Co-occurrence of infantile hypertrophic pyloric stenosis and congenital heart defects: a nationwide cohort study

Background: Recent studies suggest that infantile hypertrophic pyloric stenosis (IHPS) and congenital heart defects (CHDs) may share some genetic risk factors, but little is known about the co-occurrence of the two conditions in patients. Methods: Our study cohort included 2,212,756 persons born in Denmark 1977–2013. We identified patients with IHPS and CHD in the National Patient Register. Using log-linear Poisson regression, we estimated the (incidence) rate ratios (RRs) comparing the rate of IHPS among children with a CHD diagnosis (exposed) and the rate among those without such a diagnosis. Results: Twenty-seven thousand three hundred and fifty-seven children in the cohort were diagnosed with CHD out of whom 85 developed IHPS (RR = 2.62, 95% confidence interval (CI) 2.09–3.22]). The results were similar for those with and without other congenital malformations, for preterm and term deliveries, and for both sexes. There was, however, a significant effect of calendar period (P =.003). In the period 1977–1996, the RR of IHPS given a CHD diagnosis was 1.96 (95% CI 1.41–2.64); in the period 1997–2014, the RR was 3.75 (95% CI 2.74–4.99). Conclusion: CHD was associated with an increased risk of IHPS. Further research is needed to delineate molecular-level mechanisms that may affect both conditions.