Costs Attributable to Arteriovenous Fistula and Arteriovenous Graft Placements in Hemodialysis Patients with Medicare coverage
Keywords
Vascular access · Hemodialysis · Healthcare costs · Health economics · Arteriovenous fistula · Arteriovenous graft
Abstract
Introduction: Hemodialysis (HD) in end-stage renal disease (ESRD) patients requires vascular access (VA) through an arteriovenous fistula (AVF), a prosthetic arteriovenous graft (AVG), or a central venous catheter. While AVF or AVG is commonly used for HD, the economic implications of AVF versus AVG use have not been fully established. We describe the healthcare resource utilization and costs of AVF and AVG use for incident ESRD patients in the United States.
Methods: This observational cohort study of AVF and AVG placements used data from the United States Renal Data System to identify and follow access placements. AVF and AVG placements after ESRD onset for incident patients from 2012 to 2014 with continuous Medicare primary coverage were included. Allcause and access-related Medicare costs were averaged over the placement lifetime and expressed as per dialysis-month costs.
Results: The analysis included 38,035 AVF placements and 12,789 AVG placements. Total all-cause monthly costs for AVF averaged USD 8,508; mean monthly costs were USD 3,027 for inpatient (IP), USD 3,139 for outpatient (OP), USD 1,572 for physician services, and USD 770 for other care set tings. Access-related monthly costs averaged USD 1,699 and represented 20% of all-cause charges for AVFs. Mean allcause monthly costs for AVG were USD 9,605; by setting monthly costs were USD 3,811 for IP, USD 3,034 for OP, USD 1,881 for physician services and USD 879 for other care settings. Access-related monthly costs averaged USD 2,656 and represented 28% of all-cause charges for AVGs.
Discussion/ Conclusions: This study indicates that costs due to VA are a significant burden on Medicare budgets and on patients. The factors driving access-related utilization and costs merit attention in future research. Both optimizing process of care and discovery innovation may significantly accelerate better stewardship of available healthcare resources.
Introduction
Vascular access (VA) is critical to hemodialysis (HD) in end-stage renal disease (ESRD) and is central to patient functioning and quality of life. The type of VA is also a key driver of clinical events, particularly infections and thromboses, and consequent resource utilization and costs [1–8]. In response to reported lower rates of morbidity and mortality with arteriovenous fistulae (AVF) versus central venous catheters (CVC), yet relatively low utilization of AVF, the Fistula First initiative was launched by the Centers for Medicare and Medicaid Services in 2003. Since that time CVC use among prevalent HD patients has declined substantially; in 2016, 79% of patients were using an AVF or arteriovenous graft (AVG) without a catheter, 1 year after initiating HD [5]. While overall morbidity and mortality associated with VA may be on the decline, the economic implications of AVF versus AVG use have not been fully characterized. AVFs may require more interventions postplacement to achieve maturation and maintain patency, but may have more long-term savings than AVGs [1, 2]. Several approaches have been implemented to better understand the economic implications of VA in HD.
The 2010 Annual Data Report (ADR) from the United States Renal Data System (USRDS) reported on costs by VA type [6]. Patients were classified into cohorts based on access type and costs were tracked forward for 1 year. Access event costs (per patient per year) were found to be highest among patients with an AVG (USD 8,683), followed by patients on CVC (USD 6,402), and patients on AVF (USD 3,480). Total annual costs for HD patients were lowest for AVFs (USD 59,792) followed by AVG (USD 73,081) and CVC (USD 79,890, all 2010 dollars). Costs related to VA have recently received more atten-tion [7, 8]. In an analysis of the USRDS claims data, Thamer et al. [8] examined the impact of patency and nonuse on VA-related costs among patients using an AVF. Also using patient-level analyses, AVF patients were classified into 3 cohorts based on access type used at initiation of HD: (1) a mature AVF; (2) a CVC with a maturing AVF; or (3) CVC only with a later AVF placement. Patients were followed for up to 2.5 years. VA-related costs were identified using a defined list of procedures, which were then stratified by patency outcomes in year 1. Across all 3 patient cohorts, patients who maintained primary patency during year 1 experienced the lowest VArelated costs, with increasing costs for loss of primary patency, loss of secondary patency, and AVF nonuse.
These analyses have clearly demonstrated the substantial economic burden related to VA in HD. The choice of placing a specific access type, however, is complex and dependent on patient demographics and clinical characteristics, physician behaviors, process of care pathways, and other health system factors [9], few of which are observed in an administrative claims dataset. Moreover, the specific type of VA may change over timeframes shorter than 1 year.
Our aim in this study was to evaluate the utilization and costs (VA-specific and all-cause) related to AVF and AVG placements using the placements themselves as the unit of analysis. By attributing events and costs to the access type actually used, our analysis aims to more clearly distinguish the true cost implications of a particular type of VA in a real-world setting.
Materials and Methods
Inclusion Criteria Our cohort included all AVF and AVG placements for incident ESRD patients with continuous Medicare primary coverage as of first ESRD service between January 1, 2012, and June 30, 2014. Patients were required to have CROWNWeb reporting over the study period to identify access use. We only included incident ESRD patients with continuous Medicare primary coverage in order to have a complete history of treatment costs over the study period. Exclusion counts are shown in the study cohort flow diagram (online suppl. Fig. 1; for all online suppl. material, see www. karger.com/doi/10.1159/000502507).
Placements Placements were identified using Healthcare Common Procedure Coding System codes 36818 – 36821 and 36825 for AVF and code 36830 for AVG. Accesses placed with codes 36825 and 36830 simultaneously were considered AVG. Additional access identification methods are further described elsewhere [10]. Placement of a new AVF or AVG access marked the start of an access lifetime. Access abandonment occurred at subsequent placement, transplantation, kidney function recovery, loss to follow-up, transition to non-HD renal replacement therapy, death, or end of study period (December 31, 2014). Dialysis months for each access were calculated as the number of months from access placement to abandonment, regardless of whether the placement was ever used for dialysis.
Outcomes Healthcare utilization and claim payment amounts were attributed to the access in place at the time of service, for physician services, inpatient (IP) facility visits, outpatient (OP) facility visits, and treatment in other (skilled nursing, home health, and hospice) settings. Total utilization and costs for the access, including costs associated with CVC placement and use, were then averaged over the dialysis-month time. All-cause utilization and costs incorporated claims for all services, while VA-related utilization and costs included only claims with a diagnosis or procedure code predefined by a panel of clinician and coding specialists to be related to VA management (online suppl. Table S1). Access lifetime cost trends were captured in 6 month increments by averaging costs incurred during each 6-month period for the accesses surviving until the endpoint (6, 12, 18, and 24 months). All costs were adjusted to 2017 US Dollars
Drugs covered under the ESRD Prospective Payment System (PPS, online suppl. Table S2) over the observation period were identified in claims and attributed to the access in place at the time of administration. Total utilization was averaged over the access dialysis-months. Drug cost data were not available since in-clinic drugs are bundled in the ESRD PPS.
Finally, catheter use for dialysis was identified using CROWNWeb reports. All monthly reports indicating dialysis via catheter were associated with the arteriovenous access in place at the time.
The total reports of catheter use per access divided by the access dialysis-months yielded proportion of access months requiring some catheter use.
Statistical Analyses Statistical comparisons between the AVF and AVG placement groups included 2-sample proportion tests for binary measures, t tests, and nonparametric Wilcoxon tests for continuous measures. Alpha was set to 0.001 to account for sample size. Analyses were performed using Stata (version 15) [11]. This study was exempt from Institutional Review Board review in accordance with 45 CFR 46.101(b; 4) as the data were previously collected, and patients were deidentified before receipt of data.
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