When to refer patients with chronic kidney disease for vascular access surgery: Should age be a consideration?
2007; Elsevier BV; Volume: 71; Issue: 6 Linguagem: Inglês
10.1038/sj.ki.5002078
ISSN1523-1755
AutoresAnn M. O’Hare, Daniel Bertenthal, Louise C. Walter, Amit X. Garg, Kenneth E. Covinsky, James S. Kaufman, R.A. Rodriguez, Michael Allon,
Tópico(s)Renal and Vascular Pathologies
ResumoTo determine whether age should inform our approach toward permanent vascular access placement in patients with chronic kidney disease, we conducted a retrospective cohort study among 11 290 non-dialysis patients with an estimated glomerular filtration rate (eGFR) <25 ml/min/1.73 m2 based on 2000–2001 outpatient creatinine measurements in the Department of Veterans Affairs. For each age group, we examined the percentage of patients that had and had not received a permanent access by 1 year after cohort entry, and the percentage in each of these groups that died, started dialysis, or survived without dialysis. We also modeled the number of unnecessary procedures that would have occurred in theoretical scenarios based on existing vascular access guidelines. The mean eGFR was 17.7 ml/min/1.73 m2 at cohort entry. Twenty-five percent (n=2870) of patients initiated dialysis within a year of cohort entry. Among these, only 39% (n=1104) had undergone surgery to place a permanent access beforehand. As compared with younger patients, older patients were less likely to undergo permanent access surgery, but also less likely to start dialysis. In all theoretical scenarios examined, older patients would have been more likely than younger patients to receive unnecessary procedures. If all patients had been referred for permanent access surgery at cohort entry, the ratio of unnecessary to necessary procedures after 2 years of follow-up would have been 5:1 for patients aged 85–100 years but only 0.5:1 for those aged 18–44 years. Currently recommended approaches to permanent access placement based on a single threshold level of renal function for patients of all ages are not appropriate. To determine whether age should inform our approach toward permanent vascular access placement in patients with chronic kidney disease, we conducted a retrospective cohort study among 11 290 non-dialysis patients with an estimated glomerular filtration rate (eGFR) <25 ml/min/1.73 m2 based on 2000–2001 outpatient creatinine measurements in the Department of Veterans Affairs. For each age group, we examined the percentage of patients that had and had not received a permanent access by 1 year after cohort entry, and the percentage in each of these groups that died, started dialysis, or survived without dialysis. We also modeled the number of unnecessary procedures that would have occurred in theoretical scenarios based on existing vascular access guidelines. The mean eGFR was 17.7 ml/min/1.73 m2 at cohort entry. Twenty-five percent (n=2870) of patients initiated dialysis within a year of cohort entry. Among these, only 39% (n=1104) had undergone surgery to place a permanent access beforehand. As compared with younger patients, older patients were less likely to undergo permanent access surgery, but also less likely to start dialysis. In all theoretical scenarios examined, older patients would have been more likely than younger patients to receive unnecessary procedures. If all patients had been referred for permanent access surgery at cohort entry, the ratio of unnecessary to necessary procedures after 2 years of follow-up would have been 5:1 for patients aged 85–100 years but only 0.5:1 for those aged 18–44 years. Currently recommended approaches to permanent access placement based on a single threshold level of renal function for patients of all ages are not appropriate. Among patients initiating chronic hemodialysis, use of a catheter rather than a more permanent form of vascular access such as a graft or fistula, is associated with excess morbidity, mortality, and cost.1.Allon M. Daugirdas J. Depner T.A. et al.Effect of change in vascular access on patient mortality in hemodialysis patients.Am J Kidney Dis. 2006; 47: 469-477Abstract Full Text Full Text PDF PubMed Scopus (163) Google Scholar, 2.Astor B.C. Eustace J.A. Powe N.R. et al.Type of vascular access and survival among incident hemodialysis patients: the Choices for Healthy Outcomes in Caring for ESRD (CHOICE) Study.J Am Soc Nephrol. 2005; 16: 1449-1455Crossref PubMed Scopus (315) Google Scholar, 3.Ortega T. Ortega F. Diaz-Corte C. et al.The timely construction of arteriovenous fistulae: a key to reducing morbidity and mortality and to improving cost management.Nephrol Dial Transplant. 2005; 20: 598-603Crossref PubMed Scopus (75) Google Scholar, 4.Pastan S. Soucie J.M. McClellan W.M. Vascular access and increased risk of death among hemodialysis patients.Kidney Int. 2002; 62: 620-626Abstract Full Text Full Text PDF PubMed Scopus (359) Google Scholar In order to reduce catheter use among incident dialysis patients, it is generally agreed that patients with chronic kidney disease (CKD) who are expected to begin chronic dialysis should be referred beforehand for surgery to create a permanent access. Ideally, this referral should occur in enough time to allow for fistula maturation and repeat attempts at fistula creation (if necessary) before initiation of dialysis.5.III. NKF-K/DOQI Clinical Practice Guidelines for Vascular Access: update 2000.Am J Kidney Dis. 2001; 37: S137-S181PubMed Google Scholar Although there is broad agreement on the importance of timely surgical referral for creation of a permanent access, most patients in this country nevertheless start dialysis with a catheter.6.Allon M. Robbin M.L. Increasing arteriovenous fistulas in hemodialysis patients: problems and solutions.Kidney Int. 2002; 62: 1109-1124Abstract Full Text Full Text PDF PubMed Google Scholar, 7.Astor B.C. Eustace J.A. Powe N.R. et al.Timing of nephrologist referral and arteriovenous access use: the CHOICE Study.Am J Kidney Dis. 2001; 38: 494-501Abstract Full Text Full Text PDF PubMed Scopus (222) Google Scholar, 8.Kausz A.T. Guo H. Pereira B.J. et al.General medical care among patients with chronic kidney disease: opportunities for improving outcomes.J Am Soc Nephrol. 2005; 16: 3092-3101Crossref PubMed Scopus (50) Google Scholar, 9.Lee T. Barker J. Allon M. Associations with predialysis vascular access management.Am J Kidney Dis. 2004; 43: 1008-1013Abstract Full Text Full Text PDF PubMed Scopus (37) Google Scholar, 10.Avorn J. Winkelmayer W.C. Bohn R.L. et al.Delayed nephrologist referral and inadequate vascular access in patients with advanced chronic kidney failure.J Clin Epidemiol. 2002; 55: 711-716Abstract Full Text Full Text PDF PubMed Scopus (135) Google Scholar A significant barrier to increasing the prevalence of permanent access among incident hemodialysis patients has been a lack of evidence to suggest exactly when patients with non-dialysis-dependent CKD should be referred for this surgery. In an individual patient, the expected time before initiation of dialysis is usually unknown and clinical practice guidelines on this topic are largely opinion-based and quite variable. For example, the 2000 Kidney Disease Outcomes Quality Initiative (KDOQI) guidelines recommended that 'patients should be referred for surgery to attempt construction of a primary AV fistula when their creatinine clearance is 4 mg/dl (>352 μmol/l), or within 1 year of an anticipated need for dialysis.'5.III. NKF-K/DOQI Clinical Practice Guidelines for Vascular Access: update 2000.Am J Kidney Dis. 2001; 37: S137-S181PubMed Google Scholar In contrast, the 2006 Canadian Society of Nephrology guidelines recommend that patients be referred at a 'creatinine clearance of 15 to 20 ml per min or serum creatinine of 3.4 mg/dl to 5.6 mg/dl (300 to 500 μmol/l), depending on the size and weight of the patient.'11.Jindal K. Chan C.T. Deziel C. et al.Hemodialysis clinical practice guidelines for the Canadian Society of Nephrology.J Am Soc Nephrol. 2006; 17: S1-S27PubMed Google Scholar The recent 2006 KDOQI guideline recommends that patients be referred for fistula creation 'at least six months before the anticipated need for dialysis' and recommends that 'patients with CKD stage 5 should be… strongly encouraged to allow the evaluation for and creation of a fistula for long-term access when appropriate.12.Vascular Access Work Group Clinical practice guidelines for vascular access.Am J Kidney Dis. 2006; 48: S248-S273PubMed Google Scholar,13.Vascular Access Work Group Clinical practice guidelines for vascular access.Am J Kidney Dis. 2006; 48: S176-S247PubMed Google Scholar The question of when (and in whom) to place a permanent access in preparation for hemodialysis is a surprisingly complex one. Whereas the presence of a functioning graft or fistula is associated with improved outcomes among patients who begin dialysis, surgery to create a permanent access is clearly undesirable in patients who will never start dialysis, either because their CKD will never progress to end-stage renal disease (ESRD) or because they will die before needing dialysis. Placing permanent access in such patients subjects them to all of the risks of unnecessary surgery with no possible benefit. On the other hand, from a public health point of view, a certain number of unnecessary surgeries in patients who do not begin dialysis may be tolerated in order to maximize the proportion of patients who begin dialysis with a permanent access. As described above, many guidelines identify an ideal window of time before initiation of dialysis when permanent access should be placed (e.g. >6 months for 2006 KDOQI guideline, >1 year for 2000 KDOQI guideline). However, perhaps because clinicians can rarely predict who will need dialysis within a given time frame, most guidelines also identify a target level of renal function at which patients should be referred. This approach assumes a similar relationship between level of renal function and progression to ESRD among patients of all ages. However, at all levels of renal function, older patients are relatively more likely to die and less likely to start dialysis compared with younger patients.14.Klein R. Klein B.E. Moss S.E. et al.The 10-year incidence of renal insufficiency in people with type 1 diabetes.Diabetes Care. 1999; 22: 743-751Crossref PubMed Scopus (104) Google Scholar, 15.Vikse B.E. Bostad L. Aasarod K. et al.Prognostic factors in mesangioproliferative glomerulonephritis.Nephrol Dial Transplant. 2002; 17: 1603-1613Crossref PubMed Scopus (30) Google Scholar, 16.Drey N. Roderick P. Mullee M. Rogerson M. A population-based study of the incidence and outcomes of diagnosed chronic kidney disease.Am J Kidney Dis. 2003; 42: 677-684Abstract Full Text Full Text PDF PubMed Scopus (280) Google Scholar, 17.Evans M. Fryzek J.P. Elinder C.G. et al.The natural history of chronic renal failure: results from an unselected, population-based, inception cohort in Sweden.Am J Kidney Dis. 2005; 46: 863-870Abstract Full Text Full Text PDF PubMed Scopus (126) Google Scholar, 18.Eriksen B.O. Ingebretsen O.C. The progression of chronic kidney disease: a 10-year population-based study of the effects of gender and age.Kidney Int. 2006; 69: 375-382Abstract Full Text Full Text PDF PubMed Scopus (364) Google Scholar, 19.Iseki K. Iseki C. Ikemiya Y. Fukiyama K. Risk of developing end-stage renal disease in a cohort of mass screening.Kidney Int. 1996; 49: 800-805Abstract Full Text PDF PubMed Scopus (253) Google Scholar We therefore hypothesized that use of a single threshold level of estimated glomerular filtration rate (eGFR) to guide referral for permanent access would have different implications in older and younger patients. In the elderly, we predicted that the tension between the need to place a permanent access in patients who will begin dialysis and the need to avoid unnecessary surgery in patients who will not begin dialysis would be heightened. There were 2 352 584 patients who underwent at least one serum creatinine measurement within the United States Department of Veterans Affairs (VA) between 1 October 2000 and 30 September 2001. Among these, we excluded 11 061 patients who had already reached ESRD at the time of creatinine measurement. Among the remaining patients, we identified 19 342 whose initial eGFR measurement during the study period was <25 ml/min/1.73 m2. Because our study focused on permanent vascular access for hemodialysis (arteriovenous graft or fistula), we excluded 45 patients for whom initial ESRD treatment during follow-up was transplant and 433 patients whose initial dialysis modality was peritoneal dialysis rather than hemodialysis. Among the remaining 18 864 patients, we identified 11 290 who had a repeat eGFR<25 ml/min/1.73 m2 at least 3 months after cohort entry, or who started dialysis within 3 months of cohort entry in order to delineate a study population with clear evidence of a sustained eGFR<25 ml/min/1.73 m2. The mean age of the patient cohort was 70 years (95% confidence interval 69.8, 70.2), 2% (n=246) were female subjects, patient race was black in 22% (n=2466), white in 70% (n=7914), other in 6% (n=707), and unknown in 2% (n=203). Diabetes was diagnosed in 56%, coronary artery disease in 58%, congestive heart failure in 44%, peripheral arterial disease in 36%, cerebrovascular disease in 28%, chronic obstructive lung disease in 34%, and dementia in 7%. Patient average eGFR was 17.7 ml/min/1.73 m2 at cohort entry and was higher for older than for younger cohort members (Table 1). The median annual decrement in eGFR was -2.3 ml/min/1.73 m2 (25th to 75th percentile range -5.2 to -0.1 ml/min/1.73 m2) and was in general lower for older than for younger cohort members (Table 1). These calculations were based on follow-up creatinine measurements obtained a median of 530 days (25th to 75th percentile range 272–813 days) after cohort entry and 128 days (25th to 75th percentile range 83–254 days) before initiation of dialysis, death, or 30 September 2003, whichever came first.Table 1Baseline and median rate of decline in eGFR by age groupAge group (years)% with outpatient nephrology visit by the end of follow-up (95% CI)Mean eGFR at cohort entry (95% CI), ml/min/1.73m2Median annual change in eGFR (25th to 75th percentile range), ml/min/1.73m218–4475.2 (69.9, 80.5)15.3 (14.6, 16.0)-3.4 (-8.4, -1.5)45–5475.9 (73.4, 78.3)15.7 (15.4, 16.0)-3.6 (-7.6, -0.9)55–6475.9 (73.9, 77.8)16.0 (16.7, 17.2)-3.2 (-6.4, -0.6)65–7476.8 (75.5, 78.2)17.9 (17.7, 18.0)-2.2 (-5.0, +0.2)75–8469.8 (68.4, 71.3)18.6 (18.5, 18.8)-1.9 (-4.3, +0.4)85–10055.7 (51.1, 60.2)18.8 (18.4, 19.2)-1.3 (-4.0, +1.1)CI, confidence interval; eGFR, estimated glomerular filtration rate. Open table in a new tab CI, confidence interval; eGFR, estimated glomerular filtration rate. Overall, 15% (n=1728) of cohort patients initiated dialysis within 6 months, 25% (n=2870) within 1 year, and 40% (n=4502) within 2 years of cohort entry. However, these percentages varied considerably by age group: 32, 47, and 67%, respectively, for 18–44 year olds vs 8, 11, and 17%, respectively, for 85–100 year olds. The percentage of patients who died was 3% at 6 months, 9% at 1 year, and 22% at 2 years and also varied considerably by age group: 0.4, 4, and 6%, respectively, among 18–44 year olds vs 3, 17, and 41%, respectively, among 85–100 year olds. By 1 year after cohort entry, only 16% (n=1919) of cohort patients had undergone pre-dialysis permanent access placement surgery. Among these, 30% (n=572) had already received a permanent access by the time of cohort entry and the remainder (n=1347) underwent pre-dialysis access surgery during the year after cohort entry. Seventy-three percent (n=8269) of patients had at least one outpatient nephrology encounter (as defined in the Materials and Methods section) within 1 year of cohort entry (Table 1). Twenty-five percent (n=2870) of patients started dialysis within 1 year of cohort entry. Among these, only 39% (n=1104/2870) had received a permanent access beforehand. The percentage of cohort patients who had received a permanent access by the end of 1 year follow-up decreased dramatically with advancing age (Figure 1a). However, among patients who initiated dialysis within 1 year of cohort entry, there were no significant differences by age group in the percentage that had received a permanent access before dialysis initiation (Figure 1b), although the percentages were lowest at the extremes of age. In older age groups, the majority of patients either died without starting dialysis or survived without needing dialysis (Figure 2). Overall, low rates of permanent access placement in older patients appeared to be roughly commensurate with low rates of dialysis initiation at older ages. Rates of dialysis initiation decreased from the youngest to the oldest age group within each quartile of propensity score and regardless of whether patients had an outpatient nephrology encounter (results not shown).Figure 2One year outcomes by age group.View Large Image Figure ViewerDownload (PPT) In theoretical scenarios where patients received permanent access at cohort entry based on a selection of different eGFR thresholds, the ratio of unnecessary to necessary procedures was always higher in older than in younger patients (Figure 3a–c). This pattern was most pronounced at higher threshold levels of eGFR. For example, if all patients with an eGFR <25 ml/min/1.73 m2 (i.e. all cohort patients) had been referred for access surgery at cohort entry, the ratio of unnecessary to necessary procedures even after 2 years of follow-up would have been almost 5:1 for patients aged 85–100 years but only 0.5:1 for those aged 18–44 years. Because the percentage of patients initiating dialysis increased with falling eGFR in all age groups, among older patients these ratios were markedly lower at lower eGFR referral thresholds. In contrast, among younger patients, the ratio of unnecessary to necessary procedures varied less between scenarios. In a large national cohort of VA patients with an eGFR<25 ml/min/1.73 m2, most patients who initiated dialysis over a 1-year period had not been referred beforehand for placement of permanent access. These findings corroborate earlier studies in other populations identifying pre-dialysis access placement as a priority area for quality improvement.8.Kausz A.T. Guo H. Pereira B.J. et al.General medical care among patients with chronic kidney disease: opportunities for improving outcomes.J Am Soc Nephrol. 2005; 16: 3092-3101Crossref PubMed Scopus (50) Google Scholar,9.Lee T. Barker J. Allon M. Associations with predialysis vascular access management.Am J Kidney Dis. 2004; 43: 1008-1013Abstract Full Text Full Text PDF PubMed Scopus (37) Google Scholar At the same time, substantial age differences in rates of dialysis initiation in our cohort suggest that a uniform approach to permanent access placement in patients of all ages based solely on level of estimated renal function (implicit in many guidelines) may not be an optimal solution. Lower rates of dialysis initiation among elderly patients with CKD observed in the present study have been described in a variety of different populations.14.Klein R. Klein B.E. Moss S.E. et al.The 10-year incidence of renal insufficiency in people with type 1 diabetes.Diabetes Care. 1999; 22: 743-751Crossref PubMed Scopus (104) Google Scholar, 15.Vikse B.E. Bostad L. Aasarod K. et al.Prognostic factors in mesangioproliferative glomerulonephritis.Nephrol Dial Transplant. 2002; 17: 1603-1613Crossref PubMed Scopus (30) Google Scholar, 16.Drey N. Roderick P. Mullee M. Rogerson M. A population-based study of the incidence and outcomes of diagnosed chronic kidney disease.Am J Kidney Dis. 2003; 42: 677-684Abstract Full Text Full Text PDF PubMed Scopus (280) Google Scholar, 17.Evans M. Fryzek J.P. Elinder C.G. et al.The natural history of chronic renal failure: results from an unselected, population-based, inception cohort in Sweden.Am J Kidney Dis. 2005; 46: 863-870Abstract Full Text Full Text PDF PubMed Scopus (126) Google Scholar, 18.Eriksen B.O. Ingebretsen O.C. The progression of chronic kidney disease: a 10-year population-based study of the effects of gender and age.Kidney Int. 2006; 69: 375-382Abstract Full Text Full Text PDF PubMed Scopus (364) Google Scholar, 19.Iseki K. Iseki C. Ikemiya Y. Fukiyama K. Risk of developing end-stage renal disease in a cohort of mass screening.Kidney Int. 1996; 49: 800-805Abstract Full Text PDF PubMed Scopus (253) Google Scholar In this cohort, such age differences do not appear to be explained by confounding by other measured patient characteristics but may reflect the slower rate of eGFR decline, and higher competing risk of death among older patients in this cohort. In addition, the abbreviated Modification of Diet in Renal Disease equation was not developed nor has it been validated in an older population with severe CKD and thus may not provide accurate estimates of true GFR in this population. Goals of care may also be different among older patients, perhaps reflected in the lower rates of nephrology referral among cohort patients 75 years and older. Unfortunately, our data sources were insufficiently detailed to determine whether age differences in rates of conservative therapy (i.e. no dialysis or transplant) for renal failure could account for lower rates of dialysis initiation in this cohort. Regardless of the underlying explanation, the group of patients who initiate dialysis (and thus stand to benefit from permanent access surgery) effectively becomes a 'shrinking target' at older ages. Our results demonstrate that use of a single eGFR (or presumably creatinine clearance) threshold to guide permanent access placement in patients of all ages has the potential to result in a disproportionately large number of unnecessary procedures in older patients. For example, among patients aged 85–100 years, placement of permanent access at an eGFR<25 ml/min/1.73 m2 (consistent with the 2000 KDOQI guideline) would have turned out to be necessary in only one in six patients, even after 2 years of follow-up. On the other hand, among patients aged 18–44 years with an eGFR <25 ml/min/1.73 m2, the procedure would have been necessary in one in three patients after only 6 months and one in 1.5 patients after 2 years of follow-up. Identifying which older patients are likely to start dialysis becomes particularly challenging over the relatively short periods of time recommended in some guidelines. For example, 2006 KDOQI guidelines recommend that access be placed at least 6 months before initiation of dialysis. However, even among 85–100 year olds with an eGFR<15 ml/min/1.73 m2, only one in four patients started dialysis within six months and only one in three patients started dialysis within a year. These findings are important because unnecessary surgeries are both costly and carry a risk to the patient with no benefit during the time frame expected. Current Medicare reimbursement for physician fees alone exceeds $500 for fistula placement. This figure does not include hospital costs related to the procedure or costs associated with repeat procedures when the initial procedure is unsuccessful. Although most practice guidelines implicitly favor a uniform approach to permanent access placement for patients of all ages, age did appear to influence placement practices in this 'real world' clinical setting. Low rates of permanent access placement in elderly compared with younger cohort members were commensurate with low rates of dialysis initiation at older ages. Overall, targeting of access procedures to patients who initiated dialysis within 1 year of cohort entry appeared to be no worse in older than in younger cohort members. Rates of pre-dialysis access placement among cohort members who initiated dialysis were uniformly low for patients of all ages. Low rates of pre-dialysis access placement among incident dialysis patients of all ages signal the need for more effective strategies to decrease catheter use among patients beginning dialysis. Our results suggest that a 'one size fits all' approach toward timing of permanent access placement may not be appropriate. In younger patients, broad efforts to increase permanent access placement at relatively high levels of eGFR (e.g. <25 ml/min/1.73 m2 as recommended in the 2000 KDOQI guideline) are probably appropriate. In this cohort, younger patients experienced a faster decline in eGFR, a lower competing risk of mortality, and (perhaps for these reasons) higher rates of dialysis initiation compared with older patients. Therefore, the ratio of unnecessary to necessary procedures would have been low in younger cohort members, even if all had been referred for access at an eGFR<25 ml/min/1.73 m2. On the other hand, in the elderly, efforts to improve targeting of permanent access placement to the subset of patients who are most likely to need dialysis in the expected time frame may be more appropriate. Such an approach might perhaps involve using a lower eGFR threshold for referral for access surgery in the elderly as modeled in this analysis (e.g. <15 ml/min/1.73 m2 as recommended in the 2006 KDOQI guideline). For example, referral of those aged 85–100 years at an eGFR<15 ml/min/1.73 m2 would have incurred only 1.5 unnecessary surgeries for every one patient that was necessary after 2 years of follow-up. However, even at such low levels of eGFR, the ratio of unnecessary to necessary procedures that would have occurred among the oldest age group is still higher than for the youngest age group if referred at an eGFR<25 ml/min/1.73 m2. Thus, we would argue that age should influence our approach to permanent access placement in patients with CKD. A uniform approach to permanent access placement may be appropriate in younger patients whose rates of dialysis initiation are relatively high even at relatively preserved levels of eGFR. However, in older patients, additional predictors of progression to dialysis beyond eGFR (e.g. proteinuria, change in eGFR, functional status) are needed to identify those patients most likely to benefit from permanent access placement. Limitations include: (1) this analysis only examines the timing of access placement surgeries. From the available data, we cannot determine whether an access was functional at the time of dialysis initiation. (2) We opted to define our cohort based on two creatinine measurements drawn at least 3 months apart within the VA. This approach allowed us to define a cohort of patients with evidence of a sustained eGFR<25 ml/min/1.73 m2 whose care was most likely to be captured in the VA and Medicare data sources available to us. However, this approach involved excluding patients who died within 3 months of cohort entry or did not have a repeat creatinine measurement for other reasons and patients whose repeat eGFR was 25 ml/min/1.73 m2 or greater. Thus, our results may not be completely generalizable to all VA patients who started dialysis during follow-up or to patients receiving care outside our system. However, we would argue that although selection bias may have influenced the absolute frequency of different outcomes among cohort members, such bias is unlikely to have greatly impacted the relationship between age and outcome frequency. (3) Our study was restricted to veteran health-care users and thus may not be generalizable outside the VA system and in particular to populations not well represented in our cohort (e.g. women and patients belonging to Hispanic or other racial-ethnic groups). However, although specific rates of permanent access placement and death may differ for this cohort compared with others, age-related differences in outcomes are likely to be generalizable beyond the VA. Rates of pre-dialysis permanent access surgery among patients of all ages beginning dialysis are low and in need of improvement. However, dramatic differences between age groups in rates of chronic dialysis initiation suggest that a uniform approach to surgical referral based on a single threshold level of renal function among patients of all ages is not the optimal solution. Although such an approach may be appropriate in younger patients, our results call for a more targeted approach in the elderly directed at the minority that will begin dialysis within the desired time frame.
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