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Robert M Merion

Publications and source records attributed to Robert M Merion.

49 records · Page 3Linked to original sources
PubMed2003

Longitudinal assessment of mortality risk among candidates for liver transplantation.

Liver allocation policy recently was modified to use the Model for End-Stage Liver Disease (MELD) for patients with chronic liver disease to stratify potential recipients according to risk for waitlist death. In this study, a retrospective cohort of 760 adult patients with chronic liver disease placed on the liver transplant waitlist between January 1995 and March 2001 and followed up for up to 74 months was studied to assess the ability of the MELD to predict mortality among waitlisted candidates and evaluate the prognostic importance of changes in MELD score over time. Serial MELD scores predicted waitlist mortality significantly better than baseline MELD scores or medical urgency status. Each unit of the 40-point MELD score was associated with a 22% increased risk for waitlist death (P <.001), whereas medical urgency status was not a significant independent predictor. For any given MELD score, the magnitude and direction of change in MELD score during the previous 30 days (DeltaMELD) was a significant independent mortality predictor. Patients with MELD score increases greater than 5 points over 30 days had a threefold greater waitlist mortality risk than those for whom MELD scores increased more gradually (P <.0001). We conclude that mortality risk on the liver transplant waitlist is predicted more accurately by serial MELD score determinations than by medical urgency status or single MELD measurements. DeltaMELD score over time reflects progression of liver disease and conveys important additional prognostic information that should be considered in the further evolution of national liver allocation policy.

Adult↗
PubMed2003

Survival benefit of kidney and liver transplantation for obese patients on the waiting list.

As in the general population of the United States, obesity has become a significant problem in transplantation. Patient survival after deceased donor kidney transplantation is significantly lower among obese recipients (body mass index [BMI] > or = 30 kg/m2) than among non-obese recipients. Survival also appears to be decreased among obese liver transplant recipients. Based on these findings, some authors have argued against kidney or liver transplantation in the morbidly obese. However, the survival benefit for patients listed for and receiving either a kidney or liver transplant is not well understood. To determine if a significant survival benefit exists for obese patients after transplantation versus those on the waiting list, we studied a retrospective cohort of patients identified in the Scientific Registry of Transplant Recipients database. Adjusted, time-dependent Cox regression models were used to evaluate the relative risk (RR) of death after transplantation compared with waiting list mortality for either kidney or liver transplantation. These results demonstrate that kidney transplantation offers a significant survival benefit and is the preferred therapy for most obese dialysis patients. Although liver transplant recipients with a BMI > or = 35 kg/m2 had an increased RR for mortality compared with other recipients with a lower BMI, all groups, regardless of BMI, demonstrated a significant transplant benefit. These data suggest obesity should not be a contraindication for transplantation.

Humans↗
PubMed2002

Renal transplantations performed using non-heart-beating organ donors: going back to the future?

BACKGROUND: As more expanded-criteria organ donors are used to bridge the widening gap between organ supply and demand, non-heart-beating (NHB) donors will become increasingly important. The purpose of this study was to analyze renal transplant outcomes using this source of cadaveric (CAD) organs and compare the results with heart-beating organ sources. METHODS: Data from 98,698 adult CAD renal transplant recipients and 34,531 living donor renal transplant recipients registered in the U. S. Renal Data System database between January 1993 and June 2000 were analyzed. Kaplan-Meier survival curves were used to compare graft and patient survival rates between NHB, CAD, and living donor transplant recipients. Cox proportional hazards models were used to identify risk factors for NHB donor recipients, while adjusting for potential confounding variables. RESULTS: Recipients of NHB donor organs experienced nearly twice the incidence of delayed graft function (DGF) compared with heart-beating donors (42.4% vs. 23.3%, respectively). NHB donor transplants experienced comparable allograft survival when compared with CAD transplants at 6 years (73.2% vs. 72.5%, respectively; P=NS); patient survival was greater at 6 years for NHB compared with CAD renal transplant recipients (80.9% vs. 77.8%, respectively; P=NS). Significant factors for allograft loss for NHB donor organ recipients included the following: organ used for repeat transplants; DGF; donor age older than 35 years; and head trauma as a cause of initial injury (relative risk 2.74, 1.90, 1.78, and 1.41, respectively). CONCLUSIONS: Although exhibiting elevated DGF rates, allograft and patient survival rates of transplants from NHB donor sources are equivalent to those from conventional CAD sources. Donor age, recipient transplant number, female recipient, mechanism of injury, and DGF were the most pertinent variables leading to poor outcomes.

Adult↗
PubMed2002

Donor characteristics associated with reduced graft survival: an approach to expanding the pool of kidney donors.

BACKGROUND: Availability of cadaveric kidneys for transplantation is far below the growing need, leading to longer waiting time and more deaths while waiting. METHODS: Using national data from 1995 to 2000, we evaluated graft survival by donor characteristics and the rate of discard of retrieved organs, with the goal of increasing use of kidneys that are associated with increased risk of graft failure, that is, expanded donor kidneys. RESULTS: Cox models identified four donor factors that independently predicted significantly higher relative risk of graft loss compared with a low-risk group. These factors included donor age, cerebrovascular accident as the cause of death, renal insufficiency (serum creatinine >1.5 mg/dL), and history of hypertension. Expanded donor kidneys were defined as those with relative risk of graft loss greater than 1.70 and included all donors aged 60 years and older and those aged 50 to 59 years with at least two of the other three conditions (cerebrovascular cause of death, renal insufficiency, hypertension). The expanded donor group accounted for 14.8% of transplanted kidneys. Among organs procured from expanded donors, 38% were discarded versus 9% for all other kidneys. The risk of graft loss of expanded donor kidneys was increased in both older and younger recipients but to a greater extent in those recipients older than 50 years. CONCLUSION: By identifying donor factors associated with graft failure, these analyses may help to expand the number of transplanted kidneys by increasing the utilization of retrieved cadaveric kidneys.

Adolescent↗
PubMed2002

Evaluation of pancreatic allograft dysfunction by laparoscopic biopsy.

BACKGROUND: Histologic evaluation of a failing pancreatic allograft is necessary for accurate classification of graft dysfunction. Unlike percutaneous or transcystoscopic techniques, laparoscopic biopsy allows visualization of the allograft in addition to obtaining tissue for histologic examination. METHODS: We retrospectively reviewed all laparoscopic pancreas transplant biopsies performed over a 15-month period ending February 2002. RESULTS: There were 12 laparoscopic pancreas biopsies performed in 11 patients between 6 weeks and 8 years (mean 2.5+/-2.8 years) after transplant. Indications for biopsy were hyperglycemia (n=8), hyperamylasemia (n=3), and graft tenderness (n=1). Adequate tissue was obtained in 11 of 12 biopsies. Two patients received definitive treatment at the time of laparoscopy (pseudocyst debridement, ovarian cyst excision). CONCLUSIONS: Laparoscopic pancreas transplant biopsy allows safe visualization of the allograft and effective specimen retrieval, and in some cases provides the opportunity for therapeutic intervention.

Adult↗
PubMed2002

Epithelioid hemangioendothelioma of the liver disseminated to the peritoneum treated with liver transplantation and interferon alpha-2B.

Epithelioid hemangioendothelioma (EH) is a rare, low-grade, malignant neoplasm of vascular origin that may develop at different sites, such as in the soft tissue, lungs, or liver. We report the case of a 21-year-old female with primary EH of the liver treated by liver transplantation and review the available literature on EH. This patient developed symptomatic recurrence of the tumor in the pelvis 2 months posttransplant. Treatment with interferon alpha-2b resulted in substantial regression of the pelvic metastases and alleviation of symptoms, but the patient developed graft rejection and died of associated complications 16 months posttransplant. This report is the first showing the efficacy of interferon in this setting.

Adult↗
PubMed2002

Gender imbalance in living donor renal transplantation.

BACKGROUND: Previous studies have shown more women than men among living donors (LD) and more men among recipients of those kidneys. In this study, we compared the evolving demographics of LD transplants. METHODS: We retrospectively analyzed all LD transplants performed in our center between 1964 and 2000. RESULTS: Among 1182 LD cases, 1035 (88%) were biologically related (LRD) and 147 (12%) were unrelated (LURD). LURD donors and recipients were significantly older than LRD donors and recipients, respectively (P=0.0001). More LURD allograft recipients were male (71%) compared with LRD recipients (57%) (P=0.0013). The proportion of female donors was 55% in both groups. Spousal donations were predominantly wife-to-husband (69%). Compared with the LRD group, there was a greater proportion of female-to-male LURD transplants (46 vs. 30%) and a smaller proportion of female-to-female LURD transplants (10 vs. 25%) (P=0.0001). When spousal pairs were excluded from the analysis, there was a higher proportion of male-to-male (48 vs. 27%) donations and a lower proportion of male-to-female (18 vs. 9%) and female-to-female (25 vs. 17%) transplants in the LURD group (P=0.001). CONCLUSIONS: Gender disparities in LD transplantation are primarily due to a higher proportion of wife-to-husband donations and a lower incidence of male-to-female grafts among nonspousal LURD transplants. Strategies should be devised to ensure access for women to renal transplantation and to encourage and facilitate donation by men.

Female↗
PubMed2002

Basiliximab in pediatric liver transplantation: a pharmacokinetic-derived dosing algorithm.

The pharmacokinetics and immunodynamics of basiliximab were assessed in 37 pediatric de novo liver allograft recipients to rationally design a dose regimen for this age-group. In part one of the study, patients were given 12 mg/m2 basiliximab by bolus intravenous injection after organ perfusion and on day 4 after transplant. An interim pharmacokinetic evaluation supported a fixed-dose approach for part two of the study in which infants and children received two 10-mg doses of basiliximab and adolescents received two 20-mg doses. Blood samples were collected over a 12-week period for screening for anti-idiotype antibodies and analysis of basiliximab and soluble interleukin-2 receptor (IL-2R) concentrations. Basiliximab clearance in infants and children < 9 yr of age (n = 30) was reduced by approximately 50% compared with adults from a previous study and was independent of age to 9 yr, weight to 30 kg, and body surface area to 1.0 m2. Clearance in children and adolescents 9-14 yr of age (n = 7) approached or reached adult values. An average of 15% of the dose was eliminated via drained ascites fluid, and drug clearance via this route averaged 29% of total body clearance. Patients with > 5 L of ascites fluid drainage tended to have lower systemic exposure to basiliximab. CD25-saturating basiliximab concentrations were maintained for 27 +/- 9 days in part one of the study (mg/m2 dosing) with infants exhibiting the lowest durations. CD25 saturation lasted 37 +/- 11 days in part two of the study, based on the fixed-dose regimen (p = 0.004 vs. mg/mg2 dosing), but did not show the age-related bias observed in part one of the study. Anti-idiotype antibodies were detected in four patients, but this did not influence the clearance of basiliximab or duration of CD25 saturation. All 40 enrolled patients were included in the intent-to-treat clinical analysis. Episodes of acute rejection occurred in 22 patients (55%) during the first 12 months post-transplant. Three patients experienced loss of their graft as a result of technical complications, and six patients died during the 12-month study. Basiliximab was well tolerated by intravenous bolus injection, with no cytokine-release syndrome or other infusion-related adverse events. Hence, basiliximab was safe and well tolerated in pediatric patients undergoing orthotopic liver transplantation. To achieve similar basiliximab exposure as is efficacious in adults, pediatric patients < 35 kg in weight should receive two 10-mg doses and those > or = 35 kg should receive two 20-mg doses of basiliximab by intravenous infusion or bolus injection. The first dose should be given within 6 h after organ perfusion and the second on day 4 after transplantation. A supplemental dose may be considered for patients with a large volume of drained ascites fluid relative to body size.

Adolescent↗
PubMed2002

Long-term survival after liver transplantation in children with metabolic disorders.

BACKGROUND: Liver transplantation for inherited metabolic disorders aims to save the patient's life when the disorder is expected to progress to organ failure, and to cure the underlying metabolic defect. METHODS: We retrospectively analyzed 146 pediatric liver transplants (28 metabolic; 118 non-metabolic) performed between 1986 and 2000. RESULTS: Twenty-eight transplants were performed in 24 children with metabolic disease (8 females; 16 males; age range 3 months to 17 yr). Indications included alpha-1-antitrypsin deficiency (n = 8), two cases each of hyperoxaluria type 1, Wilson's disease, hereditary tyrosinemia type I, citrullinemia, methylmalonic acidemia, and one case each of propionic acidemia, Crigler-Najjar syndrome type I, neonatal hemachromatosis, hemophilia B, Niemann-Pick disease type B, and cystic fibrosis. Eighteen transplants were whole organ grafts and 10 were lobar or segmental. Auxiliary liver transplants were performed in two patients and three received combined liver-kidney transplants. There were three deaths from sepsis, two from chronic rejection, and one from fulminant hepatitis. Seven of 10 patients currently of school age are within 1 yr of expected grade and three who had pretransplant developmental delay have remained in special education. Actuarial survival rates at 5 and 10 yr are 78% and 68%, respectively, with mean follow-up in excess of 5 yr. These results compare favorably to 100 pediatric patients transplanted for non-metabolic etiologies (65% and 61%, respectively) (p= NS). CONCLUSIONS: Pediatric liver transplantation for metabolic disorders results in excellent clinical and biochemical outcome with long survival and excellent quality of life for most recipients.

Adolescent↗
PubMed2002

Trends in cadaveric organ donation in the United States: 1990-1999.

Despite declining in-hospital deaths, deceased donor organ donation increased in all demographic segments of the US population from 1990 to 1999. Although the rate of growth in older donors was more dramatic, there was substantial growth in the most physiologically suitable donor age groups, which contribute most to the donor pool. Nationwide, the average annual growth in donation rate for in-hospital deaths ages 1-70 was 5.0%, with wide regional variation. While the national trend is patently inadequate to meet the need for organ transplantation, the wide range of programs aimed at improving organ donation at all levels of society point to an encouraging pattern that may have resulted, in part, from these initiatives.

Adolescent↗