Case Mix, Patterns of Care, and Inpatient Outcomes Among Ontario Kidney Transplant Centers: A Population-Based Study

Prognostic score-based methods for estimating center effects based on survival probability: Application to post-kidney transplant survival

In evaluating the performance of different facilities or centers on survival outcomes, the standardized mortality ratio (SMR), which compares the observed to expected mortality has been widely used, particularly in the evaluation of kidney transplant centers. Despite its utility, the SMR may exaggerate center effects in settings where survival probability is relatively high. An example is one-year graft survival among U.S. kidney transplant recipients. We propose a novel approach to estimate center effects in terms of differences in survival probability (ie, each center versus a reference population). An essential component of the method is a prognostic score weighting technique, which permits accurately evaluating centers without necessarily specifying a correct survival model. Advantages of our approach over existing facility-profiling methods include a metric based on survival probability (greater clinical relevance than ratios of counts/rates); direct standardization (valid to compare between centers, unlike indirect standardization based methods, such as the SMR); and less reliance on correct model specification (since the assumed model is used to generate risk classes as opposed to fitted-value based 'expected' counts). We establish the asymptotic properties of the proposed weighted estimator and evaluate its finite-sample performance under a diverse set of simulation settings. The method is then applied to evaluate U.S. kidney transplant centers with respect to graft survival probability.

Extracorporeal Partial Nephrectomy with Orthotopic Autotransplantation under Pharmaco-Cold Ischaemia for Cancer of a Single Kidney: A Case Report

Up to 10% of patients with renal cell carcinoma (RCC) have locally advanced disease with venous tumour thrombosis involving the inferior vena cava (IVC). 30–50% of them present with synchronous metastatic disease. Surgical treatment remains the only potentially radical method for patients suffering from RCC and IVC tumour thrombosis without distant metastases. Five-year cancer-specific survival for such patients is 40–60%. The role of surgery in the treatment of RCC is significant, even if only cytoreductive operation is possible. Nephron-sparing surgery (NSS) is reasonably preferable for patients suffering from single kidney RCC, but it is not always radical enough. Extracorporeal approach allows to perform a radical dissection of the tumour in special complicated cases, but it is seldom used because of technical difficulties. We present a case of successful NSS by extracorporeal approach in our modification for RCC with IVC tumour thrombosis.

The Effect of Transplant Volume and Patient Case Mix on Center Variation in Kidney Transplantation Outcomes

Background

Kidney transplantation is the optimal treatment for patients with end-stage renal disease; however, long-term outcomes remain suboptimal.

Objective

The objectives of our study were to examine the variation in survival rates and determine whether center volume and case mix are associated with transplant outcomes and explain the variation across kidney transplant centers in Ontario, Canada.

Design

This was a population-based cohort study using health care administrative databases.

Setting

A total of 5 transplant centers across Ontario, Canada.

Patients

We included adults (≥18 years) undergoing primary, solitary kidney transplantation between January 1, 2000 to December 31, 2013.

Measurements

The co-primary outcomes were death-censored graft loss and total mortality.

Methods

Multivariable Cox proportional hazards regression was used to assess potential associations and describe variation, using hazard ratios (HRs) with 95% confidence intervals (CIs) for each center relative to the average across all centers.

Results

The study cohort included 5037 patients followed for a median of 5.3 years, interquartile range (2.7-8.6). In multivariable models, recipient age, body mass index, Charlson Index, time on dialysis, donor type, and age were found to be significantly associated with death-censored graft loss, and recipient age and sex, Charlson Index, time on dialysis, donor age, and time era of transplant were associated with total mortality. There was statistically significant variation across centers observed for death-censored graft loss (P = .04) with HRs ranging from 0.72 to 1.22. However, neither adjusting for case mix nor center volume meaningfully changed the HRs reflecting each center-specific effect. There was a tendency toward reduced risk of graft loss (HR, per additional 25 patients, 0.90 [95% CI, 0.78-1.04]) in centers with higher volumes. For total mortality, there was statistically significant variation across centers with HRs ranging from 0.82 to 1.13 (P = .04); however, neither adjusting for case mix or center volume meaningfully changed the HRs. Center volume was not significantly associated with total mortality (HR, per additional 25 patients, 1.04 [95% CI, 0.90-1.20]).

Limitations

This study was limited by the small number of centers included.

Conclusions

Outcomes differ across the 5 transplant centers in Ontario. We did not find any strong support for our hypotheses that case mix or center volume is responsible for these differences.