As has been widely reported, U.S. utilization of dialysis in the home setting has been on the upswing, with an 18-year high of 11.7% of patients on dialysis on either peritoneal dialysis or home hemodialysis at the end of 2015. In just the 10-year period from 2005 to 2015, the number of patients on either peritoneal dialysis or home hemodialysis has increased from a little more than 30,000 to almost 58,000.
Despite these impressive gains, the share of U.S. patients on dialysis in the home trails corresponding shares in at least 26 other countries. In general, growing home dialysis further will demand attention to both the input and output streams. The input stream refers to initiation of dialysis at home, whereas the output stream refers to discontinuation of dialysis at home.
Almost all patients who discontinue dialysis at home experience one of three events: kidney transplant; conversion to in-center hemodialysis (“technique failure”); or death. Of course, kidney transplant is a positive event. Death may be primarily attributable either to complications of peritoneal dialysis (PD) or home hemodialysis (HHD) or to any number of comorbid conditions that accompany kidney failure. In the middle is technique failure, which fundamentally constitutes a lost opportunity to continuing dialysis in the home setting.
How can technique failure be prevented?
Preventing premature or otherwise avoidable conversion to in-center hemodialysis likely requires unique strategies in patients on PD and HHD. In patients on PD, prevention of peritonitis is likely to bear fruit. However, our analysis of contemporary claims data suggests that we may be merely maintaining the status quo of peritonitis incidence. Is each PD program doing all that it can to prevent peritonitis?
In patients on HHD, our analysis of data from NxStage Medical suggests that providing appropriate support to patients and care partners in vulnerable demographic strata and carefully tailoring each patient’s prescription to optimize clinical outcomes and limit the burden of therapy are important tactics to reduce the rate of technique failure.
Peritonitis is arguably the foremost complication of PD and has been reported as the leading cause of technique failure in multiple studies. Of course, peritonitis is often diagnosed and treated in the outpatient setting. However, peritonitis may also necessitate acute care. What is unclear, because of the absence of a national and validated surveillance system, is just how often that peritonitis either results in or is observed during hospitalization. However, we do know that in the most recent annual data report from the United States Renal Data System that the rate of infection-related hospitalization in patients on PD increased more than 5% between 2014 and 2015.
Recently, we have been investigating the details of hospitalization with peritonitis in patients on PD with Medicare coverage. During the last quarter of 2017, Medicare made claims from payment year 2016 available to researchers, thus permitting an even more timely look at hospitalization patterns than can be seen in the annual data report. However, there is a wrinkle. Medicare transitioned from ICD-9 diagnosis codes to ICD-10 diagnosis codes on Oct. 1, 2015, so payment year 2016 represents the first complete year of coding in a new taxonomy. For that reason, all of the data below should be interpreted with some caution.
Materials and methods
We scoured claims in 2014, 2015 and 2016, and identified intervals of PD treatment during those 3 years. We searched for hospitalizations not only during each interval, but also during a 1-month extension after each interval, so that we might fully enumerate the contribution of peritonitis around the time of technique failure. To estimate the rate of hospitalization with peritonitis, we modulated two aspects of the case definition (Table):
- querying either the principal discharge diagnosis on the hospitalization claim or any of up to 25 diagnoses on the claim; and
- excluding or including diagnosis codes for sepsis (in addition to peritonitis), to improve the sensitivity of the case definition.
Recent trends in the rate of hospitalization with peritonitis, according to each of four definitions, are displayed in the Figure. Notably, regardless of case definition, the trend is flat. Hospitalization with peritonitis was no less likely in 2016 than in 2014. This raises the obvious question of whether a national initiative to reduce the rate of peritonitis, similar to the Nephrologists Transforming Dialysis Safety program developed by the American Society of Nephrology, is needed. Provocatively, the variation in rates among case definitions raises the question of just how frequently that peritonitis occurs. Here are some scenarios in which we have flipped the rates in the Figure to calculate patient-months per event in 2016:
- For the simplest case definition of peritonitis as the principal diagnosis, we have an estimate of 236 months per hospitalization with peritonitis in 2016.
- When we expand the case definition to include sepsis, we have an estimate of 72 months per hospitalization with peritonitis or sepsis.
- When we include secondary diagnoses of peritonitis or sepsis, those estimates of 236 and 72 months per hospitalization plummet to only 41 and 29 months per hospitalization, respectively.
Do we have an epidemic of peritonitis? The truth of the matter is that Medicare claims are unable to definitively answer this, as we lack validation for any of the relevant diagnosis codes, let alone those in the ICD-10 era. However, it is reasonable to think that peritonitis remains a major undercurrent in the output stream from PD.
At the Annual Dialysis Conference next month (see a preview of this conference on page 27), we will share results from our continuing analysis of technique failure among U.S. patients using the NxStage System One for HHD. Our cohort comprised 12,756 patients who initiated HHD training between 2010 and 2014 and successfully completed training. The cohort was unremarkable: mean age was 54 years; two in three patients were male; mean BMI was 30 kg/m2; and 70% of patients had a fistula.
The cumulative incidence of technique failure was as follows:
- 24.3% at 1 year after completion of HHD training;
- 35.% at 2 years;
- 41.1% at 3 years;
- 44.7% at 4 years; and
- 47.3% at 5 years.
Multiple observational studies indicate technique failure on HHD may be lower than on PD. However, the timing of technique failure on HHD is unique: cumulative incidence is highest during the first year at home and progressively lower during each subsequent year at home. On PD, the incidence of technique failure increases after the first year at home, particularly when catheter failure is excluded. Thus, developing mastery during HHD training and supporting the needs of patients and their care partners during the first months in the home setting are critically important.
We applied multivariable statistical modeling to identify factors that were significantly associated (P < 0.05) with the risk of technique failure. These factors are displayed in the box. Factors include both nonmodifiable demographic factors and modifiable prescription factors. No factor is necessarily causal, but collectively, these factors raise interesting questions:
- Care partners often invest tremendous energy in HHD. Do elderly care partners have enough support of their own?
- Black patients, on average, have a lower socioeconomic status. Do patients have sufficient resources, including square footage for supply storage and assistance with utilities, to continue HHD?
- Patients with higher body mass index may require more treatment hours per week to achieve adequate clearance of fluid and solutes. Does the prescription facilitate slow ultrafiltration and adequate clearance of solutes?
- Catheters and grafts are associated with increased risk of infection, relative to fistulas. Is infection prevention periodically discussed with catheter-dependent patients?
- Lower dialysate volume per session, when coupled with modest nonadherence, may result in inadequate dialysis. Is the prescription projected to deliver adequate clearance, according to the NxStage Dosing Calculator?
- For a fixed treatment frequency, lower dialysate volume typically requires longer session duration to deliver target clearance. Is the prescribed session duration burdensome?
- Six sessions per week permits only 1 day without dialysis. Regardless of the clinical benefits of frequent dialysis, can the patient and care partner tolerate such a schedule?
Prolonging the duration of dialysis in the home setting clearly requires attention to issues that are germane to PD and to other issues that are germane to HHD. Reducing the risk of peritonitis is likely to reduce the risk of PD technique failure and our analysis of claims data appears to indicate that we are far from vanquishing peritonitis. Reducing the risk of HHD technique failure necessitates attention to details that may engender clinical problems and social stress among patients and their care partners.
Of course, our national goal need not end at discretely addressing challenges with PD and HHD. We can prolong the duration of dialysis in the home setting by also minding the transition from PD to HHD. We know that PD is often prescribed to incident dialysis patients and that HHD is often prescribed to prevalent dialysis patients. However, patients rarely transition from PD to HHD. Data at the Kidney Week in 2017 showed 521 U.S. patients converted from PD to HHD in 2006 to 2012, despite more than 33,000 cases of PD technique failure during that era, and that patients who converted from PD to in-center hemodialysis accumulated an average of more than 18 days in the hospital around the time of the conversion. Transitioning patients from PD to HHD is exceptionally difficult amidst acute and post-acute care.
Considering these observations, we might ask three questions:
- How we can we prevent complications (eg, peritonitis, ultrafiltration failure and catheter failure) that prematurely interrupt PD?
- How can we increase the likelihood of a smooth transition from PD to HHD?
- How can we prolong the duration of HHD?
The answers to these questions undoubtedly vary from one place to another. Nevertheless, preventing major complications of PD, educating existing patients on PD about HHD, and minding both fixed and modifiable risk factors for HHD technique failure are cornerstones of any local initiative.
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