To verify whether ocular surface tests other than those included in primary Sjögren's syndrome (SS-I) classification criteria (Schirmer I, Break up Time, vital dye staining) may contribute to SS I diagnosis.
Two hundred and sixty-two patients (78 SS-1, 91 non-SS autoimmune diseases, 93 Sicca syndrome) filled a validated questionnaire on symptoms and were evaluated by Schirmer test without (Schirmer I) and with (Jones test) topical anaesthesia, Break Up Time (BUT), corneal aesthesiometry, tear clearance rate, vital dye (lissamine green) staining, impression conjunctival cytology, concentration of tear lysozyme and lactoferrin. Thresholds were selected from Receiver Operating Curves; sensitivity, specificity, likelihood ratio (LR+), predictive values were calculated for each test. A logistic regression model was constructed representing the best diagnostic index for SS.
Data showed a poor diagnostic performance of Schirmer test I (LR+ 1.38) and BUT (LR+ 1.05); results from lissamine green staining may be unreliable due to incorporation bias. Tear lactoferrin (LR+ 4.52), Jones test (LR+ 6.24), tear lysozyme (LR+ 8.0), symptom questionnaire (LR+ 8.62), tear clearance rate (LR+ 18.73) and corneal aesthesiometry (LR+ 20.96) exhibited high diagnostic performance also taken together in the regression model.
Because many of the tests we have screened in this study can be carried out by a trained ophthalmologist in any clinical setting, we recommend that ocular surface impairment is studied with the combination of tests proved to be helpful for the SS I diagnosis.