P2C273: A Population-based Cohort Study of the Prevalence, Risk Factors and Comorbidities of Neonatal Renal Vein Thrombosis in the United States, 2016-2020

Background: Neonatal renal vein thrombosis (nRVT) is rare and clinical reports on nRVT in the United States (US) are limited to a few case reports with small sample sizes published prior to 2002. Thus, there is paucity of population-level data on nRVT in the US. We aimed to describe the epidemiology, temporal trends in the prevalence, and outcomes associated with nRVT in the US from 2016 through 2020.

Methods: This was a repeated cross-sectional analysis of newborn hospitalizations within the Healthcare Cost and Utilization Project’s National Inpatient Sample (NIS) from 2016 through 2020. NIS is the largest, all-payer inpatient healthcare database in the US, and it is released every year. International Classification of Diseases (ICD-10) diagnostic codes were used to identify newborns with nRVT. Transfers were excluded to avoid double counting of hospitalizations. The outcomes of interest were the changes over time in the prevalence rate, the demographic characteristics, hospital course, and outcomes of nRVT. The prevalence rate of nRVT was expressed as the number of hospitalizations with nRVT per 100,000 livebirths. The exposure variables were calendar year and nRVT. Linear regression was used for analysis. Chi-square and Wilcoxon rank sum test were used for bivariate comparisons as appropriate. P-value < 0.05 was considered significant.

Results: A total of 310 neonates were diagnosed with nRVT out of 18,550,686 live births from 2016 through 2020, an overall prevalence of 1.7 per 100,000. The demographic characteristics of the study population are outlined in Table 1. Most of the neonates with RVT were males, white, born at term, and cared for in urban teaching hospitals. The prevalence rate per 100,000 live births increased from 1.4 to 2 from 2016 to 2020 but this did not reach statistical significance (P = 0.13). As summarized in Table 2, neonates with nRVT were more likely to have thrombocytopenia, respiratory distress syndrome, hypertension, congenital heart disease, acute kidney injury, require mechanical ventilation, have a central line, or require dialysis when compared to neonates without RVT. The median length of stay, the median hospital cost and the overall mortality rate for neonates with nRVT were all higher than for neonates without nRVT. In a multivariable logistic regression analysis, male sex (aOR 2.11, 95% CI: 1.17-3.77), congenital heart disease (aOR 3.77, 95% CI: 1.79-7.90), presence of a central line (aOR 14.66, 95% CI: 5.91-36.36), and mechanical ventilation (aOR 4.73, 95% CI: 2.01-11.15) were all associated with increased odds of developing nRVT.

Conclusion: Neonatal RVT remains rare and is associated with increased morbidity, mortality, and resource use. Further studies examining long-term outcomes on a national scale would be beneficial to determine the potential life-long effects of nRVT beyond the neonatal period such as hypertension, chronic kidney disease or end-stage renal disease.