Thomson WM*, Spencer AJ, Chalmers J, Carter KD

Little is known of the natural history of dry mouth among older people, because very little information is available on changes in dry mouth over time among population-based samples. Objectives: To describe changes in dry mouth over a 6-year period among older S outh Australian males and females. Methods: Prospective cohort study of people aged 60+ years at baseline (in 1991/92) who were representative of the populations of Adelaide and Mt Gambier. At the 5-year assessment in 1996/97 and again 6 years later, participants completed the Xerostomia Inventory (XI; Thomson et al, Community Dental Health 16: 12-17, 1999) and a single-item question on dry mouth. Unstimulated salivary flow was measured using the spit method. At baseline, 5 and 11 years, information was collected on medications taken in the previous 2 weeks. Results: Complete data were available for 269 dentate individuals. Between the 5- and 11-year assessments: the prevalence of xerostomia increased from 20.4% to 24.4%; the mean XI score increased from 19.8 (sd, 6.2) to 20.0 (sd, 6.5); and the mean flow rate showed no change. A salivary flow rate of <0.1 ml/min (indicating salivary gland hypofunction, or SGH) was observed among 24.2% at 5 years, but only 9.7% at 11 years. Proportionally more females than males had SGH at both 5 and 11 years (and more became new cases by 11 years). Medication prevalence increased from 58.8% to 95.7% over the assessment period, with those taking more medications having more severe xerostomia. Conclusion: While the prevalence and severity of xerostomia increase over time among older people (particularly females), the pattern with respect to salivary flow is less clear-cut. Supported by NHMRC, NIH DE-09588.