory arthritis and cutaneous disease.
Belimumab: Can be effective for mucocutaneous manifestations.
Thalidomide/Lenalidomide: For refractory severe cutaneous lupus. Specialist use only due to neuropathy/teratogenicity risk.

Topical Therapy:

Potent topical corticosteroids (e.g., mometasone furoate 0.1%) for limited duration (2–4 weeks) for active lesions.
Topical calcineurin inhibitors (tacrolimus 0.1% ointment, pimecrolimus cream) for sensitive areas (face) and maintenance.

Pregnancy & Neonatal Lupus

Pregnancy in SLE requires careful planning and multidisciplinary care (rheumatology, obstetrics, neonatology). Outcomes are best when conception occurs during stable remission (≥6 months).

Pre-Conception Counselling & Medication Management

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Teratogenic Medications to STOP before conception: Methotrexate (≥3 months prior), Mycophenolate mofetil (≥6 weeks prior), Cyclophosphamide, Leflunomide (requires cholestyramine washout).

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Medications SAFE in pregnancy: Hydroxychloroquine (MUST be continued), Azathioprine, Tacrolimus, Sulfasalazine, Low-dose prednisolone (<20 mg/day). Hydroxychloroquine reduces flares and improves outcomes.

Anti-Ro/La Antibodies & Neonatal Lupus

All pregnant SLE patients should be screened for anti-Ro (SSA) and anti-La (SSB) antibodies. These antibodies can cross the placenta and cause:

Congenital Complete Heart Block (CCHB): Risk ~2% in anti-Ro positive mothers (higher in subsequent pregnancies). Requires fetal echocardiography from 16–26 weeks gestation. First-degree block may be reversible with dexamethasone.
Neonatal Lupus Syndrome: Transient rash, cytopenias, hepatitis. Usually self-resolves by 6–8 months as maternal antibodies clear.

Monitoring During Pregnancy

Monthly disease activity assessment (SLEDAI).
Regular urine PCR, blood pressure, complement (C3/C4), and anti-dsDNA monitoring (note: complement naturally rises in pregnancy).
Screen for antiphospholipid antibodies (lupus anticoagulant, anticardiolipin, anti-β2GPI) – presence alters management (requires LMWH + aspirin).

Immunosuppression & Biologics

Treatment is tailored to disease severity and organ involvement. Hydroxychloroquine forms the foundational therapy for all patients.

Biologic Therapies (PBS Listed)

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Belimumab

Benlysta® · Anti-BLyS monoclonal antibody

Indication Active autoantibody-positive SLE despite standard therapy. Also for active LN (add-on).

Adult Dose 10 mg/kg IV every 4 weeks (after loading) or 200 mg SC weekly.

PBS Status ✔ PBS Authority Required

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Anifrolumab

Saphnelo® · Anti-IFNAR monoclonal antibody

Indication Moderate-to-severe, autoantibody-positive SLE (non-renal) with an inadequate response to standard therapy.

Adult Dose 300 mg IV every 4 weeks.

PBS Status ✔ PBS Authority Required

Off-label Biologics

Rituximab: Anti-CD20 B-cell depletor. Used off-label for refractory lupus, particularly severe LN, neuropsychiatric lupus, and autoimmune cytopenias. Dose: 1000 mg IV x 2 doses (2 weeks apart). Requires specialist initiation and monitoring.

Other Conventional Agents

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Methotrexate

Trexject® · DMARD

Role in SLE First-line for inflammatory arthritis and mucocutaneous disease. Less effective for major organ involvement.

Dose 7.5–25 mg once weekly PO/SC, with folic acid 5mg (not on MTX day).

PBS Status ✔ PBS General Benefit

Cardiovascular Risk in SLE

Cardiovascular disease (CVD) is a leading cause of late mortality in SLE. Patients have a 2–3 fold increased risk of atherosclerotic events due to a combination of chronic inflammation, traditional risk factors, corticosteroid use, and renal involvement.

Risk Factors

Disease-Related: High disease activity, lupus nephritis, antiphospholipid antibodies, elevated type I interferon signature.
Treatment-Related: Cumulative glucocorticoid dose, NSAID use.
Traditional: Hypertension, dyslipidaemia, diabetes, smoking, obesity, sedentary lifestyle.

Management Strategies

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Target LDL Cholesterol: <2.0 mmol/L for high-risk SLE patients (with nephritis, aPL, or high disease activity). Consider statin therapy regardless of baseline LDL if other risk factors are present.

Blood Pressure: Target <130/80 mmHg. Use ACEi/ARB as first-line, especially with proteinuria.
Antiplatelet/Anticoagulation: Low-dose aspirin for patients with antiphospholipid antibodies and no history of thrombosis. Full anticoagulation (usually warfarin, target INR 2.0–3.0) for definite antiphospholipid syndrome.
Minimise Glucocorticoids: Aim for prednisolone ≤7.5 mg/day or, ideally, cessation.
Lifestyle: Smoking cessation, regular aerobic exercise, Mediterranean-style diet, weight management.

Aboriginal and Torres Strait Islander Health

Aboriginal and Torres Strait Islander Health Considerations

SLE disproportionately and severely affects Aboriginal and Torres Strait Islander peoples. Key considerations for clinical practice:

Epidemiology & Severity

Higher incidence, earlier onset, more severe disease course, and increased mortality compared to non-Indigenous Australians. Lupus nephritis is more common and progresses more rapidly.

Access to Specialist Care

Geographic barriers for those in remote/very remote communities. Telehealth is crucial for rheumatology and nephrology follow-up, but requires reliable infrastructure and cultural safety.

Medication Adherence & Safety

Higher rates of hydroxychloroquine non-adherence. Critical to ensure understanding of lifelong therapy, ophthalmology screening, and infection risks from immunosuppression. Address practical barriers (cost, transport to pharmacy).

Comorbidities

Higher background rates of diabetes, renal disease, and cardiovascular risk factors, which compound SLE-related organ damage. Requires integrated, holistic care with primary health and Aboriginal Community Controlled Health Organisations (ACCHOs).

Cultural Safety

Care must be delivered in a culturally safe manner, respecting kinship systems, communication styles, and connection to Country. Involve Aboriginal Health Workers/Practitioners and use patient decision aids in appropriate languages.

📚 References

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3. Kidney Disease: Improving Global Outcomes (KDIGO) Glomerular Diseases Work Group. KDIGO 2021 Clinical Practice Guideline for the Management of Glomerular Diseases. Kidney Int. 2021;100(4S):S1-S276.
4. Australian Institute of Health and Welfare (AIHW). Aboriginal and Torres Strait Islander Health Performance Framework 2020 summary report. Canberra: AIHW; 2020.
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8. Furie R, Rovin BH, Houssiau F, et al. Two-Year, Randomized, Controlled Trial of Belimumab in Lupus Nephritis. N Engl J Med. 2020;383(12):1117-1128.
9. Morand EF, Furie R, Tanaka Y, et al. Trial of Anifrolumab in Active Systemic Lupus Erythematosus. N Engl J Med. 2020;382(3):211-221.
10. RACGP/Arthritis Australia. Musculoskeletal Care Guide for General Practice. East Melbourne: RACGP; 2023.
11. National Health and Medical Research Council (NHMRC). Australian guidelines for the prevention and control of infection in healthcare. Canberra: NHMRC; 2019.
12. Australian Technical Advisory Group on Immunisation (ATAGI). Australian Immunisation Handbook. Australian Government Department of Health, Canberra.