Expanding the Evidence Base in Transplantation: The Complementary Roles of Randomized Controlled Trials and Outcomes Research

Improved Organ Utilization and Better Transplant Outcomes With In Situ Normothermic Regional Perfusion in Controlled Donation After Circulatory Death

BACKGROUND

. We evaluated whether the use of normothermic regional perfusion (NRP) was associated with increased organ recovery and improved transplant outcomes from controlled donation after circulatory death (cDCD).

METHODS

. This is a retrospective analysis of UK adult cDCD donors' where at least 1 abdominal organ was accepted for transplantation between January 1, 2011, and December 31, 2019.

RESULTS

. A mean of 3.3 organs was transplanted when NRP was used compared with 2.6 organs per donor when NRP was not used. When adjusting for organ-specific donor risk profiles, the use of NRP increased the odds of all abdominal organs being transplanted by 3-fold for liver ( P < 0.0001; 95% confidence interval [CI], 2.20-4.29), 1.5-fold for kidney ( P = 0.12; 95% CI, 0.87-2.58), and 1.6-fold for pancreas ( P = 0.0611; 95% CI, 0.98-2.64). Twelve-mo liver transplant survival was superior for recipients of a cDCD NRP graft with a 51% lower risk-adjusted hazard of transplant failure (HR = 0.494). In risk-adjusted analyses, NRP kidneys had a 35% lower chance of developing delayed graft function than non-NRP kidneys (odds ratio, 0.65; 95% CI, 0.465-0.901)' and the expected 12-mo estimated glomerular filtration rate was 6.3 mL/min/1.73 m 2 better if abdominal NRP was used ( P < 0.0001).

CONCLUSIONS

. The use of NRP during DCD organ recovery leads to increased organ utilization and improved transplant outcomes compared with conventional organ recovery.

Changing Practice Patterns and Long-term Outcomes of Endothelial Versus Penetrating Keratoplasty: A Prospective Dutch Registry Study

PURPOSE

To compare graft survival, best-corrected visual acuity (BCVA), endothelial cell density (ECD), and refraction following penetrating keratoplasty (PK) vs endothelial keratoplasty (EK) for Fuchs endothelial dystrophy (FED) and pseudophakic bullous keratopathy (PBK).

DESIGN

Nonrandomized treatment comparison with national registry data.

METHODS

All consecutive patients undergoing first keratoplasty for FED and PBK between 1998 and 2014 were analyzed, with a maximum follow-up of 5 years (mean ± SD follow-up 39 ± 20 months, range 0-60 months). Graft survival was analyzed using Kaplan-Meier survival curves and Cox regression analysis. BCVA, ECD, and refractive error were compared using linear mixed models. Main outcome measures were graft survival, BCVA, refraction, and ECD.

RESULTS

A total of 5115 keratoplasties (PK = 2390; EK = 2725) were identified. Two-year graft survival following EK was lower compared with PK (94.5% vs 96.3%, HR = 1.56, P = .001). Five-year survival was comparable for EK and PK (93.4% vs 89.7%, HR = 0.89, P = .261). EK graft survival improved significantly over time while remaining stable for PK. One-year BCVA was better following EK vs PK (0.34 vs 0.47 logMAR, P < .001). Astigmatism was lower 1 year after EK vs PK (-1.69 vs -3.52 D, P < .001). One-year ECD was lower after EK vs PK (1472 vs 1859 cells/mm², P < .001). At 3 years, ECD did not differ between EK and PK.

CONCLUSIONS

Long-term graft survival after EK and PK is high and comparable despite lower short-term survival for EK. EK graft survival improved over time, suggesting a learning curve. EK results in better BCVA, lower astigmatism, and similar long-term ECD compared with PK for FED and PBK.

Cyclosporine versus tacrolimus: cost-effectiveness analysis for renal transplantation in Brazil

OBJECTIVE To analyze the cost-effectiveness of treatment regimens with cyclosporine or tacrolimus, five years after renal transplantation. METHODS This cost-effectiveness analysis was based on historical cohort data obtained between 2000 and 2004 and involved 2,022 patients treated with cyclosporine or tacrolimus, matched 1:1 for gender, age, and type and year of transplantation. Graft survival and the direct costs of medical care obtained from the National Health System (SUS) databases were used as outcome results. RESULTS Most of the patients were women, with a mean age of 36.6 years. The most frequent diagnosis of chronic renal failure was glomerulonephritis/nephritis (27.7%). In five years, the tacrolimus group had an average life expectancy gain of 3.96 years at an annual cost of R$78,360.57 compared with the cyclosporine group with a gain of 4.05 years and an annual cost of R$61,350.44. CONCLUSIONS After matching, the study indicated better survival of patients treated with regimens using tacrolimus. Moreover, regimens containing cyclosporine were more cost-effective [corrected].

Animal models of chronic kidney disease: useful but not perfect

Animal models of chronic kidney disease (CKD) approximate the human condition and are keys to understanding its pathogenesis and to developing rational treatment strategies. The ethical use of animals requires a detailed understanding of the strengths and limitations of each species and the disease model, and the way in which findings can be translated from animals to humans. While not perfect, the careful use of animal experiments offers the opportunity to examine individual mechanisms in an accelerated time frame.

Retrospective outcomes studies for orphan diseases: challenges and opportunities

Retrospective outcomes studies for orphan diseases are scarce in the literature because of the significant methodological and data challenges that researchers have to overcome. Over the last two decades, many opportunities have emerged to mitigate these challenges. In this editorial we examined the common challenges in retrospective outcomes studies as well as the emerging opportunities that researchers can utilize to overcome those challenges. With the introduction of two retrospective orphan disease studies in this issue, we encourage more researchers to take advantage of the emerging opportunities to conduct and publish more retrospective outcomes studies for orphan diseases. This can provide important real-world insights into orphan diseases, including how they are being treated.

Cyclosporine versus tacrolimus treated liver transplant recipients with chronic hepatitis C: outcomes analysis of the UNOS/OPTN database

Recurrent hepatitis C virus (HCV) remains a problematic cause of morbidity and mortality for liver transplant patients. Immunosuppression including calcineurin-inhibitors has been implicated in the acceleration of recurrent HCV. Recent studies suggest that outcomes may be better with cyclosporine (CSA-ME) compared to tacrolimus (TAC), but the data are inconclusive. We retrospectively analyzed data received from the United Network for Organ Sharing on 8809 chronic HCV liver transplant recipients receiving either cyclosporine microemulsion (CSA-ME) or tacrolimus (TAC) as maintenance immunosuppression prior to discharge. We analyzed patient death, graft failure, failure due recurrent disease and acute cellular rejection (ACR) for CSA-ME versus TAC treated patients. Three-year unadjusted patient and graft survival rates were 76.8% and 71.5%, respectively, in the CSA-ME group versus 79.9% and 75.0% in the TAC group. Propensity score-adjusted results suggest CSA-ME treated patients are at increased risk of patient death and graft failure [Hazards ratio (HR) = 1.17; 95% CI = 1.01-1.36 and HR = 1.19; 95% CI = 1.04-1.35, respectively] and biopsy-confirmed AR (HR = 2.03; 95% CI = 1.54-2.67) compared to TAC treated patients. These results provide evidence to reconsider the targeted administration of CSA-ME to HCV-infected liver transplant recipients.

Cyclosporine Versus Tacrolimus in Immunosuppressive Maintenance Regimens in Renal Transplants in Brazil: Survival Analysis from 2000 to 2004

BACKGROUND

In Brazil, the National Health System (SUS) is responsible for almost all renal transplants. SUS protocols recommend using cyclosporine, in association with azathioprine and corticosteroids, to maintain the immunosuppression that is essential for successful renal transplant. Alternatively, cyclosporine can be replaced by tacrolimus.

OBJECTIVE

To evaluate the effectiveness of therapeutic schema involving cyclosporine or tacrolimus after renal transplant during a 60-month follow-up period.

METHODS

A historical cohort study, from 2000 to 2004, was conducted using 5686 patients who underwent renal transplant and received cyclosporine or tacrolimus. Uni - and multivariate analyses were performed using the Cox model to examine factors associated with progression to treatment failure.

RESULTS

Most of the patients were male, aged 38 years or older, for whom the most frequent primary diagnosis of chronic renal failure (CRF) was glomerulonephritis/nephritis. Higher risk of treatment failure was associated with: therapeutic regimen (tacrolimus, HR 1.38, 95% CI 1.14 to 1.67), patient age at transplantation (additional year, HR 1.01, 95% CI 1.00 to 1.02), donor type (deceased, HR 1.60, 95% CI 1.35 to 1.89), median time of dialysis prior to transplantation (>24 mo, HR 1.29, 95% CI 1.09 to 1.52), and primary CRF diagnosis (diabetes, HR 1.54, 95% CI 1.09 to 2.17).

CONCLUSIONS

The risk of treatment failure of patients receiving tacrolimus was observed to be 1.38 times that of those receiving cyclosporine, after adjusting the model for possible confounding factors such as patient sex, patient age, graft origin, prior time of dialysis, and cause of CRF. Our results were obtained from an observational study, and further studies are necessary to evaluate whether compliance with SUS clinical protocols could result in more effective care for renal transplant recipients.

Risk factors for human corneal graft failure within the Australian corneal graft registry

BACKGROUND

Our aims were to examine graft survival and visual outcome after full-thickness corneal transplantation.

METHODS

Records of 18,686 penetrating corneal grafts, 14,622 with archival follow-up from 1 to 22 years, were examined within a national database. Kaplan-Meier survival analysis indicated variables of interest for Cox proportional hazards regression analysis. A model clustered by patient to control intereye or intergraft dependence was constructed to identify variables best predicting penetrating corneal graft failure. Visual acuity in the grafted eye was measured by Snellen acuity.

RESULTS

Probability of corneal graft survival was 0.87, 0.73, 0.60, and 0.46 at 1, 5, 10, and 15 years, respectively. Reasons for graft failure included irreversible rejection (34%), corneal endothelial cell failure including cases of glaucoma (24%), and infection (14%). Variables predicting graft failure in multivariate analysis included transplant center, location and volume of surgeon's case-load, graft era, indication for graft, number of previous ipsilateral grafts, lens status, corneal neovascularization at transplantation, a history of ocular inflammation or raised intraocular pressure, graft diameter, and postoperative events including graft neovascularization and rejection. Best-corrected Snellen acuity of 6/12 or better was achieved by 45%, and of less than 6/60 by 26%, of grafted eyes at last follow-up.

CONCLUSIONS

The short-term survival of penetrating corneal transplants is excellent, but the eventual attrition rate appears inexorable and many factors that influence graft survival significantly are not amenable to change. Most penetrating grafts are performed for visual improvement, and excellent acuity will be achieved by approximately half of all grafts.

Complementarity comes of age

The only inherent and inevitable difference between randomized controlled trials and nonrandomized studies (a term that is preferable to "outcomes research") is in the allocation of patients to different interventions. Although simple interventions, such as drugs, can and should always be evaluated using a randomized design, it is often not possible or appropriate to subject more complex interventions or policies to that approach. Rather than viewing randomized and nonrandomized designs as in competition, they should be seen as complementary. One of the major advantages of nonrandomized studies is that they can make use of existing large, high quality databases that have been assembled for other reasons and therefore provide excellent value-for-money.