Association Between Clubfoot and Neonatal Abstinence Syndrome in the United States, 2018-2022.

Purpose: The United States has seen an increase in opioid use and misuse over the last 2 decades. Infants have been impacted by the opioid epidemic, with a reported 5-fold increase in the incidence of neonatal abstinence syndrome (NAS) over the last 2 decades. There are many conditions associated with NAS, and thus, the current study sought to examine the association between NAS and clubfoot.

Methods: The study was retrospective, utilizing patient data from the Pediatric Hospital Information System (PHIS) database. Neonates presenting to any PHIS hospital between 2018 and 2022 were identified and included in the study. Patients with NAS and clubfoot were identified utilizing the International Classification of Diseases (ICD)-9 and 10 codes. Univariable and multivariable analyses were performed to investigate associations between clubfoot, race, ethnicity, insurance type, gestational age, length of stay, NAS, and comorbidity burden.

Results: A total of 458,274 patients were identified, of whom 2337 (0.5%) had a clubfoot diagnosis and 5431 (1.2%) had a diagnosis of NAS. Multivariable logistic regression revealed higher independent odds of clubfoot among patients with a diagnosis of NAS [odds ratio (OR): 1.49], patients with a greater number of comorbidities (OR: 4.75 for 1 comorbidity vs. none, and 21.19 for 2+ comorbidities, vs. none), patients with a greater gestational age (OR: 1.01 per week increase), and those with an increased length of stay (OR: 1.00 per day increase). A lower independent odds of clubfoot was observed among patients of Asian race (OR: 0.66), Hispanic/Latino ethnicity (OR: 0.80), non-Hispanic Black (OR: 0.75), and multiracial (OR: 0.80) ethnicity/race relative to non-Hispanic/Latino White patients (P<0.05 for all).

Conclusion: Patients with a diagnosis of NAS demonstrated higher odds of clubfoot, in addition to sociodemographic factors, as well as comorbidity burden.