An Overview of Solid Organ Transplantation

Percentage of low attenuation area on computed tomography detects chronic lung allograft dysfunction, especially bronchiolitis obliterans syndrome, after bilateral lung transplantation

INTRODUCTION

The percentage of low attenuation area (%LAA) on computed tomography (CT) is useful for evaluating lung emphysema, and higher %LAA was observed in patients with chronic lung allograft dysfunction (CLAD). This study investigated the relationship between the %LAA and the development of CLAD after bilateral lung transplantation (LT).

METHODS

We conducted a single-center retrospective study of 75 recipients who underwent bilateral LT; the recipients were divided into a CLAD group (n = 30) and a non-CLAD group (n = 45). The %LAA was calculated using CT and compared between the two groups from 4 years before to 4 years after the diagnosis of CLAD. The relationships between the %LAA and the percent baseline values of the pulmonary function test parameters were also calculated.

RESULTS

The %LAA was significantly higher in the CLAD group than in the non-CLAD group from 2 years before to 2 years after the diagnosis of CLAD (P < .05). In particular, patients with bronchiolitis obliterans syndrome (BOS) exhibited significant differences even from 4 years before to 4 years after diagnosis (P < .05). Significant negative correlations between the %LAA and the percent baseline values of the forced expiratory volume in 1 s (r = -.36, P = .0031), the forced vital capacity (r = -.27, P = .027), and the total lung capacity (r = -.40, P < .001) were seen at the time of CLAD diagnosis.

CONCLUSION

The %LAA on CT was associated with the development of CLAD and appears to have the potential to predict CLAD, especially BOS, after bilateral LT.

Application of plasma donor-derived cell free DNA for lung allograft rejection diagnosis in lung transplant recipients

BACKGROUND

Donor-derived cell-free DNA (dd-cfDNA) has been applied to monitor acute rejection (AR) in kidney and heart transplantation. This study was aimed to investigate the application of dd-cfDNA levels in the diagnosis of AR and chronic lung allograft dysfunction (CLAD) among the lung transplantation recipients (LTRs).

METHODS

One hundred and seventy LTRs were enrolled at the First Affiliated Hospital of Guangzhou Medical University between 1 June 2015 and 30 March 2021. Patients were divided into 4 groups: stable group, AR group, infection group and CLAD group. The level of dd-cfDNA was analyzed using target region sequencing and the performance characteristics of dd-cfDNA for diagnosis of AR and CLAD were determined, respectively.

RESULTS

Kruskal-Wallis test showed that there were some significant differences in the level of dd-cfDNA (%) among the 4 groups, with p < 0.001. Among them, the level of dd-cfDNA (%) was highest (median 2.17, IQR [1.40-3.82]) in AR group, and higher in CLAD group (median 1.07, IQR [0.98-1.31]), but lower in infection group (median 0.71, IQR [0.57-1.07]) and lowest in stable group (median 0.71, IQR [0.61-0.84]). AUC-ROC curve analysis showed that the threshold of dd-cfDNA for AR was 1.17%, with sensitivity being 89.19% and specificity being 86.47%, and the optimal threshold of 0.89% was determined of CLAD, with sensitivity being 95.00% and specificity of 76.99%.

CONCLUSIONS

Plasma dd-cfDNA could be a useful tool for the assessment of lung allograft rejection, including AR and CLAD, and holds promise as a noninvasive biomarker for "allograft injury" in both acute and chronic rejection following lung transplantation.

Increased Medical Complications Following Primary Total Hip Arthroplasty in Patients With Solid Organ Transplant: A Matched Cohort Analysis

BACKGROUND

As patient longevity increases following solid organ transplantation (SOT), more transplant patients are undergoing total hip arthroplasty (THA). The purpose of this study is to compare 90-day postoperative complications and 2-year surgical complications following primary THA in patients with and without a history of SOT.

METHODS

Patients with a history of SOT with subsequent primary THA between 2010 and 2018 were identified in a national all-payer claims database (PearlDiver Technologies). This SOT cohort was propensity-matched with a control cohort (no history of SOT) based on age, gender, Charlson Comorbidity Index, and obesity with bivariate analysis to compare outcomes between cohorts.

RESULTS

Following matching, 3103 patients were included in the SOT cohort and 6196 patients in the control cohort. The cohorts were successfully matched, with no differences in demographics or comorbidities. Relative to the control cohort, patients with a history of SOT were at significantly increased risk of renal failure (P < .001), anemia (P < .001), arrhythmia with and without atrial fibrillation (P < .001), blood transfusion (P < .001), cellulitis (P = .048), myocardial infarction (P < .001), pneumonia (P = .036), heart failure (P < .001), and sepsis (P = .038) at 90 days postoperatively. There were no significant differences between the cohorts in 2-year surgical revisions, regardless of indication.

CONCLUSION

Following primary THA, patients with a history of SOT are at increased risk of 90-day medical complications but not 2-year surgical complications or revisions relative to patients without SOT. Clinicians should be mindful of the increased risk for cardiopulmonary, renal, hematologic, and infectious complications when counseling and managing this patient population.

LEVEL OF EVIDENCE

Level IV-Retrospective Database Study.

Outcomes of Femoral Neck Fracture Treated With Hip Arthroplasty in Solid Organ Transplant Patients

Background

Solid organ transplant (SOT) patients have increased risk of complications, infection, and mortality after elective total hip arthroplasty (THA). The study aims to compare SOT recipients' clinical outcomes to a matched group of nontransplant patients after nonelective THA and hemiarthroplasty for acute femoral neck fracture (FNF).

Methods

A retrospective review identified 31 SOT patients undergoing hip arthroplasty (24 hemiarthroplasty and 7 THA) for FNF and were matched 1:1 to non-SOT patients based on age, sex, body mass index, surgical procedure, and year of surgery. Patient survivorship, perioperative outcomes, complications, and reoperations were compared. The mean follow-up was 3 years.

Results

The estimated survivorship free from mortality for SOT and non-SOT patients at 1- year was not different (77% and 84%, respectively, P = .52). The 90-day readmission rate was significantly higher with 8 (26%) in the SOT cohort and none in the non-SOT group (P < .01). Major medical complications occurred in 16% of SOT patients compared to 5% in controls (P = .21). Three (10%) reoperations/revisions were required for SOT patients and none in non-SOT group (P = .24).

Conclusion

SOT recipients undergoing nonelective hip arthroplasty for FNF demonstrated increased readmission rates compared to matched controls. For this rare clinical scenario, diligent perioperative care by surgeons and multidisciplinary transplant specialists is necessary to mitigate increased risk of SOT patients.

Increased perioperative complication rates in patients with solid organ transplants following rotator cuff repair

BACKGROUND

Rotator cuff repair is the second most common soft tissue procedure performed in orthopedics. Additionally, an increasing percentage of the population has received a solid organ transplant (SOT). The chronic use of immunosuppressants as well as a high prevalence of medical comorbidities in this population are both important risk factors when considering surgical intervention. The purpose of this study is to determine the demographic profile, comorbidity profile, and perioperative complication rate of SOT patients undergoing inpatient rotator cuff repair surgery compared to nontransplanted patients.

METHODS

The Nationwide Inpatient Sample (NIS) database was queried from years 2002-2017 to identify all patients who underwent inpatient rotator cuff repair (n = 144,528 weighted). This group was further divided into SOT (n = 286 weighted) and nontransplant (n = 144,242 weighted) cohorts. Demographic and comorbidity analyses were performed between these groups. Additionally, a matched cohort of nontransplanted patients controlled for the year of procedure, age, sex, race, income, and hospital region was created in a 1:1 ratio to the SOT group (n = 286 each) for perioperative complication rate analysis.

RESULTS

Compared to nontransplanted patients, SOT patients were more likely to have at least 1 significant medical comorbidity (98% vs. 69%, P < .001), had a higher number of total comorbidities (3.1 vs. 1.4, P < .001), and had a higher Charlson-Deyo Comorbidity Index (2.6 vs. 0.54, P < .001). Compared to the matched cohort, SOT patients experienced longer hospital stays (2.9 vs. 1.8 days, P < .001), higher surgery costs ($12,031 vs. $8476, P < .001), and were more likely to experience a perioperative complication (24% vs. 3%, P < .001) with an odds ratio of 7.7 (95% confidence interval: 3.9-15.1).

CONCLUSION

Compared with nontransplanted patients, SOT patients undergoing rotator cuff repair had a significantly higher comorbidity index, longer hospital stays, costlier surgeries, and were >7 times more likely to experience a perioperative complication. With nearly a quarter of all SOT patients experiencing a perioperative complication following rotator cuff repair, careful consideration for surgery as well as increased postoperative surveillance should be considered in this unique population.

Lung perfusion scintigraphy to detect chronic lung allograft dysfunction after living-donor lobar lung transplantation

Because chronic lung allograft dysfunction (CLAD) develops predominantly on one side after bilateral living-donor lobar lung transplantation (LDLLT), lung perfusion scintigraphy (Q-scinti) was expected to show a perfusion shift to the contralateral unaffected lung with the development of CLAD. Our study examined the potential usefulness of Q-scinti in the diagnosis of CLAD after bilateral LDLLT. We conducted a single-center retrospective cohort study of 58 recipients of bilateral LDLLT. The unilateral shift values on Q-scinti were calculated and compared between the CLAD group (N = 27) and the non-CLAD group (N = 31) from 5 years before to 5 years after the diagnosis of CLAD. The unilateral shift values in Q-scinti were significantly higher in the CLAD group than in the non-CLAD group from 5 years before the diagnosis of CLAD to 5 years after the diagnosis (P < 0.05). The unilateral shift values in Q-scinti were significantly correlated with the percent baseline values of the forced expiratory volume in 1 s (P = 0.0037), the total lung capacity (P = 0.0028), and the forced vital capacity (P = 0.00024) at the diagnosis of CLAD. In patients developing unilateral CLAD after bilateral LDLLT, Q-scinti showed a unilateral perfusion shift to the contralateral unaffected lung. Thus, Q-scinti appears to have the potential to predict unilateral CLAD after bilateral LDLLT.

National Trends In Kidney, Heart And Liver Transplants Among Patients With And Without Chronic Obstructive Pulmonary Disease In Spain (2001-2015)

Background

To describe trends and outcomes during admission for solid organ transplants, excluding lungs, in people with or without COPD in Spain (2001–2015).

Methods

We used national hospital discharge data to select all hospital admissions for kidney, heart and liver transplants. We estimated admission rates stratified by COPD status. We analyzed the Charlson Comorbidity Index, therapeutic procedures and outcomes.

Results

We identified 52,020 admissions (33,293 for kidney transplant, 3,937 for heart transplant and 14,790 for liver transplant). Patients with COPD accounted for 2.5%, 4.2% and 3.5% of kidney, heart and liver transplant patients, respectively. The number of kidney and liver transplants increased among COPD patients over the study period, whereas the number of heart transplants remained stable. In all cases, COPD patients were significantly older and had more coexisting medical conditions than those without COPD. Among patients who underwent a kidney transplant, there were no significant differences in the clinical characteristics analyzed between the groups, but the overall in-hospital mortality (IHM) rate was significantly higher in COPD patients than in those without COPD (2.22% vs 0.58%, p=0.008). There were no differences for any of the study variables or for the IHM rate in patients who underwent a heart transplant (14.63% in both groups). Among patients who underwent a liver transplant, COPD patients had lower prevalences of infection and complications than those without COPD. The IHM rate was also significantly lower in COPD patients than in non-COPD controls who underwent a liver transplant (4.07% vs 8.91%, p=0.002).

Conclusion

COPD prevalence in patients undergoing renal, heart and liver transplants is lower than it has been described in the general population. However, we did not find differences in the clinical characteristics analyzed between COPD and non-COPD patients. Furthermore, the IHM rate was only higher in COPD patients who underwent a kidney transplant but not in those undergoing a heart or liver transplant.

Complications of Solid Organ Transplantation: Cardiovascular, Neurologic, Renal, and Gastrointestinal

Despite improvements in overall graft function and patient survival rates after solid organ transplantation, complications can lead to significant morbidity and mortality. Cardiovascular complications include heart failure, arrhythmias leading to sudden death, hypertension, left ventricular hypertrophy, and allograft vasculopathy in heart transplantation. Neurologic complications include stroke, posterior reversible encephalopathy syndrome, infections, neuromuscular disease, seizure disorders, and neoplastic disease. Acute kidney injury occurs from immunosuppression with calcineurin inhibitors or as a result of graft failure after kidney transplantation. Gastrointestinal complications include infections, malignancy, mucosal ulceration, perforation, biliary tract disease, pancreatitis, and diverticular disease. Immunosuppression can predispose to infections and malignancy.

Quantification of transplant-derived circulating cell-free DNA in absence of a donor genotype

Quantification of cell-free DNA (cfDNA) in circulating blood derived from a transplanted organ is a powerful approach to monitoring post-transplant injury. Genome transplant dynamics (GTD) quantifies donor-derived cfDNA (dd-cfDNA) by taking advantage of single-nucleotide polymorphisms (SNPs) distributed across the genome to discriminate donor and recipient DNA molecules. In its current implementation, GTD requires genotyping of both the transplant recipient and donor. However, in practice, donor genotype information is often unavailable. Here, we address this issue by developing an algorithm that estimates dd-cfDNA levels in the absence of a donor genotype. Our algorithm predicts heart and lung allograft rejection with an accuracy that is similar to conventional GTD. We furthermore refined the algorithm to handle closely related recipients and donors, a scenario that is common in bone marrow and kidney transplantation. We show that it is possible to estimate dd-cfDNA in bone marrow transplant patients that are unrelated or that are siblings of the donors, using a hidden Markov model (HMM) of identity-by-descent (IBD) states along the genome. Last, we demonstrate that comparing dd-cfDNA to the proportion of donor DNA in white blood cells can differentiate between relapse and the onset of graft-versus-host disease (GVHD). These methods alleviate some of the barriers to the implementation of GTD, which will further widen its clinical application.

More than 180,000 people live with organ transplants in the US. Monitoring the health of the allograft is a critically important component of post-transplant therapy. Recently, we have demonstrated that cell-free DNA (cfDNA) enables diagnosis of post-transplant rejection. In this approach, genotyping of the recipient and the donor together with shotgun sequencing of cfDNA are used to quantify the proportion of donor-derived cfDNA (dd-cfDNA). This approach offers key advantages over the current practice of organ biopsy, which is invasive, costly, and risky. However, the difficulty and cost of establishing a pure reference donor genotype is a major barrier to its widespread clinical implementation. Here, we developed a computational approach that enables an accurate estimation of dd-cfDNA levels without the need for a donor genotype. In addition, we provide a solution of closely related recipients and donors—a scenario which is common in bone marrow and kidney transplants—by accounting for the identity-by-descent between the recipient and the donor. Last, we demonstrate a new application of cfDNA in the noninvasive diagnosis of Graft Versus Host Disease, a serious and difficult-to-diagnose complication of allogeneic bone marrow and stem cell transplantation.

The Impact of Solid Organ Transplant History on Inpatient Complications, Mortality, Length of Stay, and Cost for Primary Total Hip Arthroplasty Admissions in the United States

BACKGROUND

As the prevalence of and life expectancy after solid organ transplantation increases, some of these patients will require total hip arthroplasty (THA). Immunosuppressive therapy, metabolic disorders, and post-transplant medications may place transplant patients at higher risk of adverse events following surgery. The objective of this study was to compare inpatient complications, mortality, length of stay (LOS), and costs for THA patients with and without solid organ transplant history.

METHODS

A retrospective cross-sectional analysis was conducted using 1998-2011 Nationwide Inpatient Sample. Primary THA patients were queried (n = 3,175,456). After exclusions, remaining patients were assigned to transplant (n = 7558) or non-transplant groups (n = 2,772,943). After propensity score matching, adjusted for patient and hospital characteristics, logistic regression and paired t-tests examined the effect of transplant history on outcomes.

RESULTS

Between 1998 and 2011, THA volume among transplant patients grew approximately 48%. The overall prevalence of one or more complications following THA was greater in the transplant group than in the non-transplant group (32.0% vs 22.1%; P < .001). In-hospital mortality was minimal, with comparable rates (0.1%) in both groups (P = .93). Unadjusted trends show that transplant patients have greater annual and overall mean LOS (4.47 days) and mean admission costs ($18,402) than non-transplant patients (3.73 days; $16,899; P < .001). After propensity score matching, transplant history was associated with increased complication risk (odds ratio, 1.56) after THA, longer hospital LOS (+0.64 days; P < .001), and increased admission costs (+$887; P = .005).

CONCLUSION

Transplant patients exhibited increased odds of inpatient complications, longer LOS, and greater admission costs after THA compared with non-transplant patients.

Noninvasive monitoring of infection and rejection after lung transplantation

The survival rate following lung transplantation is among the lowest of all solid-organ transplants, and current diagnostic tests often fail to distinguish between infection and rejection, the two primary posttransplant clinical complications. We describe a diagnostic assay that simultaneously monitors for rejection and infection in lung transplant recipients by sequencing of cell-free DNA (cfDNA) in plasma. We determined that the levels of donor-derived cfDNA directly correlate with the results of invasive tests of rejection (area under the curve 0.9). We also analyzed the nonhuman cfDNA as a hypothesis-free approach to test for infections. Cytomegalovirus is most frequently assayed clinically, and the levels of CMV-derived sequences in cfDNA are consistent with clinical results. We furthermore show that hypothesis-free monitoring for pathogens using cfDNA reveals undiagnosed cases of infection, and that certain infectious pathogens such as human herpesvirus (HHV) 6, HHV-7, and adenovirus, which are not often tested clinically, occur with high frequency in this cohort.

Airway complications after lung transplantation

Airway complications after lung transplantation present a formidable challenge to the lung transplant team, ranging from mere unusual images to fatal events. The exact incidence of complications is wide-ranging depending on the type of event, and there is still evolution of a universal characterization of the airway findings. Management is also wide-ranging. Simple observation or simple balloon bronchoplasty is sufficient in many cases, but vigilance following more severe necrosis is required for late development of both anastomotic and nonanastomotic airway strictures. Furthermore, the impact of coexisting infection, rejection, and medical disease associated with high-level immunosuppression further complicates care.

Growing Up: Not an Easy Transition-Perspectives of Patients and Parents regarding Transfer from a Pediatric Liver Transplant Center to Adult Care

The transition from pediatric to adult care is a critical time when children with chronic illness sustain high morbidity and mortality. Transition services need to be focused on the adolescents' needs, which may differ from those perceived by healthcare providers. In this study, a survey of 31 patients with chronic liver disease and/or liver transplant who were "transferred" to adult services within the last 3 years was conducted. Patients were asked about their current health status and their perceptions of the overall transfer process. The mean age at transfer was 19.81 (18-21) years. Almost half the patients (47%) were not seen at the adult facility until 2-6 months after leaving the Children's hospital and 20% were not seen until 6-12 months. About 20% had their first contact with adult services through an emergency room visit. About 19% reported being out of medication during transition. Of the transplanted patients, 19% were being evaluated for a retransplant. The majority (82%) felt that an increased emphasis on promoting independence and "letting go" both by parents and by pediatric care providers was critical in their transition to independence and adult care services. This study provides thought-provoking insights, which are critical in designing the ideal transition program for children with chronic diseases.

The clinical use of regenerative therapy in COPD

Regenerative or stem cell therapy is an emerging field of treatment based on stimulation of endogenous resident stem cells or administration of exogenous stem cells to treat diseases or injury and to replace malfunctioning or damaged tissues. Current evidence suggests that in the lung, these cells may participate in tissue homeostasis and regeneration after injury. Animal and human studies have demonstrated that tissue-specific stem cells and bone marrow-derived cells contribute to lung tissue regeneration and protection, and thus administration of exogenous stem/progenitor cells or humoral factors responsible for the activation of endogenous stem/progenitor cells may be a potent next-generation therapy for chronic obstructive pulmonary disease. The use of bone marrow-derived stem cells could allow repairing and regenerate the damaged tissue present in chronic obstructive pulmonary disease by means of their engraftment into the lung. Another approach could be the stimulation of resident stem cells by means of humoral factors or photobiostimulation.

Cough reflex in lung transplant recipients

Lung transplantation has become the standard of care for particular individuals with advanced lung disease. However, this surgical procedure involves interruption of the lower vagal nerve fibers which leads to loss of the protective cough reflex. Injury of the neural pathways involved with the sensory limb of the cough reflex is associated with an increased risk of complications involving the allograft. While loss of the cough reflex was once considered permanent, recent evidence indicates functional and structural restoration is a time-dependent process that occurs 6-12 months after lung transplantation. The implication that the cough reflex may be reestablished in lung transplant recipients provides insight into the dynamic response to airway neural injury that may lead to improvements in allograft tissue repair.

Dissociation between peripheral blood chimerism and tolerance to hindlimb composite tissue transplants: preferential localization of chimerism in donor bone

BACKGROUND

Mixed chimerism induces donor-specific tolerance to composite tissue allotransplants (CTAs). In the present studies, we used a nonmyeloablative conditioning approach to establish chimerism and promote CTA acceptance.

METHODS

Wistar Furth (RT1A(u)) rats were conditioned with 600 to 300 cGy total body irradiation (TBI, day-1), and 100 x 10(6) T-cell-depleted ACI (RT1A(abl)) bone marrow cells were transplanted on day 0, followed by a 11-day course of tacrolimus and one dose of antilymphocyte serum (day 10). Heterotopic osteomyocutaneous flap transplantation was performed 4 to 6 weeks after bone marrow transplantation.

RESULTS

Mixed chimerism was initially achieved in almost all recipients, but long-term acceptance of CTA was only achieved in rats treated with 600 cGy TBI. When anti-alphabeta-T-cell receptor (TCR) monoclonal antibody (mAb) (day-3) was added into the regimens, donor chimerism was similar to recipients preconditioned without anti-alphabeta-TCR mAb. However, the long-term CTA survival was significantly improved in chimeras receiving more than or equal to 300 cGy TBI plus anti-alphabeta-TCR mAb. Higher levels of donor chimerism were associated with CTA acceptance. The majority of flap acceptors lost peripheral blood chimerism within 6 months. However, donor chimerism persisted in the transplanted bone at significantly higher levels compared with other hematopoietic compartments. The compartment donor chimerism may be responsible for the maintenance of tolerance to CTA. Long-term acceptors were tolerant to a donor skin graft challenge even in the absence of peripheral blood chimerism.

CONCLUSIONS

Mixed chimerism established by nonmyeloablative conditioning induces long-term acceptance of CTA, which is associated with persistent chimerism preferentially in the transplanted donor bone.