Kidney Transplantationcjasn Epress
Total Page:16
File Type:pdf, Size:1020Kb
Kidney TransplantationCJASN ePress. Published on April 2, 2021 as doi: 10.2215/CJN.15070920 Long-Term Management Challenges Thinking Outside the Box: Novel Kidney Protective Strategies in Kidney Transplantation Hassan N. Ibrahim,1 Dina N. Murad,1 and Greg A. Knoll2 Abstract Despite the reduction in the incidence of acute rejection, a major risk factor for graft loss, there has been only modest improvement in long-term graft survival. Most cases of kidney graft loss have an identifiable cause that is not 1 idiopathic fibrosis/atrophy or calcineurin inhibitor nephrotoxicity. Distinct immunologic and nonimmunologic Division of Renal Diseases and factors conspire to lead to a common pathway of allograft fibrosis. It remains plausible that mitigating Hypertension, nonimmunologic damage using strategies proven effective in native kidney disease may yield benefit in kidney Department of transplantation. In this review, we will focus on nonimmunologic aspects of kidney transplant care that may prove Medicine, Houston to be valuable adjuncts to a well-managed immunosuppression regimen. Topics to be addressed include the roles of Methodist Hospital, Houston, Texas hypertension and agents used to treat it, lipid lowering, sodium and water intake, elevated uric acid, metabolic 2Division of acidosis, and the use of sodium-glucose cotransporter 2 inhibitors on long-term kidney transplant health. Nephrology, CJASN 17: ccc–ccc, 2022. doi: https://doi.org/10.2215/CJN.15070920 Department of Medicine, Ottawa Hospital and Ottawa Hospital Research Introduction nonimmunologic strategies, often explored and used Institute, Ottawa, Avoidance of premature graft failure remains a key first in the nontransplant setting, remain important Ontario, Canada goal in the management of kidney transplant recip- options for the management of kidney transplant ients. Graft loss is associated with a nearly four-fold recipients. In this review, we will focus on nonimmu- Correspondence: higherriskofdeathcomparedwiththosewitha nologic aspects of kidney transplant care that may be Dr.HassanN.Ibrahim, 6550 Fannin Street, functioning graft (1,2). The Standardized Outcomes in overlooked and perhaps overshadowed by the focus Suite 1001, Houston, Nephrology—Kidney Transplantation group has on immunosuppression-based interventions. TX 77030. Email: identified kidney transplant survival as the most hnibrahim@ important priority for both patients and health care houstonmethodist.org providers (3). Preventing graft loss was the top Hypertension and Allograft Outcome priority, even over death, as transplant recipients BP lowering in both the general and CKD popula- were more concerned with quality rather than quan- tions has been associated with many beneficial effects, tity of life. Kidney transplant outcomes vary by including reduction in cardiovascular events and program and region. Registry data from 1988 to death. Data from the Systolic Blood Pressure Inter- 2014 on over 350,000 kidney transplant recipients vention Trial (SPRINT) suggest that even lower BP from the United States, the United Kingdom, Aus- targets (i.e., ,120 mm Hg) may be associated with tralia, and New Zealand are instructive (4). Long-term improved clinical outcomes, even for those with CKD ‐ adjusted graft failure risk (conditional on 1 year (5). Although the supportive data for BP lowering are fi function) was signi cantly higher in the United States more consistent for cardiovascular events and death, compared with Australia, New Zealand, and the there are also beneficial effects of BP lowering on ‐ United Kingdom. Long term kidney graft outcomes kidney outcomes. In the nontransplant CKD popula- were, however, approximately 25% worse in the tion, a meta-analysis of 11 randomized trials found United States compared with the three other devel- that more intensive BP lowering was associated with a oped nations, perhaps due to major differences in significant reduction in kidney failure events (defined health care delivery systems and extent of immuno- as either a composite of doubling of serum creatinine suppressive medications coverage. If the reasons level and 50% decline in GFR or kidney failure) (6). In behind these inferior outcomes in the United States the kidney transplant population, unfortunately, we can be firmly determined, appropriate changes may do not have similar supportivedata.Thereare result in substantial benefits to both patients and the observational data showing that a lower BP 1 year health care system in the United States. after transplantation is associated with an improve- Many strategies have been used with the intended ment in long-term graft survival, but perhaps the best goal of preserving kidney function and prolonging available evidence comes from the Folic Acid for graft survival. These include adjustments in immu- Vascular Outcome Reduction study, which showed a nosuppression to prevent and treat rejection as well as direct graded relation between systolic BP and future prevent the development of donor-specificantibody. risk of cardiovascular disease and all-cause mortality In addition to these immunologic approaches, (7,8). Unfortunately, there have been no interventional www.cjasn.org Vol 17 January, 2022 Copyright © 2022 by the American Society of Nephrology 1 2 CJASN trials evaluating whether lowering BP, to a specific target, 0.49 to 1.18) or doubling of serum creatinine (RR, 0.84; is associated with improvement in any clinically important 95% CI, 0.51 to 1.39) compared with controls. The major outcomes, such as allograft survival. Despite the lack of limitations of this systematic review are the relatively strong evidence from randomized trials in transplant short follow-up of the included trials (five trials with recipients, it seems reasonable to target a BP level similar ,2-year follow-up and overall range of follow-up of to other high-risk patients. A target BP of ,130/80 mm Hg 1–10 years), low death events (n571), and a low number has been recommended in the Kidney Disease Improving of transplant failure events (n572). KDIGO is currently Global Outcomes (KDIGO) guideline on post-transplant updating its BP guidelines for CKD. In a draft that was management (9). A similar target for kidney transplant circulated for public comment, an updated systematic recipients was suggested in the 2012 KDIGO clinical review suggested that ARB use, but not ACEi, is asso- practice guideline for the management of BP in CKD as ciated with a reduction in kidney allograft loss. This well as in the recently published American College of finding suggests that in addition to CCBs, ARB use for Cardiology/American Heart Association BP guidelines the management of hypertension may be preferred over (10,11). Until further evidence accumulates, a lower other agents given this salutary effect on graft survival. “SPRINT-like” target of ,120 mm Hg may not be an Attheendoftheday,however,atrialwith.10,000 appropriate goal given the higher risk of AKI and GFR recipients would be needed to prove superiority of renin- decline seen with more intensive BP control (12,13). These angiotensin-aldosterone system (RAAS) blockade in trans- concerns may conceivably be more serious in the setting of plant recipients. lack of robust autoregulation of renal blood flow in the Although RAAS blockade has been shown to prevent denervated allograft. progression of proteinuric kidney disease, it has never been shown to reduce structural damage or kidney failure in patients with preserved kidney function akin to that of a Choice of Antihypertensive Agent newly transplanted kidney. In fact, neither losartan nor Although there is no direct randomized trial–driven enalapril prevented expansion of the mesangial glomerular evidence to support a certain BP target in kidney transplant volume in normoalbuminuric, normotensive, normal, or recipients, there are data suggesting that calcium channel high GFR type 1 diabetic subjects who were treated for blockers (CCBs) may be the preferred antihypertensive in 5 years (19). The failure of RAAS blockade to show benefit this population (14). In a systematic review of 60 trials in transplantation similar to that observed in native kidney (n53802 patients), with 29 trials (n52262 recipients) com- disease may reflect the small sizes of the trials conducted paring CCBs with placebo or no treatment, ten trials and the low overall event rate, but it is also conceivable that involving 445 recipients comparing angiotensin- RAAS is not overly activated in kidney transplantation converting enzyme inhibitors (ACEis) with placebo or no (20–22). In the 5-year-long randomized trial of losartan treatment, and seven trials (n5405) comparing ACEis with versus placebo, we measured plasma renin activity (PRA) CCBs, Cross et al. (14) found that CCBs compared with and plasma aldosterone annually in 153 kidney transplant placebo or no treatment were associated with a 25% lower recipients. PRA and aldosterone were in the normal range risk of graft loss (relative risk [RR], 0.75; 95% confidence the entire duration of the trial; those on losartan exhibited interval [95% CI], 0.57 to 0.99) and an improvement in GFR higher PRA but similar plasma aldosterone levels (16,22). (mean difference, 4.5 ml/min per 1.73 m2;95%CI,2.2to Furthermore, PRA and plasma aldosterone levels did not 6.7). Although this supports the notion that CCBs are the vary by immunosuppressive agents used, and neither preferred antihypertensive agents in preventing allograft baseline nor serial PRA or aldosterone were associated failure, it is worth noting