Clinical significance of quantitative immunohistology in labial salivary glands for diagnosing Sjogren's syndrome.
OBJECTIVE
Because patients with primary Sjögren's syndrome (pSS) are at risk of developing other autoimmune phenomena and malignant lymphoma, it is important to distinguish pSS from non-Sjögren's (nSS) sicca syndrome. However, this distinction might be difficult because of the lack of a gold standard for pSS. We studied the clinical significance of quantitative immunohistology (QIH) in labial salivary glands for diagnosing pSS.


METHODS
In a model mimicking the making of a clinical diagnosis, five experts diagnosed 396 patients as nSS, 'indefinite', pSS or secondary SS (sSS) using 25 clinical parameters. Patients were diagnosed twice, namely without (yielding gold-standard diagnoses) and with knowledge of QIH. The numbers of changes in diagnosis from 'indefinite' to 'definite' (nSS, pSS or sSS) or vice versa were compared. Patient groups with vs without a changed diagnosis in the four gold-standard diagnosis groups were compared regarding objective autoimmune parameters.


RESULTS
Sensitivity, specificity, positive and negative predictive value for abnormal QIH in pSS vs nSS were 93, 86, 76 and 96%, respectively. Changes in diagnosis from 'indefinite' to 'definite' (31%) were found more often (P = 0.00) than changes from 'definite' to 'indefinite' (10%). Knowledge of QIH distinguished patient groups within the gold-standard nSS, indefinite and pSS patient group with regard to autoimmune parameters.


CONCLUSIONS
In view of the consequences of distinguishing pSS from nSS, these results point to an additional diagnostic role for QIH in clinical practice.
van Woerkom
J M
JM
Department of Rheumatology and Clinical Immunology, F02.127 University Medical Center Utrecht, PO Box 85500, 3508 GA Utrecht, The Netherlands. jm.woerkom@gelre.nl
Kruize
A A
AA
Barendregt
P J
PJ
Kater
L
L
Hené
R
R
Bootsma
H
H
Custers
R J H
RJ
Jacobs
J W G
JW
Bijlsma
J W J
JW
D001323:Autoantibodies / Q000032:analysis; D001799:Blood Sedimentation; D005260:Female; D006801:Humans; D007070:Immunoglobulin A / Q000032:analysis; D007074:Immunoglobulin G / Q000097:blood; D008214:Lymphocytes / Q000276:immunology; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012217:Rheumatoid Factor / Q000032:analysis; D012469:Salivary Glands / Q000276:immunology*; D012680:Sensitivity and Specificity; D012859:Sjogren's Syndrome / Q000175:diagnosis / Q000276:immunology*
D001323:Autoantibodies; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D012217:Rheumatoid Factor