The Impact of Technology on the Diagnosis of Congenital Malformations

Loreen Straub; Krista F. Huybrechts; Brian T. Bateman; Helen Mogun; Kathryn J. Gray; Lewis B. Holmes; Sonia Hernandez-Diaz

Disclosures

Am J Epidemiol. 2019;188(11):1892-1901. 

In This Article

Abstract and Introduction

Abstract

As technology improves and becomes more widely accessible, more subclinical congenital malformations are being detected. Using a cohort of 1,780,156 pregnant women and their offspring nested in the 2000–2013 US Medicaid Analytic eXtract, we contrasted time trends in malformations which do not necessarily present with overt clinical symptoms early in life and are more likely to be diagnosed via imaging (secundum atrial septal defect, patent ductus arteriosus, ventricular septal defect, pulmonary artery anomalies, pulmonary valve stenosis, hydrocephalus) with trends in malformations that are unlikely to escape clinical diagnosis (tetralogy of Fallot, coarctation of the aorta, transposition of the great vessels, hypoplastic left heart syndrome, oral cleft, abdominal wall defect). Logistic regression was used to account for trends in risk factors while assessing the impact of increased screening intensity. Prevalence of the diagnosis of secundum atrial septal defect rose from 2.3‰ in 2000–2001 to 7.5‰ in 2012–2013, of patent ductus arteriosus from 1.9‰ to 4.1‰, and of ventricular septal defect from 3.6‰ to 4.5‰. Trends were not explained by changes in the prevalence of risk factors but were attenuated when accounting for screening tests. The other malformations showed no temporal trends. Findings suggest that increased screening partially explains the observed increase in diagnosis of milder cases of select common malformations.

Introduction

The reported risk of congenital malformations varies dramatically between studies, with estimates ranging from around 2% to over 10%.[1–7] Potential explanations for such variability include differences in the prevalence of risk factors in the study populations, different windows of ascertainment (e.g., follow-up from days to years after birth),[2] inclusion or exclusion of prenatal diagnoses and pregnancy losses,[8–10] and the definition of congenital malformation itself (e.g., restriction to major malformations, exclusion of chromosomal anomalies, exclusion of prematurity-related conditions). An additional determinant of the risk estimate when ascertaining the presence of malformations is the quality of information and the need to use algorithms that might maximize specificity at the cost of sensitivity.

Another source of heterogeneity emerged in the last few decades with the advent of prenatal ultrasonography in the 1980s and echocardiography in the 1990s.[8,11] Prenatal and postnatal screening tests improve diagnosis but also increase the detection of anatomical variants with no clinical repercussions. For example, echocardiograms can identify features that are within the spectrum of normality, including small muscular ventricular septal defect (VSD), a common feature which usually closes spontaneously within the first year of life.[12] However, excluding all muscular VSDs as a physiological feature would be inappropriate, since a large muscular VSD can produce congestive heart failure and therefore has medical importance. Overall, improving technology and increasing accessibility have continued to result in the detection of more defects[13,14] and may contribute to geographical and temporal variations in the apparent prevalence of certain malformations. Thus, to allow appropriate interpretation and comparison of reported prevalence, it would be useful to determine which malformations are more prone to exhibiting changes in prevalence due to changes in methods of ascertainment (e.g., access to echocardiograms).

Using data from a large nationwide cohort of publicly insured pregnant women and their offspring, we evaluated time trends in the prevalence of specific congenital malformations and examined the impact of "technology-detected malformations"—that is, malformations that would be asymptomatic and therefore undiagnosed but become more frequently diagnosed because of technology.

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