Salivary flow rate in children and teenagers with Down syndrome: Systematic review and meta-analysis.

The purpose of our review was to group the evidence and attempt to provide a consensus on the behavior of salivary flow rate in patients with Down syndrome. Observational studies evaluating salivary flow rate in children and teenagers with Down syndrome compared with non-syndrome individuals were selected. Ten sources of information were researched. The risk of bias was assessed by using the Newcastle Ottawa Scale tool . Inverse Variance was ty the SMD (95% Confidence Interval). The certainty of the evidence was determined according to the GRADE approach. Fourteen studies were evaluated. The results showed, with a very low certainty of evidence, that children and teenagers with Down syndrome present a lower salivary flow rate compared with non-syndrome controls (SMD: -1.71, 95%IC: -2.81; -0.60, p < 0.05), with significant differences in the saliva collection methods (p < 0.05) (Unstimulated saliva, SMD -5.07, 95%CI: -7.96; -2.18, p < 0.01; Stimulated saliva, SMD -0.80, 95%IC: -1.78; 0.17, p = 0.11). The behavior of the salivary flow rate is not significantly different between the age groups (p = 0.60) (up to 5 years old, SMD -1.85, 95%CI: -2.90; -0.81, p < 0.01; 2 to 18 years old, SMD -1.51, 95%CI: -2.24; -0.78, p < 0.01), and the sex (p = 0.70) (Male, SMD -1.77, 95%CI: -2.39; -1.16, p < 0.01; Female, SMD -1.53, 95%CI: -2.58; -0.48, p < 0.01). Children and teenagers with Down syndrome present a lower salivary flow rate with an unstimulated saliva collection method compared to non-syndrome.