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Lupus referrals suggest misdiagnosis is common.

A study of patients referred by community-based rheumatologists and primary care physicians suggests overdiagnosis of lupus may be as much of a problem as missed diagnoses, underscoring the need for more accurate diagnosis biomarkers.

The study looked at 476 patients referred to the University of Florida Autoimmune Disease Center, Gainesville, between September 2001 and September 2002.

Of 263 patients with a presumptive diagnosis of systemic lupus erythematosus (SLE), only 134 (51%) had that diagnosis confirmed by specialists at the clinic, Sonali Narain, M.D., and colleagues reported (Arch. Intern. Med. 2004;164:2435-41).

Among the physician participants in the study, rheumatologists were almost four times as likely to make an accurate diagnosis of lupus as nonrheumatologists, but even they weren't right 100% of the time.

Rheumatologists referred 45 patients with a diagnosis of SLE, and the clinic's specialists confirmed their diagnosis in 33, or 73% of the cases. Nonrheumatologists referred 192 SLE cases, and the diagnosis was confirmed in 102 (53%) of the cases.

Upon evaluation at the clinic, 129 (49%) of the 263 lupus-referral patients were given another diagnosis, such as Sjogren's syndrome, scleroderma, or fibromyalgia, and 4 were never given a definitive diagnosis.

Among those given alternative diagnoses, the largest proportion--76 patients--were seropositive for antinuclear antibodies (ANA) but did not have autoimmune disease. In fact, ANA testing was the most common reason for the mistaken diagnoses, Dr. Narain said in an interview. Prior to the study, "it was pretty apparent" that physicians were overdiagnosing lupus on the basis of ANA results, but the problem had not been quantified, she noted.

At least one expert isn't convinced the referring physicians were necessarily in error.

Some referring primary care physicians may have sent patients to the center because they saw a positive ANA result, and were not sure what to do, so they suggested a diagnosis of SLE to make sure that the diagnosis would be ruled out, surmised Robert H. Shmerling, M.D., a rheumatologist at the Beth Israel Deaconess Medical Center, Boston, who has published on the predictive value of ANA testing.

Moreover, lupus is such a difficult diagnosis to make that even experts can be fooled and disagree. There could be a problem in assuming the center's diagnosis is always correct, Dr. Shmerling pointed out.

The American College of Rheumatology's (ACR's) 11-item criteria are classification criteria, intended for a clinical research setting, not for clinical diagnosis. Lupus has no established set of clinical criteria for diagnosis, Dr. Shmerling noted.

In the interview, Dr. Narain said the center physicians were confident in their diagnosis because the center has had a long-standing focus on lupus and has resources and expertise in the field.

Her report compared the patients who met 4 of the 11 ACR criteria, and so were diagnosed with SLE, with those who met only 3 criteria. Patients diagnosed with the disease were much likelier to have serious symptoms, such as organ involvement.

The investigators found that the erroneous diagnoses could have serious consequences, in addition to the emotional turmoil inflicted on the patient by being told they have a chronic disease, and the expense of the referral. Some of the patients (39) found not to have autoimmune disease were being treated with corticosteroids, as much as 60 mg a day--a fact that could reinforce the notion that these diagnoses were taken seriously by the referrers.

Apart from Dr. Shmerling's skepticism, however, most other experts noted that the findings seemed credible because they jibe with their experience.

"It is interesting to see this published, because I think it is something we all have thought for a long time," said Susan Manzi, M.D., codirector of the University of Pittsburgh's Lupus Center for Excellence. Lupus is a very difficult diagnosis to make for anyone who doesn't see a lot of it, and so, while better education for physicians might make some difference, the condition will probably remain underdiagnosed and misdiagnosed until more specific biomarkers are found, Dr. Manzi said.

Underdiagnosis is, indeed, also an issue. A recent survey by the Lupus Foundation of America found that lupus patients had visited an average of three physicians before getting their diagnosis, and 51% went more than 4 years before their condition was identified. While more basic research proceeds, epidemiologists are aiming to get a handle on lupus's exact prevalence, and in so doing see its range of presentations more clearly and define it better, said Duane Peters, a spokesperson for the foundation.

To that end, the Centers for Disease Control and Prevention is trying to identify every newly diagnosed lupus case in four counties, two in Georgia and two in Michigan. Records from every hospital and laboratory in the counties, as well as contacting physicians' offices, will be culled. The investigation is expected to last until 2007.

The study was prompted by a 2002 CDC report indicating that in the 10 preceding years, the number of deaths attributable to lupus increased by 60%, a figure that flabbergasted many experts who at the time believed that lupus recognition was improving and translating into better care.

"If we get a handle on lupus, we might even get a better handle on other autoimmune diseases as well," said Chad Helmick, M.D., the CDC medical epidemiologist in charge of the project.


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Title Annotation:Rheumatology
Author:Kirn, Timothy F.
Publication:Internal Medicine News
Geographic Code:1USA
Date:Feb 15, 2005
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