Birth prevalence of anorectal malformations in England and 5-year survival: a national birth cohort study.

OBJECTIVE

To determine the birth prevalence, maternal risk factors and 5-year survival for isolated and complex anorectal malformations.

DESIGN

National birth cohort using hospital admission data and death records.

SETTING

All National Health Service England hospitals.

PATIENTS: Live-born singletons delivered from 2002 through 2018, with evidence in the first year of life of a diagnosis of an anorectal malformation and repair during a hospital admission, or anorectal malformation recorded on the death certificate. Cases were further classified as isolated or complex depending on the presence of additional anomalies.

MAIN OUTCOME MEASURES: Birth prevalence of anorectal malformations per 10 000 live births, risk ratios for isolated and complex anorectal malformation by maternal, infant and birth characteristics, and 5-year survival.

RESULTS

We identified 3325 infants with anorectal malformations among 9 474 147 live-born singletons; 61.7% (n=2050) of cases were complex. Birth prevalence was 3.5 per 10 000 live births (95% CI 3.4 to 3.6). Complex anorectal malformations were associated with maternal age extremes after accounting for other sociodemographic factors. Compared with maternal ages 25-34 years, the risk of complex anorectal malformations was 31% higher for ≥35 years (95% CI 17 to 48) and 13% higher for ≤24 years (95% CI 0 to 27). Among 2376 anorectal malformation cases (n=1450 complex) born from 2002 through 2014, 5-year survival was lower for complex (86.9%; 95% CI 85.1% to 88.5%) than isolated anorectal malformations (98.2%; 95% CI 97.1% to 98.9%). Preterm infants with complex anorectal malformations had the lowest survival (73.4%; 95% CI 68.1% to 78.0%).

CONCLUSIONS

Differences in maternal risk factors for isolated and complex anorectal malformations may reflect different underlying mechanisms for occurrence. Five-year survival is high but lowest for preterm children with complex anorectal malformations.