Minor salivary flow as a diagnostic tool for screening hyposalivation in Medication-Induced Xerostomia

We aimed to determine whether minor salivary flow (MSF) rate, measured via a rapid paper-based test, can serve as a reliable screening tool for detecting hyposalivation. This study, conducted in a real-world clinical setting, evaluated the diagnostic performance of MSF against unstimulated whole saliva (UWS) as the reference standard in individuals experiencing xerostomia due to medications.

We conducted a cross-sectional study of 135 adults aged 45-64 years with xerostomia and ongoing anticholinergic medication use. MSF was measured using a one-minute Shrimer strip placed in the upper labial vestibule, and reliability was assessed via triplicate measurements in a subsample (n = 40). UWS flow was used as the reference standard for reduced (hyposalivation) saliva secretion. The diagnostic performance of MSF was analyzed using Receiver Operating Characteristic (ROC) curves, and multivariable logistic regression assessed its predictive utility after adjusting for demographic and clinical covariates.

MSF demonstrated high internal consistency (Cronbach's α = 0.94) and strong inter-replicate agreement (r = 0.83-0.87). Participants with hypo ratetion had significantly lower MSF than those without (mean difference = 2.41 µL/cm²/min, p < 0.001). At an optimal MSF cutoff, sensitivity was 80.0% and specificity was 54.5% (with Area Under the Curve; AUC = 0.726). In multivariable models, MSF and xerostomia severity were independent predictors of hyposalivation, with an overall model AUC of 0.827.

MSF, measured using a simple, non-invasive method, is a reliable and moderately accurate screening tool for identifying hyposalivation in adults with medication-induced xerostomia. These findings support its use in clinical settings; however, further refinement and validation are necessary to establish diagnostic thresholds and determine its applicability.