Comparison of vascular access outcomes in patients with end-stage renal disease attributed to systemic lupus erythematosus vs. other causes: a retrospective cohort study

End-stage renal disease (ESRD) patients who undergo hemodialysis with a permanent vascular access [arteriovenous fistula (AVF) or grafts (AVG)] rather than a temporary catheter generally have better outcomes [1‐7] and lower associated healthcare costs [8]. Thus, national U.S. clinical guidelines promote the early placement of AVFs and AVG (at least 6 months and 3–6 weeks prior to anticipated dialysis start, respectively), such that a mature, functioning vascular access is in place on first dialysis [9]. Centers for Medicare & Medicaid Services (CMS) tracks early placement through the ESRD Medical Evidence form (CMS-2728), which collects data on access type at first dialysis for all patients starting ESRD treatment. CMS also promotes the placement of a permanent vascular access among hemodialysis patients through regionally implemented quality incentive programs such as Fistula First, Catheter Last [10].

Previously, we found that systemic lupus erythematosus (SLE) patients who developed ESRD were 40 % less likely to have a permanent vascular access in place at the start of dialysis than other ESRD patients, despite being more likely than other ESRD patients to have other indicators of advanced ESRD care planning, such as receipt of pre-ESRD nephrology care and earlier placement on the deceased donor kidney transplant waitlist [11, 12]. Further, O’Shaughnessy et al. [13] recently noted that ESRD patients with SLE were also less likely than ESRD patients with other types of glomerulonephritis to have an AVF in place at dialysis start. Here, using national claims data on ESRD patients, we examined whether subsequent placement of permanent vascular access differed for SLE-ESRD patients compared to other ESRD patients who started hemodialysis with only a catheter. Additionally, among U.S. patients who used a permanent access on their first hemodialysis treatment, we examined whether early loss of patency, as evidenced by procedures aimed at maintaining vascular access patency or placement of a new vascular access, differed for SLE-ESRD vs. other ESRD patients.

We found that, among U.S. hemodialysis patients starting treatment in 2010 without a permanent access in place, those with SLE-ESRD were equally as likely as other ESRD patients to have an AVF or AVG placed in the first year of dialysis after adjustment for potential confounders, particularly age. These results, which were robust to sensitivity analyses, suggest that the differential prevalence of permanent access in place at the start of hemodialysis seen in prior studies of both adults (24 % vs. 36 % for SLE vs. other ESRD patients) [11‐13] and children (23 % vs. 43 %) [15, 16] is not the result of SLE-ESRD patients being more likely than other ESRD patients to have their permanent access placed after, rather than before, hemodialysis start. Further, it suggests that the substantial gap in permanent access placement by SLE status at ESRD start does not narrow, even after a year on treatment, which may subject SLE-ESRD patients receiving hemodialysis to greater risk of morbidity and mortality [1‐8] than their non-SLE counterparts.

One reason providers and patients might delay placement of permanent access in a patient approaching ESRD treatment that the patient is expected to receive a kidney transplant shortly after hemodialysis treatment begins. This scenario may be more common in SLE-ESRD patients, who tend to be younger and, potentially, better transplant candidates, as suggested by their relatively greater rates of placement on the deceased donor waitlist and transplantation [12, 17]. Here, we found that, while early transplantation was nearly twice as common among the SLE-ESRD vs. other ESRD patients with only a catheter for access at the start of hemodialysis, the absolute likelihood of transplantation within the first year of hemodialysis among these SLE-ESRD patients was only 2.5 %, suggesting that expected early transplantation is not a justification for lack of permanent access placement at or before hemodialysis start. Similarly, providers may be more likely to anticipate renal recovery in SLE-ESRD [18] and avoid vascular surgery referral, but we found that, while SLE patients who started dialysis with a catheter only were more likely to recover renal function within a year than their non-SLE counterparts, fewer than 3 % of these SLE patients recovered renal function. Thus, anticipated recovery is also not likely to play a large role in the continuing gap in permanent vascular access placement by SLE status among hemodialysis patients after the first year of hemodialysis treatment. The predominance of female sex among SLE-ESRD patients might be another reason for the continued disparity in vascular access placement by SLE status over the first year of hemodialysis, due to potentially greater difficulty placing AVFs [19] and greater prevalence of body image issues associated with permanent vascular access [20] among females. However, adjustment for sex did not change our results. Differential provider referrals for vascular access surgery by SLE status could be also affected by greater likelihood of intravenous treatment history and/or hypercoagulability in SLE patients, particularly those who may have anti-phospholipid syndrome [21]; data were not available to examine these potential factors.

We also found that, among hemodialysis patients who started treatment with a permanent vascular access, loss of patency of the vascular access was actually less common among SLE-ESRD than other ESRD patients. However, this association was not statistically significant, even before adjustment. These results suggest that any provider perceptions about increased risk of vascular access problems for SLE-ESRD patients vs. other ESRD patients on hemodialysis due to clinical features of SLE [21], which could lead to fewer referrals to vascular access surgery, could be overestimated or even unfounded. However, these results should be interpreted with caution due to the potential for confounding by indication. In other words, it is possible that SLE-ESRD patients who started hemodialysis with a permanent vascular access were referred for vascular access surgery because they were at lesser risk for loss of vascular access patency than other SLE-ESRD patients, due to clinical features of their SLE not captured in these administrative data. Thus, we can only conclude that, among those ESRD patients who are observed to have a permanent access placed prior to the start of hemodialysis, SLE status is likely not associated with greater risk of loss of patency.

We found that AVFs were placed more often than AVGs in both SLE-ESRD and other ESRD patients in the first year of dialysis, which is in line with national clinical practice guidelines [9] and quality improvement programs such as the Fistula First, Catheter Last initiative [10]. However, the null association of permanent vascular access placement with SLE status did not differ by type of permanent access placed. We also found that loss of vascular access patency was more common among patients starting hemodialysis with AVGs vs. AVFs, which is consistent with prior evidence that access outcomes are poorer in AVGs than AVFs [1, 22, 23]. Results were suggestive that SLE-ESRD patients with AVGs were less likely to experience loss of patency than other ESRD patients with AVGs, whereas there was no association of SLE status with revisions among patients with AVFs. However, differences by SLE status were not statistically significant, likely due to lack of power in subgroup analyses.

This study has several important strengths, including the capture of all U.S. patients treated for ESRD, limited loss to follow-up due to universal coverage of ESRD services by CMS, completion of the CMS-2728 for all treated patients, and availability of claims data for all inpatient and outpatient services after start of dialysis. However, there are limitations, in addition to those noted above, which deserve mention. There is the potential for selection bias in the exclusion of a large number of patients without Medicare Part B coverage, and SLE-ESRD patients were more likely than other ESRD patients (33.5 % vs. 25.4 %) to be excluded due to lack of Part B coverage. This exclusion, while necessary to include outpatient events, also limits generalizability to the entire U.S. ESRD population. There is also the potential for misclassification of the outcomes using claims data. We cannot address the question of whether SLE-ESRD and other ESRD patients who start hemodialysis with a permanent access in place at dialysis start have the same rates of access maturation and eventual use, because administrative data do not capture which access was used during each dialysis session. As with all observational studies, residual confounding by unmeasured factors such as differences in training and experience of regional vascular access surgeons [24] is possible. There is also the possibility of over-adjustment, given that some variables may be mediators as well as confounders and that our power was limited due to small sample sizes in some subgroups, such as SLE patients with AVGs. However, we found that, after adjustment for age, further adjustment did not change results substantially. Sensitivity of the attribution of ESRD cause to SLE on the CMS-2728 has been suggested to be low [25], although our more recent study suggested much higher sensitivity (79 %) for the capture of U.S. patients with a validated diagnosis of SLE who have progressed to ESRD [26]; however, many SLE patients may remain in the comparison group. Misclassification of access revision could have occurred by including placement of a new access in the definition, since accesses may be placed for other reasons, including aneurysm formation and steal syndrome. Data are from 2010 and may not reflect current clinical practice regarding vascular access placement and revisions generally, or specifically in SLE patients. Finally, while we performed multiple sensitivity analyses, we cannot fully address the possibility of missed events in the first 90 days of dialysis, which may differentially occur in SLE-ESRD patients.

We found that SLE-ESRD patients were not more likely to have a permanent access placed in the first year of dialysis, despite a substantial gap in access placement at the start of hemodialysis [12] and despite an observed lack of association of SLE status with subsequent loss of access patency. SLE-ESRD patients are seen by multiple providers, potentially increasing opportunities for shared decision-making and coordinated care; yet, this population does not have adequate hemodialysis vascular access. Future studies should focus on provider and patient perceptions of permanent vascular access for hemodialysis in SLE-ESRD and, more generally, on the roles of nephrologists, rheumatologists, and patients in ensuring high-quality care and optimal outcomes in hemodialysis.

AVF, arteriovenous fistula; AVG, arteriovenous graft; BMI, body mass index; CMS, Centers for Medicare & Medicaid Services; ESRD, end-stage renal disease; HCPCS, healthcare common procedure coding system; SLE, systemic lupus erythematosus