Early Childhood Caries Experience Associated with Upper Respiratory Infection in US Children: Findings from a Retrospective Cohort Study

Introduction: Both Early Childhood Caries (ECC) and Upper Respiratory Infection (URI) are infectious diseases. The oral cavity is considered a potential reservoir of respiratory pathogens due to the anatomical proximity between the oral cavity and respiratory system, which implies a potential association between ECC and URI. Hence, this study aimed to evaluate the association between ECC experience and URI incidence in preschool children. Methods: This retrospective cohort study collected data via electronic health records. The exposure was ECC before 3 years of age. The dependent variable was the incidence of URI between 4-6 years of age. To analyze the factors associated with the time-to-event of URI, we used log-rank tests and Cox regression models to compare the survival of URI between the ECC and Caries- Free (CF) groups, adjusting factors including demographic-socioeconomic characteristics and medical conditions. To analyze factors associated with the number of URI episodes, we used negative binomial regression models adjusting for factors mentioned above. Results: A total of 497 US preschool children were included, with 117 ECC and 380 CF children. More children with ECC (58.1%) developed URI than the CF group (47.6%) during the follow-up period (4-6 years of age) (p=0.04). The ECC children were at 1.6 times higher risk to develop URI than the CF children even after accounting for other URI risk factors (Hazard Ratio 1.57 (1.13, 2.10), p=0.007). Conclusions: Our study suggests a potential association between ECC and URI, with an inference that early life ECC experience could be used as a predictor for developing URI in preschool age. The causal relationship between ECC and URI incidence in young children needs to be investigated through future studies.