Background Ultrasonography (US) is useful method in visualizing of salivary glands abnormalities in patients (pts) with primary Sjogren's syndrome (pSS). According to previous studies, parenchymal inhomogeneity in salivary glands is the most relevant sonographic sign in pSS (1-3). However, assesment of inter-observer agreement is needed.
Objectives To evaluate the inter-observer agreement between 5 observers (3 experienced, 2 unexperienced) in US assessment of inhomogeneity of salivary glands in pts with suspected pSS and healthy subjects
Methods Twenty-four pts with suspected pSS (all female, mean age 50.2±11.2, range 22 to 74) and eight healthy subjects (all female, mean age 48.6±10.4, range 23 to 62) were recruited from clinic patients and medical staff of Institute of Rheumatology, Belgrade, Serbia. Informed consent was obtained from all the subjects and the study was approved by the ethics committee. Esaote My Lab 70 ultrasound machine with a 4-13 MHz linear array transducer was used for the US examination of salivary glands. In each subjects, 2 parotid and 2 submandibular glands were examined independently by 5 ultrasound investigators blinded for clinical findings. Homogeneity of salivary glands were evaluated in accordance with 4-grade system: Grade 0– homogenious punctiform pattern isoechogenic to normal thyroid gland; Grade 1–mild inhomogeinety without focal hypo/anechoic rounded areas; Grade 2–moderate inhomogeinety with or without small focal hypo/anechoic rounded areas; Grade 3–severe inhomogeinety without or with focal hypo/anechoic rounded areas occupaing whole crossection of a gland. Grade 2 and 3 were considered pathological. Data were analysed using SPSS version 16.0. Interobserver agreement was calculated by the weighted kappa (κ)-statistics. A κ-value of <0.20 was considered poor agreement, 0.21-0.40 fair, 0.41–0.60 moderate, 0.61–0.80 good and 0.81–1.00 excellent (4).
Results A total of 128 salivary glands (64 parotid glands and 64 submandibular glands in 32 subjects) were examined by each of 5 observers. Multirater kappa agreement with 95% CI for right parotid glands was good 0.79 (0.68-0.87, p=0.000). The percentage of agreement observed for right parotid glands were in range from 59.3% to 84.3%. The weighted kappa for left parotid glands was excellent 0.810 (0.71-0.89, p=0.000). The percentage of agreement observed for left parotid glands was in range from 56.2% to 87.5%. Similar to right parotid glands, multirater kappa agreement for right and left submandibular glands were good, 0.71 (0.57-0.82, p=0.000) and 0.73 (0.60-0.84, p=0.000) respectively. The percentage of agreement observed for right and left submandibular glands was in range from 37.52 to 78.1% and 40.6 to 84.3% respectively.
Conclusions Our 4-grade system of US assessment of parenchymal inhomogeneity of salivary glands showed good to excellent inter-observer agreement in pts with suspected pSS. Thus, US is a reliable method for objective evaluation of salivary glands.
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Disclosure of Interest None declared