A Systematic Review of Adherence to Immunosuppression among Pediatric Heart Transplant Patients

The improving Medication Adherence in Adolescents and young adults following Liver Transplantation (iMALT) multisite trial: Design and trial implementation considerations

BACKGROUND/AIMS

Medication non-adherence is a leading cause of transplant rejection, organ loss, and death; yet no rigorous controlled study to date has shown compelling clinical benefits from an adherence-improving intervention. Non-adherent patients are less likely to participate in trials, and therefore, most studies enroll a majority of adherent patients who do not stand to benefit from the intervention, as they do not have the condition (non-adherence) under investigation. The improving Medication Adherence in adolescent Liver Transplant recipients trial specifically targets non-adherent patients to investigate whether a remote intervention to improve adherence results in reduced incidence of biopsy-confirmed rejection.

METHODS

Improving Medication Adherence in adolescent Liver Transplant is a randomized single-blind controlled multisite, multinational National Institutes of Health-funded trial involving 13 pediatric transplant centers in the United States and Canada. An innovative, objective adherence biomarker-the Medication Level Variability Index, which is the standard deviation of a series of medication blood levels for each patient, is used to identify non-adherent patients at risk for rejection. The index is computed using electronic health record information for all potentially eligible patients based on repeated reviews of the entire clinic's roster. Identified patients, after consent, are randomized to intervention versus control (treatment as usual) arms. The remote intervention is delivered for 2 years by trained interventionists who reside in various locations in the United States. The primary outcome is the incidence of biopsy-confirmed acute cellular rejection, as confirmed by a majority vote of three pathologists who are masked to the study allocation and clinical information.

DISCUSSION

Improving Medication Adherence in adolescent Liver Transplant includes several innovative design elements. The use of a validated, objective adherence index to survey a large cohort of transplant recipients allows the teams to avoid bias inherent in both convenience sampling and referral-based recruitment and enroll only patients whose computed index indicates substantially increased risk of rejection. The remote intervention paradigm helps to engage patients who are by definition hard to engage. The use of an objective, masked medical (rather than behavioral) outcome measure reduces the likelihood of biases related to clinical information and ensures broad acceptance by the field. Finally, monitoring for potential adverse events related to increased medication exposure due to the adherence intervention acknowledges that a successful intervention (increasing adherence) could have detrimental side effects via increased exposure to and potential toxicity of the medication. Such monitoring is almost never attempted in clinical trials evaluating adherence interventions.

Quality care close to home: Objectives and early outcomes of a second paediatric heart transplant service in Australia

AIM

We describe the experience of a new paediatric heart transplant (HT) centre in Australia. New South Wales offers quaternary paediatric cardiac services including comprehensive care pre- and post-HT; however, perioperative HT care has previously occurred at the national paediatric centre or in adult centres. Internationally, perioperative HT care is highly protocol-driven and a majority of HT occurs in low volume centres. Establishing a low volume paediatric HT centre in New South Wales offers potential for quality HT care close to home.

METHODS

Retrospective review of programme data for the first 12 months was undertaken. Patient selection was audited against the programme's intended initiation criteria. Longitudinal patient data on outcomes and complications were obtained from patient medical records.

RESULTS

The programme's initial phase offered HT to children with non-congenital heart disease and no requirement for durable mechanical circulatory support. Eight patients met criteria for HT referral. Three underwent interstate transfer to the national paediatric centre. Five children (13-15 years, weight 36-85 kg) underwent HT in the new programme. Individual predicted 90-day mortality was 1.3-11.6%, with increased risk for recipients transplanted from veno-arterial extracorporeal membrane oxygenation (VA-ECMO) and with restrictive/hypertrophic cardiomyopathies. Survival at 90 days and for duration of follow-up is 100%. Observed programme benefits include mitigation of family dislocation and improved continuity of care within a family-centred programme.

CONCLUSION

Audit of the first 12 months' activity of a second paediatric HT centre in Australia demonstrates adherence to proposed patient selection criteria and excellent 90-day patient outcomes. The programme demonstrates feasibility of care close to home, providing continuity for all patients including those requiring increased rehabilitation and psychosocial support post-transplantation.

Recent advances in biological pumps as a building block for bioartificial hearts

The field of biological pumps is a subset of cardiac tissue engineering and focused on the development of tubular grafts that are designed generate intraluminal pressure. In the simplest embodiment, biological pumps are tubular grafts with contractile cardiomyocytes on the external surface. The rationale for biological pumps is a transition from planar 3D cardiac patches to functional biological pumps, on the way to complete bioartificial hearts. Biological pumps also have applications as a standalone device, for example, to support the Fontan circulation in pediatric patients. In recent years, there has been a lot of progress in the field of biological pumps, with innovative fabrication technologies. Examples include the use of cell sheet engineering, self-organized heart muscle, bioprinting and in vivo bio chambers for vascularization. Several materials have been tested for biological pumps and included resected aortic segments from rodents, type I collagen, and fibrin hydrogel, to name a few. Multiple bioreactors have been tested to condition biological pumps and replicate the complex in vivo environment during controlled in vitro culture. The purpose of this article is to provide an overview of the field of the biological pumps, outlining progress in the field over the past several years. In particular, different fabrication methods, biomaterial platforms for tubular grafts and examples of bioreactors will be presented. In addition, we present an overview of some of the challenges that need to be overcome for the field of biological pumps to move forward.