Fistula Placement in Incident Patients, 2005-2006,

Fistula Placement in Incident Patients, 2005-2006,

As Viewed from Medical Evidence Report Forms

Northwest Renal Network

March 16, 2007

The Centers for Medicare and Medicaid Services (CMS) uses the Medical Evidence Report Form 2728 to register patients and establish entitlement for Medicare payment for chronic dialysis. Since June 2005, this form has included questions on the vascular access in use and in place by incident end stage renal disease (ESRD) patients, and whether these patients were under the care of a nephrologist prior to their initiation of chronic dialysis. This report provides a summary of the Network’s analysis of the first eighteen months of data collection with these questions, particularly as they apply to the placement of arteriovenous fistulae (AVF) in hemodialysis patients.

Definitions

In all cases this report refers only to incident hemodialysis patients.
Early referral rate - The percentage of patients who had been under the care of a nephrologist prior to initiating dialysis.
Early-referral patients- patients who had been under the care of a nephrologist prior to initiating dialysis.
AVF-in-place rate- The percentage of patients who began chronic dialysis with an AVF in place.
Unless otherwise indicated, the “AVF-in-place rate” refers to all incident hemodialysis patients.

When overall AVF-in-place rates show statistical significance, the AVF-in-place rate for only those patients who had been under a nephrologist’s care prior to beginning chronic dialysis will also be analyzed. Comparing the overall AVF-in-place rate to the early-referral AVF-in-place rate allows for tentative conclusions about how the effects of early referral and the effects of AVF placement differ.

The focus is on AVF-in-place rather than AVF-in-use because AVF-in-place is a more meaningful measure for incident patients. Incident-patient AVF rates vary greatly depending on how incidence is defined. For example, Fistula First (FF) data measures the access in place at the end of the calendar month in which an incident patient began chronic dialysis. FF data is collected at the facility level. Clinical Performance Measures (CPM) data consider the access in use at the beginning of chronic dialysis and 90 days later. CPM data is collected at the patient level, but only on a 5% Network sample. The Medical Evidence Report data evaluated in this document measures the access in place at the time when a patient began chronic dialysis. This Form 2728 data is collected at the patient level, for a 100% sample.

Early Referral

Many of these patients – 68% – had been under a nephrologist’s care prior to their initiation of chronic dialysis. This may be surprising if it was perceived that the percentage was much lower. Slightly more than a third of all new Network ESRD patients had been cared for by a nephrologist for more than one year before they began chronic dialysis. This table provides details.

	Number of Patients	Percent of All Incident Hemodialysis Patients	Incident Patients Under Nephrologist Care Prior to Initiating Chronic Dialysis - Percentage Breakdown by Length of Time Under Care
Under Care of a Nephrologist for < 6 Months Prior to Initiating Chronic Dialysis	241	5.8%	8.6%
Under Care of a Nephrologist for 6-12 Months Prior to Initiating Chronic Dialysis	1175	28.5%	41.9%
Under Care of a Nephrologist for > 12 Months Prior to Initiating Chronic Dialysis	1389	33.6%	49.5%
Under Care of a Nephrologist Prior to Initiating Chronic Dialysis *(sum of three rows above)*	2805	67.9%	100.0%
Not under Care of a Nephrologist Prior to Initiating Chronic Dialysis	1144	27.7%
Don't Know	180	4.4%
Totals	4129	100.0%

AVF Placement

A patient who had been under a nephrologist’s care prior to beginning chronic dialysis was 3.1 times as likely to begin dialysis with an AVF in place.

Of all incident Network hemodialysis patients, 40.8% (95% confidence interval 39.9% to 43.0%) began chronic dialysis with an AVF in place. The Network goal for incident-patient AVF-in-place rate matches the corresponding KDOQI Guideline at 50%.

Among patients who had been under the care of a nephrologist prior to initiating chronic dialysis, 51.6% (49.7% to 53.4%) began dialysis with an AVF in place, compared to 17.9% (14.5% to 18.9%) of patients who had not been under a nephrologist’s care. This difference is highly significant statistically (p << 0.001), as the following graph shows.

The longer a patient had been under a nephrologist’s care prior to initiating chronic dialysis, the greater the likelihood that they began dialysis with an AVF in place, as the graph and table below show. These four groups are all highly statistically significantly different from one another (p << 0.001).

		Percent of Patients with AVF in Place	95% Confidence Interval



Length of Time Under Care of a Nephrologist Prior to Initiating Chronic Dialysis	None	17.9%	15.8% to 20.0%
	0-6 Months	32.4%	26.5% to 38.3%
	6-12 Months	46.7%	43.9% to 49.6%
	>12 Months	59.0%	56.4% to 61.6%

Trend

These differences have not changed significantly over the course of the eighteen months of available data. The following graphs show the early-referral and AVF-in-place rates for each of the three six-month periods.

The average increase from one six-month period to the next was 2.1 percentage points for all incident patients and 2.2 percentage points for early-referral patients.

By Gender

Males were 2% more likely than females to have been under care of a nephrologist prior to initiating chronic dialysis, but the difference was not statistically significant, as this graph shows. 71.7% (95% confidence interval 69.9% to 73.5%) of males and 70.1% (67.8% to 72.3%) of females were under a nephrologist’s care before their chronic dialysis began.

However, males were 17% (p < 0.001) more likely to begin dialysis with an AVF in place, as the following graph illustrates. 43.4% (95% confidence interval 41.4% to 45.3%) of all incident male patients began dialysis with an AVF in place, compared to 36.9% (34.6% to 39.2%) of all female incident patients.

Among patients who had been under a nephrologist’s care prior to initiating chronic dialysis, males were only 13% more likely to begin dialysis with an AVF in place (p < 0.005), implying perhaps that early referral was able to reduce the difference between male and female AVF rates. 54.0% (95% confidence interval 51.6% to 56.3%) of early-referral males and 48.0% (45.0% to 50.9%) of early-referral females began dialysis with an AVF in place. This graph shows the difference.

By Age

There were no statistically significant differences among age groups in early-referral rates, although 0-to-19-year-olds were 11% more likely to have been under a nephrologist’s care prior to beginning chronic dialysis than 40-to-59-year-olds, and 20-to-39-year-olds were 11% less likely to have been, as the following graph and table illustrate.

Age	Early-Referral Rate	95% Confidence Interval	AVF-in-Place Rate	95% Confidence Interval



0-19	80.6%	66.7% to 94.6%	29.0%	13.1% to 45.0%
20-39	64.9%	59.7% to 70.1%	38.1%	32.9% to 43.4%
40-59	72.5%	69.9% to 75.1%	44.3%	41.5% to 47.1%
60-79	70.9%	68.8% to 72.9%	41.4%	39.1% to 43.6%
>79	71.5%	67.9% to 75.0%	34.3%	30.7% to 37.9%

There were significant differences among age groups in AVF-in-place rates (p < 0.005). Incident patients older than 79 were 17% less likely to begin dialysis with an AVF than 60-to-79-year-olds (p < 0.01). Patients under 19 received AVFs at the lowest rate, but their standard error was too large to indicate significant difference, because of their small number (n = 31). These differences are illustrated below.

By Race

Analysis by race produced significant variation in both early-referral and AVF-in-place rates, both at p < 0.025. However, among only patients who had been under the care of a nephrologist prior to initiating chronic dialysis, there were no race differences in AVF-in-place rates, implying that race was a significant variable in early referral more than it was in AVF placement. In early-referral rates, white patients were significantly lower (10% lower) than black patients (p < 0.05). American Indian/Alaskan Native patients were least likely to have been under a nephrologist’s care prior to initiating dialysis (6% less likely than whites), but because of the relatively small number of ESRD American Indian/Alaskan Natives (n = 118), the difference was not statistically significant. This graph compares early-referral rates.

Race	Early-Referral Rate	95% Confidence Interval	AVF-in-Place Rate	95% Confidence Interval



American Indian / Alaskan Native	66.1%	57.6% to 74.6%	38.1%	29.6% to 46.6%
Asian	75.9%	69.9% to 82.0%	49.7%	42.8% to 56.7%
Black	78.2%	73.1% to 83.2%	46.4%	40.4% to 52.3%
White	70.3%	68.7% to 71.8%	39.9%	38.3% to 41.5%
Pacific Islander	76.7%	66.0% to 87.4%	35.9%	24.2% to 47.7%

AVF rates by race, tabled above and graphed below, reveal that Asian incident patients received significantly more (25% more) AVFs than white incident patients (p < 0.05).

AVF-in-place rates by race for only those patients who were under the care of a nephrologist prior to initiation of chronic dialysis are graphed below. No differences in this graph are statistically significant.

By State

Incident hemodialysis patients residing in Idaho or Montana had been under a nephrologist’s care prior to beginning chronic dialysis significantly less frequently than patients in Oregon or Washington (p < 0.005). As this graph and table show, Montana patients were 14% less likely and Idaho patients 16% less likely than Washington patients to have been under a nephrologist’s care prior to starting chronic dialysis. While Alaska’s early-referral rate was equal to those in Oregon and Washington, there were not enough Alaska patients to demonstrate a significant difference from the rates in Idaho and Montana rates.

State of Residence	Early-Referral Rate	95% Confidence Interval	AVF-in-Place Rate	95% Confidence Interval



Alaska	72.5%	63.4% to 81.7%	33.9%	25.5% to 42.2%
Idaho	61.0%	55.9% to 66.1%	27.8%	23.1% to 32.4%
Montana	62.6%	56.5% to 68.8%	45.0%	38.7% to 51.3%
Oregon	73.0%	70.5% to 75.6%	40.3%	37.6% to 43.1%
Washington	72.5%	70.6% to 74.4%	43.1%	41.0% to 45.2%

However, Montana residents began dialysis with an AVF in place more often than residents of any other Network state – Montana residents were 62% more likely to begin dialysis with an AVF in place than Idaho patients. While the differences were not significant, Alaska residents were less likely to receive an AVF than Washington or Oregon residents, even though they were as likely to have been under a nephrologist’s care prior to beginning dialysis.

The graph of AVF-in-place rates for early-referral patients only confirms that these differences are practice pattern or community resource differences more than differences in early referral patterns (p < 0.005). Incident early-referral hemodialysis patients in Montana were 55% more likely than Idaho patients and 58% more likely than Alaska patients to begin chronic dialysis with an AVF in place.

By Insurance Type

These analyses and the graphs below exclude all patients with more than one type of insurance. Early-referral rates vary significantly with the type of insurance an incident patient had (p << 0.05). Patients with group insurance had been under the care of a nephrologist prior to beginning chronic dialysis 14% more often than patients with Medicare-only insurance. Patients with no insurance were least likely to have been early-referral patients – 42% less likely than Medicare-only patients. Patients with VA insurance were most likely to have been under a nephrologist’s care prior to beginning chronic dialysis.

Those with no insurance were significantly less likely (by about 30%) than those with Medicaid, group, or “other” insurance to begin chronic dialysis with an AVF in place (p < 0.025), as the following graph and table illustrate. In the table, note the differences in age. Medicare Advantage patients have the highest AVF rates in spite of having the highest average age, and uninsured patients have the lowest AVF rates in spite of having the lowest average age.

Type of Insurance	Average Patient Age	Early-Referral Rate	95% Confidence Interval	AVF-in-Place Rate	95% Confidence Interval


Medicaid	49	70.2%	65.6% to 74.8%	44.5%	39.7% to 49.4%
VA	58	80.6%	67.6% to 93.5%	36.6%	21.8% to 51.3%
Medicare	70	66.8%	62.8% to 70.8%	39.1%	35.1% to 43.2%
Medicare Advantage	75	71.3%	63.0% to 79.6%	45.4%	36.4% to 54.3%
Group	50	76.1%	72.3% to 79.8%	43.0%	38.8% to 47.3%
Other	54	72.2%	66.5% to 77.9%	44.8%	38.7% to 51.0%
None	46	38.8%	32.4% to 45.3%	30.8%	24.9% to 36.7%

Among early-referral patients, those with no insurance were still significantly less likely (about 30% less likely) to have an AVF in place at the beginning of dialysis than those with Medicaid or group insurance (p < 0.05).

By Nephrologist

Examining the Medical Evidence Report data based on the responsible nephrologist reveals a broad range of AVF-in-place rates, with two primary modes, one below the Network average at 25-30% AVF-in-place and the other just above the KDOQI Guideline at 50-55% AVF-in-place. This graph is a histogram of nephrologists AVF-in-place rates. While rates range from 0% to 100%, the tails are reasonably long. Most nephrologists fall between 20% and 70% AVF-in-place. The bimodality implies that some nephrologists’ practice patterns may not reflect the shift towards optimizing the placement and use of AVFs, or that their community lacks the resources for them to receive early referrals or create AVFs in a timely manner.

Sixty-three percent of Network nephrologists are below the Network goal and KDOQI Guideline (both 50% AVF in place) for incident hemodialysis patients. The percentage of nephrologists whose incident-patient AVF-in-place rate falls below 50% ranges from 93% in Idaho to 43% in Western Washington, as shown in this table.

State or Region	Percent of Nephrologists with Incident Patient AVF-in-Place Rate *Lower than* 50%
Idaho	93%
Alaska	86%
Eastern Washington	76%
Montana	71%
Oregon	64%
Western Washington	43%
Network	63%