Epidemiology of clubfoot in Sweden from 2016 to 2019: A national register study

BACKGROUND: This study aimed to estimate the birth prevalence of children born with isolated or non-isolated clubfoot in Sweden using a national clubfoot register. Secondarily we aimed to describe the clubfoot population with respect to sex, laterality, severity of deformity, comorbidity and geographic location. METHODS: A national register, the Swedish Pediatric Orthopedic Quality register, was used to extract data on newborn children with clubfoot. To calculate the birth prevalence of children with isolated or non-isolated clubfoot between 1(st) of January 2016 and 31(st) of December 2019, we used official reports of the total number of Swedish live births from the Swedish Board of Statistics. The Pirani score and predefined signs of atypical clubfoot were used to classify clubfoot severity at birth. RESULTS: In total 612 children with clubfoot were identified. Of these, 564 were children with isolated clubfoot, generating a birth prevalence of 1.24/1000 live births (95% confidence interval 1.15–1.35). About 8% were children with non-isolated clubfoot, increasing the birth prevalence to 1.35/1000 live births (95% confidence interval 1.25–1.46). Of the children with isolated clubfoot, 74% were boys and 47% had bilateral involvement. The children with non-isolated clubfoot had more severe foot deformities at birth and a greater proportion of clubfeet with atypical signs compared with children with isolated clubfoot. CONCLUSION: We have established the birth prevalence of children born with isolated or non-isolated clubfoot in Sweden based on data from a national register. Moreover, we have estimated the number of children born with atypical clubfeet in instances of both isolated and non-isolated clubfoot. These numbers may serve as a baseline for expected birth prevalence when planning clubfoot treatment and when evaluating time trends of children born with clubfoot.