Aims To assess the prevalence and determine predictors of Sjögren's syndrome (SS) in patients with clinically significant aqueous-deficient dry eye.

Methods Patients enrolled in an industry-sponsored, multicentre clinical trial (NCT00784719) were assessed prospectively for the presence of SS. Ocular testing included Schirmer test, corneal fluorescein staining, conjunctival lissamine green staining, and tear-film breakup time. Review of systems questionnaire, medical history, dry eye questionnaire and laboratory work-up (Sjögren-specific antibody A (SSA), Sjögren-specific antibody B (SSB), rheumatoid factor (RF) and antinuclear antibody (ANA)) were obtained.

Results Of 327 patients, 38 (11.6%) had SS: 21 (6.4%) with primary SS (pSS), and 17 (5.2%) with secondary SS. Nine patients (3%) were newly diagnosed using the applied diagnostic criteria based on American–European consensus criteria. Patients with SS had significantly worse conjunctival and corneal staining, Schirmer test (with and without anaesthesia), and symptoms compared with patients without SS. pSS Was significantly more likely to occur in patients with positive ANA (OR: 13.9) and RF (OR: 4.8).

Conclusions Ophthalmologists caring for patients with clinically significant dry eye should have a high index of suspicion for underlying SS and low threshold for serological work-up. RF and ANA are recommended as useful tests in SSA/SSB-negative patients for further diagnostic referral.