Systemic Lupus Erythematosus (SLE) - Boston Foot



Systemic Lupus Erythematosus (SLE)

Dr. Vivek Rajagopal MD, MRCP

Consultant Rheumatologist

West Suffolk Hospital, Bury St Edmunds, UK

SLE is a multi system auto immune disease with a broad spectrum of clinical presentations. It is a chronic illness that may be life threatening when major organs are affected but more commonly results in chronic debilitating ill health. No single cause has been found, though factors such as sunlight and drugs may precipitate the condition in genetically predisposed individuals.

Epidemiology

Incidence / Prevalence - Varies according to the characteristics of the population studied. In the USA, annual incidence ranges from 1.8 - 7.6 cases per 100,000 per year. In Europe, this is between 3.3 - 4.8 per 100,000. The prevalence ranges in the USA is between 14.6 to 50 cases per 100,000 . It is similar in various countries in Europe; between 28 to 36/ 100,000. More common in females ( 9:1 ratio) . The disease can be more severe in blacks and hispanics with increased frequency of renal and CNS involvement.

Clinical features

The disease can potentially affect any organ. Observational studies suggest that cutaneous involvement , oral ulcers and arthralgia are the commonest features.

Cutaneous involvement - occurs in up to 85% of SLE patients. Butterfly rash – erythematous, often blotchy and found over the cheek and across the nose. Typically, the nasolabial fold is spared. Other lesions such as maculopapular, discoid , splinter haemorrhages, dilated capillaries at the nail base, angioneurotic oedema and livido reticularis can also occur. Discoid lesions , scarring alopecia and hyperkeratosis are seen in discoid lupus(DLE) which is confined to the skin. Only 5% of DLE patients develop systemic involvement. A subset of patients can have Subacute cutaneous lupus(SCLE)- They have widespread annular or maculopapular rash with Anti Ro antibodies. A small proportion can go on to develop major organ involvement. The rashes are exacerbated by UV light.

Arthralgia - occurs in 90% of SLE patients. Characteristically, it is polyarticular, symmetrical, episodic and fleeting in nature. Symptoms invariably exceed the objective clinical findings and can this cause a delay in diagnosis. Joint effusions are uncommon. Only 10% of SLE patients have a deforming arthritis. 30 - 50% of patients may also complain of myalgia with mild weakness.

Renal involvement - seen in 70% of SLE patients at some stage of their disease. Various pathological subtypes have been labeled from I to VI based on renal biopsy. Type IV has the worst prognosis, resulting in 11 to 48% with end stage renal disease at 5 years. Renal disease starts with asymptomatic proteinuria and hence, these patients should be screened with urine dipstick at least every 6 months for proteinuria and this should also be checked when they visit a physician with symptoms.

CNS – patients can develop a variety of CNS manifestations ranging from psychosis, strokes, and movement disorders to seizures. Depression is also more common in SLE and responds to treatment with antidepressants.

Serositis - Pleural and pericardial effusions with pleuritic or pericardial pain is characteristic - responds to treatment with steroids

Haematological abnormalities - Normochromic, normocytic anaemia is the common feature. Antibody mediated haemolytic anaemia, neutropenia and thrombocytopenia can occur in severe SLE.

Investigations

Autoimmune profile - A panel of tests including Antinuclear antibody(ANA), double stranded DNA(ds-DNA), Extractable nuclear antigens(ENA) – which comprise a group of antibodies such as Anti- Ro, Anti – La, Anti – centromere and Anti – nucleolar antibodies, complement (C3, C4) levels. Complement Haemolytic activity( CH50) – is used in some centres instead of C3 and C4.A detailed review regarding these tests is beyond the scope of this chapter, these tests are crucial in diagnosis of SLE.

A positive ANA is seen in 98 to 99% of patients with SLE. The specificity is low as ANA positivity is seen in up to 15% of the population and more so in patients with chronic infections.

A positive ds- DNA is highly specific for lupus and higher titres are seen in patients with renal involvement.

Anti- Ro and Anti – La antibodies are seen in subacute cutaneous lupus as well as in SLE where their presence is associated with neonatal lupus and congenital heart block.

Low C3 and C4 – suggests disease activity as complement is consumed in active lupus.

Other Investigations

Low platelets and prolonged APTT – suggests the presence of Anti phospholipid Syndrome which is associated with SLE in upto 40% of cases. This should be investigated further by checking lupus anticoagulant and Anti phospholipid antibodies.

Relevant biopsies (eg; lung renal , skin) may be needed to confirm involvement of specific organs.

Diagnosis

The diagnosis of lupus is established by the presence of a positive auto immune profile in patients with relevant clinical features. The American College of Rheumatology has established a set of criteria mainly for epidemiological purposes, but these criteria are quite useful in diagnosing lupus at an individual level as well.

Lupus nephritis – can be suspected when a patient with SLE develops proteinuria with casts and requires a renal biopsy for confirmation.

CNS disease – requires referral to a specialist for diagnosis and management.

Treatment

The treatment of lupus has to be individualized as patients have different degrees of severity and organ involvement.

Minor manifestations such as oral ulcers, arthralgia and skin lesions can be treated with NSAIDS and hydroxychloroquine. Topical steroids are useful for oral ulcers. Oral corticosteroids in short courses 15mg daily for 1 week, 10mg for 2nd week, 5mg for 3rd week can be used to control flares of arthritis.

Physical measures such as use of sunblocks, avoidance of excessive sun exposure can also reduce frequency of flares.

Lupus nephritis – needs to be managed with aggressive immunosuppressants. An induction regime using either cyclophosphamide or mycophenolate with prednisolone followed by a maintanence regime using azathioprine or mycophenolate is the standard practice.

Managing cardiovascular risk is increasingly recognised as important as SLE is associated with accelerated atherosclerosis.

Newer therapies such as Rituximab, anti BAFF will be used more frequently as evidence accumulates on their effectiveness. Rituximab is currently used in refractory nephritis and SLE induced thrombocytopenia.

Prognosis

Advances in treatment have greatly improved the long term outlook for patients with severe SLE. The majority of patients experience prolonged periods of drug free remission with minor flares which can be treated symptomatically. Patients with nephritis usually require long term maintenance therapy with immunosuppresants. Fatigue and depression tend to be the problems which can be refractory to treatment. Premature mortality occurs mainly due to cardiovascular disease and this can be improved through aggressive management of cardiovascular risk factors as well as maintaining remission.

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