Age-based disparity in outcomes of intestinal transplants in pediatric patients

New insights in immunomodulation for intestinal transplantation

Tolerance is the Holy Grail of solid organ transplantation (SOT) and remains its primary challenge since its inception. In this topic, the seminal contributions of Thomas Starzl at Pittsburgh University outlined foundational principles of graft acceptance and tolerance, with chimerism emerging as a pivotal factor. Immunologically, intestinal transplantation (ITx) poses a unique hurdle due to the inherent characteristics and functions of the small bowel, resulting in increased immunogenicity. This necessitates heavy immunosuppression (IS) while IS drugs side effects cause significant morbidity. In addition, current IS therapies fall short of inducing clinical tolerance and their discontinuation has been proven unattainable in most cases. This underscores the unfulfilled need for immunological modulation to safely reduce IS-related burdens. To address this challenge, the Leuven Immunomodulatory Protocol (LIP), introduced in 2000, incorporates various pro-tolerogenic interventions in both the donor to the recipient, with the aim of facilitating graft acceptance and improving outcome. This review seeks to provide an overview of the current understanding of tolerance in ITx and outline recent advances in this domain.

Long-term outcomes of intestinal transplantation from donors aged under 1 year

BACKGROUND

The aim of the study was to analyze the long-term outcomes of transplants utilizing ITx donors <1 year and to compare these results with older donors.

METHODS

Between January 2007 and December 2019, the primary ITx donors in the Children's Hospital of Pittsburgh of UPMC were retrospectively reviewed. Short- and long-term outcomes of recipients receiving a deceased donor organ from donors <1 year were compared with those found in all other recipients.

RESULTS

During the study period, there were 89 primary ITx donors, using 30 donors (33.7%) aged <1 year. The mean age of their recipients was 1.6 ± 0.7 (0.7-3.2) years. The 30 graft types were isolated intestine (n = 3, 10.0%), liver bowel (n = 20, 66.7%), and multivisceral (n = 7, 23.3%). Technical complications occurred in 12 (40.0%) recipients. Candidates transplanted with intestine allografts from donors <1 year of age had shorter wait times (p < .001), more liver-inclusive grafts (p < .001), and less donor-specific antibodies (DSA) (p = .014). During follow-up, the recipients had less graft loss (p = .018), and more remained alive with graft in place (p = .011). Among children transplanted with such donors, 3-year and graft survival rates were 86.7% and 82.9% compared to 62.8% and 49.9% in the cohort of donors >1 year (p = .032 and .011).

CONCLUSIONS

Donor age <1 year was associated with improved graft survival. Optimal utilization of this population for toddler candidates would increase intestine availability, reduce time to transplantation, and potentially improve long-term outcome.

Beyond 10 years, with or without an intestinal graft: Present and future?

Long-term outcomes in children undergoing intestinal transplantation remain unclear. Seventy-one children underwent intestinal transplantation in our center from 1989 to 2007. We report on 10-year posttransplant outcomes with (group 1, n = 26) and without (group 2, n = 9) a functional graft. Ten-year patient and graft survival rates were 53% and 36%, respectively. Most patients were studying or working, one third having psychiatric disorders. All patients in group 1 were weaned off parenteral nutrition with mostly normal physical growth and subnormal energy absorption. Graft histology from 15 late biopsies showed minimal abnormality. However, micronutrient deficiencies and fat malabsorption were frequent; biliary complications occurred in 4 patients among the 17 who underwent liver transplantation; median renal clearance was 87 mL/min/1.73 m² . Four patients in group 1 experienced late acute rejection. Among the 9 patients in group 2, 4 died after 10 years and 2 developed significant liver fibrosis. Liver transplantation and the use of a 3-drug regimen including sirolimus or mycophenolate mofetil were associated with improved graft survival. Therefore, intestinal transplantation may enable a satisfactory digestive function in the long term. The prognosis of graft removal without retransplantation is better than expected. Regular monitoring of micronutrients, early psychological assessment, and use of sirolimus are recommended.

Visceral transplantation in patients with intestinal-failure associated liver disease: Evolving indications, graft selection, and outcomes

Intestinal failure (IF)-associated liver disease (IFALD) is widely recognized as a lethal complication of long-term parenteral nutrition. The pathophysiology of IFALD is poorly understood but appears to be multifactorial and related to the inflammatory state in the patient with IF. Visceral transplant for IFALD includes variants of intestine, liver, or combined liver-intestine allografts. Graft selection for an individual patient depends on the etiology of IF, abdominal and vascular anatomy, severity of IFALD, and potential for intestinal rehabilitation. The past decade has witnessed dramatic improvement in the management of IFALD, principally due to improved lipid emulsion formulations and the multidisciplinary care of the patient with IF. As the recognition and treatment of IFALD continue to improve, the requirement of liver-inclusive visceral grafts appears to be decreasing, representing a paradigm shift in the care of the patient with IF. This review highlights the current indications, graft selection, and outcomes of visceral transplantation for IFALD.

Pre-emptive Intestinal Transplant: The Surgeon's Point of View

Pre-emptive transplantation is a well-established practice for certain types of end-organ failure such as in the use of kidney transplantation. For irreversible intestinal failure, total parenteral nutrition (TPN) remains the gold standard, due to the suboptimal long-term results of intestinal transplantation. As such, the only role for pre-emptive transplantation, if at all, will be for patients identified to be at high risk of complications and mortality while on definitive long-term TPN. In these patients, the timing of early listing and transplantation could become life-saving, taking into account that mortality on the waiting list is still the highest for intestinal candidates. The development of simulation models or pre-transplant scoring systems could help in selecting patients based on potential outcome on TPN or with transplantation, and recent reports from high-volume centers identify few underlying pathologic conditions and some TPN complications as at higher risk of increased morbidity and mortality. A pre-emptive transplant could be used as a rehabilitative procedure in a well-selected case-by-case scenario, among TPN patients at risk of liver failure, repeated central line infections, mesenteric infarction, short bowel syndrome (SBS) <50 cm or with end stoma, congenital mucosal disease, desmoid tumors: These conditions must be carefully evaluated, not to underestimate the clinical stage nor to over-estimate the impact of a temporary situation. At the present time, diseases with a variable and unpredictable course, such as intestinal dysmotility disorders, or quality of life and financial issues are still far from being considered as indications for a pre-emptive transplant.

Cost of ambulatory care for the pediatric intestinal failure patient: One-year follow-up after primary discharge

BACKGROUND

Survival of children with intestinal failure has improved over the last decade, resulting in increased health care expenditures. Our objective was to determine outpatient costs for the first year after primary discharge.

METHODS

A retrospective analysis was performed in pediatric intestinal failure (PIF) patients between 2010 and 2012. Patients were stratified into 3 groups (1=enteral support with no devices [7 patients], 2=enteral support with devices (gastrostomy and/or ostomy) [19 patients], 3=home parenteral nutrition (HPN) [22 patients]). Data abstraction included clinical characteristics and costs related to medication, enteral/parenteral nutrition, and supplies were calculated. Data were analyzed using one way ANOVA.

RESULTS

Forty-eight patients (mean age 7.6months; 31 males [65%]) were studied. See attached table for results. HPN patients had significantly more ambulatory visits (p<0.0001), number of admitted days (p=0.01), and productive days lost (p<0.0001). Total cost of care was significantly higher for HPN patients (mean=$320,368.50, p<0.0001) when compared to other groups. Costs covered by the health care system were significantly higher for patients on HPN (mean=$316,101.56, p<0.0001).

CONCLUSION

The outpatient expenditures to care for PIF patients in the first year post primary discharge are significant. Our single payer health care system supports the majority of costs, but families are also incurring expenses related to travel and lost productivity. Children on HPN have more visits to hospital, but have access to more funding options. Children solely on gastrostomy or stoma therapy, however, have a significantly greater personal financial burden.

Impact of Intestinal Rehabilitation Program and Its Innovative Therapies on the Outcome of Intestinal Transplant Candidates

OBJECTIVES

The outcome of children with intestinal failure has improved during the past decade following the introduction of novel therapies by dedicated intestinal rehabilitation programs (IRP). The aim of the present study was to assess the impact of IRP on the outcome of intestinal transplant (IT) candidates and the transplant waiting list.

METHODS

A retrospective cohort study of children assessed for IT (n = 84) during a 10-year period. Comparisons were made among the following 3 time periods: before the establishment of our center's IRP (1999-2002; n = 33), early IRP (2003-2005; n = 18), and late IRP (2006-2009; n = 33). The following endpoints were used: patient outcome following IT assessment (not listed, listed and removed from the list, received transplant, died while on the list), patient characteristics at IT assessment, and patient status at the end of the study.

RESULTS

The late-IRP era was associated with an increase in patients who were not listed (42% vs 28% at other periods, P = NS) and patients who were removed from the IT waiting list because of clinical improvement (P < 0.0005), and a decrease in those who died before transplant (15% vs >60% at other periods, P < 0.0005). The cause of death shifted from traditional causes such as liver failure or sepsis to other comorbid conditions (P < 0.005). Improved liver function at listing was also observed during late IRP (P < 0.005).

CONCLUSIONS

Treatment by IRP, coupled with recent advances in the medical management of intestinal failure, is associated with improved survival and outcome of patients waiting for IT, and may lead to overall reduction in the number of IT in the future.

Developing trends in the intestinal transplant waitlist

The United Network for Organ Sharing database was examined for trends in the intestinal transplant (ITx) waitlist from 1993 to 2012, dividing into listings for isolated ITx versus liver-intestine transplant (L-ITx). Registrants added to the waitlist increased from 59/year in 1993 to 317/year in 2006, then declined to 124/year in 2012; Spline modeling showed a significant change in the trend in 2006, p < 0.001. The largest group of registrants, <1 year of age, determined the trend for the entire population; other pediatric age groups remained stable, adult registrants increased until 2012. The largest proportion of new registrants were for L-ITx, compared to isolated ITx; the change in the trend in 2006 for L-ITx was highly significant, p < 0.001, but not isolated ITx, p = 0.270. New registrants for L-ITx, <1 year of age, had the greatest increase and decrease. New registrants for isolated ITx remained constant in all pediatric age groups. Waitlist mortality increased to a peak around 2002, highest for L-ITx, in patients <1 year of age and adults. Deaths among all pediatric age groups awaiting L-ITx have decreased; adult L-ITx deaths have dropped less dramatically. Improved care of infants with intestinal failure has led to reduced referrals for L-ITx.

Intestinal transplantation in infants with intestinal failure

Intestinal failure (IF) occurs when a person's functional intestinal mass is insufficient. Patients with IF are placed on parenteral nutrition (PN) while efforts are made to restore intestinal function through surgical or medical intervention. Patients who fail standard IF therapies may be candidates for intestinal transplantation (IT). Clinical outcomes for IT have improved to make this therapy the standard of care for patients who develop complications of PN. The timing of referral for IT is critical because accumulated complications of PN can render the patient ineligible for IT or can force the patient to await multiorgan transplantation.

Intestinal transplantation: a review

Parenteral nutrition is a life-saving therapy for patients with intestinal failure. Intestinal transplantation is now recognized as a treatment for patients who develop complications of parenteral nutrition and in whom attempts at intestinal rehabilitation have failed. Patients with parenteral nutrition related liver disease will require a liver graft typically part of a multivisceral transplant. Isolated intestinal transplants are more commonly performed in adults while multivisceral transplants are most commonly performed in infants. Isolated intestinal transplants have the best short-term outcome, with over 80 % survival at 1 year. Patients requiring multivisceral transplants have a high rate of attrition with a 1 year survival less than 70 %. Prognostic factors for a poor outcome include patient hospitalization at the time of transplant and donor age greater than 40 years while systemic sepsis and acute rejection are the major determinant of early postoperative outcome. For patients surviving the first year the outcome of transplantation of the liver in addition to intestine affords some survival advantage though long-term outcome does not yet match other abdominal organs. Outcomes for intestinal retransplantation are poor as a result of immunology and patient debility. Overall intestinal transplantation continues to develop and is a clear indication with cost and quality of life advantages in patients with intestinal failure that do not remain stable on parenteral nutrition.