DR. CORA LIM-MEDICAL INSIDER
Systemic Lupus Erythematosus
PART 5
Let us continue with our discussion of Systemic Lupus Erythematosus.
Diagnosis
The 1997 American College of Rheumatology (ACR) specify 11 criteria that occur in SLE.
In order to be classified with SLE, at least four must be present either serially or simultaneously. The study shows that the SLICC criteria demonstrate greater sensitivity but lower specificity than the 1997 ACR criteria but may still fail to classify some patients with disease.
Both of these classification criteria were designed to be highly specific for research purposes, and should not be used as diagnostic criteria although they are widely used in clinical practice.
Ultimately, a diagnosis of SLE is based on clinical judgement and recognition of patterns of signs and symptoms supported by serological tests and following exclusion of other diagnoses.
Investigations
As SLE is such a heterogeneous disease, the study says that investigations depend on the particular presentation. However, all patients will need blood tests for ANA, ENA, anti-dsDNA and complement as well as full blood count, which may demonstrate cytopenias, renal and liver function tests and vitamin D levels.
Urinalysis should also be performed as a screen for renal involvement and proteinuria quantified, if present. Depending on the exact constellation of symptoms, further investigations – such as radiographs of the hands and feet, musculoskeletal ultrasound, pulmonary function studies, electrocardiograms and echocardiography, chest X-ray and high resolution computerised tomography scan, renal ultrasound and biopsy, magnetic resonance imaging brain and lumbar puncture – may be indicated.
Monitoring
European League Against Rheumatism recommendations for the management of SLE stipulate that regular monitoring of disease activity is an integral part of treatment. A number of validated disease activity indices, constructed from cohort and cross-sectional studies, are widely used in both clinical practice and clinical trials – such as the British Isles Lupus Assessment Group (BILAG) and the Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K).
Most patients with SLE should be followed up by a physician with expertise in monitoring disease activity and treatment response. Routine clinical monitoring allows earlier detection of active disease. This should include regular checks of blood pressure in order to monitor cardiovascular disease risk and screen for renal disease.
Urinalysis for red cells, white cells, proteinuria and cellular casts is useful for detecting clinically unapparent renal disease. If this is abnormal, it should be followed with quantification of proteinuria using either a 24-hour urinary protein collection or a protein:creatinine ratio and calculation of glomerular filtration rate.
Full blood count, liver function tests and urea and electrolytes should be routinely monitored in all patients with SLE and especially those on immunosuppressive drugs.
Concurrent measures of erythrocyte sedimentation rate and C-reactive protein (CRP) can help to distinguish between a flare of SLE and infection. In disease flares, erythrocyte sedimentation rate is raised with a normal CRP. A raised CRP in SLE is indicative of infection. However, there can be a modest rise in CRP with active serositis or arthritis in the absence of infection. (To be continued)