Psychological and somatic predictors of perceived and measured ocular dryness of patients with primary Sjögren's syndrome

Objective. To test if age, disease activity, pain, fatigue, and depression are associated with subjective and objective ocular dryness of patients with primary Sjögren's syndrome (pSS). Methods. Sixty female patients with pSS and 60 age matched healthy controls filled out visual analog scale (VAS) scores of ocular dryness and pain, and questionnaires regarding fatigue (Multidimensional Fatigue Inventory) and depression (Zung). Lacrimal tear production was measured by Schirmer I test. As surrogate indicators of disease activity the erythrocyte sedimentation rate, hemoglobin concentration, and total serum immunoglobulin G were determined. Results. Perceived ocular sicca symptoms were not related to Schirmer I test scores. The rate of tear production was related to age (r = -0.47, p < 0.001), disease activity (r = -0.27, p < 0.05), and pain (r = 0.42, p < 0.001). Age and pain together explained 42% of the variance of the Schirmer I test results. Conclusion. Not unexpectedly, age and disease activity were associated with ocular dryness, but contrary to expectation, pain was associated with more instead of less tear production. We did not find evidence that pain, fatigue, or depression are associated with reduced tear production or perceived ocular dryness.