Relationship between disease duration and salivary flow rates in patients with primary Sjögren's syndrome. The relationship between disease duration (the time from first complaints induced by or related to oral dryness until referral) and mean (standard error of the mean) salivary flow rates in primary Sjögren's syndrome (pSS) patients. Normal values are derived from historic controls (n = 36). SM/SL, submandibular/sublingual glands; UWS, unstimulated whole saliva. *Significant difference versus patients with early-onset pSS (≤1-year oral complaints; P < 0.005) by Mann-Whitney U test. †Significant difference versus patients with early-onset pSS (P < 0.05) by Mann-Whitney U test. Reprinted with permission from .