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.
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.
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.
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.
•Xerostomia is highly prevalent among SS patients and is associated with several clinical characteristics of SS.•Test diagnostics of xerostomia and other findings indicate that xerostomia is an important indicator of SS.•Findings of the study have implications for SS classification systems and SS intervention trials.
Research in Context
Data on the prevalence of xerostomia/dry mouth in SS are lacking, despite it being a chief complaint of patients. SS is a complex autoimmune disorder that is defined on the basis of classification criteria. There is ongoing debate on the selection of criteria and a consensus has not yet been reached by the scientific community. There is push to eliminate both xerostomia and hyposalivation, an objective sign of low salivary flow, from SS classification. This study offers evidence on the importance of xerostomia with implications for SS classification. Clinical trials to test newer treatment modalities for SS use classification criteria to define an SS case. Therefore, classification criteria are critical for research and advancement of newer therapeutics for SS. Xerostomia should be targeted as a patient-centered research outcome in SS intervention trials.