Ten-Year Efficacy and Safety of Once-Daily Tacrolimus in Kidney Transplant: A Prospective Cohort Study.

Tacrolimus is a cornerstone in the immunosuppressive therapy of kidney transplantation. The once-daily formulation of tacrolimus has been shown to improve adherence of patients without affecting short-term efficacy. However, long-term proof of once-daily tacrolimus efficacy and safety is still lacking. From January 2009 to November 2013, 170 clinically stable kidney transplant patients were offered to change from the ongoing twice-daily tacrolimus (TDT) formulation to a once-daily tacrolimus (ODT) regimen. Kidney transplant recipients agreeing to the change to be treated with an ODT regimen (n = 105, estimated glomerular filtration rate [eGFR] 57.1 ± 1.6 mL/min/1.73 m2) and patients continuing on a TDT formulation (n = 65, eGFR 52.0 ± 2.2 mL/min/1.73 m2) were prospectively followed (median follow-up time 10.4 and 12.6 years in the ODT and TDT groups, respectively, P = not significant). At the end of the follow-up, patients in both groups experienced similar eGFR (50.4 ± 2.2 vs 48.0 ± 2.7 mL/min/1.73 m2 in the ODT and TDT groups, respectively, P = not significant). No differences were observed in biopsy-proven acute rejection, overall graft survival, doubling of serum creatinine, and new onset of proteinuria. The 2 groups also had a comparable rate of death, sepsis, and neoplasia. In conclusion, ODT appears safe and effective in stable kidney graft recipients even 10 years after transplantation. These findings support the use of ODT as a primary tacrolimus formulation in patients with kidney transplantation.

Association between environmental predisposing risk factors and leg disorders in broiler chickens.

Footpad dermatitis and lameness are a major welfare concern in broiler chicken farming. In general, footpad lesions are linked to poor environmental conditions. Ulcers that arise from advanced lesions can negatively affect the gait of the birds, with effects on the animal welfare, including, in the worst cases, inability to reach the feed or water. In this study, the degree of footpad dermatitis and lameness was manually scored on 4 broiler farms across Europe, as part of an EU-wide welfare assessment program. The welfare of the chickens was assessed 3 times per production cycle (at wk 3, 4, and 5), scoring footpad dermatitis, lameness, and litter quality. In the same broiler farms, variables such as air temperature and relative humidity were automatically measured over the same period. These variables were combined into a widely accepted thermal comfort index and associated to upper and lower thresholds, which made it possible to quantify the percentage of time the birds spent out of the thermal comfort zone (POOC). The data was analyzed by combining data from the welfare assessments with environmental data collected by the automated monitoring systems. Considering the comparison between POOC classes, the highest probabilities of footpad dermatitis and lameness were obtained when POOC values exceeded the 70% threshold. Therefore, the analysis showed that footpad dermatitis and lameness were more frequent when the flock was exposed to poor environmental conditions for prolonged periods ( < 0.001). Since environmental conditions can be continuously measured, and the risk factor for footpad dermatitis and lameness increases with poor environmental conditions, there is the possibility to develop a detection and control system of severe lesions.

Kidney Intragraft Homing of De Novo Donor-Specific HLA Antibodies Is an Essential Step of Antibody-Mediated Damage but Not Per Se Predictive of Graft Loss.

Donor-specific HLA antibody (DSA)-mediated graft injury is the major cause of kidney loss. Among DSA characteristics, graft homing has been suggested as an indicator of severe tissue damage. We analyzed the role of de novo DSA (dnDSA) graft homing on kidney transplantation outcome. Graft biopsy specimens and parallel sera from 48 nonsensitized pediatric kidney recipients were analyzed. Serum samples and eluates from graft biopsy specimens were tested for the presence of dnDSAs with flow bead technology. Intragraft dnDSAs (gDSAs) were never detected in the absence of serum dnDSAs (sDSAs), whereas in the presence of sDSAs, gDSAs were demonstrated in 72% of biopsy specimens. A significantly higher homing capability was expressed by class II sDSAs endowed with high mean fluorescence intensity and C3d- and/or C1q-fixing properties. In patients with available sequential biopsy specimens, we detected gDSAs before the appearance of antibody-mediated rejection. In sDSA-positive patients, gDSA positivity did not allow stratification for antibody-mediated graft lesions and graft loss. However, a consistent detection of skewed unique DSA specificities was observed over time within the graft, likely responsible for the damage. Our results indicate that gDSAs could represent an instrumental tool to identify, among sDSAs, clinically relevant antibody specificities requiring monitoring and possibly guiding patient management.

Technical note: Validation of a commercial system for the continuous and automated monitoring of dairy cow activity.

Current farm sizes do not allow the precise identification and tracking of individual cows and their health and behavioral records. Currently, the application of information technology within intensive dairy farming takes a key role in proper routine management to improve animal welfare and to enhance the comfort of dairy cows. An existing application based on information technology is represented by the GEA CowView system (GEA Farm Technologies, Bönen, Germany). This system is able to detect and monitor animal behavioral activities based on positioning, through the creation of a virtual map of the barn that outlines all the areas where cows have access. The aim of this study was to validate the accuracy, sensitivity, and specificity of data provided by the CowView system. The validation was performed by comparing data automatically obtained from the CowView system with those obtained by a manual labeling procedure performed on video recordings. Data used for the comparisons were represented by the zone-related activities performed by the selected dairy cows and were classified into 2 categories: activity and localization. The duration in seconds of each of the activities/localizations detected both with the manual labeling and with the automated system were used to evaluate the correlation coefficients among data; and subsequently the accuracy, sensitivity, specificity, and positive and negative predictive values of the automated monitoring system were calculated. The results of this validation study showed that the CowView automated monitoring system is able to identify the cow localization/position (alley, trough, cubicles) with high reliability in relation to the zone-related activities performed by dairy cows (accuracy higher than 95%). The results obtained support the CowView system as an innovative potential solution for the easier management of dairy cows.

Acquisition of C3d-Binding Activity by De Novo Donor-Specific HLA Antibodies Correlates With Graft Loss in Nonsensitized Pediatric Kidney Recipients.

Alloantibody-mediated graft injury is a major cause of kidney dysfunction and loss. The complement-binding ability of de novo donor-specific antibodies (dnDSAs) has been suggested as a prognostic tool to stratify patients for clinical risk. In this study, we analyzed posttransplant kinetics of complement-fixing dnDSAs and their role in antibody-mediated rejection development and graft loss. A total of 114 pediatric nonsensitized recipients of first kidney allograft were periodically monitored for dnDSAs using flow bead assays, followed by C3d and C1q assay in case of positivity. Overall, 39 patients developed dnDSAs, which were C1q(+) and C3d(+) in 25 and nine patients, respectively. At follow-up, progressive acquisition over time of dnDSA C1q and C3d binding ability, within the same antigenic specificity, was observed, paralleled by an increase in mean fluorescence intensity that correlated with clinical outcome. C3d-fixing dnDSAs were better fit to stratify graft loss risk when the different dnDSA categories were evaluated in combined models because the 10-year graft survival probability was lower in patients with C3d-binding dnDSA than in those without dnDSAs or with C1q(+) /C3d(-) or non-complement-binding dnDSAs (40% vs. 94%, 100%, and 100%, respectively). Based on the kinetics profile, we favor dnDSA removal or modulation at first confirmed positivity, with treatment intensification guided by dnDSA biological characteristics.

Vocalisation sound pattern identification in young broiler chickens.

In this study, we describe the monitoring of young broiler chicken vocalisation, with sound recorded and assessed at regular intervals throughout the life of the birds from day 1 to day 38, with a focus on the first week of life. We assess whether there are recognisable, and even predictable, vocalisation patterns based on frequency and sound spectrum analysis, which can be observed in birds at different ages and stages of growth within the relatively short life of the birds in commercial broiler production cycles. The experimental trials were carried out in a farm where the broiler where reared indoor, and audio recording procedures carried out over 38 days. The recordings were made using two microphones connected to a digital recorder, and the sonic data was collected in situations without disturbance of the animals beyond that created by the routine activities of the farmer. Digital files of 1 h duration were cut into short files of 10 min duration, and these sound recordings were analysed and labelled using audio analysis software. Analysis of these short sound files showed that the key vocalisation frequency and patterns changed in relation to increasing age and the weight of the broilers. Statistical analysis showed a significant correlation (P<0.001) between the frequency of vocalisation and the age of the birds. Based on the identification of specific frequencies of the sounds emitted, in relation to age and weight, it is proposed that there is potential for audio monitoring and comparison with 'anticipated' sound patterns to be used to evaluate the status of farmed broiler chicken.

Discerning pig screams in production environments.

Pig vocalisations convey information about their current state of health and welfare. Continuously monitoring these vocalisations can provide useful information for the farmer. For instance, pig screams can indicate stressful situations. When monitoring screams, other sounds can interfere with scream detection. Therefore, identifying screams from other sounds is essential. The objective of this study was to understand which sound features define a scream. Therefore, a method to detect screams based on sound features with physical meaning and explicit rules was developed. To achieve this, 7 hours of labelled data from 24 pigs was used. The developed detection method attained 72% sensitivity, 91% specificity and 83% precision. As a result, the detection method showed that screams contain the following features discerning them from other sounds: a formant structure, adequate power, high frequency content, sufficient variability and duration.

Abdominal compartment syndrome: an underrated complication in pediatric kidney transplantation.

The transplantation of a large kidney in small children can lead to many complications, including an underrated complication known as abdominal compartment syndrome (ACS), which is defined as intra-abdominal pressure (IAP)≥20 mm Hg with dysfunction of at least one thoracoabdominal organ. Presenting signs of ACS include firm tense abdomen, increased peak inspiratory pressures, oliguria, and hypotension. Between June 1, 1985, and September 30, 2013, our center performed 420 kidney transplants (deceased/living related donors: 381/39) in 314 pediatric recipients (female/male: 147/167). ACS occurred in 9 pediatric patients (weight<15 kg) who received a large kidney from adult donors. In 1 case, the patient underwent abdominal decompression with re-exploration and closure with mesh in the immediate postoperative period. In a second case, the patient developed a significant respiratory compromise with hemodynamic instability necessitating catecholamines, sedation, and assisted ventilation. For small children transplanted with a large kidney, an early diagnosis of ACS represents a critical step. From 2005 we have measured IAP during transplantation via urinary bladder pressure, and immediately after wound closure we use intraoperative and postoperative duplex sonography to value flow dynamics changes. We recommend that bladder pressure should be routinely checked in small pediatric kidney recipients who are transplanted with a large graft.

Laparoscopic approach for down-staging in hepatocellular carcinoma patients who are candidates for liver transplantation.

INTRODUCTION: The aim of this study was to assess the impact of laparoscopic thermoablation (LTA) and laparoscopic resection (LR) as neoadjuvant therapy before orthotopic liver transplantation (OLT) for hepatocellular carcinoma (HCC). METHODS: From June 2005 to November 2010, 50 consecutive patients affected by HCC with liver cirrhosis were treated with LTA under ultrasound guidance or LR. Of them, 10 patients (mean age, 58.3 ± 5.59 years; male:female, 8:2) underwent OLT. They were mostly Child-Pugh class A (80%). RESULTS: A LTA of 12 nodules was achieved in 7 patients and an LR of 3 HCC nodules in the other 3 subjects. The mean length of surgery was 163 minutes (range; 60-370). The mean hospital stay was 6.1 days. Transient mild postoperative liver failure was reported in 1 case. Complete tumor necrosis was observed in 10 thermoablated nodules (83.3%) via spiral computerized tomographic scan at 1 month after treatment; the resected patients showed absence of recurrence. All patients underwent OLT after a mean interval of 7 months. The histology of the native liver showed complete necrosis in 9/12 thermoablated nodules (75%); a recurrence at surgical site occurred in 1 patient in the resection group. CONCLUSIONS: Laparoscopic ultrasound can be used in potential OLTs candidates to accurately stage HCC in advanced cirrhosis with minimal morbidity. LTA and LR proved to be safe and effective techniques for HCC patients, representing a valid "bridge" to OLT.

Posttransplant de novo donor-specific hla antibodies identify pediatric kidney recipients at risk for late antibody-mediated rejection.

The emerging role of humoral immunity in the pathogenesis of chronic allograft damage has prompted research aimed at assessing the role of anti-HLA antibody (Ab) monitoring as a tool to predict allograft outcome. Data on the natural history of allografts in children developing de novo Ab after transplantation are limited. Utilizing sera collected pretransplant, and serially posttransplant, we retrospectively evaluated 82 consecutive primary pediatric kidney recipients, without pretransplant donor-specific antibodies (DSA), for de novo Ab occurrence, and compared results with clinical-pathologic data. At 4.3-year follow up, 19 patients (23%) developed de novo DSA whereas 24 had de novo non-DSA (NDSA, 29%). DSA appeared at a median time of 24 months after transplantation and were mostly directed to HLA-DQ antigens. Among the 82 patients, eight developed late/chronic active C4d+ antibody-mediated rejection (AMR), and four C4d-negative AMR. Late AMR correlated with DSA (p < 0.01), whose development preceded AMR by 1-year median time. Patients with DSA had a median serum creatinine of 1.44 mg/dL at follow up, significantly higher than NDSA and Ab-negative patients (p < 0.005). In our pediatric cohort, DSA identify patients at risk of renal dysfunction, AMR and graft loss; treatment started at Ab emergence might prevent AMR occurrence and/or progression to graft failure.

Kidney transplantation from living donors genetically related or unrelated to the recipients: a single-center analysis.

Living-donor programs have gradually become an attractive strategy to expand the donor pool for kidney transplantation (KT). Grafts from living-related donors (LRD) display superior function and longer survival than those obtained from cadaveric sources. Recent reports have shown that outcomes from living-unrelated donors (LUD) are not worse than those from LRD. In this study, we evaluated 135 procedures using living donors performed in our center between 1987 and 2010 (LRD: n = 111; LUD: n = 24). Among the LRD, most donors were mothers (n = 61; 54.95%), fathers (n = 25; 22.52%), and sisters (n = 16; 14.41%). The LUD included wives (n = 17; 70.83%) and husbands (n = 7; 29.17%). The mean recipient ages for LRD versus LUD were 26.94 ± 13.51 and 50.04 ± 8.86 years, respectively (P < .0001). The recipient female/male distribution was 33/78 (29.73%/70.27%) for the LRD versus 6/18 (25%/75%) for the LUD group (P = .643). The donor age was 48.79 ± 9 years in LRD and 49.25 ± 8.44 years in LUD (P = .696). The donor female/male distribution was 72/39 (64.86%/35.16%) in LRD and 17/7 (70.83%/29.17%) in LUD (P = .576). The follow up was 123.79 ± 87.87 months (range, 0.91-279.93). Overall patient and graft survivals were 94.1% and 67.6%, respectively. There was no significant difference in patient survival after stratifying for donor type (LRD: 93.9%; LUD: 95.8%; P = .961) or in graft survival after stratifying for donor type (LRD: 63.8%; LUD: 87.8%; P = .124). Entering donor type as an independent variable in a univariate Cox regression, we observed no significance for either recipient (P = .961) or graft survival (P = .142). The results of this study suggest that LUD utilization should be encouraged in KT programs.

The pregnancy rate and live birth rate after kidney transplantation: a single-center experience.

Kidney transplantation is the treatment of choice for end-stage renal disease (ESRD). Kidney transplantation recipients live longer and have better quality of life than patients on dialysis. Hypothalamic gonadal dysfunction in females who have ESRD may be reversed within the first few months after kidney transplantation, such as the ability to have children. Despite thousands of successful pregnancies in transplantation recipients, there is limited information about it. In this study, we evaluated the pregnancy rates and live birth rates in women (n = 133) who underwent kidney transplantation in our center from 1983 to 2010. Recipients of a second kidney transplantation and recipients of multiorgan transplantations were excluded. We observed 33 pregnancies with 11 live births (33.3%), 12 spontaneous abortions (36.36%), and 10 therapeutic abortions (30.3%). The pregnancy rate was 18%. The live birth rate was 33.3%. Therapeutic abortions were 36.3%, and the pregnancies resulting in fetal loss were 30.3%. The pregnancies were identified in 32 women. The majority of women (n = 32; 96.9%) had a single pregnancy, whereas 1 woman (3.1%) had two pregnancies. In our series, the pregnancy rates for kidney transplantation recipients were markedly lower and decreased more rapidly than those reported in the general population.

Encapsulating peritoneal sclerosis after kidney transplantation: a single-center experience from 1982 to 2010.

Encapsulating peritoneal sclerosis (EPS), a severe complication of long-term peritoneal dialysis (PD), produces a 50% mortality rate. EPS is characterized by progressive and excessive fibrotic thickening of the peritoneum, leading to encapsulation of the bowel and intestinal obstruction which may present after kidney transplantation (KT), a condition known as posttransplantation EPS. In this study we reviewed 1,500 KT performed in our center from 1982 to 2010, seeking to evaluate the influence of EPS incidence on kidney recipient and graft survival. We detected severe posttransplantation EPS among 16 adult single-kidney cadaveric-donor recipients. The EPS patients (age, 46.68 ± 10.62 years; female/male 5/11) were initially compared with a strictly selected group (n = 48) of non-EPS patients (age, 46.35 ± 10.26 years; female/male, 18/30). Peritoneal dialysis (PD) duration was significantly higher in the EPS group (47.75 ± 9.77 vs. 25.87 ± 10.43 months; P < .0001). This relationship was not only evident on univariate analysis, but also in a multivariate logistic regression model that entered previously selected variables: age (P = .518), sex (P = .796), serum creatinine (P = .441), estimated glomerular filtration rate (P = .566), and diagnostic category (P = .804). Diagnostic plots confirmed the reliability of the logistic regression models. In conclusion, EPS which negatively influences the outcome and quality of life of kidney recipients, was related to PD duration before to KT.

A single-center analysis to evaluate kidney function parameters after liver transplantation in adult patients.

Severe renal dysfunction may occur after orthotopic liver transplantation (OLT). In this study, we retrospectively analyzed a single-center series of adult liver recipients (n = 62) seeking to identify patients prone to develop renal dysfunction during follow-up. Liver recipients (age range, 53.54 ± 8.19 years; female/male: 21/41) who underwent a first OLT from a brain dead donor were enrolled according to strict criteria. We enrolled only liver recipients with 5 serum creatinine (SCr) measurements after hospital discharge and at least 1 measurement/year with a follow-up period of not less than 2 years. We estimated glomerular filtration rate (eGFR) using the formula developed by the Mayo Clinic. The average rate of SCr change after OLT was 0.0065 ± 0.013 mg/dL/mo. By calculating the per-patient slope, the average rate of SCr change was 0.000165 ± 0.000383 mg/dL (0.000007 ± 0.000017 mg/dL/mo). In regression models evaluated with SCr as the dependent variable versus post-OLT time, no significance was observed (P = .130). The average rate of eGFR change after OLT was -0.462 ± 0.883 mL/min/mo. By calculating the per-patient slope, the average rate of eGFR change was -0.009 ± 0.0026 mL/min (-0.0004 ± 0.0012 mL/min/mo). In the regression models evaluated with eGFR as dependent variable versus post-OLT time, no significance occurred (P = .168). By applying the regression prediction to SCr at 3 to 5 versus the 1 to 2 post-OLT measurements, we noted 3 male liver recipients (MLR) whose SCr values were significantly higher than the predicted values: MLR1: P = .048 at measurement 4; MLR2: P = .019 at measurement 4; and MLR3: P = .017 at measurement 5. Conversely, we did not observed a significant difference between observed versus predicted eGFR values. Clinical decisions on immunosuppressive treatments for liver recipients should be determined also on the basis of the series of post-OLT kidney function, which should be studied with rigorous evaluation of fitted regression models.

Evaluation of metabolic acidosis in patients with a kidney graft: comparison of the bicarbonate-based and strong ion-based methods.

BACKGROUND: According to the traditional bicarbonate-based approach, metabolic acidosis is highly prevalent in kidney transplant recipients. However, the bicarbonate-based approach has been questioned by intensivists using strong ion difference-based methods. METHODS: We compared the results obtained by the strong ion-based with the traditional approach based on bicarbonate among a cohort of 83 kidney transplant recipients. RESULTS: Fifty-five percent of the patients were acidotic based on venous bicarbonate (<23 mmol/L) and 49% by the use of the effective strong ion difference (SID(effective)) (<37 mmol/L). Bicarbonate and SID(effective) were linearly correlated (r=0.94; P<.0001), with a slope close to 1. A greater percentage of patients presented with an increase in unexplained anions by the strong ion gap (SIG) than by the anion gap corrected (AG(corrected)) method (42 vs 32%, respectively). AG(corrected) and SIG were directly related (r=0.919; P<.0001), but the best fit of the relationship was polynomial with a progressively greater effect on SIG with increased AG(corrected), suggesting that as anions progressively accumulate, their detection by SIG increases. By multiple regression analysis, plasma chloride, potassium, uric acid, and phosphate predicted blood bicarbonate. Analogously, chloride, potassium and uric acid predicted SID(effective). Age was a predictor of changes in AG(corrected), whereas age and plasma urea predicted SIG. CONCLUSIONS: The use of the SID yielded results that were similar to the traditional bicarbonate-based approach. Conversely, SIG appeared to be more sensitive than AG for detection of anion accumulation among patients with a kidney graft.

Italian continuing medical education program: an evidence-based course for surgeons and health personnel of a regional transplantation center.

In the organ transplantation area the application of the evidence-based medicine (EBM) methods may be limited by several, heterogeneous conditions, eg, mandatory laws and protocols, logistic concerns, as well as donor/recipient matching. In this report we have described the results of a first EBM-oriented course for surgeons and health personnel in a regional transplantation center under the Italian Continuing Medical Education (CME) program. The course was formally approved for 25 credits. It included a maximum of 70 medical and nursing staff registrants; 50 of the spots were reserved for our transplantation center. The course was scheduled in 10 sessions from June to November 2010. Each session was composed of 2 phases: (1) first, computer-assisted education including slide presentations (2 hours); and (2) subsequent discussion led by experts (1.5 hours). The registered participants were expected to be able to correctly answer a multiple-choice, 10-question questionnaire at the end of each session. The majority of the participants considered the course relevant to their need to be updated and effective to improve their clinical skills. The requirements to obtain credits by the Italian CME program for live events were overall presence ≥80% and correct responses in the postsession questionnaires ≥70%. However, among the initially registered participants 31.5% failed at least one of these requirements. The main reason for failure was exceeding the maximum number of absences. Paradoxically, the absences were largely caused by the simultaneous execution of surgical/medical transplantation procedures. For professional figures engaged in complex medical activities, the Italian CME program should consider different threshold limits for the maximum number of absences allowed at live events.

Percutaneous embolization of periduodenal varix due to portal hypertension in a patient with kidney-pancreas transplantation: a case report.

Kidney-pancreas transplantation is a valid therapeutic option for patients with insulin-dependent diabetes mellitus. However, vascular complications associated with pancreas transplantation are not uncommon. Herein we have reported a 32-year-old woman with a history of insulin-dependent diabetes mellitus and celiac disease. She underwent liver transplantation for acute hepatitis. After 7 years, the patient developed end-stage kidney disease beginning hemodialysis and being listed for a kidney-pancreas transplantation, which was successfully performed when she was 29 years old with enteric diversion (Roux intestinal loop reconstruction). Five years after kidney-pancreas transplantation, she was admitted to our hospital with serious intestinal bleeding and poor liver function. The ultrasound showed a pattern like a arteriovenous fistula near the head of the pancreas. Computed Tomography was not diagnostic; an arteriogram showed the presence of a mesenteric varix and a mesenteric-caval shunt through the duodenum of the pancreatic graft. The liver biopsy and portal pressure gradient showed portal hypertension and liver cirrhosis. To obtain time a waiting a new liver, the patient underwent percutaneous embolization of the mesenteric varix through jugular access. The procedure was uneventful. The patient was successfully transplanted 2 months later. Pancreas function was always satisfactory.

A time series analysis performed on a 25-year period of kidney transplantation activity in a single center.

Following the example of many Western countries, where a "minimum volume rule" policy has been adopted as a quality parameter for complex surgical procedures, the Italian National Transplant Centre set the minimum number of kidney transplantation procedures/y at 30/center. The number of procedures performed in a single center over a large period may be treated as a time series to evaluate trends, seasonal cycles, and nonsystematic fluctuations. Between January 1, 1983, and December 31, 2007, we performed 1376 procedures in adult or pediatric recipients from living or cadaveric donors. The greatest numbers of cases/y were performed in 1998 (n = 86) followed by 2004 (n = 82), 1996 (n = 75), and 2003 (n = 73). A time series analysis performed using R Statistical Software (Foundation for Statistical Computing, Vienna, Austria), a free software environment for statistical computing and graphics, showed a whole incremental trend after exponential smoothing as well as after seasonal decomposition. However, starting from 2005, we observed a decreased trend in the series. The number of kidney transplants expected to be performed for 2008 by using the Holt-Winters exponential smoothing applied to the period 1983 to 2007 suggested 58 procedures, while in that year there were 52. The time series approach may be helpful to establish a minimum volume/y at a single-center level.

Application and validation of Cox regression models in a single-center series of double kidney transplantation.

A useful approach to reduce the number of discarded marginal kidneys and to increase the nephron mass is double kidney transplantation (DKT). In this study, we retrospectively evaluated the potential predictors for patient and graft survival in a single-center series of 59 DKT procedures performed between April 21, 1999, and September 21, 2008. The kidney recipients of mean age 63.27 +/- 5.17 years included 16 women (27%) and 43 men (73%). The donors of mean age 69.54 +/- 7.48 years included 32 women (54%) and 27 men (46%). The mean posttransplant dialysis time was 2.37 +/- 3.61 days. The mean hospitalization was 20.12 +/- 13.65 days. Average serum creatinine (SCr) at discharge was 1.5 +/- 0.59 mg/dL. In view of the limited numbers of recipient deaths (n = 4) and graft losses (n = 8) that occurred in our series, the proportional hazards assumption for each Cox regression model with P < .05 was tested by using correlation coefficients between transformed survival times and scaled Schoenfeld residuals, and checked with smoothed plots of Schoenfeld residuals. For patient survival, the variables that reached statistical significance were donor SCr (P = .007), donor creatinine cleararance (P = .023), and recipient age (P = .047). Each significant model passed the Schoenfeld test. By entering these variables into a multivariate Cox model for patient survival, no further significance was observed. In the univariate Cox models performed for graft survival, statistical significance was noted for donor SCr (P = .027), SCr 3 months post-DKT (P = .043), and SCr 6 months post-DKT (P = .017). All significant univariate models for graft survival passed the Schoenfeld test. A final multivariate model retained SCr at 6 months (beta = 1.746, P = .042) and donor SCr (beta = .767, P = .090). In our analysis, SCr at 6 months seemed to emerge from both univariate and multivariate Cox models as a potential predictor of graft survival among DKT. Multicenter studies with larger recipient populations and more graft losses should be performed to confirm our findings.