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Updated: Jul 9, 2026
Ultrasonographic Evaluation of Salivary Glands for Sjogren's Syndrome: Diagnostic and Monitoring Insights
Published on: October 13, 2023
Age-specific reference values for unstimulated whole saliva flow rate in primary Sjögren's syndrome: a
Yang Yang1, Xin-Xiang Huang1, Dan-Li Meng1
1Department of Rheumatology and Immunology, People's Hospital of Guangxi Zhuang Autonomous Region, Nanning, 530016, China.
Background:
The clinical phenotype of primary Sjögren's syndrome (pSS) varies with age at onset, yet evidence on age and unstimulated whole saliva (UWS) flow rate in pSS is limited and conflicting. This study describes the age-specific distribution of UWS flow rate in pSS patients and provides reference values for clinical use.
Methods:
This retrospective cross-sectional study included pSS patients diagnosed per 2016 ACR/EULAR criteria, stratified by age at diagnosis: early-onset (≤ 35 years), middle-onset (35-65 years), and elderly-onset (≥ 65 years). UWS flow rate was compared across groups. Linear regression assessed the age-UWS association, adjusting for sex, pre-diagnostic period, and anticholinergic use. For each age group, we calculated the 5th, 25th, 50th, 75th, and 95th percentiles of UWS flow rate as reference values.
Results:
Of 338 pSS patients (early-onset ≤ 35 years: 40; middle-onset 35-65 years: 193; elderly-onset ≥ 65 years: 105), UWS flow rate decreased significantly with age. Each 10-year increase was associated with a 0.04 mL/min decrease (β= -0.04, 95% CI: -0.06 to -0.03, P < 0.001), independent of sex, pre-diagnostic period, and anticholinergic use. The median UWS flow rate was 0.29[0.20-0.47] mL/min in the early-onset group, 0.20[0.10-0.39] mL/min in the middle-onset group, and 0.14[0.05-0.22] mL/min in the elderly-onset group, with significant differences between early- and middle-onset (P = 0.013) and between middle- and elderly-onset (P < 0.001). Age-specific percentiles were established as reference values.
Conclusion:
UWS flow rate in pSS patients declines with age, independent of confounders. The age-specific reference values provided herein facilitate longitudinal monitoring and interpretation of UWS measurements in clinical practice.
