Managing systemic lupus erythematosus in primary care
Roshini Claire Anthony speaks with Dr Annie Law, a consultant at the Department of Rheumatology & Immunology, Singapore General Hospital, on how primary care physicians can help in the management of systemic lupus erythematosus (SLE).
According to a cohort study conducted in 2001, the prevalence of SLE in Singapore is 40/100,000 people. A multisystemic autoimmune disease, SLE may affect the skin, joints, kidneys, lungs, heart, central nervous system, and blood. Early recognition and diagnosis of the disease is important to allow early treatment of the disease, thus reducing the risk of irreversible organ damage.
Diagnosing SLE can be a challenge especially in its early stages as the signs and symptoms wax and wane. Early and accurate diagnosis of SLE can be made when there are compatible clinical manifestations and a positive immunological test.
Classification criteria can be used as a good guide in making a diagnosis of SLE. The 2012 Systemic Lupus International Collaborating Clinics (SLICC) Classification Criteria was developed to be more clinically relevant. To fulfil the criteria, a patient must have at least one clinical and one immunological criteria and two others from the expanded list of items
(Table 1) or have biopsy-proven lupus nephritis and a positive antinuclear antibody (ANA) or anti-double stranded DNA antibody (anti-dsDNA Ab).
Routine screening to diagnose SLE is not necessary and only patients who present with clinical symptoms of SLE should be screened. Screening involves basic blood investigations such as a full blood count to look for cytopenia, serum creatinine, erythrocyte sedimentation rate, and urine microscopy (to assess the presence of proteinuria, haematuria, and urinary cast). Other more specific tests include serum complements C3 and C4 (low complements reflect disease activity), ANA, and anti-dsDNA Ab.
Identifying and diagnosing SLE can be difficult especially in the early phase of the disease as new and different symptoms appear over weeks or months. There are several ways to overcome these challenges. These include taking a detailed clinical history and performing a detailed physical examination. If clinical suspicion arises, screening tests to detect ANA should be performed. ANAs are present in about 95 percent of SLE patients. However, a positive test occurs in about 5 to 10 percent of the adult population, and on its own has poor diagnostic value in the absence of clinical features of autoimmune rheumatic disease. It is also crucial to rule out other diseases.
There are no local treatment guidelines; however, GPs can refer to international guidelines such as SLICC. The two key international management guidelines are those produced by The British Society for Rheumatology in 2017 (Guideline for the management of SLE in adults) and the American College of Rheumatology in 2012 (Guidelines for screening, treatment, and management of lupus nephritis).
GPs should refer the patient to a rheumatologist as early as possible if any clinical suspicion arises.
Among the challenges GPs will face in treating SLE patients are differentiating SLE flares versus infections in SLE patients, recognizing potential complications from the treatment of SLE, and drug-drug interactions from treatment of SLE. One way to overcome these challenges is to have a good clinical summary of the initial clinical presentation of SLE as lupus flares tend to be stereotypic (ie, manifest in a similar way).
At times, an infection can mimic or mask a lupus flare. However, patients with a lupus flare often present stereotypically as mentioned and often exhibit other active symptoms such as alopecia, oral ulcers, rash, lethargy, fever, or major organ involvement
(Figure 1). If an infection is present, a patient may experience chills, which are rare in fever secondary to SLE, and provide a history that helps in localizing the site of infection. To confirm the clinical diagnosis, blood test such as a full blood count, procalcitonin, erythrocyte sedimentation rate, complements, and appropriate microbiological samples or imaging should be performed.
It is important that GPs are familiar with the medications that the patient is taking so as to recognize the potential side effects and drug-drug interactions encountered by the patient.
As SLE is a multisystemic disease, complications can arise from any organ system resulting in renal impairment, cytopenia, serositis, myocarditis, stroke, seizure, psychosis, and many others. As such, GPs should refer the patient to a rheumatologist as early as possible if they have any doubts or suspicions of SLE.