Association between deleterious oral habits and asthma in children: a systematic review and meta-analysis

Deleterious oral habits (DOH) have been described as a common finding in pediatric series. Studies have investigated their association with local and systemic health problems. In this study, the association between DOH and asthma was investigated. PubMed, Scopus, Lilacs, Web of Science, Google Scholar, and OpenThesis were accessed to identify observational studies that evaluated the association between DOH (thumb sucking, pacifier use, onychophagia or nail biting, bottle feeding) and asthma in children aged 2-17 years. Information on DOH was obtained from the verbal report of the children's parents. Asthma diagnosis was performed by a physician or using the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire. We used a random-effects model to pool the results. The odds ratio (OR) was used as measure of association between DOH and asthma. The National Institutes of Health Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies was used to assess risk of bias. The GRADE approach was used to assess the quality of evidence. Five studies were included and data from 18,733 children aged 2 to 13 years were analyzed. We found an association between bottle feeding and asthma (OR = 1.25; 95%CI 1.13-1.38; p < 0.001) with moderate level of certainty. Despite the association between pacifier use and asthma (OR = 1.11; 95%CI 1.00-1.24; p = 0.05), the quality of evidence was low. Only one study provided data on nail biting and thumb-sucking, and the individual results showed no association between these habits and asthma. This meta-analysis found an association between bottle feeding, pacifier use, and asthma in children.