The occurrence of xerostomia and salivary gland hypofunction in a population-based sample of older South Australians.

This paper examines the prevalence of and concurrence between the symptoms of dry mouth (xerostomia) and reduced salivary flow (SGH) among a population-based sample of older South Australians. Participants in a longitudinal dental study of older people were asked a global question about their experience of dry mouth ("How often does your mouth feel dry?"), and those who responded "Always" or "Frequently" were categorized as xerostomic. Unstimulated whole salivary flow rate was measured, and individuals whose flow rate was less than 0.1 mL/min were categorized as SGH cases. Saliva samples were collected from 700 individuals, of whom 683 (97.7%) answered the dry-mouth question. The mean unstimulated salivary flow rate was 0.27 mL/min (SD 0.22). The prevalence of SGH was 22.1%, and the prevalence of xerostomia was 20.5%, but only 5.7% of participants had both conditions. Almost two-thirds of the sample had neither condition. Males and females differed in the degree of concurrence between the two conditions. It appears that, in the group studied, xerostomia and SGH were largely discrete conditions, supporting the assertion by other workers that low salivary flow may not be the key factor in the etiology of xerostomia among older people.