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New referral strategy accurately detects SpA in low-prevalence setting
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CHICAGO — A newly developed referral strategy for spondyloarthritis had a better balance of sensitivity and specificity than other existing referral strategies, such as ASAS criteria, according to research presented at the ACR/ARHP 2018 Annual Meeting.
“Over the years, we have been implementing strategies to get patients to rheumatologists early so that SpA is diagnosed earlier in the disease course,” Alexandre R. Sepriano, PhD student at Leiden University in The Netherlands, told Healio Rheumatology. “There are different ways of achieving that. One was the development of the ASAS classification criteria that raised awareness of early forms of disease. The other is the development of referral strategies.”
Currently, there is no consensus on the optimal referral strategy for SpA, according to Sepriano. In addition, few studies have compared the efficacy of existing referral strategies for the whole SpA spectrum, including axial SpA and peripheral SpA. Therefore, Sepriano and colleagues used data from a nationwide epidemiological study, EpiReumaPt, to develop a novel referral strategy and compare its performance with other referral strategies.
During the EpiReumaPt study, more than 10,000 participants in Portugal were randomly selected from the general population to participate in a face-to-face interview assessing for the prevalence of rheumatic diseases. Patients with at least one indication of a rheumatic disease, as well as 20% of patients with no indications, were then referred to an appointment with a rheumatologist. During a final phase, three researchers, including Sepriano, reviewed all the participants’ data and made a definitive judgement on a SpA diagnosis.
The researchers used self-reported data from the EpiReumaPt trial to compute the EpiReumaPt referral strategy. Because imaging and laboratory data were not available, existing referral strategies were modified to exclude these parameters during the head-to-head comparison, which included ASAS, EpiReumaPt, CafaSpA one, Brandt I, Braun IBP, MASTER, Brandt II, Hermann, CafaSpA two, Braun 2 step, and Brandt III.
Of the 3,877 participants included in the current analysis, 92 were diagnosed with SpA, yielding a national prevalence of 1.6%.
The positive predictive values of all referral strategies ranged from 2.2% to 7.6%. ASAS and EpiReumaPt performed with the highest sensitivities, which were 85% and 72%, respectively. Brandt III had the lowest sensitivity — 7.9% — but the highest specificity — 98.4%. In contrast, ASAS performed with a specificity of 38.8%, and EpiReumaPt was associated with a 67.6% specificity, making it the most balanced referral strategy in the analysis, Sepriano said.
Both ASAS and EpiReumaPt also had the lowest post-screening probabilities of SpA among participants without the disease (0.6% and 0.7%, respectively).
The number of patients needed to be referred for one additional SpA diagnosis was 63 for ASAS vs. 36 for EpiReumaPt.
“This is still quite high, but we need to take into account that this study was not done in the usual setting of practice,” Sepriano noted. “This was based on the general population, so this figure needs to be interpreted in that regard.”
He concluded that the overall message is that, in settings where it is difficult to obtain imaging and laboratory results, it will be useful for clinicians to have a set of questions when making the decision whether to refer patients to a rheumatologist.
“The referral strategy can be useful, but always keep in mind that clinical judgment should overrule,” he said. – by Stephanie Viguers
Reference:
Sepriano A, et al. Abstract 1599. Presented at: ACR/ARHP Annual Meeting, Oct. 20-24, 2018; Chicago.
Disclosure: Sepriano reports no relevant financial disclosures.