Effect of donors' intravenous drug use, cigarette smoking, and alcohol dependence on kidney transplant outcome

Impact of donor smoking history on kidney transplant recipient outcomes: A systematic review and meta-analysis

BACKGROUND

Impact of donor smoking history on kidney transplant recipient outcomes is undefined.

METHODS

We systematically searched, critically appraised, and summarized associations between donor smoking and primary outcomes of death-censored and all-cause graft failure (DCGF, ACGF), and secondary outcomes of allograft histology, delayed graft function, serum creatinine, estimated glomerular filtration rate, and mortality. We searched MEDLINE, Embase, and Cochrane Databases from 2000 to 2023. Risk of bias was assessed using Risk of Bias in Non-randomized Studies - of Exposure tool. Quality of evidence was assessed by Grading of Recommendations Assessment, Development and Evaluation Working Group recommendations. We pooled results using inverse variance, random-effects model and reported hazard ratios for time-to-event outcomes or binomial proportions. Statistical heterogeneity was assessed with I2 statistic.

RESULTS

From 1785 citations, we included 17 studies. Donor smoking was associated with modestly increased DCGF (HR 1.05 (95% CI: 1.01, 1.09); I2 = 0%; low quality of evidence), predominantly in deceased donors, and ACGF in adjusted analyses (HR 1.12 (95% CI: 1.06, 1.19); I2 = 20%; very low quality of evidence). Other outcomes could not be pooled meaningfully.

CONCLUSIONS

Kidney donor smoking history was associated with modestly increased risk of death-censored graft failure and all-cause graft failure. This review emphasizes the need for further research, standardized reporting, and thoughtful consideration of donor factors like smoking in clinical decision-making on kidney utilization and allocation.

Effect of Donor Cigarette Smoking in Kidney Transplantation: Re-Evaluation of Long-Term Outcomes

Cigarette smoking is a common risk factor associated with negative long-term outcomes in kidney transplant recipients. However, whether donor smoking decreases graft longevity or negatively impacts recipient survival after kidney transplantation remains unknown. Therefore, this study aims to investigate the long-term outcome in patients who received a kidney graft from a deceased smoking or non-smoking donor. A total of 580 patients were divided into two groups: patients who received a graft from a smoking donor (n = 276) and those who received a graft from a non-smoking donor (n = 304). Analysis of demographic factors showed that the non-smoking cohort was older, had more extended criteria donors and longer warm ischemia times. The primary composite endpoint of patient and graft survival was better in the smoking donor cohort when analyzed using Kaplan-Meier method but not when controlled for covariates in multivariate analyses. These findings do not support a previously reported negative impact of deceased donor smoking on kidney transplant recipients. Thus, the underlying results should not be interpreted in favor of a positive donor smoking history, but rather remind the transplant community that donor smoking should not be considered as a deciding factor in refusing an otherwise acceptable kidney graft.

A modified Kidney Donor Risk Index for pediatric kidney transplant recipients

BACKGROUND

The Kidney Donor Risk Index (KDRI) by Rao et al. was developed to measure the quality of kidney allografts. While Rao's KDRI has been found to be a robust measure of kidney allograft survival for adult kidney transplant recipients, many studies have indicated the need to create a distinct pediatric KDRI.

METHODS

Our retrospective study utilized data from the United Network for Organ Sharing database. We examined 9295 deceased donor recipients' data for age < 18 years from 1990 to 2020. We performed a multivariate Cox regression to determine the significant recipient and transplant factors impacting pediatric kidney allograft survival.

RESULTS

Multivariate analysis found 5 donor factors to be independently associated with graft failure or recipient death: age, female sex, anoxia as the cause of death, history of cigarette use, and cold ischemia time. Using receiver operator characteristic (ROC) curve analysis and analyzing the predictive value of each KDRI at 1, 5, and 10 years, the proposed pediatric KDRI had a statistically significant and higher predictive value for pediatric recipients at 5 (0.60 versus 0.57) and 10 years (0.61 versus 0.57) than the Rao KDRI.

CONCLUSIONS

The proposed pediatric KDRI may provide a more accurate and simpler index to assess the quality of kidney allografts for pediatric recipients. However, due to the mild increase in predictive capabilities over the Rao index, the study serves as a proof of concept to develop a pediatric KDRI. Further studies should focus on increasing the index's predictive capabilities. A higher resolution version of the Graphical abstract is available as Supplementary information.

Deceased Donor Characteristics and Kidney Transplant Outcomes

Kidney transplantation is the therapy of choice for people living with kidney failure who are suitable for surgery. However, the disparity between supply versus demand for organs means many either die or are removed from the waiting-list before receiving a kidney allograft. Reducing unnecessary discard of deceased donor kidneys is important to maximize utilization of a scarce and valuable resource but requires nuanced decision-making. Accepting kidneys from deceased donors with heterogenous characteristics for waitlisted kidney transplant candidates, often in the context of time-pressured decision-making, requires an understanding of the association between donor characteristics and kidney transplant outcomes. Deceased donor clinical factors can impact patient and/or kidney allograft survival but risk-versus-benefit deliberation must be balanced against the morbidity and mortality associated with remaining on the waiting-list. In this article, the association between deceased kidney donor characteristics and post kidney transplant outcomes for the recipient are reviewed. While translating this evidence to individual kidney transplant candidates is a challenge, emerging strategies to improve this process will be discussed. Fundamentally, tools and guidelines to inform decision-making when considering deceased donor kidney offers will be valuable to both professionals and patients.

Practice Patterns for the Acceptance of Medically Complex Living Kidney Donors with Hematuria, Sickle Cell Trait, Smoking, Illegal Drug Use, or Urological Issues: A Multinational Survey

Background  To review the practice patterns for the acceptance of medically complex living kidney donors (MCLKD) among the transplant providers of the international transplant community. Methods  We distributed a survey globally, through major international transplantation societies, among nephrologists and transplant surgeons (TS). The survey contained questions regarding potential donors with microscopic hematuria, sickle cell trait, renal cysts, kidney stones, smoking, or illegal drug use. Results  There were 239 respondents from 29 countries, including nephrologists (42%) and TS (58%). Although most respondents would investigate microscopic hematuria, one-third of them indicated they would decline these potential donors without investigation. Interestingly, most respondents accepted heavy smokers, intermittent illegal drug users (with advice to quit), and those with incidentally identified kidney stones, remote history of renal colic or simple renal cysts. We found multiple areas of consensus in practice with some interesting differences between nephrologists and TS. Conclusions  This survey highlights the practice patterns of the acceptance of MCLKDs among the international community. In the absence of clear guidelines, this survey provides additional information to counsel kidney donors with microscopic hematuria, sickle cell trait, renal cysts, kidney stones, heavy smoking, or illegal drug use.

How to manage cigarette smoking in kidney transplant candidates and recipients?

Tobacco smoking is a frequent problem affecting many kidney transplant (KT) candidates and recipients. The negative impact of active smoking on KT outcomes has been demonstrated. Consequently, most guidelines strongly recommend quitting smoking before considering kidney transplantation. However, nicotine addiction is a complex multifactorial disease and only 3–5% of the patients who try to quit by themselves achieve prolonged abstinence. Smoking cessation programmes (SCPs) have proven their efficacy in the general population to increase the rate of quitting and should therefore be proposed to all smoking KT candidates and recipients. Nevertheless, SCPs have not been evaluated in the KT field and not all KT centres have easy access to these programmes. In this work, we aim to review the current knowledge on the subject and provide an overview of the available interventions to help smoking patients quit. We detail non-pharmaceutical and pharmaceutical approaches and discuss their use in KT candidates and recipients.

Impact of recipient and donor smoking in living-donor kidney transplantation: a prospective multicenter cohort study

The smoking status of kidney transplant recipients and living donors has not been explored concurrently in a prospective study, and the synergistic adverse impact on outcomes remains uncertain. The self-reported smoking status and frequency were obtained from recipients and donors at the time of kidney transplantation in a prospective multicenter longitudinal cohort study (NCT02042963). Smoking status was categorized as "ever smoker" (current and former smokers collectively) or "never smoker." Among 858 eligible kidney transplant recipients and the 858 living donors, 389 (45.3%) and 241 (28.1%) recipients were considered ever smokers at the time of transplant. During the median follow-up period of 6 years, the rate of death-censored graft failure was significantly higher in ever-smoker recipients than in never-smoker recipients (adjusted HR, 2.82; 95% CI 1.01-7.87; P = 0.048). A smoking history of >20 pack-years was associated with a significantly higher rate of death-censored graft failure than a history of ≤20 pack-years (adjusted HR, 2.83; 95% CI 1.19-6.78; P = 0.019). No donor smoking effect was found in terms of graft survival. The smoking status of the recipients and donors or both did not affect the rate of biopsy-proven acute rejection, major adverse cardiac events, all-cause mortality, or post-transplant diabetes mellitus. Taken together, the recipient's smoking status before kidney transplantation is dose-dependently associated with impaired survival.

Successful Expectant Management of Nonocclusive Thrombosis in Simultaneous Pancreas-Kidney Transplantation

BACKGROUND

Simultaneous pancreas-kidney (SPK) transplantation can be complicated by thrombosis in the early post-transplant period.

METHODS

We performed a single-center retrospective study examining risk factors, management, and outcomes of modern era SPK transplants. We reviewed 235 recipients over 10 years (January 1, 2008, to September 1, 2017). We used multivariate analysis to examine donor, recipient, and operative risk factors for thrombosis.

RESULTS

Forty-one patients (17%) had a thrombosis diagnosed on postoperative imaging, but 61% of these patients (n = 25/41) did not lose their graft secondary to the thrombosis. Nine patients (22%) were managed with watchful waiting and serial imaging, 12 (29%) were managed with therapeutic anticoagulation, and 4 (10%) required laparotomy and graft thrombectomy. Sixteen of 235 pancreas grafts (6.8%) required pancreatectomy, and 10 of these cases occurred in the first half of the study, before 2012. The risk of thrombosis leading to graft loss increased 11.2-fold in recipients with a body mass index (calculated as weight in kilograms divided by height in meters squared) > 25 compared with others (odds ratio, 11.2; 95% CI, 1.1-116.7; P = .043).

CONCLUSIONS

The majority of SPK transplants (61%) complicated by thrombosis of the pancreatic graft were salvaged by use of imaging, anticoagulation, and in select cases, laparotomy and graft thrombectomy.

Why Living Kidney Donor Candidates Are Turned Down? A Single-Center Cohort Study

Introduction Living donor kidney transplantation is the best replacement therapy for patients with end-stage renal disease. It offers more benefits than deceased donor transplantation. However, living kidney donors (LKDs) undergo an extensive evaluation to ensure their suitability for donation, and this can result in rejection of many potential donors. Aim The aim of this study was to recognize the reasons for declining LKDs in our Organ Transplant Center at King Abdulaziz Medical City. Settings and Design This was a retrospective study to determine the various reasons to reject an LKD at the Organ Transplant Center. Methods and Material All the LKDs from January 2016 to December 2019 were included. Declined donors were reviewed and data were obtained from the electronic database and transplant nephrology shared files. Statistical analysis We performed data analysis using SPSS version 24.0 (IBM Corp., Armonk, NY, USA). Data for continuous variables were presented as mean ± standard deviation and were compared using t-test. Categorical variables were presented as frequencies and percentages; chi-square test was used to test for main association and then Bonferroni adjustment was used for post-hoc testing. Statistical significance was considered if a two-tailed p-value of <0.05 was achieved. Results A total of 410 potential LKDs were evaluated, of whom 241 (58.8%) successfully underwent donor nephrectomy and 169 (41.2%) were unable to proceed for kidney donation. The most common reasons for rejection of LKDs were medical (47.9%) followed by immunological reasons mainly blood group incompatibility (19.5%). Other reasons were donor withdrawal (15.4%), recipient-related reasons (7.1%), surgically unfit to proceed for nephrectomy (4.7%), or psychological reasons (2.3%). Conclusions A significant proportion of potential LKDs did not complete the kidney donation process due to medical, immunological, and surgical reasons. In addition, a proportion of LKDs decided to withdraw at some point during the evaluation process. Investing in donors' educational programs and implementing a standardized evaluation process are essential to increase LKDs pool.

Effects of Smoking on Solid Organ Transplantation Outcomes

Tobacco smoking is the leading preventable cause of death worldwide. Both donor and recipient smoking have been shown to increase graft loss and mortality in solid organ transplant recipients in many studies. Only in lung transplants is smoking a universal contraindication to transplantation. Transplant centers implement different policies regarding smoking recipients and allografts from smoking donors. Due to scarcity of available allografts, the risks of smoking have to be weighed against the risks of a longer transplant waitlist period. Although transplant centers implement different strategies to encourage smoking cessation pre- and post-transplant, not many studies have been published that validate the efficacy of smoking cessation interventions in this vulnerable population. This article summarizes the results of studies investigating prevalence, impact on outcomes, and cessationinterventions for smoking in the transplant population. We report herein a review of the elevated risks of infection, malignancy, graft loss, cardiovascular events, and mortality in solid organ transplant populations.

Association of Kidney Donor Risk Index with the Outcome after Kidney Transplantation in the Eurotransplant Senior Program

Background

We evaluated the Kidney Donor Risk Index (KDRI) scoring system for kidney transplantation in the Eurotransplant Senior Program (ESP) that allocates kidneys from older donors to older recipients (≥65 years).

Material/Methods

We retrospectively analyzed data of 37 kidney transplant recipients and 36 kidney donors who participated in kidney transplantation program according to the ESP at our center from January 2004 until December 2013.

Results

Mean recipient and donor age was 67.9±2.6 and 70.5±4.0 years respectively. The mean KDRI score was 1.7±0.27. Uncensored graft survival after 1 year and 5 years was 64.2% and 53.7% respectively. Subgroup analysis showed that in kidney transplantation with KDRI >1.83, graft survival was significantly reduced compared to lower KDRI subgroups. KDRI was significantly correlated with serum creatinine level at discharge (r=0.4).

Conclusions

ESP kidneys represent a group of high-risk grafts with high KDRI scores. Higher KDRI scores in ESP kidneys was associated with reduced postoperative short-term and long-term graft outcomes. KDRI might be useful in decision-making for selecting donors for ESP kidney transplantation.

Impact of Cigarette Smoking on Living Kidney Donors

BACKGROUND

Smoking is known to result in a decline in renal allograft function and survival of recipients; however, the effect of smoking on living kidney donors remains unknown. In this study we evaluated the impact of cigarette smoking on renal function of kidney donors.

METHODS

Among 1056 donors who underwent nephrectomy, 612 completed the 6-month follow-up protocol and were enrolled in the study. The association of smoking status, including pack-years smoking history, and postoperative renal function was evaluated.

RESULTS

Among donors, 68.1% had never smoked, 8% were former smokers, and 23.9% were current smokers. Donors who never smoked were older than former and current smokers (42.3 ± 11.8, 41.9 ± 11.1, and 38.3 ± 10.9 years, respectively; P < .001). There was no difference in preoperative renal function between groups; however, postoperative estimated glomerular filtration rate (eGFR) was lower in former and current smokers than in those who never smoked (64.6 ± 13.8, 64.7 ± 12.3, and 67.8 ± 13.1 mL/min/1.73 m², respectively; P = .023). In former and current smokers, pack-years smoking history was negatively associated with pre- and postoperative eGFR (r = -0.305 and -0.435, P < .001), and correlated with postoperative percent eGFR decline (r = 0.248, P < .001). Smoking history was associated with postoperative development of chronic kidney disease (CKD). Especially in former smokers, a smoking history of more than 12 pack-years was strongly associated with development of CKD (odds ratio = 7.5, P = .003).

CONCLUSION

Even if they no longer smoke, donors with a smoking history require close observation due to increased risk of CKD development after kidney donation. A detailed pack-years smoking history should be obtained, and smoking cessation strategies should be implemented in kidney donors.

Deceased-Donor Smoking History Is Associated With Increased Recipient Mortality After Kidney Transplant: A Population-Cohort Study

OBJECTIVES

Historical data have suggested that donor smoking is associated with detrimental clinical outcomes for recipients of kidneys from deceased donors. However, the effects of smoking status of a kidney donor on the outcomes of the recipient in a contemporary setting of immunosuppression and transplant practice have not yet been ascertained.

MATERIALS AND METHODS

This retrospective, population-cohort study analyzed data of all deceased-donor kidney-alone transplant procedures performed in the United Kingdom between April 2001 and April 2013. Our study included 11?199 deceased-donor kidney allograft recipients, with median follow-up of 46 months posttransplant.

RESULTS

In our cohort, 5280 deceased donors (47.1%) had a documented history of smoking. Deceased donors with versus those without smoking history were more likely to be younger (mean age of 48 vs 50 years; P < .001), be of white ethnicity (96.6% vs 95.3%; P < .001), and have brain death before donation (77.1% vs 74.9%; P = .006). On unadjusted survival analyses, overall patient survival was significantly shorter in patients who received kidney allografts from deceased donors with smoking history (hazard ratio of 1.12, 95% confidence interval, 1.00-1.25; P = .044). No significant association was seen for death-censored or overall graft survival. Our multivariate survival analyses showed that, after accounting for confounding factors, the effects of donor smoking status remained significant for patient survival (hazard ratio of 1.16, 95% CI, 1.03-1.29; P =.011) but not graft survival.

CONCLUSIONS

This population-cohort study suggests that deceased-donor kidneys from smokers contribute to an increased risk of death for kidney allograft recipients. These study findings imply donor smoking history should be factored into the risk stratification decision for recipient selection to optimize decision making; however, further clarification and validation of these data are warranted.

Donor Body Mass Index as a Risk Factor for Delayed Onset of Graft Function

Delayed graft function continues to pose a significant challenge to clinicians in the context of kidney transplantation. The objective of this retrospective, 5-year analysis is to identify the parameters of beating heart donors and those of recipients that affect the delayed development of graft function. The monitored group was composed of 152 beating heart donors and 179 recipients. Delayed graft function was identified in 32 (17%) patients. The predictor for development of delayed graft function was the body mass index of the donor (odds ratio: 1.1473; 95% confidence interval [CI]: 1.0017-1.3140; P = .0472), and the independent risk factors were donor body mass index 30 to 34.9 kg/m² (hazard ratio [HR]: 6.0215; 95% CI: 1.4188-25.556; P = .0149), donor body mass index ≥35 kg/m² (HR: 13.5484; 95% CI: 1.4575-125.938; P = .0220), and abuse of alcohol in the donor's history (HR: 1.779; 95% CI: 1.0679-2.964; P = .0270).

Smoking in Renal Transplantation; Facts Beyond Myth

Smoking is one of the preventable leading causes of death worldwide. Most of the studies focused on the association between smoking and cardiovascular disease, pulmonary diseases, malignancy and death. However, the direct effect of smoking on the renal system was undermind. There are emerging evidence correlating tobacco use with pathological changes in the normal kidneys. The effect is more obvious on the renal allograft most probably due to the chronic immune suppression status and the metabolic effect of the drugs. Several studies have documented a deleterious effect of smoking on the renal transplant recipients. Smoking was associated with lowering patient and graft survival. Smoking cessation proved to improve graft survival and to a lesser extent recipient survival. Even receiving a renal transplant from a smoker donor increases the risk of death for the recipient and carries a poorer graft survival compared to non-smoking donors. Most of the studies investigating the effect of smoking were based on self-reporting questioners, which may be misleading due to poor recall or the desire to give socially acceptable answers. This made the need of a reliable biomarker of ultimate importance. Cotinine was proposed as a promising biomarker that may help to provide objective evidence regarding the status of smoking and the dose of nicotine exposure, yet there are still some limitations of its use. The aim of this work is to review the current evidence to improve our understanding of this critical topic. Indeed, this will help to guide better-designed studies in the future.

Cigarette Smoking and Its Hazards in Kidney Transplantation

Cigarette smoking affects many organs. It causes vasoconstriction through activation of sympathetic nervous system which leads to elevation of blood pressure and reduction in glomerular filtration rate and filtration pressure. It also causes thickening of renal arterioles. Cigarette smoking increases the risk of microalbuminuria and accelerates progression of microalbuminuria to macroalbuminuria. Furthermore, it causes rapid loss of glomerular filtration rate in chronic kidney disease patients. After kidney donation, these factors may be injurious to the solitary kidney. Kidney donors with history of cigarette smoking are prone to develop perioperative complications, pneumonia, and wound infection. Postkidney transplantation various stressors including warm and cold ischemia time, delayed graft function, and exposure to calcineurin inhibitors may result in poor graft function. Continuation of cigarette smoking in kidney transplant recipients will add further risk. In this review, we will specifically discuss the effects of cigarette smoking on normal kidneys, live kidney donors, and kidney transplant recipients. This will include adverse effects of cigarette smoking on graft and patient survival, cardiovascular events, rejection, infections, and cancers in kidney transplant recipients. Lastly, the impact of kidney transplantation on behavior and smoking cessation will also be discussed.

Heavy alcohol use in lung donors increases the risk for primary graft dysfunction

BACKGROUND

Heavy alcohol use is known to increase the risk of acute lung injury and the acute respiratory distress syndrome. This is in part due to increased production of reactive oxygen species. We hypothesized that recipients of lungs from heavy drinkers would be more susceptible to lung injury following transplantation.

METHODS

In this retrospective cohort study, donor histories and transplant outcomes were reviewed in 192 consecutive lung transplant recipients. Donors were classified as No Alcohol Use, Moderate Alcohol Use, or Heavy Alcohol Use based on documented donor histories.

RESULTS

Freedom from mechanical ventilation took longer in the lung transplant recipients whose donors had Heavy Alcohol Use, compared with those whose donors had No Alcohol Use or Moderate Alcohol Use (p = 0.01). At admission to the intensive care unit, the Heavy Alcohol Use group had median PaO2 /FiO2 ratio 219 (interquartile range [IQR]: 162 to 382), compared with 305 (IQR: 232 to 400) in the Moderate Alcohol Use group and 314 (IQR: 249 to 418) in the No Alcohol Use group (p = 0.005). The odds of developing severe primary graft dysfunction (PGD) in the Heavy Alcohol Use group versus the No Alcohol Use group were 8.7 times greater (95% confidence interval 1.427 to 53.404, p = 0.019) after controlling for factors known to be associated with PGD.

CONCLUSIONS

Recipients of donors with a heavy alcohol use history had an over 8 times greater risk of developing severe PGD following lung transplant. The increase in PGD resulted in poorer gas exchange in the recipients of donor lungs from heavy alcohol users, and these recipients subsequently required mechanical ventilation for a longer time following transplant. Further investigation into lung donors with heavy alcohol use histories is necessary to determine those at highest risk for PGD following transplant.

The role of disparities and socioeconomic factors in access to kidney transplantation and its outcome

BACKGROUND

Research focused on identifying vulnerable populations and revealing specific risk factors for barriers along the pathway from ESRD to kidney transplantation has been mostly descriptive and the causes of existing disparities remain unclear. However, several socio-economic factors that are associated with the access to and the outcome of the kidney transplantation have been identified.

SUMMARY

While the presence of racial, gender, and geographic disparities is noted, we were interested mostly to describe potential socio-economic factors associated with and possibly responsible for the presence of such disparities. In this review we focused on five factors: education level, employment status, income, presence of substance addiction or abuse, and marital status. We describe the new method to quantify patients' socio-economic status and identify the group of high risk in terms of the transplant outcome, easily calculated social adaptability index, previously associated with clinical outcome in several patient populations including those with kidney transplant. At the end, based on literature analyzed we offer potential interventions that potentially can be used in order to reduce the degree of disparities.

CONCLUSION

Based on review of literature socio-economic factors are associated with and possibly responsible for healthcare disparities. Social adaptability index allows quantifying the degree of socio-economic status and identifying the group of high risk for inferior transplant outcome.

Cigarette smoking in living kidney donors: donor and recipient outcomes

BACKGROUND

Living kidney donor pools are expanding with the use of "medically complex" donors. Whether or not to include cigarette smokers as living kidney donors remains unclear. The aim of this study was to determine the relationship between donor smoking and recipient outcomes. We hypothesized that donor smoking would increase donor complications and decrease allograft and recipient survival over time.

METHODS

The charts of 602 living kidney donors and their recipients were retrospectively reviewed. Kaplan-Meier survival analysis and Cox modeling were used to assess the relationships between smoking and recipient and allograft survival.

RESULTS

No difference in postoperative complications was seen in smoking versus non-smoking donors. Donor smoking at time of evaluation did not significantly decrease allograft survival (HR = 1.19, p = 0.52), but recipient smoking at evaluation did reduce allograft survival (HR = 1.74, p = 0.05). Both donor and recipient smoking decreased recipient survival (HR = 1.93, p < 0.01 vs HR = 1.74, p = 0.048).

DISCUSSION

When controlled for donor and recipient factors, cigarette smoking by living kidney donors significantly reduced recipient survival. This datum suggests that careful attention to smoking history is an important clinical measure in which to counsel potential donors and recipients. Policy efforts to limit donors with a recent smoking history should be balanced with the overall shortage of appropriate kidney donors.

Nicotine signaling and progression of chronic kidney disease in smokers

The deleterious health effects of cigarette smoking are far reaching, and it remains the most important modifiable risk factor for improving overall morbidity and mortality. In addition to being a risk factor for cancer, cardiovascular disease and lung disease, there is strong evidence, both from human and animal studies, demonstrating a role for cigarette smoking in the progression of chronic kidney disease (CKD). Clinical studies have shown a strong correlation between cigarette smoking and worsening CKD in patients with diabetes, hypertension, polycystic kidney disease, and post kidney transplant. Nicotine, in addition to its role in the addictive properties of cigarette smoking, has other biological effects via activation of non-neuronal nicotinic acetylcholine receptors (nAChRs). Several nAChR subunits are expressed in the normal kidney and blockade of the α7-nAChR subunit ameliorates the effects of nicotine in animal models of CKD. Nicotine increases the severity of renal injury in animal models including acute kidney injury, diabetes, acute nephritis and subtotal nephrectomy. The renal effects of nicotine are also linked to increased generation of reactive oxygen species and activation of pro-fibrotic pathways. In humans, nicotine induces transitory increases in blood pressure accompanied by reductions in glomerular filtration rate and effective renal plasma flow. In summary, clinical and experimental evidence indicate that nicotine is at least in part responsible for the deleterious effects of cigarette smoking in the progression of CKD. The mechanisms involved are the subject of active investigation and may result in novel strategies to ameliorate the effects of cigarette smoking in CKD.

Tobacco smoking and solid organ transplantation

Smoking, both by donors and by recipients, has a major impact on outcomes after organ transplantation. Recipients of smokers' organs are at greater risk of death (lungs hazard ratio [HR], 1.36; heart HR, 1.8; and liver HR, 1.25), extended intensive care stays, and greater need for ventilation. Kidney function is significantly worse at 1 year after transplantation in recipients of grafts from smokers compared with nonsmokers. Clinicians must balance the use of such higher-risk organs with the consequences on waiting list mortality if the donor pool is reduced further by exclusion of such donors. Smoking by kidney transplant recipients significantly increases the risk of cardiovascular events (29.2% vs. 15.4%), renal fibrosis, rejection, and malignancy (HR, 2.56). Furthermore, liver recipients who smoke have higher rates of hepatic artery thrombosis, biliary complications, and malignancy (13% vs. 2%). Heart recipients with a smoking history have increased risk of developing coronary atherosclerosis (21.2% vs. 12.3%), graft dysfunction, and loss after transplantation. Self-reporting of smoking is commonplace but unreliable, which limits its use as a tool for selection of transplant candidates. Despite effective counseling and pharmacotherapy, recidivism rates after transplantation remain high (10-40%). Transplant services need to be more proactive in educating and implementing effective smoking cessation strategies to reduce rates of recidivism and the posttransplantation complications associated with smoking. The adverse impact of smoking by the recipient supports the requirement for a 6-month period of abstinence in lung recipients and cessation before other solid organs.

Cigarette smoke exposure hinders long-term allograft survival by suppressing indoleamine 2, 3-dioxygenase expression

Cigarette smoke causes cancer and increases the vulnerability of smokers to infections. Epidemiologic studies have shown that smoking is one of major risk factors for late allograft rejection. Despite statistical data that associate smoking with allograft rejection, no any study has been conducted to prove that cigarette smoke directly causes allograft rejection in a cause-effect manner. In particular, investigation into immunologic mechanisms underlying smoke-related allograft rejection is lacking. Here we found that second hand smoke (SHS) hindered long-term islet allograft survival induced by CD154 costimulatory blockade plus donor-specific splenocyte transfusion (DST), although it failed to alter acute islet allograft rejection. SHS did not directly interfere with vigorously alloreactive T-cell proliferation in vivo and in vitro. Neither naturally occurring nor induced CD4+CD25+ Treg cell numbers were significantly reduced by SHS. However, SHS suppressed mRNA and protein expression of indoleamine 2, 3-dioxygenase (IDO) and its activity upon transplantation while IDO overexpression in islet allografts restored their long-term survival induced by CD154 blockade. Therefore, SHS prevents long-term allograft survival by inhibiting IDO expression and activity. Thus, our study for the first time demonstrates that SHS shortens allograft survival in a cause-effect manner and unveils a novel immunologic mechanism underlying smoking-related allograft rejection.

Effect of smoking on kidney transplant outcomes: analysis of the United States Renal Data System

BACKGROUND

We investigated the effect of smoking on postkidney transplant outcomes in the United States Renal Data System.

METHODS

In a retrospective cohort of 41,705 adult Medicare primary renal transplant recipients in the United States Renal Data System database transplanted from January 1, 2000, to June 30, 2006, and followed through October 31, 2006, we assessed Medicare claims for smoking. The association between renal allograft loss and death and smoking as a time-dependent variable was assessed with Cox nonproportional hazards regression.

RESULTS

Of 41,705 Medicare primary adult renal transplant patients, there were 9.9% patients who had evidence of prior smoking and 4.6% patients with new claims for smoking after transplant. Incident smoking (new onset smokers) occurred at a mean of 1.29±0.88 years after transplant. In the adjusted analysis, factors associated with new smoking included male gender, history of drug or alcohol use, history of chronic obstructive pulmonary disease, and later year of transplant. Compared with never smokers, incident smoking after transplant was associated with increased risk of death-censored allograft loss (adjusted hazard ratio [AHR] 1.46 [95% confidence interval {CI}: 1.19-1.79]; P<0.001) and death (AHR 2.32 [95% CI: 1.98-2.72]; P<0.001). In a sensitivity analysis excluding patients with history of chronic obstructive pulmonary disease, similar results were obtained with increased risk of death-censored allograft loss (AHR 1.43 [95% CI: 1.16-1.76]; P=0.001) and death (AHR 2.26 [95% CI: 1.91-2.66]; P<0.001).

DISCUSSION

Incident smoking was detrimental to graft and patient survival. Transplant programs should screen those at risk during transplant follow-up and have smoking cessation programs.

Obstructive sleep apnea and kidney disease: is there any direct link?

BACKGROUND

Obstructive sleep apnea (OSA) is a common and underrecognized disorder affecting at least 2% and 4% of women and men, respectively. Chronic kidney disease (CKD), on the other hand, affects around 13% of US adults. Both of these conditions share some risk factors such as age, obesity, and smoking and are associated with increased cardiovascular morbidity and mortality. By itself OSA may play a role in the development of arterial hypertension, metabolic syndrome, type 2 diabetes mellitus, and dyslipidemia with potential impact on CKD development and/or progression. But the data regarding OSA and CKD are relatively scant.

DISCUSSION

Moreover, several studies had shown possible harmful effects on kidney function independent from conventional risk factors. CKD is associated with excessive fluid volume, with potential shift during recumbency towards the neck area with increased upper airway resistance. Thus, OSA and CKD may be the results of each other and when present together may impose much greater cardiovascular risk than either disease alone.

Smoking: a risk factor for progression of chronic kidney disease and for cardiovascular morbidity and mortality in renal patients--absence of evidence or evidence of absence?

Although it is beyond any doubt that smoking is the number one preventable cause of death in most countries, smoking as an independent progression factor in renal disease has been questioned against the background of evidence-based criteria. This is because information from large, randomized, prospective studies that investigate the effects of smoking on renal function in healthy individuals as well as in patients with primary or secondary renal disease are lacking. Since 2003, a substantial number of clinical and experimental data concerning the adverse renal effects of smoking have been published, including large, prospective, population-based, observational studies. These more recent data together with evidence from experimental studies clearly indicate that smoking is a relevant risk factor, conferring a substantial increase in risk for renal function deterioration. This review summarizes the present knowledge about the renal risks of smoking as well as the increased cardiovascular risk caused by smoking in patients with chronic kidney disease. The conclusion is that smoking is an important renal risk factor, and nephrologists have to invest more efforts to motivate patients to stop smoking.

Methamphetamine use in deceased kidney donors impairs one-yr graft function

BACKGROUND

Methamphetamine (MA) has cumulative deleterious effects on multiple organ systems. A history of MA exposure in kidney donors may affect adversely graft function in recipients.

METHODS

Between September 2000 and March 2004, all deceased kidney donors were identified from the local registry (97 donors). Twenty donors (21%) with any MA exposure through history or toxicology were selected. Donors that did not fulfill UNOS standard criteria were excluded. Donor characteristics and subsequent recipient characteristics were retrospectively compared with a control group without MA exposure histories. The main outcome measure was mean serum creatinine at one-yr post-transplant (Cr365). Secondary outcome measures of delayed graft function and rejection episodes were reviewed.

RESULTS

Baseline serum creatinine at seven d post-transplant were equivalent between groups (Cr7 = 2.5 +/- 2.0 vs. 2.8 +/- 3.4, p = 0.75). At one yr, Cr365 was significantly elevated in recipients of MA exposed kidneys compared with controls (1.9 +/- 1.0 vs. 1.4 +/- 0.4, p = 0.028). When adjusted for confounding variables, MA exposure lost its statistical significance (p = 0.07-0.09) as an independent predictor of increased Cr365.

CONCLUSION

Donor MA exposure may be associated with increased Cr365 in recipients. Transplant centers can expect to encounter donors with MA use histories at rates higher that regional use rates. Larger studies may demonstrate MA exposure as an independent predictor of impaired graft function.

Balancing organ quality, HLA-matching, and waiting times: impact of a pediatric priority allocation policy for deceased donor kidneys in Quebec

Deceased donor kidney allocation policy must balance the desire for high-quality organs, good human leukocyte antigen (HLA) matching, and minimal waiting times. We describe a 10-fold reduction in waiting times and an improvement in nonimmunologic indices of organ quality for child recipients after a change in organ allocation policy in Quebec, Canada. The new policy gives first priority to children (<18 yr) irrespective of HLA matching or waiting time. HLA matching after the policy change was predictably much worse. This study highlights the trade-offs that must be considered both in setting allocation policy and in decisions for individual recipients. We also consider potential unintended negative effects of such a policy change.

Marginal Lung Donors: A Diminishing Margin of Safety?

Lung donor shortages have resulted in the critical appraisal of cadaveric donor acceptability criteria and the gradual relaxation of once strict guidelines. Many centers have reported their results with these "extended criteria" donors and an increasing number of multicenter registry studies have also been published. The results have been contradictory and leave many questions unanswered. Important new data has however come to light since the last review of the subject by the International Society for Heart and Lung Transplantation Pulmonary Council. We review the current literature focusing on recent developments in the pursuit of an expanded lung donor pool with acceptable outcomes.

Role of Maintenance Immunosuppressive Regimen in Kidney Transplant Outcome

Data of long-term immunosuppressive protocol comparison are lacking. The goal of this study was to compare kidney transplant outcome using three common immunosuppressive protocols. A retrospective study was performed of the graft and recipient survival using US Renal Data System data (n = 31,012) between January 1, 1995, and December 31, 1999, with the follow-up through December 31, 2000, on prednisone + cyclosporine + mycophenolate mofetil (PCM; n = 17,108), prednisone + tacrolimus + mycophenolate mofetil (PTM; n = 7225), or prednisone + cyclosporine + azathioprine (PCA; n = 6679). Compared with PCM, there is an increased risk for allograft failure associated with PTM (hazard ratio [HR] 1.09; P < 0.05) and PCA (HR 1.15; P < 0.001). Similar associations were demonstrated in the following subgroups: Early (before 1997) and late (in or after 1997) transplant periods, in living-donor transplants, and in adult and kidney-only recipients. This association also was found between PCA regimen and graft survival in the entire patient population (HR 1.15; P < 0.001) and in the studied subgroups. PCA (HR 1.15; P < 0.005), but not PTM (HR 1.01; P = 0.816), regimen was associated with increased recipient mortality in the entire patient population and in patient subgroups. Secondary outcomes (serum creatinine values at given time points, acute rejection rate, and posttransplantation malignancies) are also discussed. These data suggest that a PCM regimen is associated with lower risk for graft failure compared with a PTM regimen and with lower risk for graft failure and recipient death compared with a PCA regimen.