Neonatal necrotizing enterocolitis has a high fatality rate among infants affected by the condition. The morbidity and long term health outcomes among NEC survivors are highly influenced by the pathological stage of NEC and the extent of damage to the intestines [11, 26–28]. Surgical intervention is an important surrogate for severity of NEC and the associated high risk of mortality and poor developmental outcomes, regardless of the surgical procedure used [9–16, 29–32]. Previous studies of healthcare costs associated with NEC have shown that both medically and surgically treated NEC infants incur significantly higher inpatient hospital expenditures than similar infants without NEC due to longer length of stay in neonatal intensive care units [10, 33–35]. However, the healthcare costs of NEC survivors over the long term have not been studied to date despite increasing evidence of poor health outcomes among these children.
In this study we compared the healthcare utilization of 250 NEC survivors in the Medicaid population to that of controls matched on prematurity and ELBW status, black race and presence of birth defects, from 6 months to 3 years of age. When matching NEC infants to controls, we found that patent ductus arteriosus was more frequently observed in the NEC group. The association of PDA and NEC is well known and is thought to be due to excessive left to right shunting leading to systemic hypoperfusion, a known risk factor for NEC . We found that 28 infants in the NEC group (9%) and 119 infants in the matched control group (4%) had undergone surgical PDA ligation or division procedures. While additional costs due to PDA surgery can be incurred during the initial hospitalization period, the cost of PDA over the long-term should be no different in infants with or without NEC. In other words, a PDA-NEC association that was observed in the data would not have an impact on the main findings of this paper.
We found that medical NEC survivors incurred $5000 more in healthcare costs on average than matched controls between 6 to 12 months of age. These incremental costs were mainly driven by ambulatory care expenses, possibly attributable to management of artificial GI openings and follow-up care received for other developmental problems observed during this period. These included failure to thrive, feeding difficulties, BPD and NDD. However, the healthcare costs of medical NEC survivors did not differ from matched controls after 12 months of age. These results indicate that the likelihood of experiencing developmental complications leading to increased utilization of healthcare resources over the long term (> 1 year of age) is not significant in comparing medical NEC survivors to matched controls.
On the other hand, the all-inclusive healthcare costs among surgical NEC survivors continued to be higher than matched controls beyond 6 months with the adjusted incremental costs being statistically significant up to 2 years of age. The incremental costs of surgical NEC between 2 to 3 years were still substantial and the lack of statistical significance could be due to the very small number of surgical NEC infants remaining in this time period (n = 35). Our findings show that surgical NEC survivors incurred an average $60,000 more in healthcare costs than matched controls over the period from 6 months to 3 years of age.
The high costs among surgical NEC survivors were initially driven by inpatient expenditures. However, the frequency of hospital admissions and level of inpatient expenditures decreased over time. Home healthcare and other ambulatory care expenditures were the main drivers of costs among surgical NEC children from 1 to 3 years of age. The net difference in costs between surgical NEC children and matched controls was smaller in the extremely low birth weight group (BW <1,000g) compared to the cost difference found in children born with BW ≥ 1,000g. A similar trend was noted in the risk of chronic health conditions wherein the odds ratios for the association of surgical NEC with developmental health conditions were smaller for infants with BW < 1,000g compared to BW ≥ 1,000g (though only the combined odds ratios were reported due to the very small number of NEC infants with BW < 1,000g). These results are to be expected given the already higher rate of complications in extremely low birth weight status and the consequent decrease in the marginal effect of surgical NEC on healthcare costs in these children. Nevertheless, the results clearly show that children born with extremely low birth weight and who survive severe NEC incurred higher healthcare costs than children with only one of these risk factors.
The intensity of healthcare use and costs among surgical NEC survivors could be driven by one or more factors such as: treatment for post-surgical complications (e.g., short bowel syndrome (SBS) / intestinal malabsorption which was seen more often in the surgical NEC group), costs associated with nutrition (e.g., length of total parenteral nutrition (TPN) support required by survivors and the complications associated with TPN), treatment of infections associated with ostomies (a significantly higher proportion of surgical NEC survivors lived with open ostomies for a significant period of time), and costs of care for very frequently reported conditions such as failure to thrive, NDD and nutritional and metabolic disturbances.
In a study among infants with short bowel syndrome, Spencer, et al. reported the average costs of SBS between year 1 to year 5 to be US$ 250,000-300,000 per year and that parenteral nutrition alone contributed to roughly $200,000 each year . These costs appear to be much higher than the 90th percentile of costs among surgical NEC infants that we observed in the Medicaid cohort. The higher costs in the Spencer, et al. study are partly due to the use of billable Medicaid charges for home healthcare services, whereas we used the actual Medicaid paid amounts which typically represent very low reimbursement rates for these services. Also, children with SBS represent those who have the most severe health status among surgical NEC survivors. Our surgical NEC sample had 13 out of 62 patients (21%) between 6–12 months and 7 out of 35 patients (20%) between 24–36 months receiving care for intestinal malabsorption and the average costs in this sub-group would have been much higher. Also, it could not be ascertained from the claims data how many patients had severe SBS as defined in the Spencer, et al. study (i.e. loss of ≥ 70% of small intestinal length, ≥ 2 months of parenteral nutrition dependence, etc.).
Regardless of the data source, the healthcare costs reported in this paper are to be treated as highly conservative, since very expensive treatments such as small bowel transplantation were not accounted for in the analyses (because these procedures were not covered under Texas Medicaid during the study period). Transplant procedures may be required for long term survival in a small proportion of surgical NEC survivors with failure of intestinal function . Also, a significant proportion of surgical NEC infants in the Medicaid sample were found to have NDD and the odds ratios were comparable to those reported in other studies [15–17]. The extent to which NDD influences direct healthcare costs is not very clear, although NDD can have a significant impact on diagnostic screening tests, physical and occupational therapy, and special education costs. More research using multiple data sources is needed to specifically understand the economic impact of neurodevelopmental delay among survivors of surgical NEC.
While the healthcare costs discussed above are highly relevant from a payer perspective, it should be remembered that the long term costs from a societal perspective would also account for the value of lives lost due to mortality attributed to NEC during the first 6 months of life. The value of a statistical life (VSL) is estimated at $7.4 million according to the 2002 Environmental Protection Agency (EPA) estimates . Medicaid covers 40% of live births in the U.S. If the NEC mortality rate observed in the current study were to be applied to the overall Medicaid population in the U.S., approximately 700–900 Medicaid infants would be expected to die because of NEC annually and the total economic value of lives lost to NEC would be 5.2 – 6.6 billion US$.
This paper investigates the real world utilization of a longitudinal cohort of NEC survivors. Unfortunately, attrition in the sample resulted in smaller cohorts over time. However, the extent of attrition in the NEC and control groups was comparable and the balance in the baseline characteristics between the NEC and control cohorts was maintained over time. Additionally, a set of exploratory analyses (not shown in this paper) that was conducted to evaluate the probability of attrition over time showed that demographics and health outcomes in the previous time periods (e.g., healthcare costs, disability status and hospitalizations) together explained less than 10% of total variation in attrition in the Medicaid cohort. This suggests that attrition in the Medicaid cohort is predominantly caused by extrinsic factors that do not impact health outcomes (e.g., loss of Medicaid eligibility due to income changes, availability of employer insurance, migration to a different state, etc.)
A significant limitation of this study could be that our findings may not be generalizable to the universe of NEC survivors. This is because the study’s findings were derived from a sample of children that belonged to low-income families with a higher proportion of Hispanic children and, possibly, with a higher baseline risk for poor health status than NEC survivors in the commercially insured population. Additional research using healthcare utilization data obtained from a representative sample of commercially insured NEC survivors is needed in order to improve the generalizability of our findings. Nevertheless, given the fact that Medicaid is one of the largest payers of healthcare for children in the US, the estimates from this population are very useful in understanding the overall economic burden of surgical NEC from a US public payer perspective. Besides generalizability, the study also suffers from some of the classical limitations of using claims data that are not collected for research purposes. Most importantly, these data do not contain specific information that may be of potential research interest, such as gestational age of infants at birth, birth order, maternal characteristics such as education, income and breast feeding practices. Considering that data on the NEC population may be significantly hard to find in practice or simply too expensive to collect prospectively, we consider that the benefit of finding easy to collect longitudinal economic data outweighs the significant challenges of using retrospective claims data. Further research is needed on long term costs that are not captured by medical claims, such as special education costs and caregiver productivity costs.