Subjective Xerostomia and Chairside Salivary Dysfunction in Institutionalized Older Adults: Concordance and Exploratory Derivation of a Five-Item Short Form

Abstract

Background/Objectives: In institutionalized older adults, we examined the concordance between self-reported xerostomia and chairside salivary dysfunction and explored whether a smaller subset of Xerostomia Inventory items could retain comparable screening performance. Methods: This cross-sectional study included institutionalized older adults. The 11-item Xerostomia Inventory was compared with a six-marker chairside whole-saliva panel, with all variables scaled 0 (normal) to 1 (pathological). We measured how closely symptoms tracked each objective marker, how well the questionnaire identified hyposalivation, and whether fewer questions could be comparable with the full 11-item inventory. Results: The study included 90 participants, with a mean age of 79.5 years; 55.6% were women. Symptoms tracked every marker in the expected direction (correlation τ-b 0.32 to 0.62). The questionnaire identified objective hyposalivation with an area under the ROC curve of 0.87 (95% CI 0.78–0.96) and substantial chance-corrected agreement (Cohen’s κ 0.69, 95% CI 0.51–0.87). A five-item short form reproduced the objective findings as well as the full questionnaire did (cross-validated R2 0.56 ± 0.03 versus 0.56). Conclusions: In this high-prevalence institutional cohort, self-reported symptoms agreed with graded salivary function more closely than the older discordance literature would suggest, though still within the range of recent studies rather than beyond it. A five-item subset, chosen for its alignment with the objective salivary axis rather than for internal consistency, recovered as much as the full inventory, which points to a short, function-oriented score as a plausible first-stage screen. We would treat this short form as a candidate first-stage screening approach that requires external validation, rather than as a replacement for objective salivary assessment or as a validated replacement for the Xerostomia Inventory.