The development and initial validation of the Liverpool sicca index to assess symptoms and dysfunction in patients with primary Sjögren''s syndrome

Background: A validated measure to assess sicca‐related symptoms in patients with primary Sjögren's syndrome (1°SS) is required for clinical studies. Methods: A self‐administered questionnaire was developed to assess sicca‐related symptoms and dysfunction in 1°SS. This was administered to three groups of 40 respondents to measure construct validity: 1°SS patients, non‐SS patients reporting xerostomia and a non‐patient group. The frequency of scores and the mean score for each question were calculated for each group. Reliability was assessed by test/retest. Results: The measure consisted of 28 items divided into five domains. Scores for questions in domains were generally worse (higher) for 1°SS patients than for patients with xerostomia. The non‐patient group reported the best (lowest) scores for all questions. The Kappa statistic for all but four questions was greater than 0.6, suggesting good reliability. Conclusion: Questionnaire showed good construct validity and reliability. The Liverpool sicca index needs to be further validated in larger, multicentre studies.