Parotidomegaly is a criterion of the EULAR Primary Sjögren Syndrome Disease Activity Index (ESSDAI). The cut-off value was set at 3 cm in length for the parotid gland, 2 cm for the submandibular glands. However, clinical appreciation of salivary glands size remains hazardous. The objective is to evaluate inter-observer reproducibility of parotid gland measurement by palpation, and to secondary evaluate its reliability compared to US assessment.
Outpatients with primary Sjögren Syndrome (pSS) or with a diagnostic suspicion, in a single reference centre, were included. They underwent clinical examination by two independent investigators (VDP and DC), evaluating: parotid gland swelling, parotid gland size (direct measurement with a decameter under the mandibular angle), and pain. Cohen's kappa coefficient was calculated to determine inter-observer concordance for parotid gland swelling, and intraclass correlation coefficient to determine inter-observer agreement of gland size measurement.
Thirty-four patients (33 women, 1 man) were included. Clinical data were complete for 33 patients. Inter-observer concordance Kappa coefficient was 0.90 [0.76-1.00] for detection of parotidomegaly over 66 parotid glands. It was of 0.60 [0.42-0.73] for gland length measurement. For one observer, the median cut-off for defining parotidomegaly was 4.15 cm; for the second observer, it was of 4.92 cm. For submandibular glands palpation, no correlation was found between investigators. A significant association between clinical parotidomegaly and a larger echographic surface was found.
Clinical measurement of parotidomegaly was concordant between two observers on a binary mode (presence/absence). However, concordance on direct measurement was weak. US could be a complementary examination.