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KDOQI practice guidelines recommend predialysis blood pressure <140/90mmHg; however, most prior studies had found elevated mortality with low, not high, systolic blood pressure. This is possibly due to unmeasured confounders affecting systolic blood pressure and mortality. To lessen this bias, we analyzed 24,525 patients by Cox regression models adjusted for patient and facility characteristics. Compared with predialysis systolic blood pressure of 130–159mmHg, mortality was 13% higher in facilities with 20% more patients at systolic blood pressure of 110–129mmHg and 16% higher in facilities with 20% more patients at systolic blood pressure of ≥160mmHg. For patient-level systolic blood pressure, mortality was elevated at low (<130mmHg), not high (≥180mmHg), systolic blood pressure. For predialysis diastolic blood pressure, mortality was lowest at 60–99mmHg, a wide range implying less chance to improve outcomes. Higher mortality at systolic blood pressure of <130mmHg is consistent with prior studies and may be due to excessive blood pressure lowering during dialysis. The lowest risk facility systolic blood pressure of 130–159mmHg indicates this range may be optimal, but may have been influenced by unmeasured facility practices. While additional study is needed, our findings contrast with KDOQI blood pressure targets, and provide guidance on optimal blood pressure range in the absence of definitive clinical trial data.

Chronic renal failure is a risk after transplantation of a nonrenal organ. This population-based cohort analysis evaluated the incidence, risk factors, and hazard of death associated with chronic renal failure in 69,321 patients who received nonrenal transplants between 1990 and 2000. During a median of 36 months, chronic renal failure had developed in 11,426 patients (16.5 percent). Of these patients, 28.9 percent required maintenance dialysis or renal transplantation. A cohort analysis of the risks in 69,321 patients. Chronic renal failure is a recognized complication of organ transplantation. 1 – 8 Calcineurin-inhibitor therapy, a key component of immunosuppressive regimens for patients undergoing transplantation, has been implicated as a principal cause of post-transplantation renal dysfunction, 9 , 10 which may lead to severe tubular atrophy, interstitial fibrosis, and focal hyalinosis of small renal arteries and arterioles. 11 – 16 Furthermore, renal disease before transplantation, perioperative hemodynamic insults to the kidneys, nephrotoxic effects of other drugs, dyslipidemia, hypertension, and diabetes mellitus can all contribute to chronic renal failure in recipients of nonrenal organs. 17 , 18 Renal failure after the transplantation of a nonrenal organ complicates medical management, . . .

There has been an increasing interest in the analysis of recurrent event data (Cook and Lawless, 2002, Statistical Methods in Medical Research11, 141–166). In many situations, a terminating event such as death can happen during the follow‐up period to preclude further occurrence of the recurrent events. Furthermore, the death time may be dependent on the recurrent event history. In this article we consider frailty proportional hazards models for the recurrent and terminal event processes. The dependence is modeled by conditioning on a shared frailty that is included in both hazard functions. Covariate effects can be taken into account in the model as well. Maximum likelihood estimation and inference are carried out through a Monte Carlo EM algorithm with Metropolis–Hastings sampler in the E‐step. An analysis of hospitalization and death data for waitlisted dialysis patients is presented to illustrate the proposed methods. Methods to check the validity of the proposed model are also demonstrated. This model avoids the difficulties encountered in alternative approaches which attempt to specify a dependent joint distribution with marginal proportional hazards and yields an estimate of the degree of dependence.

In patients with end-stage renal disease, successful renal allotransplantation improves the quality of life and increases survival, as compared with long-term dialysis treatment. 1 – 3 The survival advantage of renal transplantation varies among patients, 4 – 7 but this variability has not been well characterized. Most studies have not considered the fact that transplant recipients are derived from a highly selected subgroup of patients on dialysis who are deemed suitable candidates for transplantation. Patients on dialysis who are placed on the waiting list for cadaveric renal transplantation are on average younger and healthier and of higher socioeconomic status than those who are not . . .

Health-related quality of life as a predictor of mortality and hospitalization: The Dialysis Outcomes and Practice Patterns Study (DOPPS). We investigated whether indicators of health-related quality of life (HRQOL) may predict the risk of death and hospitalization among hemodialysis patients treated in seven countries, taking into account serum albumin concentration and several other risk factors for death and hospitalization. We also compared HRQOL measures with serum albumin regarding their power to predict outcomes. We analyzed data from the Dialysis Outcomes and Practice Patterns Study (DOPPS), an international, prospective, observational study of randomly selected hemodialysis patients in the United States (148 facilities), five European countries (101 facilities), and Japan (65 facilities). The total sample size was composed of 17,236 patients. Using the Kidney Disease Quality of Life Short Form (KDQOL-SFTM), we determined scores for three components of HRQOL: (1) physical component summary (PCS), (2) mental component summary (MCS), and (3) kidney disease component summary (KDCS). Complete responses on HRQOL measures were obtained from 10,030 patients. Cox models were used to assess associations between HRQOL and the risk of death and hospitalization, adjusted for multiple sociodemographic variables, comorbidities, and laboratory factors. For patients in the lowest quintile of PCS, the adjusted risk (RR) of death was 93% higher (RR = 1.93, P < 0.001) and the risk of hospitalization was 56% higher (RR = 1.56, P < 0.001) than it was for patients in the highest quintile level. The adjusted relative risk values of mortality per 10-point lower HRQOL score were 1.13 for MCS, 1.25 for PCS, and 1.11 for KDCS. The corresponding adjusted values for RR for first hospitalization were 1.06 for MCS, 1.15 for PCS, and 1.07 for KDCS. Each RR differed significantly from 1 (P < 0.001). For 1g/dL lower serum albumin concentration, the RR of death adjusted for PCS, MCS, and KDCS and the other covariates was 1.17 (P < 0.01). Albumin was not significantly associated with hospitalization (RR = 1.03, P> 0.5). Lower scores for the three major components of HRQOL were strongly associated with higher risk of death and hospitalization in hemodialysis patients, independent of a series of demographic and comorbid factors. A 10-point lower PCS score was associated with higher elevation in the adjusted mortality risk, as was a 1g/dL lower serum albumin level. More research is needed to assess whether interventions to improve quality of life lower these risks among hemodialysis patients.

Survival analysis is often used to compare experimental and conventional treatments. In observational studies, the therapy may change during follow‐up and such crossovers can be summarized by time‐dependent covariates. Given the ever‐increasing donor organ shortage, higher‐risk kidneys from expanded criterion donors (ECD) are being transplanted. Transplant candidates can choose whether to accept an ECD organ (experimental therapy), or to remain on dialysis and wait for a possible non‐ECD transplant later (conventional therapy). A three‐group time‐dependent analysis of such data involves estimating parameters corresponding to two time‐dependent indicator covariates representing ECD transplant and non‐ECD transplant, each compared to remaining on dialysis on the waitlist. However, the ECD hazard ratio estimated by this time‐dependent analysis fails to account for the fact that patients who forego an ECD transplant are not destined to remain on dialysis forever, but could subsequently receive a non‐ECD transplant. We propose a novel method of estimating the survival benefit of ECD transplantation relative to conventional therapy (waitlist with possible subsequent non‐ECD transplant). Compared to the time‐dependent analysis, the proposed method more accurately characterizes the data structure and yields a more direct estimate of the relative outcome with an ECD transplant.

The Dialysis Outcomes and Practice Patterns Study (DOPPS): An international hemodialysis study. The Dialysis Outcomes and Practice Patterns Study (DOPPS) is a prospective, longitudinal, observational study of hemodialysis patients and facilities in seven countries with large populations of dialysis patients: France, Germany, Italy, Japan, Spain, the United Kingdom, and the United States. This paper describes the study design, analytic methods, and preliminary findings of the DOPPS. The goal of the study is to determine which practice patterns are associated with the best patient outcomes, with adjustment for a wide range of patient case-mix characteristics. The primary outcomes of interest are mortality, hospitalization, quality of life, and vascular access events. The facility sample from the seven countries consists of 327 hemodialysis centers in which 24,392 patients were treated when the study began. A random sample of 10,332 patients has been selected thus far for more detailed longitudinal data collection. Departing patients are replaced during the study using random selection. A study coordinator at each dialysis facility collects baseline and longitudinal patient data. Patients are asked to complete a questionnaire that addresses quality of life on a yearly basis. The medical director and nurse manager in each facility complete a practice pattern questionnaire. Preliminary data are presented concerning the sample facilities and the census of patients treated in each facility at the start of the study. Dialysis facilities vary widely in size and type (freestanding vs. institutionally-based) across countries. Variation is also seen in patient age, sex distribution, and diabetes mellitus as the attributed cause of end-stage renal disease (ESRD). At this early phase, the DOPPS has proved to be technically feasible and has revealed basic differences in hemodialysis facilities and patients across the seven participating countries.

Kidney transplantation and wait-listing rates from the international Dialysis Outcomes and Practice Patterns Study (DOPPS). The international Dialysis Outcomes and Practice Patterns Study (DOPPS I and II) allows description of variations in kidney transplantation and wait-listing from nationally representative samples of 18- to 65-year-old hemodialysis patients. The present study examines the health status and socioeconomic characteristics of United States patients, the role of for-profit versus not-for-profit status of dialysis facilities, and the likelihood of transplant wait-listing and transplantation rates. Analyses of transplantation rates were based on 5267 randomly selected DOPPS I patients in dialysis units in the United States, Europe, and Japan who received chronic hemodialysis therapy for at least 90 days in 2000. Left-truncated Cox regression was used to assess time to kidney transplantation. Logistic regression determined the odds of being transplant wait-listed for a cross-section of 1323 hemodialysis patients in the United States in 2000. Furthermore, kidney transplant wait-listing was determined in 12 countries from cross-sectional samples of DOPPS II hemodialysis patients in 2002 to 2003 (N = 4274). Transplantation rates varied widely, from very low in Japan to 25-fold higher in the United States and 75-fold higher in Spain (both P values <0.0001). Factors associated with higher rates of transplantation included younger age, nonblack race, less comorbidity, fewer years on dialysis, higher income, and higher education levels. The likelihood of being wait-listed showed wide variation internationally and by United States region but not by for-profit dialysis unit status within the United States. DOPPS I and II confirmed large variations in kidney transplantation rates by country, even after adjusting for differences in case mix. Facility size and, in the United States, profit status, were not associated with varying transplantation rates. International results consistently showed higher transplantation rates for younger, healthier, better-educated, and higher income patients.

Vascular access use in Europe and the United States: Results from the DOPPS. A direct broad-based comparison of vascular access use and survival in Europe (EUR) and the United States (US) has not been performed previously. Case series reports suggest that vascular access practices differ substantially in the US and EUR. We report on a representative study (DOPPS) which has used the same data collection protocol for> 6400 hemodialysis (HD) patients to compare vascular access use at 145 US dialysis units and 101 units in five EUR countries (France, Germany, Italy, Spain, and the United Kingdom). Logistic analysis evaluated factors associated with native arteriovenous fistula (AVF) versus graft use or permanent access versus catheter use for prevalent and incident HD patients. Times to failure for AVF and graft were analyzed using Cox proportional hazards regression. AVF was used by 80% of EUR and 24% of US prevalent patients, and was significantly associated with younger age, male gender, lower body mass index, non-diabetic status, lack of peripheral vascular disease, and no angina. After adjusting for these factors, AVF versus graft use was still much higher in EUR than US (AOR = 21, P < 0.0001). AVF use within facilities varied from 0 to 87% (median 21%) in the US, and 39 to 100% (median 83%) in EUR. For patients who were new to HD, access use was: 66% AVF in EUR versus 15% in US (AOR = 39, P < 0.0001), 31% catheters in EUR vs. 60% in US, and 2% grafts in EUR vs. 24% in US. In addition, 25% of EUR and 46% of US incident patients did not have a permanent access placed prior to starting HD. In EUR, 84% of new HD patients had seen a nephrologist for> 30 days prior to ESRD compared with 74% in the US (P < 0.0001); pre-ESRD care was associated with increased odds of AVF versus graft use (AOR = 1.9, P = 0.01). New HD patients had a 1.8-fold greater odds (P = 0.002) of starting HD with a permanent access if a facility's typical time from referral to access placement was ≤2 weeks. AVF use when compared to grafts was substantially lower (AOR = 0.61, P = 0.04) when surgery trainees assisted or performed access placements. When used as a patient's first access, AVF survival was superior to grafts regarding time to first failure (RR = 0.53, P = 0.0002), and AVF survival was longer in EUR compared with the US (RR = 0.49, P = 0.0005). AVF and grafts each displayed better survival if used when initiating HD compared with being used after patients began dialysis with a catheter. Large differences in vascular access use exist between EUR and the US, even after adjustment for patient characteristics. The results strongly suggest that a facility's preferences and approaches to vascular access practice are major determinants of vascular access use.