In 1990 the American College of Rheumatology created a diagnostic classification system for the vasculitides. The intent was to provide a standard for researchers to use in studies of these elusive and hard-to-classify syndromes.
Since 1990 these research criteria have crept into the clinical practice and the diagnostic tool kit of your average working rheumatologist
and primary care doctor.
A study was designed to test this standard by applying
the ACR classification criteria in the diagnosis of Wegener's granulomatosis, giant-cell arteritis, polyarteritis nodosa, and hypersensitivity vasculitis in 198 patients referred for evaluation of possible vasculitis.
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Results
- The predictive values for the four vasculitides WORKED FOR ONLY 1/3 OF THE ENTIRE STUDY GROUP.
- THE CRITIERIA WERE VALID 29% to 75% for patients with a final diagnosis of vasculitis.
Conclusions and Recommendations
- The 1990 ACR classification criteria function poorly in the diagnosis of specific vasculitides.
- Using these criteria create some potential problems because diagnostic tests or criteria work are less accurate with rare or orphan diseases.
- Patients who do not have a vasculitis may meet ACR vasculitis criteria, and patients who have a specific type of vasculitis may meet more than one set of ACR criteria.
- The authors recommend that the American College of Rheumatology reappraise these criteria.
Diagnostic criteria used in Study: symptoms and signs
Patients coming into the study reported these common symptoms:
- fatigue
- myalgia (tenderness or pain in the muscles) or weakness
- weight loss, sinus symptoms, and headaches.
Examination disclosed these common features:
- neuropathy or foot drop
- palpable purpura ( purple discolorations perceptible to touch )
- oral or nasal ulcers.
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Laboratory and Diagnostic Tests and Findings
Sedimentation rate
was greater THAN than 50 mm/h in 43% of patients. Sed rate or ESR shows A NONSPECIFIC indicator of disease, esp. an inflammatory process (REF RATE in males, 10)
Chest radiography
Twelve percent of patients displayed fixed infiltrates or nodules.
ANA
56 patients were positive for antinuclear antibody (ANA) WITH 9 OF 56 getting a positive vasculitis diagnosis.
ANCA
Twenty-nine patients had positive results at baseline.
At follow-up, vasculitis was ultimately diagnosed in 12 of these 29 patients.
Surgically invasive tests
One hundred eleven patients underwent angiography, biopsy,
or both.
Angiography: vasculitis was diagnosed in 7 of 18 patients.
Biopsies: One hundred five patients underwent at least one biopsy.
Skin biopsies and temporal artery biopsies were most commonly performed. Kidney and lung biopsies) were less frequently performed.
Specific Diagnostic Conclusions
Using ACR criteria Vasculitis was diagnosed in 51 OF 198 patients.
Diagnosis in these 51 patients ranged from systemic to limited forms of vasculitis.
Fifteen patients with vasculitis met two or more sets of ACR vasculitis criteria.
Thirteen patients with a diagnosis of vasculitis did not meet any
ACR criteria.
Of the 28 patients who were given specific diagnoses
of Wegener granulomatosis, polyarteritis nodosa, giant-cell
arteritis, or hypersensitivity vasculitis, 14 met the relevant
ACR criteria sets for these conditions alone.
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Pitfalls in Diagnosis of Vasculitis
The authors of the study lead the patient to conclude that diagnosing the vasculitides - these rare syndromes - requires as much art and craft as science. The study further reinforces the need to find a skilled rheumatologist-clinician who has more than a text book understanding of vasculitis.
Many vasculitis patients remain in a diagnostic limbo or fall into a
a category called "overlaps" where a patient may exhibit signs and symptoms of Wegener's and Churg-Strauss or some other equally credible and exotic combination creating difficulty in writing a practical treatment plan.
Some patients have had as many as 5 biopsies performed with results less than satisfactory. As the authors state “Not all vasculitides have specific diagnostic features. Although a biopsy is often helpful for diagnosing vasculitis, some tissue specimens yield nonspecific findings.”
Often patients "get their diagnosis" by drug trials and treatment results. Most rheumatologists rely on some combination of clinical,
laboratory, and biopsy (or angiographic) data, as well as
“clinical intuition”, to diagnose vasculitis in patients, but they are comfortable with imprecise diagnoses that often evolve over
time.
The authors point out the pitfalls associated with the use of
“ANCA tests including the fact that more than 50% of the positive test results in our study occurred in patients who did not have a vasculitis”.
Study results indicate that many patients who do not have a vasculitis may meet ACR vasculitis criteria; this is a particular problem for clinicians who are making diagnostic or treatment decision.
The study concludes that the ACR criteria should not be used for
diagnosis of vasculitis.
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