As a part of this study, the international set of classification criteria was to be developed for primary Sjögren’s syndrome (SS) while adhering to the American College of Rheumatology (ACR) and the European League Against Rheumatism (EULAR) guidelines. With the help of these criteria, the assessment of individuals for SS was determined. The multi-criterion decision analysis was used to assign preliminary importance weights to the list of candidates. Besides, the resulting draft criteria were tested and adapted on primary SS cases and non-SS controls with the existing cohort data with case/non-case status assessed through expert clinical judgment. After this, the performance of the classification criteria was validated through a separate cohort of patients. 

A total of 5 items were used in the final classification criteria including anti-SSA/Ro antibody positivity and focal lymphocytic sialadenitis with a focus score of ≥1 foci/4 mm2, each scoring 3; an abnormal ocular staining score of ≥5 (or van Bijsterveld score of ≥4), a Schirmer’s test result of ≤5 mm/5 minutes, and an unstimulated salivary flow rate of ≤0.1 ml/minute, each scoring 1.

A total score of less than or equal to 4 for the above items meet the criteria for primary SS had signs of SS. In the final validation, sensitivity and specificity against clinician-expert–derived case/non-case status was high.