Background: Risk factors for gastroesophageal reflux disease in preterm neonates have not been yet clearly defined.
Aim: To identify factors associated with increased esophageal acid exposition in preterm infants during the stay in the neonatal unit.
Methods: A case-control study in preterm infants who had undergone prolonged monitoring of distal esophageal pH, following clinical indication. Eighty-seven preterms with reflux index (percentage of total time of esophageal pHmetry) > or = 10% (cases) and 87 unpaired preterms were selected with reflux index <10% (controls). Demographic variables, signs and symptoms, main diagnoses and some aspects of treatment were studied. Simple and multiple logistic regression analysis adjusted for birthweight and postconceptional age at the pH study were used.
Results: The factors associated with a greater chance of reflux index > or = 10% in preterms were: vomiting, regurgitation, Apnea, female gender. The variables that were associated with a lower frequency of increased reflux index were: volume of enteral intake at the onset of symptoms > or = 147 mL/kg/day, and postnatal corticoid use.
Conclusions: Vomiting, regurgitation, apnea, female gender and acute respiratory distress during the first week of life were variables predictive of increased esophageal acid exposition in preterm infants with birthweight <2000 g. Bronchopulmonary dysplasia and use of caffeine were not associated with reflux index > or = 10%.