Lupus Clinical Overview
H. Michael Belmont, M.D.
Medical Director, Hospital for Joint Diseases
New York University Medical Center
Lupus Introduction
The prognosis for patients with Lupus (SLE) has greatly improved over the last few decades with at least 80-90% of all patients surviving ten years. Thereafter life expectancy approximates that of age matched controls. This improvement reflects the general advancements in health care (i.e. dialysis, antibiotics, antihypertensives, newer immunosuppressives with more favorable efficacy to toxicity ration) but also the specialized care available for patients with SLE.
SLE is a complex disorder affecting a predominately young population and shares similarities with HIV infection as regards the propensity for multiple organ involvement, potentially life-threatening episodes, and need for sophisticated monitoring. Patients with SLE are appropriate for a Center of Excellence since medical care by experienced clinicians with access to state of the art diagnostic and therapeutic measures will result in improved outcomes and the most cost-effective utilization of resources. Expert care of patients with SLE will lead to fewer hospitalizations secondary to uncontrolled disease exacerbation, less severe renal disease with fewer patients experiencing end stage renal disease requiring chronic dialysis, fewer episodes of avascular necrosis requiring total joint replacement, and less severe osteoporosis and fractures. More judicious use of steroids and steroid sparing agents can also reduce the severity of atherosclerosis and resulting incidence of myocardial infarctions and cerebral vascular accidents which now complicate the natural history of SLE. Preventive measures such as influenza and pneumococcal vaccination, TB testing, and patient education regarding the dangers of ultraviolet light, a prudent diet, and exercise will also assure patient satisfaction and improved health status.
Lupus Clinical Discussion
Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by immune dysregulation resulting in the production of antinuclear antibodies (ANA), generation of circulating immune complexes, and activation of the complement system. SLE is notable for unpredictable exacerbations and remissions and a predilection for clinical involvement of the joints, skin, kidney, brain, serosa, lung, heart, and gastrointestinal tract. The pathologic hallmark of the disease is recurrent, widespread, and diverse vascular lesions.
Lupus (SLE) is not a rare disorder. Although reported at both extremes of life (e.g. diagnosed in infants and in the tenth decade of life) chiefly it affects women of child bearing age. Among children, SLE occurs three times more commonly in females than in males. In the 60% of SLE patients who experience onset of their disease between puberty and the fourth decade of life the female to male ratio is 9:1. Thereafter, the female preponderance again falls to that observed in prepubescents.
Lupus is three times more common in African American blacks than American caucasians. SLE is also more common in Asians and in China may be more common than Rheumatoid Arthritis. The ethnic group at greatest risk is African Caribbean blacks. The annual incidence of SLE ranges from six to 35 new cases per 100,000 population in relatively low-risk to high-risk groups. The prevalence of SLE in the United States is an issue of some debate. Prevalence estimates of between 250,000 to 500,000 are contradicted by a recent nationwide telephone poll suggesting a prevalence of between one and two million.
The clinical features of Lupus (SLE) are protean and may mimic infectious mononucleosis, lymphoma, or other systemic disease. Therefore, the American College of Rheumatology developed criteria to include patients with SLE and exclude those with other disorders (Table 1). These criteria are best used to insure the appropriateness of subjects for epidemiological or research studies. Although many patients do not fulfill the rigid criteria at first encounter most will when followed over periods of time.
The etiology of Lupus (SLE) remains unknown. A genetic predisposition, sex hormones, and environmental trigger(s) likely result in the disordered immune response that typifies the disease.
A role for genetics is suggested by the increased percentage of two histocompatibility antigens in patients with SLE, HLA-DR2 and HLA-DR3. In addition, there is an increased frequency of the extended haplotype HLA-A1, B8, DR3. The role for heredity is further supported by the concordance for this illness among monozygotic twins. The polygenic nature, however, of this genetic predisposition as well as the contribution of environmental factors is suggested by the only moderate concordance rate which is reported to be between 25 and 60%.
The origin of autoantibody production in SLE is unclear but a role has been suggested for an antigen driven process, spontaneous B-cell hyper-responsiveness, or impaired immune regulation. Regardless of the etiology of autoantibody production, SLE is associated with the impaired clearance of circulating immune complexes secondary to decreased CR1 expression, defective Fc receptor function, or deficiencies of early complement components such as C4A.
More is known about the pathogenic cellular and molecular events which are responsible for vascular lesions in SLE than the origins of autoimmunity. Disease manifestations result from recurrent vascular injury due to immune complex deposition, leukothrombosis, or thrombosis (Table 2). Additionally, cytotoxic antibodies can mediate autoimmune hemolytic anemia and thrombocytopenia, while antibodies to specific cellular antigens can disrupt cellular function. An example of the latter, is the association between anti-neuronal antibodies and neuropsychiatric SLE.
The health status of a patient with Lupus (SLE) is related not only to disease activity, but to the damage that results from recurrent episodes of disease flare (i.e. deforming arthropathy, shrinking lung, end stage renal disease, organic mental syndrome, etc.), as well as the adverse effects of treatment (i.e. avascular necrosis of bone, infections, and precocious atherosclerosis, etc.).
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Lupus (SLE) Subsets
Discoid, drug-induced, neonatal, and Ro (ANA negative) lupus are related to SLE and warrant brief description.
Discoid lupus is an illness characterized by a non-photosensitive, chronic and potentially scarring skin disease. This illness is usually unaccompanied by ANA or other autoantibodies. Perhaps 10% of patients with discoid lupus will develop the systemic illness.
Drugs such as procainamide or hydralazine can induce the production of antinuclear antibodies, especially anti-histone antibodies, and occasionally a SLE-like illness. Drug induced lupus is usually characterized by fever, hematological abnormalities such as an autoimmune hemolytic anemia or autoimmune thrombocytopenia, or serositis. Skin, renal and neurologic manifestations are uncommon.
Neonatal or congenital lupus occurs when the transplacental acquisition of autoantibodies, specifically anti-Ro (SS-A), produce int he neonate a transient photosensitive rash, confential complete heart block, thrombocytopenia or rarely hepatobiliary dysfunction.
ANA negative or Ro lupus is defined by the absence of an ANA and the present of a lupus-like illness. This disorder is manifest most often by a partially photosensitive skin rash referred to as subacute cutaneous lupus erythematosus. These patients often demonstrate anti-Ro antibodies in the serum and, given the cytoplasmic residence of the Ro antigen, these patients may be ANA negative.
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