Significance and Implications of Patient-reported Xerostomia in Sjögren's Syndrome: Findings From the National Institutes of Health Cohort

Background Xerostomia is a chief complaint of patients with Sjögren's syndrome (SS). However, newer proposals for SS classification remove xerostomia and hyposalivation from the criteria list. Given these developments and the importance of patient-centered research outcomes, we sought to evaluate the utility of patient-reported xerostomia with implications for classification criteria, and clinical trials targeting SS treatment modalities. Methods A nested case-control study was designed within The National Institute of Dental and Craniofacial Research/National Institutes of Health (NIDCR/NIH) SS Cohort - one of the largest SS cohorts in the US. Clinical characteristics of those with and without xerostomia in SS and other salivary gland dysfunctions were compared. Several analytical methods were employed, including multivariable logistic regression modeling. Findings The NIDCR/NIH Sjögren's Syndrome Clinic has an open cohort with ongoing enrollment since 1984. This open cohort comprised of 2046 participants by August 27, 2015. Baseline data of 701 SS, 355 Sicca, and 247 ISS participants within the source cohort were analyzed. Xerostomia was highest among SS participants (87.4%, 95% CI: 84.8%–89.8%) compared to Sicca (72.4%, 95% CI: 67.4%–77.0%, p < 0.001) and ISS groups (38.1%, 95% CI: 32.0%–44.4%, p < 0.001). Those with xerostomia were more likely to have SS than Sicca/ISS (OR = 4.98, 95% CI: 3.78–6.56). The ability of xerostomia to screen for SS among those with salivary gland dysfunction was higher than screening for Sicca/ISS. Screening diagnostics of xerostomia were of greater utility compared to hyposalivation. After adjusting for confounding in multivariable modeling, SS participants with xerostomia were more likely to be White (Black/African Americans (OR: 0.40, 95% CI: 0.23–0.68, p-value = 0.001) and Asians (OR: 0.49, 95% CI: 0.25–0.96, p-value = 0.038) were less likely to have xerostomia compared to Whites), have dry eye symptoms for > 3 months (OR: 5.80, 95% CI: 3.62–9.28, p-value < 0.001), a lower Van Bijsterveld score (OR: 0.55, 95%CI: 0.34–0.90, p-value = 0.017), a lower stimulated salivary flow rate (OR: 1.67, 95% CI: 1.06–2.65, p-value = 0.028), a focus score of > 2 (OR: 1.92, 95% CI: 1.20–3.09, p-value = 0.007), and salivary gland swelling (OR: 49.39, 95% CI: 2.02–1206.30, p-value = 0.017). Age, gender, fatigue, pain, anxiety, and autoantibodies were not significantly associated with xerostomia. Interpretation Findings from this study indicate that patient-reported xerostomia is highly prevalent among SS patients and is associated with several clinical phenotypes of this complex syndrome, thereby making it an important indicator of SS. The evidence also suggests that xerostomia is not limited to low salivary flow but might be reflective of compositional changes of saliva. Consequently, these findings suggest the need to consider xerostomia in the development of SS classification criteria and in patient-centered outcomes research in SS intervention trials. This research was supported by the Intramural Research Program of the National Institutes of Health (NIH), National Institute of Dental and Craniofacial Research (NIDCR) Grant # DE000704-15. Dr. Baer is supported by RO1-DE-12354-15A1.