Valarie B Ashby

University of Michigan, Ann Arbor, Michigan, United States

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Publications (29)268.79 Total impact

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    ABSTRACT: Objective To evaluate evidence of practice changes affecting kidney transplant program volumes, and donor, recipient and candidate selection in the era surrounding the introduction of Centers for Medicare and Medicaid Services (CMS) conditions of participation (CoPs) for organ transplant programs.DataScientific Registry of Transplant Recipients; CMS ESRD and Medicare claims databases.DesignRetrospective analysis of national registry data.MethodsA Cox proportional hazards model of 1-year graft survival was used to derive risks associated with deceased-donor kidney transplants performed from 2001 to 2010.FindingsAmong programs with ongoing noncompliance with the CoPs, kidney transplant volumes declined by 38 percent (n = 766) from 2006 to 2011, including a 55 percent drop in expanded criteria donor transplants. Volume increased by 6 percent (n = 638) among programs remaining in compliance. Aggregate risk of 1-year graft failure increased over time due to increasing recipient age and obesity, and longer ESRD duration.Conclusions Although trends in aggregate risk of 1-year kidney graft loss do not indicate that the introduction of the CoPs has systematically reduced opportunities for marginal candidates or that there has been a systematic shift away from utilization of higher risk deceased donor kidneys, total volume and expanded criteria donor utilization decreased overall among programs with ongoing noncompliance.
    Health Services Research 05/2014; · 2.29 Impact Factor
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    ABSTRACT: We sought to compare liver transplant waiting list access by demographics and geography relative to the pool of potential liver transplant candidates across the United States using a novel metric of access to care, termed a liver wait-listing ratio (LWR). We calculated LWRs from national liver transplant registration data and liver mortality data from the Scientific Registry of Transplant Recipients and the National Center for Healthcare Statistics from 1999 to 2006 to identify variation by diagnosis, demographics, geography, and era. Among patients with ALF and CLF, African Americans had significantly lower access to the waiting list compared with whites (acute: 0.201 versus 0.280; pre-MELD 0.201 versus 0.290; MELD era: 0.201 versus 0.274; all, P<0.0001) (chronic: 0.084 versus 0.163; pre-MELD 0.085 versus 0.179; MELD 0.084 versus 0.154; all, P<0.0001). Hispanics and whites had similar LWR in both eras (both P>0.05). In the MELD era, female subjects had greater access to the waiting list compared with male subjects (acute: 0.428 versus 0.154; chronic: 0.158 versus 0.140; all, P<0.0001). LWRs varied by three-fold by state (pre-MELD acute: 0.122-0.418, chronic: 0.092-0.247; MELD acute: 0.121-0.428, chronic: 0.092-0.243). The marked inequity in early access to liver transplantation underscores the need for local and national policy initiatives to affect this disparity.
    Transplantation 03/2014; · 3.78 Impact Factor
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    ABSTRACT: In 2003, the US kidney allocation system was changed to eliminate priority for HLA-B similarity. We report outcomes from before and after this change using data from the Scientific Registry of Transplant Recipients (SRTR). Analyses were based on 108 701 solitary deceased donor kidney recipients during the 6 years before and after the policy change. Racial/ethnic distributions of recipients in the two periods were compared (chi-square); graft failures were analyzed using Cox models. In the 6 years before and after the policy change, the overall number of deceased donor transplants rose 23%, with a larger increase for minorities (40%) and a smaller increase for non-Hispanic whites (whites) (8%). The increase in the proportion of transplants for non-whites versus whites was highly significant (p < 0.0001). Two-year graft survival improved for all racial/ethnic groups after implementation of this new policy. Findings confirmed prior SRTR predictions. Following elimination of allocation priority for HLA-B similarity, the deficit in transplantation rates among minorities compared with that for whites was reduced but not eliminated; furthermore, there was no adverse effect on graft survival.
    American Journal of Transplantation 06/2011; 11(8):1712-8. · 6.19 Impact Factor
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    ABSTRACT: Coincident with an increasing national interest in equitable health care, a number of studies have described disparities in access to solid organ transplantation for minority patients. In contrast, relatively little is known about differences in posttransplant outcomes between patients of specific racial and ethnic populations. In this paper, we review trends in access to solid organ transplantation and posttransplant outcomes by organ type, race and ethnicity. In addition, we present an analysis of categories of factors that contribute to the racial/ethnic variation seen in kidney transplant outcomes. Disparities in minority access to transplantation among wait-listed candidates are improving, but persist for those awaiting kidney, simultaneous kidney and pancreas and intestine transplantation. In general, graft and patient survival among recipients of solid organ transplants is highest for Asians and Hispanic/Latinos, intermediate for whites and lowest for African Americans. Although much of the difference in outcomes between racial/ethnic groups can be accounted for by adjusting for patient characteristics, important observed differences remain. Age and duration of pretransplant dialysis exposure emerge as the most important determinants of survival in an investigation of the relative impact of center-related versus patient-related variables on kidney graft outcomes.
    American Journal of Transplantation 04/2010; 10(4 Pt 2):1090-107. · 6.19 Impact Factor
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    ABSTRACT: The effect of demand for kidney transplantation, measured by end-stage renal disease (ESRD) incidence, on access to transplantation is unknown. Using data from the U.S. Census Bureau, Centers for Medicare & Medicaid Services (CMS) and the Organ Procurement and Transplantation Network/Scientific Registry of Transplant Recipients (OPTN/SRTR) from 2000 to 2008, we performed donation service area (DSA) and patient-level regression analyses to assess the effect of ESRD incidence on access to the kidney waiting list and deceased donor kidney transplantation. In DSAs, ESRD incidence increased with greater density of high ESRD incidence racial groups (African Americans and Native Americans). Wait-list and transplant rates were relatively lower in high ESRD incidence DSAs, but wait-list rates were not drastically affected by ESRD incidence at the patient level. Compared to low ESRD areas, high ESRD areas were associated with lower adjusted transplant rates among all ESRD patients (RR 0.68, 95% CI 0.66-0.70). Patients living in medium and high ESRD areas had lower transplant rates from the waiting list compared to those in low ESRD areas (medium: RR 0.68, 95% CI 0.66-0.69; high: RR 0.63, 95% CI 0.61-0.65). Geographic variation in access to kidney transplant is in part mediated by local ESRD incidence, which has implications for allocation policy development.
    American Journal of Transplantation 04/2010; 10(4 Pt 2):1069-80. · 6.19 Impact Factor
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    ABSTRACT: The Hispanic ethnic group is heterogeneous, with distinct genetic, cultural, and socioeconomic characteristics, but most prior studies of patients with end-stage renal disease focus on the overall Hispanic ethnic group without further granularity. We examined survival differences among Mexican-American, Puerto Rican, and Cuban-American dialysis patients in the United States. Prospective observational study. Data from individuals randomly selected for the End-Stage Renal Disease Clinical Performance Measures Project (2001 to 2005) were examined. Mexican-American (n = 2,742), Puerto Rican (n = 838), Cuban-American (n = 145), and Hispanic-other dialysis patients (n = 942) were compared with each other and with non-Hispanic (n = 33,076) dialysis patients in the United States. Patient characteristics of interest included ethnicity/race, comorbidities, and specific available laboratory values. The major outcome of interest was mortality. In the fully adjusted multivariable model, 2-year mortality risk was significantly lower for the Mexican-American and Hispanic-other groups compared with non-Hispanics (adjusted hazard ratio, 0.79; 95% confidence interval, 0.73 to 0.85; adjusted hazard ratio, 0.81; 95% confidence interval, 0.71 to 0.92, respectively). Differences in 2-year mortality rates within the Hispanic ethnic groups were statistically significant (P = 0.004) and ranged from 21% lower mortality in Mexican Americans to 3% higher mortality in Puerto Ricans compared with non-Hispanics. Include those inherent to an observational study, potential ethnic group misclassification, and small sample sizes for some Hispanic subgroups. Mexican-American and Hispanic-other dialysis patients have a survival advantage compared with non-Hispanics. Furthermore, Mexican Americans, Cuban Americans, and Hispanic others had a survival advantage compared with their Puerto Rican counterparts. Future research should continue to examine subgroups within Hispanic ethnicity to understand underlying reasons for observed differences that may be masked by examining the Hispanic ethnic group as only a single entity.
    American Journal of Kidney Diseases 01/2009; 53(4):647-57. · 5.29 Impact Factor
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    ABSTRACT: Growth in the number of active patients on the kidney transplant waiting list has slowed. Projections based on the most recent 5-year data suggest the total waiting list will grow at a rate of 4138 registrations per year, whereas the active waiting list will increase at less than one-sixth that rate, or 663 registrations per year. The last 5 years have seen a small trend toward improved unadjusted allograft survival for living and deceased donor kidneys. Since 2004 the overall number of pancreas transplants has declined. Among pancreas recipients, those with simultaneous kidney-pancreas transplants experienced the highest pancreas graft survival rates. In response to the ongoing shortage of deceased donor organs, the US Health Resources and Services Administration launched the Organ Donation Breakthrough Collaborative in September 2003 and the Organ Transplantation Breakthrough Collaborative (OTBC) in October 2005. The 58 DSA Challenge is prominent among the goals adopted by the OTBC. Its premise: were each of the 58 existing donation service areas to increase the number of kidney transplants performed within their boundaries by 10 per month, an additional 7000 transplants over current annual levels would result. Such an increase could potentially eliminate the national kidney transplantation waiting list by 2030.
    American Journal of Transplantation 05/2008; 8(4 Pt 2):946-57. · 6.19 Impact Factor
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    ABSTRACT: Transplant tourism, where patients travel to foreign countries specifically to receive a transplant, is poorly characterized. This study examined national data to determine the minimum scope of this practice. US national waiting list removal data were analyzed. Waiting list removals for transplant without a corresponding US transplant in the database were reviewed via a data validation query to transplant centers to identify foreign transplants. Additionally, waiting list removal records with text field entries indicating a transplant abroad were identified. We identified 373 foreign transplants (173 directly noted; 200 from data validation); most (89.3%) were kidney transplants. Between 2001 and 2006, the annual number of waiting list removals for transplant abroad increased. Male sex, Asian race, resident and nonresident alien status and college education were significantly and independently associated with foreign transplant. Recipients from 34 states, plus the District of Columbia, received foreign transplants in 35 countries, led by China, the Philippines and India. Transplants in foreign countries among waitlisted candidates in the US are increasingly performed. The data reported here represent the minimum number of cases and the full extent of this practice cannot be determined using existing data. Additional reporting requirements are needed.
    American Journal of Transplantation 05/2008; 8(4 Pt 2):988-96. · 6.19 Impact Factor
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    ABSTRACT: Disparities in time to placement on the waiting list on the basis of socioeconomic factors decrease access to deceased-donor renal transplantation for some groups of patients with end-stage renal disease. This study was undertaken to determine candidate factors that influence duration of dialysis before placement on the waiting list among candidates for deceased-donor renal transplantation in the United States from January 2001 to December 2004 and the impact of Medicare eligibility rules on access. Access to the waiting list was measured as the percentage of all wait-listed candidates in the Scientific Registry of Transplant Recipients database who were listed before dialysis and by the duration of dialysis before placement on the waiting list. Multivariate logistic and linear regressions were used to determine variables that were predictive of preemptive listing and the duration of dialysis before listing. The odds for preemptive placement on the waiting list improved during the course of the study period, whereas the median duration of prelisting dialysis did not. The candidate factors that were associated with low rates of preemptive listing and prolonged exposure to prelisting dialysis included Medicare insurance, minority race/ethnicity, and low educational attainment. In patients who were listed after the age of 64 yr, the adverse effect of Medicare insurance on access largely disappeared. The disparity in dialysis exposure could potentially be diminished by concerted efforts on the part of the nephrology and transplant communities to promote early referral and preemptive placement on the waiting list, by calculating waiting time from the date of initiation of dialysis for patients who are on dialysis at the time of referral, and by relaxing Medicare eligibility requirements.
    Clinical Journal of the American Society of Nephrology 03/2008; 3(2):463-70. · 5.07 Impact Factor
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    ABSTRACT: Elderly patients (ages 70 yr and older) are among the fastest-growing group starting renal-replacement therapy in the United States. The outcomes of elderly patients who receive a kidney transplant have not been well studied compared with those of their peers on the waiting list. Using the Scientific Registry of Transplant Recipients, we analyzed data from 5667 elderly renal transplant candidates who initially were wait-listed from January 1, 1990 to December 31, 2004. Of these candidates, 2078 received a deceased donor transplant, and 360 received a living donor transplant by 31 December 2005. Time-to-death was studied using Cox regression models with transplant as a time-dependent covariate. Mortality hazard ratios (RRs) of transplant versus waiting list were adjusted for recipient age, sex, race, ethnicity, blood type, panel reactive antibody, year of placement on the waiting list, dialysis modality, comorbidities, donation service area, and time from first dialysis to first placement on the waiting list. Elderly transplant recipients had a 41% lower overall risk of death compared with wait-listed candidates (RR=0.59; P<0.0001). Recipients of nonstandard, that is, expanded criteria donor, kidneys also had a significantly lower mortality risk (RR=0.75; P<0.0001). Elderly patients with diabetes and those with hypertension as a cause of end-stage renal disease also experienced a large benefit. Transplantation offers a significant reduction in mortality compared with dialysis in the wait-listed elderly population with end-stage renal disease.
    Transplantation 04/2007; 83(8):1069-74. · 3.78 Impact Factor
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    ABSTRACT: This article focuses on geographic variability in patient access to kidney transplantation in the United States. It examines geographic differences and trends in access rates to kidney transplantation, in the component rates of wait-listing, and of living and deceased donor transplantation. Using data from Centers for Medicare and Medicaid Services and the Organ Procurement and Transplantation Network/Scientific Registry of Transplant Recipients, we studied 700,000+ patients under 75, who began chronic dialysis treatment, received their first living donor kidney transplant, or were placed on the waiting list pre-emptively. Relative rates of wait-listing and transplantation by State were calculated using Cox regression models, adjusted for patient demographics. There were geographic differences in access to the kidney waiting list and to a kidney transplant. Adjusted wait-list rates ranged from 37% lower to 64% higher than the national average. The living donor rate ranged from 57% lower to 166% higher, while the deceased donor transplant rate ranged from 60% lower to 150% higher than the national average. In general, States with higher wait-listing rates tended to have lower transplantation rates and States with lower wait-listing rates had higher transplant rates. Six States demonstrated both high wait-listing and deceased donor transplantation rates while six others, plus D.C. and Puerto Rico, were below the national average for both parameters.
    American Journal of Transplantation 01/2007; 7(5 Pt 2):1412-23. · 6.19 Impact Factor
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    ABSTRACT: Understanding how transplant data are collected is crucial to understanding how the data can be used. The collection and use of Organ Procurement and Transplantation Network/Scientific Registry of Transplant Recipients (OPTN/SRTR) data continues to evolve, leading to improvements in data quality, timeliness and scope while reducing the data collection burden. Additional ascertainment of outcomes completes and validates existing data, although caveats remain for researchers. We also consider analytical issues related to cohort choice, timing of data submission, and transplant center variations in follow-up data. All of these points should be carefully considered when choosing cohorts and data sources for analysis. The second part of the article describes some of the statistical methods for outcome analysis employed by the SRTR. Issues of cohort and follow-up period selection lead into a discussion of outcome definitions, event ascertainment, censoring and covariate adjustment. We describe methods for computing unadjusted mortality rates and survival probabilities, and estimating covariate effects through regression modeling. The article concludes with a description of simulated allocation modeling, developed by the SRTR for comparing outcomes of proposed changes to national organ allocation policies.
    American Journal of Transplantation 02/2006; 6(5 Pt 2):1228-42. · 6.19 Impact Factor
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    ABSTRACT: Transplantation using kidneys from deceased donors who meet the expanded criteria donor (ECD) definition (age > or =60 years or 50 to 59 years with at least 2 of the following: history of hypertension, serum creatinine level >1.5 mg/dL [132.6 micromol/L], and cerebrovascular cause of death) is associated with 70% higher risk of graft failure compared with non-ECD transplants. However, if ECD transplants offer improved overall patient survival, inferior graft outcome may represent an acceptable trade-off. To compare mortality after ECD kidney transplantation vs that in a combined standard-therapy group of non-ECD recipients and those still receiving dialysis. Retrospective cohort study using data from a US national registry of mortality and graft outcomes among kidney transplant candidates and recipients. The cohort included 109,127 patients receiving dialysis and added to the kidney waiting list between January 1, 1995, and December 31, 2002, and followed up through July 31, 2004. Long-term (3-year) relative risk of mortality for ECD kidney recipients vs those receiving standard therapy, estimated using time-dependent Cox regression models. By end of follow-up, 7790 ECD kidney transplants were performed. Because of excess ECD recipient mortality in the perioperative period, cumulative survival did not equal that of standard-therapy patients until 3.5 years posttransplantation. Long-term relative mortality risk was 17% lower for ECD recipients (relative risk, 0.83; 95% confidence interval, 0.77-0.90; P<.001). Subgroups with significant ECD survival benefit included patients older than 40 years, both sexes, non-Hispanics, all races, unsensitized patients, and those with diabetes or hypertension. In organ procurement organizations (OPOs) with long median waiting times (>1350 days), ECD recipients had a 27% lower risk of death (relative risk, 0.73; 95% confidence interval, 0.64-0.83; P<.001). In areas with shorter waiting times, only recipients with diabetes demonstrated an ECD survival benefit. ECD kidney transplants should be offered principally to candidates older than 40 years in OPOs with long waiting times. In OPOs with shorter waiting times, in which non-ECD kidney transplant availability is higher, candidates should be counseled that ECD survival benefit is observed only for patients with diabetes.
    JAMA The Journal of the American Medical Association 12/2005; 294(21):2726-33. · 29.98 Impact Factor
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    ABSTRACT: This article provides detailed explanations of the methods frequently employed in outcomes analyses performed by the Scientific Registry of Transplant Recipients (SRTR). All aspects of the analytical process are discussed, including cohort selection, post-transplant follow-up analysis, outcome definition, ascertainment of events, censoring, and adjustments. The methods employed for descriptive analyses are described, such as unadjusted mortality rates and survival probabilities, and the estimation of covariant effects through regression modeling. A section on transplant waiting time focuses on the kidney and liver waiting lists, pointing out the different considerations each list requires and the larger questions that such analyses raise. Additionally, this article describes specialized modeling strategies recently designed by the SRTR and aimed at specific organ allocation issues. The article concludes with a description of simulated allocation modeling (SAM), which has been developed by the SRTR for three organ systems: liver, thoracic organs, and kidney-pancreas. SAMs are particularly useful for comparing outcomes for proposed national allocation policies. The use of SAMs has already helped in the development and implementation of a new policy for liver candidates with high MELD scores to be offered organs regionally before the organs are offered to candidates with low MELD scores locally.
    American Journal of Transplantation 05/2005; 5(4 Pt 2):950-7. · 6.19 Impact Factor
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    ABSTRACT: Benefits in terms of reductions in mortality corresponding to improvements in Kidney Disease Outcomes Quality Initiative (K/DOQI) compliance for adequacy of dialysis dose and anemia control have not been documented in the literature. We studied changes in achieving K/DOQI guidelines at the facility level to determine whether those changes are associated with corresponding changes in mortality. Adjusted mortality and fractions of patients achieving K/DOQI guidelines for urea reduction ratios (URRs; > or =65%) and hematocrit levels (> or =33%) were computed for 2,858 dialysis facilities from 1999 to 2002 using national data for patients with end-stage renal disease. Linear and Poisson regression were used to study the relationship between K/DOQI compliance and mortality and between changes in compliance and changes in mortality. In 2002, facilities in the lowest quintile of K/DOQI compliance for URR and hematocrit guidelines had 22% and 14% greater mortality rates (P < 0.0001) than facilities in the highest quintile, respectively. A 10-percentage point increase in fraction of patients with a URR of 65% or greater was associated with a 2.2% decrease in mortality (P = 0.0006), and a 10-percentage point increase in percentage of patients with a hematocrit of 33% or greater was associated with a 1.5% decrease in mortality (P = 0.003). Facilities in the highest tertiles of improvement for URR and hematocrit had a change in mortality rates that was 15% better than those observed for facilities in the lowest tertiles (P < 0.0001). Both current practice and changes in practices with regard to achieving anemia and dialysis-dose guidelines are associated significantly with mortality outcomes at the dialysis-facility level.
    American Journal of Kidney Diseases 01/2005; 45(1):127-35. · 5.29 Impact Factor
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    ABSTRACT: The worsening shortage of donor kidneys for transplant and the aging of both the donor and candidate populations have contributed to the increasing importance of ECD kidney transplantation. While ECD transplants have an increased risk of graft failure, for most candidates patient survival is still improved over remaining on dialysis. Because of this risk, however, ECD kidneys have a high likelihood of discard; significant geographic variation in discard and transplant rates impedes maximum utilization of these kidneys. The ECD allocation system was implemented to help facilitate expeditious placement of ECD kidneys to pre-consented candidates by a simplified allocation algorithm. Under this system, recovery and transplantation of ECD kidneys have increased at rates not seen with non-ECD kidneys and not predicted by preexisting trends. More disappointing has been the lack of effect on the percentage of discards and DGF, despite significant reductions in CIT. The disadvantage in graft survival for ECD kidneys extends equally across the spectrum of recipient characteristics, such that no one group of candidates has a proportionately smaller increase in risk. However, benefit analyses comparing the risk of accepting an ECD kidney versus waiting for a non-ECD kidney demonstrate a significant ECD benefit for older and diabetic candidates in regions with prolonged waiting times. The potential value of an ECD kidney to an individual candidate hinges upon the ability to receive it substantially earlier than a non-ECD kidney. Thus, future allocation efforts may focus on ensuring that is the case. In allocation driven by net benefit, ECD kidneys may become an alternative for those who might not otherwise receive a kidney transplant.
    Clinical transplants 01/2005;
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    ABSTRACT: Several observational studies reported lower mortality risk among hemodialysis patients treated with doses greater than the standard dose. The present study evaluates, with observational data, the secondary randomized Hemodialysis (HEMO) Study finding that greater dialysis dose may benefit women, but not men. Data from 74,120 US hemodialysis patients starting end-stage renal disease therapy were analyzed. Patients were classified into 1 of 5 categories of hemodialysis dose according to their average urea reduction ratio (URR), and their relative risk (RR) for mortality was evaluated by using Cox proportional hazards models. Similar analyses using equilibrated Kt/V were completed for 10,816 hemodialysis patients in the Dialysis Outcomes and Practice Patterns Study (DOPPS) in 7 countries. For both men and women, RR was substantially lower in the URR 70%-to-75% category compared with the URR 65%-to-70% category. Among women, RR in the URR greater-than-75% category was significantly lower compared with the URR 70%-to-75% group (P < 0.0001); however, no further association with mortality risk was observed for the greater-than-75% category among men (P = 0.22). RR associated with doses greater than the Kidney Disease Outcomes Quality Initiative guidelines (URR > or = 65%) was significantly different for men compared with women (P < 0.01). Similar differences by sex were observed in DOPPS analyses. The agreement of these observational studies with the HEMO Study supports the existence of a survival benefit from greater dialysis doses for women, but not for men. Responses to greater dialysis dose by sex deserve additional study to explain these differences.
    American Journal of Kidney Diseases 06/2004; 43(6):1014-23. · 5.29 Impact Factor
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    ABSTRACT: HLA typing and the time a patient has spent on the waiting list are the primary criteria used to allocate cadaveric kidneys for transplantation in the United States. Candidates with no HLA-A, B, and DR mismatches are given top priority, followed by candidates with the fewest mismatches at the HLA-B and DR loci; this policy contributes to a higher transplantation rate among whites than nonwhites. We hypothesized that changing this allocation policy would affect graft survival and the racial balance among transplant recipients. We estimated the relative rates of kidney transplantation according to race resulting from the current allocation policy and racial differences in HLA antigen profiles, using a Cox model for the time from placement on the waiting list to transplantation. Another model, also adjusted for HLA-B and DR antigen profiles, estimated the relative rates of kidney transplantation that would result if the distribution of these antigen profiles were identical among the racial and ethnic groups. We also investigated the effect of HLA matching on the risk of graft failure, using a Cox model for the time from the first transplantation to graft failure. The results of the two analyses were used to estimate the change in the racial balance of transplantation and graft-failure rates that would result from the elimination of HLA-B matching or HLA-B and DR matching as a means of assigning priority. Eliminating the HLA-B matching as a priority while maintaining HLA-DR matching as a priority would decrease the number of transplantations among whites by 4.0 percent (166 fewer transplantations over a one-year period), whereas it would increase the number among nonwhites by 6.3 percent and increase the rate of graft loss by 2.0 percent. Removing HLA-B matching as a priority for the allocation of cadaveric kidneys could reduce the existing racial imbalance by increasing the number of transplantations among nonwhites, with only a small increase in the rate of graft loss.
    New England Journal of Medicine 03/2004; 350(6):545-51. · 54.42 Impact Factor
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    ABSTRACT: Data from the Scientific Registry of Transplant Recipients offer a unique and comprehensive view of US trends in kidney and pancreas waiting list characteristics and outcomes, transplant recipient and donor characteristics, and patient and allograft survival. Important findings from our review of developments during 2002 and the decade's transplantation trends appear below. The kidney waiting list has continued to grow, increasing from 47,830 in 2001 to 50,855 in 2002. This growth has occurred despite the increasing importance of living donor transplantation, which rose from 28% of total kidney transplants in 1993 to 43% in 2002. Policies and procedures to expedite the allocation of expanded criteria donor (ECD) kidneys were developed and implemented during 2002, when 15% of deceased donor transplants were performed with ECD kidneys. Unadjusted 1- and 5-year deceased donor kidney allograft survivals were 81% and 51% for ECD kidney recipients, and 90% and 68% for non-ECD kidney recipients, respectively. Although more patients have been placed on the simultaneous kidney-pancreas waiting list, the number of these transplants dropped from a peak of 970 in 1998 to 905 in 2002. This decline may be due to competition for organs from increasing numbers of isolated pancreas and islet transplants.
    American Journal of Transplantation 02/2004; 4 Suppl 9:72-80. · 6.19 Impact Factor
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    ABSTRACT: It is highly desirable to base decisions designed to improve medical practice or organ allocation policies on the analyses of the most recent data available. Yet there is often a need to balance this desire with the added value of evaluating long-term outcomes (e.g. 5-year mortality rates), which requires the use of data from earlier years. This article explains the methods used by the Scientific Registry of Transplant Recipients in order to achieve these goals simultaneously. The analysis of waiting list and transplant outcomes depends strongly on statistical methods that can combine data from different cohorts of patients that have been followed for different lengths of time. A variety of statistical methods have been designed to address these goals, including the Kaplan-Meier estimator, Cox regression models, and Poisson regression. An in-depth description of the statistical methods used for calculating waiting times associated with the various types of organ transplants is provided. Risk of mortality and graft failure, adjusted analyses, cohort selection, and the many complicating factors surrounding the calculation of follow-up time for various outcomes analyses are also examined.
    American Journal of Transplantation 02/2004; 4 Suppl 9:106-13. · 6.19 Impact Factor

Publication Stats

3k Citations
268.79 Total Impact Points

Institutions

  • 1999–2014
    • University of Michigan
      • • Department of Biostatistics
      • • Department of Surgery
      • • Department of Internal Medicine
      Ann Arbor, Michigan, United States
  • 2010
    • University of Massachusetts Medical School
      Worcester, Massachusetts, United States
  • 2008
    • McGill University
      • Division of Nephrology
      Montréal, Quebec, Canada
  • 2004
    • University of California, San Francisco
      San Francisco, California, United States
    • Georgia Health Sciences University
      Augusta, Georgia, United States