The relation between xerostomia and hyposalivation in subjects with rheumatoid arthritis or fibromyalgia

Aim of this study was to evaluate the relation between xerostomia and hyposalivation in 100 subjects with either rheumatoid arthritis or fibromyalgia, and further, to evaluate the predictive value of xerostomia on hyposalivation. Unstimulated and chewing stimulated whole saliva was collected in the morning with the subjects in a strict fasting condition and then about 2 hours later, after intake of a standardised breakfast. All participants filled in a questionnaire, mainly dealing with xerostomia. Forty subjects demonstrated a pathological fasting unstimulated whole saliva secretion rate, the corresponding number for fasting stimulated secretion being 39. For unstimulated, but not for stimulated saliva, the fasting secretion rate was significantly lower than the non-fasting. Xerostomia was reported by 74 subjects, this group having significantly lower both unstimulated and stimulated secretion rates than the non-xerostomic group. On the individual level, the predictive value of xerostomia on hyposalivation showed high sensitivity but unsatisfactory specificity. In conclusion, this study underlines the importance of applying strictly standardised procedures when collecting saliva, and that fasting unstimulated whole saliva is the diagnostic salivary secretion of choice. Finally, xerostomia was found to predict hyposalivation on a group, but not on an individual level.