Predictors of treatment with dialysis modalities in observational studies for comparative effectiveness research

BACKGROUND

The Institute of Medicine has identified the comparative effectiveness of renal replacement therapies as a kidney-related topic among the top 100 national priorities. Given the importance of ensuring internal and external validity, the goal of this study was to identify potential sources of bias in observational studies that compare outcomes with different dialysis modalities.

METHODS

This observational cohort study used data from the electronic medical records of all patients that started maintenance dialysis in the calendar years 2007-2011 and underwent treatment for at least 60 days in any of the 2217 facilities operated by DaVita Inc. Each patient was assigned one of six dialysis modalities for each 91-day period from the date of first dialysis (thrice weekly in-center hemodialysis (HD), peritoneal dialysis (PD), less-frequent HD, home HD, frequent HD and nocturnal in-center HD).

RESULTS

Of the 162 644 patients, 18% underwent treatment with a modality other than HD for at least one 91-day period. Except for PD, patients started treatment with alternative modalities after variable lengths of treatment with HD; the time until a change in modality was shortest for less-frequent HD (median time = 6 months) and longest for frequent HD (median time = 15 months). Between 30 and 78% of patients transferred to another dialysis facility prior to change in modality. Finally, there were significant differences in baseline and time-varying clinical characteristics associated with dialysis modality.

CONCLUSIONS

This analysis identified numerous potential sources of bias in studies of the comparative effectiveness of dialysis modalities.

PD First: peritoneal dialysis as the default transition to dialysis therapy

Peritoneal dialysis (PD) and in-center hemodialysis (HD) are accepted as clinically equivalent dialysis modalities, yet in-center HD is the predominant renal replacement therapy (RRT) modality offered to new end-stage renal disease (ESRD) patients in the United States and most other industrialized nations. This predominance has little to do with clinical outcomes, patient choice, cost, or quality of life. It has been driven by ease of HD initiation, physician experience and training, inadequate pre-ESRD patient education, ample in-center HD capacity, and lack of adequate infrastructure for PD-related care. As compared with in-center HD, PD is a widely applicable, yet underutilized modality of RRT that provides comparable clinical outcomes, superior quality of life measures, significant cost savings, and many other unmeasured advantages. A "PD First" approach not only has advantages for patients but also physicians, healthcare systems, and society. In this review, we will summarize evidence demonstrating that PD should be the default modality when new ESRD patients are transitioning to dialysis therapy when preemptive transplantation is not an option and highlight the essential infrastructural requirements to allow for a "PD First" model.

Relationship of body size and initial dialysis modality on subsequent transplantation, mortality and weight gain of ESRD patients

BACKGROUND

Whether peritoneal dialysis (PD) treatment leads to greater weight gain than with hemodialysis (HD) and if this limits access of obese end-stage renal disease patients to renal transplantation has not been examined. We undertook this study to determine the interrelationship between body size and initial dialysis modality on transplantation, mortality and weight gain.

METHODS

Time to transplantation, time to death and weight gain were estimated in a 1:1 propensity score-matched cohort of incident HD and PD patients treated in facilities owned by DaVita Inc. between 1 July 2001 through 30 June 2006 followed through 30 June 2007 (4008 pairs) in four strata of body mass index (BMI) (<18.5, 18.5-24.99, 25.00-29.99 and ≥ 30 kg/m(2)).

RESULTS

Transplantation was significantly more likely in PD patients [adjusted hazards ratio (aHR) 1.48, 95% confidence interval (95% CI) 1.29-1.70]; the probability of receiving a kidney transplant was significantly higher in each strata of BMI >18.5 kg/m(2), including with BMI ≥ 30 kg/m(2) (aHR 1.45, 95% CI 1.11-1.89). PD patients had significantly lower all-cause mortality for patients with BMI 18.50-29.99 kg/m(2). Both these findings were confirmed on analyses of the entire unmatched incident cohort (PD 4008; HD 58 471). The effect of dialysis modality on weight gain was tested in 687 propensity score-matched pairs; the odds of >2, >5 or >10% weight gain were significantly lower in PD patients.

CONCLUSION

Treatment with PD is less likely to be associated with a significant weight gain and does not limit the access of obese patients to renal transplantation.

Dialysis at a crossroads--Part II: A call for action

A previous commentary pointed out that the renal community has led American healthcare in the development and continuous improvement of quality outcomes. However, survival, hospitalization, and quality of life for US dialysis patients is still not optimal. This follow-up commentary examines the obstacles, gaps, and metrics that characterize this unfortunate state of affairs. It posits that current paradigms are essential contributors to quality outcomes but are no longer sufficient to improve quality. New strategies are needed that arise from a preponderance of evidence, in addition to beyond a reasonable doubt standard. This work offers an action plan that consists of new pathways of care that will lead to improved survival, fewer hospitalizations and rehospitalizations, and better quality of life for patients undergoing dialysis therapy. Nephrologists in collaboration with large and small dialysis organizations and other stakeholders, including the Centers for Medicare and Medicaid Services, can implement these proposed new pathways of care and closely monitor their effectiveness. We suggest that our patients deserve nothing less and must receive even more.

Vascular access for HD: aligning payment with quality

The Fistula First Breakthrough Initiative (FFBI) has improved the awareness of the value of fistula creation in patients with end-stage renal disease (ESRD). The FFBI Health Policy Workgroup has been charged with reviewing the relationship of policy and economic issues to this project. This article reviews the efforts and successes of renal community clinical activities and reemphasizes the economic impact of fistula creation and catheter reduction on the health care system. Major obstacles are discussed, and existing tools and efforts designed to address them are outlined. The FFBI Health Policy Workgroup then identifies less frequently recognized barriers to the achievement of the FFBI goals and suggests solutions to them. It concludes that nephrologists need to assume the leadership role and drive fistula creation and central venous catheter reduction to achieve programmatic success.

Dialysis practices that distinguish facilities with below- versus above-expected mortality

BACKGROUND AND OBJECTIVES

Mortality rates vary widely among dialysis facilities even after adjustment with standardized mortality ratios (SMRs). This variation may occur because top-performing facilities use practices not shared by others, because the SMR fails to capture key patient characteristics, or both. Practices were identified that distinguish top- from bottom-performing facilities by SMR.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

A cross-sectional survey was performed of staff across three organizations. Staff members rated the perceived quality of their units' patient-, provider-, and facility-level practices using a six-point Likert scale. Facilities were divided into those with above- versus below-expected mortality on the basis of SMRs from U.S. Renal Data Service facility reports. Mean Likert scores were computed for each practice using t tests. Practices that were statistically significant (P ≤ 0.05) and achieved at least a medium effect size of ≥0.4 were reported. Significant predictors were entered into a linear regression model.

RESULTS

Dialysis facilities with below-expected mortality reported that patients in their unit were more activated and engaged, physician communication and interpersonal relationships were stronger, dieticians were more resourceful and knowledgeable, and overall coordination and staff management were superior versus facilities with above-expected mortality. Staff ratings of these practices explained 31% of the variance in SMRs.

CONCLUSIONS

Patient-, provider-, and facility-level practices partly explain SMR variation among facilities. Improving SMRs may require processes that reflect a coordinated, multidisciplinary environment (i.e., no one group, practice, or characteristic will drive facility-level SMRs). Understanding and improving SMRs will require a holistic view of the facility.

Prevalence and correlates of cognitive impairment in hemodialysis patients: the Frequent Hemodialysis Network trials

BACKGROUND AND OBJECTIVES

Cognitive impairment is common among persons with ESRD, but the underlying mechanisms are unknown. This study evaluated the prevalence of cognitive impairment and association with modifiable ESRD- and dialysis-associated factors in a large group of hemodialysis patients.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Cross-sectional analyses were conducted on baseline data collected from 383 subjects participating in the Frequent Hemodialysis Network trials. Global cognitive impairment was defined as a score <80 on the Modified Mini-Mental State Exam, and impaired executive function was defined as a score >or=300 seconds on the Trailmaking B test. Five main categories of explanatory variables were examined: urea clearance, nutritional markers, hemodynamic measures, anemia, and central nervous system (CNS)-active medications.

RESULTS

Subjects had a mean age of 51.6 +/- 13.3 years and a median ESRD vintage of 2.6 years. Sixty-one subjects (16%) had global cognitive impairment, and 110 subjects (29%) had impaired executive function. In addition to several nonmodifiable factors, the use of H1-receptor antagonists and opioids were associated with impaired executive function. No strong association was found between several other potentially modifiable factors associated with ESRD and dialysis therapy, such as urea clearance, proxies of dietary protein intake and other nutritional markers, hemodynamic measures, and anemia with global cognition and executive function after adjustment for case-mix factors.

CONCLUSIONS

Cognitive impairment, especially impaired executive function, is common among hemodialysis patients, but with the exception of CNS-active medications, is not strongly associated with several ESRD- and dialysis-associated factors.

Dialysis practices that distinguish top- versus bottom-performing facilities by hemoglobin outcomes

BACKGROUND

Because there is wide variation in outcomes across dialysis facilities, it is possible that top-performing units use practices not shared by others. The Identifying Best Practices in Dialysis (IBPiD) Study seeks to identify practices that distinguish top- from bottom-performing facilities by key outcomes, including achievement of recommended hemoglobin targets.

STUDY DESIGN

Observational study with cross-sectional study ascertainment of predictors and outcomes.

PREDICTORS

Facility dialysis practices ascertained using practice surveys of dialysis staff who indicated their level of agreement that each practice occurs in their facility (1-6 on a Likert scale).

SETTING & PARTICIPANTS

423 personnel in 90 dialysis facilities from 1 for-profit and 2 not-for-profit dialysis organizations.

OUTCOMES

Percentage of patients per month per facility with hemoglobin levels of 11-12 g/dL. We divided facilities by median into top- versus bottom-performing groups and compared mean scores for each practice using t tests. We report practices that were statistically significant and achieved at least a medium effect size (ES) >or=0.4.

RESULTS

17 of 155 tested predictors were significant. Achievement of hemoglobin level targets was related most strongly to the use of chairside computers (ES, 0.8 [95% CI, 0.4-1.4]), extent/quality of educational videos (ES, 0.6 [95% CI, 0.2-1.1]), frequency of calling per diem staff if short staffed (ES, 0.6 [95% CI, 0.21-1.1]), policy that nurses pass written competency examinations before hire (ES, 0.6 [95% CI, 0.2-1.0]), and technician cannulation mastery (ES, 0.6 [95% CI, 0.2-1.1]).

LIMITATIONS

This is a cross-sectional study that can address only associations, not causations. Future research should measure the longitudinal predictive value of these practices.

CONCLUSIONS

High-performing facilities report more effective education programs, better staff management, higher staff competency, and higher use of chairside computers, a potential marker of information technology proficiency. This suggests that hemoglobin level management is enhanced by processes reflecting a coordinated multidisciplinary environment.

Relationship among length of facility ownership, clinical performance, and mortality

BACKGROUND AND OBJECTIVES

The association between level of performance in achieving guideline-recommended clinical indicators and relative reduction in patient mortality is inconsistent among large dialysis organizations (LDOs). Because growth rates among providers differ, we reasoned that clinical performance and mortality rates in dialysis facilities may be related to length of facility ownership.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We examined achievement of clinical performance indicators among prevalent long-term hemodialysis patients who were enrolled in cohorts of DaVita facilities between December 2005 and December 2007. We compared results in 606 facilities owned before December 1, 2004 (existing), with those seen in 504 facilities that were acquired in October 2005 (newly acquired).

RESULTS

At baseline, existing compared with newly acquired DaVita facilities showed higher levels of clinical performance and lower patient mortality. These differences persisted up to 2 years for selected outcomes, including dialysis adequacy and anemia management. Substantial improvement was seen in both cohorts for mineral bone disease outcomes; however, 2 years after acquisition, between-cohort differences in relative risk for death were no longer discernible.

CONCLUSIONS

These findings confirm that intervention to improve quality outcomes in dialysis facilities produces direct benefits that are tangible to patients. Our results also provide new evidence that length of ownership may be a significant factor in determining facility performance within a large dialysis organization.

Ownership patterns of dialysis units and peritoneal dialysis in the United States: utilization and outcomes

BACKGROUND

Peritoneal dialysis (PD) provides outcomes similar to hemodialysis, but its use has decreased in the United States despite its potential for substantial taxpayer savings. We undertook this study to determine the relationship between dialysis unit ownership with PD use and outcomes.

STUDY DESIGN

Observational study.

SETTING & PARTICIPANTS

All incident dialysis patients (1996 to 2004) from the US Renal Data System.

PREDICTOR

Large dialysis organization (LDO), defined as corporations owning 20 or more freestanding dialysis units located in more than 1 state.

OUTCOMES & MEASUREMENTS

Odds for an incident dialysis patient undergoing PD and hazards for death on follow-up in incident PD patients for each of the 5 LDOs (non-LDO as reference).

RESULTS

During the 9-year period, 785,531 patients started maintenance dialysis therapy; the proportion receiving care in LDOs increased from 39% to 63%. There were consistent differences in PD use. It was significantly lower in LDO 2 (adjusted odds ratio [OR], 0.66; 95% confidence interval [CI], 0.64 to 0.68), LDO 3 (OR, 0.82; 95% CI, 0.80 to 0.85), and LDO 4 (OR, 0.96; 95% CI, 0.92 to 0.995) and higher in LDO 1 (adjusted OR, 1.06; 95% CI, 1.02 to 1.11) and LDO 5 (adjusted OR, 1.09; 95% CI, 1.06 to 1.12). Between 2000 and 2004, LDO 2 had the least use and greatest risk of death (hazard ratio, 1.08; 95% CI, 1.02 to 1.14); LDO 1 had greater use and the lowest death risk (hazard ratio, 0.87; 95% CI, 0.78 to 0.96).

LIMITATIONS

Only cross-sectional associations can be described.

CONCLUSIONS

Three of the 5 LDOs had consistently lower PD use. Patients treated in the LDO with the lowest use of PD had the greatest risk of death. Understanding relationships among providers, physicians, and dialysis modality use may help devise strategies for increasing PD use in appropriate patients. This has the potential to reduce the cost of renal replacement therapy and further improve outcomes.

Is there "cherry picking" in the ESRD Program? Perceptions from a Dialysis Provider Survey

BACKGROUND AND OBJECTIVES

Changes in ESRD reimbursement policy, including proposed bundled payment, have raised concern that dialysis facilities may use "cherry picking" practices to attract a healthier, better insured, or more adherent patient population.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

As part of a national survey to measure beliefs about drivers of quality in dialysis, respondents were asked about their perceptions of cherry picking, including the frequency and effect of various cherry picking strategies on dialysis outcomes. We surveyed a random sample of 250 nurse members of the American Nephrology Nurses Association, 250 nephrologist members of the American Medical Association, 50 key opinion leaders, and 2000 physician members of the Renal Physicians Association. We tested hypothesized predictors of perception, including provider group, region, age, experience, and the main practice facility features.

RESULTS

Three-quarters of respondents reported that cherry picking occurred "sometimes" or "frequently." There were no differences in perceptions by provider or facility characteristics, insurance status, or health status. In multivariable regression, perceived cherry picking was 2.8- and 3.5-fold higher in the northeast and Midwest, respectively, versus the west. Among various cherry picking strategies, having a "low threshold to 'fire' chronic no-shows/late arrivers," and having a "low threshold to 'fire' for noncompliance with diet and meds" had the largest perceived association with outcomes.

CONCLUSIONS

Under current reimbursement practices, dialysis caregivers perceive that cherry picking is common and important. An improved understanding of cherry picking practices, if evident, may help to protect vulnerable patients if reimbursement practices were to change.

Identifying best practices in dialysis care: results of cognitive interviews and a national survey of dialysis providers

BACKGROUND AND OBJECTIVES

Because there is wide variation in case-mix adjusted outcomes across dialysis facilities, it is possible that top-performing facilities use practices not shared by others. We sought to catalogue "best practices" that may account for interfacility variations in outcomes.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This multidisciplinary study identified candidate best practices in dialysis through a staged process, including systematic review, cognitive interviews, and a national "virtual focus group" of dialysis providers. The resulting candidate practices were rank-ordered by perceived importance as determined by mean RAND Appropriateness Scores from a national survey of nephrologists, nurses, and opinion leaders.

RESULTS

A total of 155 candidate best practices were identified. Among these, respondents believed dialysis outcomes are most strongly related to 1) characteristics of multidisciplinary care conferences, 2) technician proficiency in protecting vascular access, 3) training of nurses to provide education in fluid management, vascular access, and nutrition, 4) use of random and blinded audits of staff performance, and 5) communication and teamwork among staff. In contrast, there was wide disagreement about the importance of facility-based health maintenance practices, optimal staffing ratios, frequency of dialysis-based physician visits, and optimal frequency of multidisciplinary care.

CONCLUSIONS

This study provides a "conceptual map" of candidate dialysis best practices and highlights areas of general agreement and disagreement. These findings can help the dialysis community think critically about what may define "best practice" and provide targets for future research in quality improvement.

Chronic peritoneal dialysis in the United States: declining utilization despite improving outcomes

In the United States, chronic peritoneal dialysis take-on has declined among incident ESRD patients. Although increasing age, co-morbidity, and body size may explain part of this decline, other factors likely contribute. Among incident ESRD patients in the United States, we found that peritoneal dialysis take-on significantly decreased from 11% in 1996 to 1997 to 7% in 2002 to 2003 (P < 0.001 for the trend). This decrease remained after adjusting for patient demographics, case-mix, and laboratory data, suggesting the involvement of other factors. This decline in utilization occurred during a time of improving outcomes for incident peritoneal dialysis patients, measured as reduced hazards for death or for the need to transfer to hemodialysis. In contrast, among patients initially treated with hemodialysis, the 12-month adjusted hazards for death or transfer to peritoneal dialysis slightly worsened or were unchanged over this same period. Therefore, the decline in peritoneal dialysis take-on cannot be entirely explained by increasing age, co-morbidity and body size of incident ESRD patients. The decline in utilization has occurred at a time when the early outcomes of CPD patients have improved.

The association of poverty with the prevalence of albuminuria: data from the Third National Health and Nutrition Examination Survey (NHANES III)

BACKGROUND

Albuminuria is a major risk factor for the development and progression of chronic kidney disease (CKD) and cardiovascular disease. Socioeconomic factors also have been reported to modify CKD and cardiovascular risk factors and clinical outcomes. The extent to which poverty influences the prevalence of albuminuria, particularly among racial/ethnic minority populations, is not well established. The influence of poverty on the prevalence of albuminuria and the implication of this relationship for the racial and/or ethnic differences in the prevalence of albuminuria were examined.

METHODS

We examined data from 6,850 male and 7,634 female adults from a national probability survey conducted between 1988 and 1994.

RESULTS

In univariate analysis, poverty, defined as less than 200% federal poverty level (FPL), was associated with the presence of both microalbuminuria (odds ratio [OR], 1.35; 95% confidence interval, 1.22 to 1.49) and macroalbuminuria (OR, 1.78; 95% confidence interval, 1.40 to 2.26). The association of less than 200% FPL with microalbuminuria persisted in a multivariate model controlling for age, sex, race, education, obesity, hypertension, diabetes, reduced glomerular filtration rate, and medication use (OR, 1.18; 95% confidence interval, 1.05 to 1.33). FPL less than 200% was not associated with macroalbuminuria in the multivariate model. When multivariate analysis is stratified by FPL (<200% and > or =200%), differences in ORs for microalbuminuria and macroalbuminuria among racial/ethnic minority participants compared with whites were more apparent among the less affluent participants in the FPL-less-than-200% stratum.

CONCLUSION

FPL less than 200% is associated with microalbuminuria, and differences in FPL levels may account for some of the observed differences in prevalence of albuminuria between racial/ethnic minority participants and their white counterparts.

Long-term outcome of individuals with pure red cell aplasia and antierythropoietin antibodies in patients treated with recombinant epoetin: a follow-up report from the Research on Adverse Drug Events and Reports (RADAR) Project

Since its introduction in 1988, recombinant human erythropoietin (epoetin) has been standard treatment for patients with anemia due to chronic kidney disease. From 1998 to 2004, nearly 200 epoetin-treated persons with chronic kidney disease developed antibodies to epoetin, resulting in pure red cell aplasia (PRCA). The majority of these patients received Eprex, an epoetin alfa product marketed exclusively outside the United States. Herein, we report on the long-term outcome of these individuals. For 170 chronic kidney disease patients who developed epoetin-associated PRCA and had 3 months or more follow-up information available, case reports from the Food and Drug Administration and epoetin manufacturers were reviewed for information on clinical characteristics of the patients, immunosuppressive treatments, epoetin responsiveness, and hematologic recovery. Overall, 64% of the PRCA patients received immunosuppressive therapy, including 19 who also underwent a renal transplantation. Thirty-seven percent experienced a hematologic recovery, with higher hematologic recovery rates among PRCA patients who received immunosuppressive therapy (57% vs 2%, P < .001). Among 34 patients who received epoetin after the onset of PRCA, 56% regained epoetin responsiveness. The highest rates of epoetin responsiveness were observed among persons whose antierythropoietin antibodies were undetectable when epoetin was administered (89%). Among chronic kidney disease patients with epoetin-associated PRCA, epoetin discontinuation and immunosuppressive therapy or renal transplantation is necessary for hematologic recovery. Reinitiation of epoetin therapy among individuals could be considered if antierythropoietin antibodies are undetectable.

Paper chromatography prior to cortisol RIA allows for accurate use of the dexamethasone suppression test in chronic renal failure

The assessment of the hypothalamic-pituitary-adrenal axis in patients with chronic renal failure (CRF) on hemodialysis is often hampered by abnormal responses to the standard 1-mg dexamethasone suppression test. Various mechanisms have been proposed to explain this lack of suppressibility. The present study was designed to look into the mechanisms possible for these findings in patients with CRF. We studied 6 patients with CRF on hemodialysis and 5 healthy subjects utilizing the 1-mg dexamethasone suppression test as well as the 50-mg hydrocortisone suppression test. Samples were assayed for dexamethasone, adrenocorticotropic hormone, corticosterone, and cortisol by both direct radioimmunoassay (RIA) and RIA after paper chromatography. Utilizing the direct cortisol RIA, 4 of 6 patients with CRF exhibited blunted dexamethasone suppression, while all 6 patients showed normal suppressibility after dexamethasone when cortisol was measured after paper chromatography. In contrast, all controls showed normal suppressibility regardless of the cortisol assay procedure used. The hydrocortisone suppression test was unreliable in the setting of CRF. Mean dexamethasone levels were similar in both groups. Plasma adrenocorticotropic hormone levels were significantly higher in the CRF patients, possibly indicative of an underlying hypothalamic-pituitary-adrenal axis abnormality. Abnormalities in dexamethasone suppression testing in patients with CRF may be explained by the overestimation of cortisol levels by direct RIA rather than by alteration of dexamethasone absorption or metabolism. Measurement of cortisol after paper chromatography is superior to direct RIA of cortisol in patients with CRF.

Plasma and dialysate immunoglobulin G in continuous ambulatory peritoneal dialysis patients: a multicenter study

Peritoneal dialysate immunoglobulin (Ig)G concentrations were measured in 120 continuous ambulatory peritoneal dialysis (CAPD) patients evaluated at four dialysis centers in different countries to assess the normal range for dialysate IgG and to investigate the relationships of this protein levels with peritoneal episodes, For 65 of these patients, plasma IgG levels were determined, and IgG clearances were calculated. The mean dialysate concentration of IgG was 6.9 +/- 4.2 mg/dl, and there was no difference between men and women or between patients who had or had not previously undergone hemodialysis. Dialysate IgG concentrations were significantly related to residual renal creatinine clearance and negatively correlated with dialysate volume, plasma albumin and total protein. There were no significant correlations between IgG levels in the dialysate and age, protein losses in the dialysate, time on CAPD or time from the last peritonitis episode. Plasma and dialysate IgG were unrelated to the incidence of peritonitis, statistical analysis being performed with different methods. These results suggest that IgG levels in the dialysate or plasma are not a major factor in the prevention of CAPD peritonitis.