Non-invasive, saliva-based Sjögren’s diagnosis model shows good performance
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Key takeaways:
- Analysis of Sjögren’s saliva samples revealed upregulation of five immune-related proteins.
- Assessing proteins, combined with existing methods, had high diagnostic sensitivity and specificity.
A non-invasive diagnostic model, based partially on saliva samples, distinguished between patients with and without Sjögren’s disease with high sensitivity and specificity, according to data published in Arthritis Research & Therapy.
The finding comes as alternatives to minor salivary gland biopsy — a critical, but invasive, step in Sjögren’s diagnosis — are increasingly needed, Xinwei Zhang, of the department of rheumatology and clinical immunology at the First Affiliated Hospital of Xiamen University, in China, and colleagues wrote.
“[Minor salivary gland] biopsy involves only a small incision in the lower lip and is easily performed under local anesthesia, [but] it is an invasive approach that brings complications, such as bleeding, pain and temporary sensory defect, sometimes even more serious like tissue necrosis and constant impaired sensory defect,” they added. “These possible complications may discourage patients from cooperating with rheumatologists to perform this procedure, which can undoubtedly impede the timely treatment. Thus, there is a growing need for an easier and non-invasive prediction method for [primary Sjögren’s disease].”
To determine whether proteins in the saliva could serve as biomarkers to make a Sjögren’s diagnosis, Zhang and colleagues analyzed saliva from inpatients initially admitted to their unit with suspected Sjögren’s disease, who also underwent minor salivary gland biopsies, between January 2021 and August 2022.
The researchers first used liquid chromatography-tandem mass spectrometry to reveal protein differences between saliva from six patients with Sjögren’s disease and six patients without it. The analysis revealed five immune-related proteins upregulated among those with Sjögren’s — complement C3, complement factor B, clusterin, calreticulin and neutrophil elastase.
Then, in a cohort of 186 patients, 65% of whom were diagnosed with primary Sjögren’s disease, enzyme-linked immunosorbent assay showed “notable” increases of each of those proteins among patients with confirmed primary Sjögren’s, compared with individuals who did not have the condition.
Finally, to construct a potential non-invasive model for Sjögren’s diagnosis, the researchers used logistic regression to decide on the following six components: the proteins complement factor B, clusterin and neutrophil elastase; the autoantibodies anti-SSA/Ro60 and anti-SSA/Ro52; and Schirmer’s test, which measures how well tear glands keep eyes moist.
In the 186-patient cohort, the six-marker model more accurately distinguished patients with primary Sjögren’s, compared with a model only including the autoantibodies and Schirmer’s test. According to the researchers, the six-marker model was found to have an area under the curve of 0.930 (95% CI, 0.877-0.965; P < .001) vs. 0.832 (95% CI, 0.767-0.896; P < .001) in the more limited model, with 84.85% sensitivity and 92.45% specificity.
Similar results were seen in a validation cohort with 72 patients.
“As biopsy is an invasive examination and the six-marker prediction model showed potential to replace [minor salivary gland biopsy], it’s recommended to use the model before [minor salivary gland biopsy] to reduce the number of unnecessary biopsies while missing fewer [primary Sjögren’s disease] patients,” Zhang and colleagues wrote. “As the non-invasive model can be repeated to monitor the patient’s condition, it would be valuable to explore further the application of the model in disease assessment and treatment plans.”
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