Rheumatology Advance Access originally published online on November 15, 2005
Rheumatology 2006 45(4):470-477; doi:10.1093/rheumatology/kei191
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Clinical significance of quantitative immunohistology in labial salivary glands for diagnosing Sjögren's syndrome
Department of Rheumatology and Clinical Immunology, University Medical Center Utrecht, Utrecht, 1 Department of Rheumatology, Erasmus University Medical Centre, Rotterdam and 2 Department of Rheumatology, University Medical Centre Groningen, Groningen, The Netherlands.
Correspondence to: J. M. van Woerkom, Department of Rheumatology and Clinical Immunology, F02.127 University Medical Center Utrecht, PO Box 85500, 3508 GA Utrecht, The Netherlands. E-mail: jm.woerkom{at}gelre.nl
Objectives. 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.
Conclusion. In view of the consequences of distinguishing pSS from nSS, these results point to an additional diagnostic role for QIH in clinical practice.
KEY WORDS: Primary Sjögren's syndrome, Sicca syndrome, Quantitative immunohistology