Reappraisal of tests for xerostomia.

Our goal was to establish the practical usefulness of combinations of tests (saliva flow rate, SFR; salivary lysozyme, Lys; salivary lactoferrin, Lf; sialography, SG; salivary gland scintigraphy, SGS; and labial salivary gland biopsy, SGB) for the oral component of Sjögren's syndrome (SS). These tests were applied to 40 patients with primary SS (group A, defined by the presence of keratoconjunctivitis sicca, a positive response to two of three selected questions for xerostomia and the presence of two of four autoantibodies), 16 patients with secondary SS (group B), 16 patients with connective tissue disease but no evidence of secondary SS (group C) and 14 normal controls (to establish the threshold of the six tests). SFR was decreased in 68, 56 and 19% of the patients in groups A-C respectively [sensitivity (sens) 68%, specificity (sp) 81%, positive predictive value (PPV) 90% and negative predictive value (NPV) 50% for primary SS]. Lys was elevated in 3, 0 and 0% of the patients in groups A-C (sens 3%, sp 100%, PPV 100% and NPV 66%). Lf was reduced in 58, 69 and 25% of the patients in groups A-C (sens 58%, sp 75%, PPV 82% and NPV 53%). SG was positive in 74, 27 and 13% of the patients (sens 74%, sp 87%, PPV 93% and NPV 41%). SGS was positive in 75, 63 and 25% of the patients (sens 75%, sp 75%, PPV90% and NPV 45%). SGB was abnormal in 95, 94 and 25% (sens 95%, sp 75%, PPV 90%, NPV 14%).(ABSTRACT TRUNCATED AT 250 WORDS)