Incorporating Salivary Gland Ultrasonography in ACR-EULAR Criteria for Sjogren Syndrome

Salivary gland ultrasonography can be incorporated into the American College of Rheumatology-European League Against Rheumatism (ACR-EULAR) criteria for primary Sjogren syndrome (pSS), with no decrease in criteria accuracy, sensitivity, or specificity, according to research results published in Arthritis Care and Research.

Researchers sought to determine whether the performance of the ACR-EULAR criteria for pSS was affected by the addition of salivary gland ultrasonography. Previous clinical cohort studies found that the incorporation to this criteria increased sensitivity with only a minor decrease in specificity.

The total study population included 243 patients with primary or nonprimary Sjogren syndrome (non-pSS), although all of them fulfilled the ACR-EULAR criteria.

Overall, the accuracy of the salivary gland ultrasound was good (area under the curve [AUC] 0.860; 95% CI, 0.821-0.900) with an optimal cutoff value of ≥1.5. Based on this cutoff point, salivary gland ultrasound was positive in 106 patients with pSS and 6 patients with npSS, and negative in 41 and 90 patients, respectively. Absolute agreement with the clinical diagnosis was 80.7%; sensitivity and specificity were 72.1% and 93.8%, respectively.

Salivary gland ultrasonography was added to the ACR-EULAR criteria using a weight of either 1, 2, or 3. Researchers found that criteria performance including the ultrasound was the highest when assigned a weight of 1 point. The optimal cutoff was confirmed to be ≥4.

Among the 124 patients who underwent labial gland biopsy, original ACR-EULAR criteria demonstrated an AUC of 0.965 with a sensitivity and specificity of 95.9% and 92.2%, respectively. Following the addition of salivary gland ultrasound, the AUC was 0.966 with a sensitivity and specificity of 97.3% and 88.2%, respectively. Similar results were found in the 198 patients who underwent parotid gland biopsy.

When salivary gland ultrasonography replaced salivary gland biopsy or anti-Sjogren-syndrome-related antigen A (anti-SSA) antibodies, criteria sensitivity substantially decreased. However, no major changes in accuracy, sensitivity, or specificity occurred when the ultrasound replaced the Ocular Staining Score, Schirmer’s test, or the unstimulated whole saliva flow.

One potential study limitation was the use of clinical diagnosis, instead of expert consensus, as a gold standard for diagnosis of pSS. However, the researchers noted that even the use of expert consensus may have introduced bias depending on expert familiarity with the salivary gland ultrasound.

“The validity of the ACR-EULAR criteria remains high after the incorporation of [salivary gland ultrasound],” the researchers of the study concluded. “[Salivary gland ultrasound] is noninvasive, nonirradiating, inexpensive, and relatively easy to perform in an outpatient setting.”

They added, “Incorporation of [salivary gland ultrasound] into the ACR-EULAR criteria improves their feasibility in clinical practice by allowing rheumatologists to choose from a larger array of tests.”

Disclosure

This work was supported in part by Bristol-Myers Squibb, and conducted in line with the Declaration of Helsinki. The research protocol was in accordance with the Medical Ethics Committee of the UMCG. Please see original text for a full list of disclosures. 

Reference

van Nimwegen JF, Mossel E, Delli K, et al. Incorporation of salivary gland ultrasonography into the ACR-EULAR criteria for primary Sjögren’s syndrome [published online June 29, 2019]. Arthritis Care Res. doi: 10.1002/acr.24017