MADRID – New classification criteria for scleroderma presented at the annual European Congress of Rheumatology correctly identify more patients who could potentially be included in epidemiological studies and clinical trials than is possible with existing classification systems.
The new system is still a proposal and is under review by the European League Against Rheumatism (EULAR) and the American College of Rheumatology (ACR), according to Dr. Frank van den Hoogen, who is the director of the rheumatology center at Sint Maartenskliniek in Nijmegen and head of the department of rheumatology at Radboud University in Nijmegen, both in the Netherlands.
In a validation cohort, the ACR-EULAR criteria had a sensitivity of 91% and a specificity of 92% to correctly identify patients with systemic sclerosis. By comparison, the 1980 Preliminary ARA Criteria had a sensitivity of 75% and a specificity of 72%.
The whole process of developing the ACR-EULAR criteria has taken about 5 years, Dr. van den Hoogen explained in an interview. "The ARA criteria were not as sensitive as we wanted because they excluded some patients with limited disease and also patients with newly diagnosed disease," he added.
"The purpose of classification criteria is to include similar patients in research," Dr. van den Hoogen said. "Classification criteria are not synonymous with diagnostic criteria," he explained, "[they] are generally more standardized and less inclusive." This is because physicians will see patients with multiple symptoms and it would not be possible to include every symptom seen in routine practice in a set of classification criteria. Nevertheless, diagnostic criteria do tend to mirror classification criteria.
The process of determining which items to include was driven by both data and consensus. Delphi exercises and a nominal group technique were used to create a set of potential items for the classification of systemic sclerosis.
Several patient cases were then reviewed by leading scleroderma experts based in Europe and North America. The cases represented the full spectrum of systemic sclerosis, including those with a low and those with a high probability of having the disease. Experts ranked the importance of the symptoms exhibited by each of these cases, and a whittled down list with a scoring system was obtained. Systemic sclerosis was present if a score of 9 or more was achieved.
Skin thickening of the fingers of both hands extending past the metacarpophalangeal (MCP) joints was considered to be indicative of scleroderma, and was given a score of 9. Conversely, patients with skin involvement likely to be due to another scleroderma-like disorder or skin thickening sparing the fingers were not likely to have systemic sclerosis.
Other items included skin thickening of the fingers, with subitems of puffy fingers (score = 2) and whole finger skin thickening, distal to the MCP (4); fingertip lesions, with subitems of digital tip ulcers (2) and pitting scars (3), telangiectasia (2), abnormal nailfold capillaries (2); pulmonary arterial hypertension, interstitial lung disease, or both (2); Raynaud’s phenomenon (3); and the presence of any scleroderma-related autoantibodies (3).
The ability of these criteria to correctly identify patients with and without systemic sclerosis was then prospectively tested in a random sample of 200 individuals and further validated in a cohort of 405 individuals that included both early and prevalent cases of scleroderma and its mimics who had been collected from several European and North American scleroderma centers.
"The proposed ACR-EULAR criteria for the classification of systemic sclerosis should allow more patients to be classified correctly as systemic sclerosis," Dr. van den Hoogen said. This includes those with early (less than 3 years) scleroderma and the 20% of patients who have limited disease but who do not meet current classification criteria.
Sara Freeman/IMNG Medical Media
Dr. Suzana Jordan
"New ACR [EULAR] criteria show increased sensitivity in comparison to the old [ARA] criteria," concurred Dr. Suzana Jordan of University Hospital Zurich. She presented findings on the use of the proposed system in 317 patients from the Zurich scleroderma cohort. This cohort mainly consists of patients with early or mild disease.
Applying the criteria to this Swiss patient population, Dr. Jordan noted that "75% of systemic sclerosis patients were correctly identified compared to just over half of all patients (51%) using the ARA criteria." Furthermore, "50% of early scleroderma patients who did not fulfill the old criteria met the new," she concluded.
Dr. van den Hoogen said that he had no disclosures, except that this work was funded jointly by EULAR and the ACR.