Dialysate Sodium Lowering in Maintenance Hemodialysis A Randomized Clinical Trial

INTRODUCTION

Lowering dialysate sodium may improve volume and blood pressure control in maintenance hemodialysis patients.

METHODS

We randomized 42 participants 2:1 to dialysate sodium 135 vs. 138 mEq/L for 6 months. This was followed by a 12 week extension in which sodium was increased to 140 mEq/L in low arm participants. The primary outcome was intradialytic hypotension (IDH). Secondary outcomes included dialysis disequilibrium symptoms, ER visits/hospitalizations, interdialytic weight gain, blood pressure (BP). Longitudinal changes across arms were analyzed using linear mixed regression.

RESULTS

Treatment to dialysate sodium 135 vs. 138 mEq/L was not associated with a difference in a change in the rate of IDH (mean change (95%CI) 2.8 (0.8,9.5) vs. 2.7 (1.1, 6.2) events per 100 treatments per month; ratio of slopes 0.96(0.26,3.61) or ER visits/hospitalizations (7.3 (2.3, 12.4) vs. 6.7 (2.9, 10.6) events per 100 patient months; difference 0.6(-6.9,5.8). Symptom score was unchanged in the 135 mEq/L arm (0.7 (-1.4,2.7) and decreased in the 138 mEq/l arm (5.0,8.5,2.0); difference 6.0 (2.1,9.8)). Interdialytic weight gain declined in the 135 mEq/L arm and was unchanged in the 138 mEq/L arm,(-0.3(-0.5,0.0) vs. 0.3 (0.0, 0.6) kg over 6 months; difference (-0.6 (-0.1,-1.0) kg). In the extension phase, raising dialysate sodium from 135 to 140 mEq/L was associated with an increase in interdialytic weight gain (0.2 (0.1, 0.3) kg), predialysis BP (7.0 (4.8, 9.2)/ 3.9 (2.6, 5.1) mm Hg) and a reduction in IDH [OR 0.66 (0.45, 0.97)].

CONCLUSION

Use of a dialysate sodium of 135 as compared with 138 mEq/L was associated with a small reduction in interdialytic weight gain without impact on IDH or predialysis BP, but with an increase in symptoms. Raising dialysate sodium from 135 to 140mEq/L was associated with a reduction in IDH, a small increase in interdialytic weight gain and a marked increase in predialysis BP.

Association of Longitudinal Urinary Metabolic Biomarkers With ADPKD Severity and Response to Metformin in TAME-PKD Clinical Trial Participants

Introduction

Dysregulated cellular metabolism contributes to autosomal dominant polycystic kidney disease (ADPKD) pathogenesis. The Trial of Administration of Metformin in Polycystic Kidney Disease (TAME-PKD) tested the effects of metformin treatment over 2 years in adult ADPKD patients with mild-moderate disease severity. Metformin was found to be safe and tolerable with an insignificant trend toward reduced estimated glomerular filtration rate (eGFR) decline compared to placebo. Here we tested whether targeted urinary metabolic biomarkers measured in TAME-PKD participants correlated with disease progression, severity, and metformin treatment in cross-sectional and longitudinal analyses.

Methods

Concentrations of total protein, targeted metabolites (lactate, pyruvate, and succinate), and glycolytic enzymes (pyruvate kinase-M2, lactate dehydrogenase-A, and pyruvate dehydrogenase kinase-1) were measured and normalized by creatinine or osmolality in urine specimens and compared with height-adjusted total kidney volume (htTKV) and eGFR at the different study timepoints.

Results

In cross-sectional analyses utilizing placebo group data, urinary succinate normalized by creatinine negatively correlated with ln (htTKV), whereas protein excretion strongly positively correlated with ln (htTKV), and negatively correlated with eGFR. Significant time-varying negative associations occurred with eGFR and the lactate/pyruvate ratio and with urine protein normalized by osmolality, indicating correlations of these biomarkers with disease progression. In secondary analyses, urinary pyruvate normalized by osmolality was preserved in metformin-treated participants but declined in placebo over the 2-year study period with a significant between-arm difference, suggesting time-dependent urinary pyruvate changes may serve as a discriminator for metformin treatment effects in this study population.

Conclusion

Proteinuria with enhanced glycolytic and reduced oxidative metabolic markers generally correlated with disease severity and risk of progression in the TAME-PKD study population.

Seroresponse to Inactivated and Recombinant Influenza Vaccines Among Maintenance Hemodialysis Patients

RATIONALE & OBJECTIVE

High-dose influenza vaccine provides better protection against influenza infection in older adults than standard-dose vaccine. We compared vaccine seroresponse among hemodialysis patients over a period of 4 months after administration of high-dose trivalent inactivated (HD-IIV3), standard-dose quadrivalent inactivated (SD-IIV4), or quadrivalent recombinant quadrivalent (RIV4) influenza vaccine.

STUDY DESIGN

Prospective observational study.

SETTING & PARTICIPANTS

Patients at 4 hemodialysis clinics who received influenza vaccine.

EXPOSURE

Type of influenza vaccine.

OUTCOME

Hemagglutination inhibition (HI) titers were measured at baseline and at 1, 2, 3, and 4 months after vaccination. The primary outcome was seroprotection rates at HI titers of at least 1:40 and at least 1:160 (antibody levels providing protection from infection in approximately 50% and 95% of immunocompetent individuals, respectively) at 1, 2, 3, and 4 months after vaccination.

ANALYTICAL APPROACH

We calculated geometric mean titer as well as seroprotection and seroconversion rates. Adjusted generalized linear models with additional trend analyses were performed to evaluate the association between vaccine type and outcomes.

RESULTS

254 hemodialysis patients were vaccinated against influenza with HD-IIV3 (n = 141), SD-IIV4 (n = 36), or RIV4 (n = 77). A robust initial seroresponse to influenza A strains was observed after all 3 vaccines. Geometric mean titer and seroprotection (HI titer ≥1:160) rates against influenza A strains were higher and more sustained with HD-IIV3 than SD-IIV4 or RIV4. More than 80% of patients vaccinated with HD-IIV3 were seroprotected (HI titer ≥1:160) at month 4 (P < 0.001), whereas, among patients vaccinated with SD-IIV4 or RIV4, seroprotection rates were similar to those at baseline. Seroprotection rates were lower against B strains for all vaccines.

LIMITATIONS

Because of the use of observational data, bias from unmeasured confounders may exist. Some age subgroups were small in number. Clinical outcome data were not available.

CONCLUSIONS

Hemodialysis patients exhibited high seroprotection rates after all 3 influenza vaccines. The seroresponse waned more slowly with HD-IIV3 compared with SD-IIV4 and RIV4 vaccines.

Primary results of the randomized trial of metformin administration in polycystic kidney disease (TAME PKD)

Autosomal dominant polycystic kidney disease (ADPKD) is characterized by growth of kidney cysts and glomerular filtration rate (GFR) decline. Metformin was found to impact cystogenesis in preclinical models of polycystic disease, is generally considered safe and may be a promising candidate for clinical investigation in ADPKD. In this phase 2 two-year trial, we randomly assigned 97 patients, 18-60 years of age, with ADPKD and estimated GFR over 50 ml/min/1.73 m², in a 1:1 ratio to receive metformin or placebo twice daily. Primary outcomes were medication safety and tolerability. Secondary outcomes included estimated GFR decline, and total kidney volume growth. Thirty-eight metformin and 39 placebo participants still received study product at 24-months. Twenty-one participants in the metformin arm reduced drug dose due to inability to tolerate, compared with 14 in the placebo arm (not significant). Proportions of participants experiencing serious adverse events was similar between the groups. The Gastrointestinal Symptoms Rating Scale score was low at baseline and did not significantly change over time. The annual change for estimated GFR was -1.71 with metformin and -3.07 ml/min/1.73m² per year with placebo (mean difference 1.37 {-0.70, 3.44} ml/min/1.73m²), while mean annual percent change in height-adjusted total kidney volume was 3.87% in metformin and 2.16% per year in placebo, (mean difference 1.68% {-2.11, 5.62}). Thus, metformin in adults with ADPKD was found to be safe and tolerable while slightly reducing estimated GFR decline but not to a significant degree. Hence, evaluation of efficacy requires a larger trial, with sufficient power to detect differences in endpoints.

Comparison of Dialysis Unit and Home Blood Pressures: An Observational Cohort Study

RATIONALE & OBJECTIVE

Prior studies of patients receiving maintenance hemodialysis have shown that, on average, blood pressure (BP) measured predialysis is higher than BP measured at home. We hypothesized that a subset of hemodialysis patients has BP that is higher when measured at home than when measured predialysis and this subgroup of patients has a higher prevalence of left ventricular hypertrophy.

STUDY DESIGN

Prospective cohort.

SETTING & PARTICIPANTS

97 hypertensive hemodialysis patients enrolled in the Blood Pressure in Dialysis Study (BID), a randomized trial of comparing target predialysis BP ≤140/90 to 155-165/90 mm Hg.

EXPOSURE

Differences between predialysis and next-day home systolic BP measured ≥6 times over 1 year.

OUTCOME

Left ventricular mass index (LVMI) by cardiac magnetic resonance imaging.

ANALYTICAL APPROACH

A hierarchical clustering analysis divided patients into 3 clusters based on the average and variability of differences in systolic predialysis and home BP. Clusters were compared with respect to clinical factors and LVMI.

RESULTS

Mean differences between predialysis and home systolic BP were 19.1 (95% CI, 17.0 to 21.1) mm Hg for cluster 1 ("home lower"), 3.7 (95% CI, 1.6 to 5.8) mm Hg for cluster 2 ("home and predialysis similar"), and -9.7 (95% CI, -12.0 to -7.4) mm Hg for cluster 3 ("home higher"). Systolic BP declined during dialysis in clusters 1 and 2 but increased in cluster 3. Interdialytic weight gains did not differ. After adjusting for sex and treatment arm, LVMI was higher in cluster 3 than in clusters 1 and 2: differences in means of 10.6 ± 4.96 (SE) g/m² (P = 0.04) and 12.0 ± 5.08 g/m² (P = 0.02), respectively.

LIMITATIONS

Limited statistical power.

CONCLUSIONS

Nearly one-third of participants had home BPs higher than predialysis BPs. These patients had LVMI higher than those with similar or lower BPs at home, indicating that their BP may have been undertreated.

Association of Baseline Urinary Metabolic Biomarkers with ADPKD Severity in TAME-PKD Clinical Trial Participants

BACKGROUND

Recent work suggests that dysregulated cellular metabolism may play a key role in the pathogenesis of autosomal dominant polycystic kidney disease (ADPKD). The TAME-PKD clinical trial is testing the safety, tolerability, and efficacy of metformin, a regulator of cell metabolism, in patients with ADPKD. This study investigates the cross-sectional association of urinary metabolic biomarkers with ADPKD severity among TAME-PKD trial participants at baseline.

METHODS

Concentrations of total protein, targeted metabolites (lactate, pyruvate, succinate, and cAMP), and key glycolytic enzymes (pyruvate kinase M2 [PKM2], lactate dehydrogenase A [LDHA], and pyruvate dehydrogenase kinase 1 [PDK1]) were measured by ELISA, enzymatic assays, and immunoblotting in baseline urine specimens of 95 TAME-PKD participants. These analytes, normalized by urinary creatinine or osmolality to estimate excretion, were correlated with patients' baseline height-adjusted total kidney volumes (htTKVs) by MRI and eGFR. Additional analyses were performed, adjusting for participants' age and sex, using multivariable linear regression.

RESULTS

Greater htTKV correlated with lower eGFR (r=-0.39; P=0.0001). Urinary protein excretion modestly correlated with eGFR (negatively) and htTKV (positively). Urinary cAMP normalized to creatinine positively correlated with eGFR. Among glycolytic enzymes, PKM2 and LDHA excretion positively correlated with htTKV, whereas PKM2 excretion negatively correlated with eGFR. These associations remained significant after adjustments for age and sex. Moreover, in adjusted models, succinate excretion was positively associated with eGFR, and protein excretion was more strongly associated with both eGFR and htTKV in patients <43 years old.

CONCLUSIONS

Proteinuria correlated with ADPKD severity, and urinary excretion of PKM2 and LDHA correlated with ADPKD severity at baseline in the TAME-PKD study population. These findings are the first to provide evidence in human urine samples that upregulated glycolytic flux is a feature of ADPKD severity. Future analysis may reveal if metformin treatment affects both disease progression and the various urinary metabolic biomarkers in patients throughout the study.

COVID-19 Among US Dialysis Patients: Risk Factors and Outcomes From a National Dialysis Provider

Rationale & Objective

During the coronavirus disease 2019 (COVID-19) pandemic, patients receiving maintenance dialysis are a highly vulnerable population due to their comorbidities and circumstances that limit physical distancing during treatment. This study sought to characterize the risk factors for and outcomes following COVID-19 in this population.

Study Design

Retrospective cohort study.

Setting & Participants

Maintenance dialysis patients in clinics of a midsize national dialysis provider that had at least 1 patient who tested positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from February to June 2020.

Predictors

Demographics, dialysis characteristics, residence in a congregated setting, comorbid conditions, measurements of frailty, and use of selected medications.

Outcomes

COVID-19, defined as having a positive SARS-CoV-2 test result, and all-cause mortality among those with COVID-19.

Analytical Approach

Logistic regression analyses conducted to identify clinical characteristics associated with COVID-19 and risk factors associated with mortality among patients following COVID-19.

Results

438 of 7948 (5.5%) maintenance dialysis patients developed COVID-19. Male sex, Black race, in-center dialysis (vs home dialysis), treatment at an urban clinic, residence in a congregate setting, and greater comorbidity were associated with contracting COVID-19. Odds of COVID-19 were 17-fold higher for those residing in a congregated setting (odds ratio [OR], 17.10 [95% CI, 13.51-21.54]). Of the 438 maintenance dialysis patients with COVID-19, 109 (24.9%) died. Older age, heart disease, and markers of frailty were associated with mortality.

Limitations

No distinction was detected between symptomatic and asymptomatic SARS-CoV-2 positivity, with asymptomatic screening limited by testing capacity during this initial COVID-19 surge period.

Conclusions

COVID-19 is common among patients receiving maintenance dialysis, particularly those residing in congregate settings. Among maintenance dialysis patients with COVID-19, mortality is high, exceeding 20%.

Baseline Characteristics and Patient-Reported Outcomes of ADPKD Patients in the Multicenter TAME-PKD Clinical Trial

Background

Autosomal dominant polycystic kidney disease (ADPKD) has been associated with metabolic disturbances characterized by downregulation of AMP-activated protein kinase (AMPK), a critical sensor of the cellular energy status. Therapeutic activation of AMPK by metformin could inhibit cyst enlargement by inhibition of both the mammalian target of rapamycin pathway and fluid secretion via the CFTR chloride channel.

Methods

We designed a phase-2, randomized, placebo-controlled, clinical trial to assess the safety, tolerability, and efficacy of metformin on total kidney volume in adults without diabetes (age 18-60 years) with ADPKD and eGFR of ≥50 ml/min per 1.73 m². There were no eligibility criteria relating to kidney volume. In addition to demographics and clinical/family history, baseline parameters included eGFR, total kidney and liver volumes measured by MRI, and patient-reported outcomes were ascertained by the Medical Outcomes Study Short Form-36, the Gastrointestinal Safety Rating Scale, and the HALT-PKD pain questionnaire.

Results

We successfully randomized 97 participants recruited from two university-based clinical sites in Baltimore and Boston. The mean age of participants was 41.9 years, 72% were female, and 94% of participants were White. The majority of study participants had early stage disease, with a mean eGFR of 86.8±19.0 ml/min per 1.73 m². Approximately half of the study participants (48%) were classified as high risk for progression (Mayo imaging classes 1C, 1D, or 1E). There was no correlation between kidney and/or liver size and health-related quality of life (HRQoL) or gastrointestinal symptom severity.

Conclusions

We report successful recruitment in this ongoing, novel, clinical trial of metformin in ADPKD, with a study sample comprising patients with early stage disease and nearly a half of participants considered at high estimated risk for progression. Participants reported a low gastrointestinal symptom burden at baseline, and HRQoL similar to that of the general population, with no differences in symptoms or HRQoL related to organomegaly.

Clinical Trial registry name and registration number

Metformin as a Novel Therapy for Autosomal Dominant Polycystic Kidney Disease (TAME), NCT02656017.

Multidisciplinary Medication Therapy Management and Hospital Readmission in Patients Undergoing Maintenance Dialysis: A Retrospective Cohort Study

RATIONALE & OBJECTIVES

Dialysis patients frequently experience medication-related problems. We studied the association of a multidisciplinary medication therapy management (MTM) with 30-day readmission rates.

STUDY DESIGN

Retrospective cohort study.

SETTING & PARTICIPANTS

Maintenance dialysis patients discharged home from acute-care hospitals between May 2016 and April 2017 who returned to End-Stage Renal Disease Seamless Care Organization dialysis clinics after discharge were eligible. Patients who were readmitted within 3 days, died, or entered hospice within 30 days were excluded.

EXPOSURE

MTM consisting of nurse medication reconciliation, pharmacist medication review, and nephrologist oversight was categorized into 3 levels of intensity: no MTM, partial MTM (defined as an incomplete MTM process), or full MTM (defined as a complete MTM process).

OUTCOME

The primary outcome was 30-day readmission.

ANALYTICAL APPROACH

Time-varying Prentice, Williams, and Peterson total time hazards models explored associations between MTM and time to readmission after adjusting for age, race, sex, diabetes comorbidity, albumin level, vascular access type, kidney failure cause, dialysis vintage and modality, marital status, home medications, frequent prior hospitalizations, length of stay, discharge diagnoses, hierarchical condition category, and facility standardized hospitalization rates. Propensity score matching was performed to examine the robustness of the associations in a comparison between the full- and no-MTM exposure groups on time to readmission.

RESULTS

Among 1,452 discharges, 586 received no MTM, 704 received partial MTM, and 162 received full MTM; 30-day readmission rates were 29%, 19%, and 11%, respectively (P < 0.001). Compared with no MTM, discharges with full MTM had the lowest time-varying risk for readmission within 30 days (HR, 0.26; 95% CI, 0.15-0.45); discharges with partial MTM also had lower readmission risk (HR, 0.50; 95% CI, 0.37-0.68). In propensity score-matched sensitivity analysis, full MTM was associated with lower 30-day readmission risk (HR, 0.20; 95% CI, 0.06-0.69).

LIMITATIONS

Reliance on observational data. Residual bias and confounding.

CONCLUSIONS

MTM services following hospital discharge were associated with fewer 30-day readmissions in dialysis patients. Randomized controlled studies evaluating different MTM delivery models and cost-effectiveness in dialysis populations are warranted.

Transfers to Hemodialysis Among US Patients Initiating Renal Replacement Therapy With Peritoneal Dialysis

RATIONALE & OBJECTIVE

Identifying patients who are likely to transfer from peritoneal dialysis (PD) to hemodialysis (HD) before transition could improve their subsequent care. This study developed a prediction tool for transition from PD to HD.

STUDY DESIGN

Retrospective cohort study.

SETTING & PARTICIPANTS

Adults initiating PD between January 2008 and December 2011, followed up through June 2015, for whom data were available in the US Renal Data System (USRDS).

PREDICTORS

Clinical characteristics at PD initiation and peritonitis claims.

OUTCOMES

Transfer to HD, with the competing outcomes of death and kidney transplantation.

ANALYTICAL APPROACH

Outcomes were ascertained from USRDS treatment history files. Subdistribution hazards (competing-risk) models were fit using clinical characteristics at PD initiation. A nomogram was developed to classify patient risk at 1, 2, 3, and 4 years. These data were used to generate quartiles of HD transfer risk; this quartile score was incorporated into a cause-specific hazards model that additionally included a time-dependent variable for peritonitis.

RESULTS

29,573 incident PD patients were followed up for a median of 21.6 (interquartile range, 9.0-42.3) months, during which 41.2% transferred to HD, 25.9% died, 17.1% underwent kidney transplantation, and the rest were followed up to the study end in June 2015. Claims for peritonitis were present in 11,733 (40.2%) patients. The proportion of patients still receiving PD decreased to <50% at 22.6 months and 14.2% at 5 years. Peritonitis was associated with a higher rate of HD transfer (HR, 1.82; 95% CI, 1.76-1.89; P < 0.001), as were higher quartile scores of HD transfer risk (HRs of 1.31 [95% CI, 1.25-1.37), 1.51 [95% CI, 1.45-1.58], and 1.78 [95% CI, 1.71-1.86] for quartiles 2, 3, and 4 compared to quartile 1 [P < 0.001 for all]).

LIMITATIONS

Observational data, reliant on the Medical Evidence Report and Medicare claims.

CONCLUSIONS

A large majority of the patients who initiated renal replacement therapy with PD discontinued this modality within 5 years. Transfer to HD was the most common outcome. Patient characteristics and comorbid diseases influenced the probability of HD transfer, death, and transplantation, as did episodes of peritonitis.

The TiME Trial: A Fully Embedded, Cluster-Randomized, Pragmatic Trial of Hemodialysis Session Duration

BACKGROUND

Data from clinical trials to inform practice in maintenance hemodialysis are limited. Incorporating randomized trials into dialysis clinical care delivery should help generate practice-guiding evidence, but the feasibility of this approach has not been established.

METHODS

To develop approaches for embedding trials into routine delivery of maintenance hemodialysis, we performed a cluster-randomized, pragmatic trial demonstration project, the Time to Reduce Mortality in ESRD (TiME) trial, evaluating effects of session duration on mortality (primary outcome) and hospitalization rate. Dialysis facilities randomized to the intervention adopted a default session duration ≥4.25 hours (255 minutes) for incident patients; those randomized to usual care had no trial-driven approach to session duration. Implementation was highly centralized, with no on-site research personnel and complete reliance on clinically acquired data. We used multiple strategies to engage facility personnel and participating patients.

RESULTS

The trial enrolled 7035 incident patients from 266 dialysis units. We discontinued the trial at a median follow-up of 1.1 years because of an inadequate between-group difference in session duration. For the primary analysis population (participants with estimated body water ≤42.5 L), mean session duration was 216 minutes for the intervention group and 207 minutes for the usual care group. We found no reduction in mortality or hospitalization rate for the intervention versus usual care.

CONCLUSIONS

Although a highly pragmatic design allowed efficient enrollment, data acquisition, and monitoring, intervention uptake was insufficient to determine whether longer hemodialysis sessions improve outcomes. More effective strategies for engaging clinical personnel and patients are likely required to evaluate clinical trial interventions that are fully embedded in care delivery.

High-Dose Seasonal Influenza Vaccine in Patients Undergoing Dialysis

BACKGROUND AND OBJECTIVES

High-dose influenza vaccine, which contains fourfold more antigen than standard dose, is associated with fewer cases of influenza and less influenza-related morbidity in the elderly general population. Whether the high-dose influenza vaccine benefits patients on dialysis, whose immune response to vaccination is less robust than that of healthy patients, is uncertain.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We compared hospitalizations and deaths during the 2015-2016 and 2016-2017 influenza seasons by vaccine type (standard trivalent, standard quadrivalent, and high-dose trivalent influenza vaccine) administered within a national dialysis organization. The association of vaccine type with outcomes was estimated using Cox proportional hazards regression with adjustment for patient factors and "center effect." Analyses were stratified by age and dialysis modality.

RESULTS

Between September 1 and December 31, 2015, standard dose trivalent, standard dose quadrivalent, and high-dose trivalent influenza vaccines were administered to 3057 (31%), 5981 (61%), and 805 (8%) patients, respectively. The adjusted rates of first hospitalizations by vaccine type during the influenza season were 8.43, 7.88, and 7.99 per 100 patient-months, respectively, and the adjusted rates of death were 1.00, 0.97, and 1.04, respectively. These differences were not significant. In 2016, 3614 (39%) received quadrivalent vaccine, and 5700 (61%) received high-dose trivalent vaccine. The adjusted rates of first hospitalization by vaccine type were 8.71 and 8.04 per 100 patient-months, respectively, and the adjusted rates of death were 0.98 and 1.02, respectively. Receipt of high dose was associated with a significant reduction in hospitalization (hazard ratio, 0.93; 95% confidence interval, 0.86 to 1.00; P=0.04); there was no significant association with death. There was no significant heterogeneity of either association by age group or dialysis modality.

CONCLUSIONS

Receipt of high-dose compared with standard dose influenza vaccine in 2016-2017 was associated with lower rates of hospitalization in patients on dialysis, although that was not seen in 2015-2016.

Evaluation of non-response to the In-Center Hemodialysis Consumer Assessment of Healthcare Providers and Systems (ICH CAHPS) survey

Background

The In-Center Hemodialysis Consumer Assessment of Healthcare Providers and Systems (ICH CAHPS) Survey is the first patient reported outcome measure included in the U.S. Medicare End Stage Renal Disease Quality Incentive Program. Administered twice yearly, it assesses in-center dialysis experience and survey responses are tied to dialysis facility payments. Low response rates, currently approximately 35%, raise concern for possible underrepresentation of patient groups.

Methods

Cross-sectional analysis of survey administration in 2012 to all in-center hemodialysis patients in Dialysis Clinic, Inc. (DCI) facilities nationally over 18 years old who received hemodialysis at their facility for at least 3 months. Patient-level covariates included demographic, clinical, laboratory, and functional characteristics. Random effects multivariable logistic regression was used to assess survey non-response.

Results

Among 11,055 eligible patients 6541 (59%) were non-responders. Of the remaining 4514 responders, 549 (14%) surveys were not usable due to presence of proxy help or incomplete responses. Non-responders were more likely to be men, non-white, younger, single, dual Medicare/Medicaid eligible, less educated, non-English speaking, and not active on the transplant list; non-responders had longer ESRD vintage, lower body mass index, lower serum albumin, worse functional status, and more hospitalizations, missed treatments, and shortened treatments. Similar associations were found using more parsimonious multivariable analyses and after imputing missing data.

Conclusions

Non-responders to the ICH CAHPS significantly differed from responders, broadly spanning individuals with fewer socioeconomic advantages and greater illness burden, raising limitations in interpreting facility survey results. Future research should assess reasons for non-response to improve ICH CAHPS generalizability and utility.

Electronic supplementary material

The online version of this article (10.1186/s12913-018-3618-4) contains supplementary material, which is available to authorized users.

A Randomized Clinical Trial of Metformin to Treat Autosomal Dominant Polycystic Kidney Disease

BACKGROUND

Metformin inhibits cyclic AMP generation and activates AMP-activated protein kinase (AMPK), which inhibits the cystic fibrosis transmembrane conductance regulator and Mammalian Target of Rapamycin pathways. Together these effects may reduce cyst growth in autosomal dominant polycystic kidney disease (ADPKD).

METHODS

A phase II, double-blinded randomized placebo-controlled trial of 26 months duration. Participants will include nondiabetic adults (n = 96) aged 18-60 years, with an estimated glomerular filtration rate (eGFR) ≥50 mL/min/1.73 m2 and ADPKD, recruited from university-based practices in Baltimore and Boston. Participants will be randomized in 1: 1 ratio to metformin or placebo at 500 mg once daily, increased every 2 weeks to a maximum of 1,000 mg twice daily as tolerated. Dose is decreased if eGFR falls to 30-45 mL/min/1.73 m2 and discontinued at eGFR < 30 mL/min/1.73 m2.

RESULTS

The primary outcomes are safety, assessed by the rates of hypoglycemia, elevated lactic acid levels, adverse events, and tolerability assessed by the Gastrointestinal Severity Rating Scale and maximum tolerated dose of study medication. Secondary outcomes include changes in total kidney and liver volumes, pain, and health-related quality of life, and changes in urinary metabolomic biomarkers.

CONCLUSIONS

Results of this trial will provide important information on the feasibility, safety, and tolerability of long-term use of metformin in patients with -ADPKD and provide preliminary information regarding its efficacy in slowing disease progression. Furthermore, results may support or refute the hypothesis that metformin effects on disease progression are mediated through the activation of the AMPK pathway. These results will be essential for the justification and design of a full-scale efficacy trial.

Longitudinal Assessment of Left Ventricular Mass in Autosomal Dominant Polycystic Kidney Disease

Introduction

The high burden of cardiovascular morbidity and mortality in autosomal dominant polycystic kidney disease (ADPKD) is related to development of hypertension and left ventricular hypertrophy. Blood pressure reduction has been shown to reduce left ventricular mass in ADPKD; however, moderators and predictors of response to lower blood pressure are unknown.

Methods

This was a post hoc cohort analysis of HALT PKD study A, a randomized placebo controlled trial examining the effect of low blood pressure and single versus dual renin−angiotensin blockade in early ADPKD. Participants were hypertensive ADPKD patients 15 to 49 years of age with estimated glomerular filtration rate (eGFR) > 60 ml/min per 1.73 m² across 7 centers in the United States. Predictors included age, sex, baseline eGFR, systolic blood pressure, total kidney volume, serum potassium, and urine sodium, potassium, albumin, and aldosterone. Outcome was left ventricular mass index (LVMI) measured using 1.5-T magnetic resonance imaging at months 0, 24, 48, and 60.

Results

Reduction in LVMI was associated with higher baseline systolic blood pressure and larger kidney volume regardless of blood pressure control group assignment (P < 0.001 for both). Male sex and baseline eGFR were associated with a positive annual slope in LVMI (P < 0.001 and P = 0.07, respectively).

Conclusion

Characteristics associated with higher risk of progression in ADPKD, including higher systolic blood pressure, larger kidney volume, and lower eGFR are associated with improvement in LVMI with intensive blood pressure control, whereas male sex is associated with a smaller slope of reduction in LVMI.

Patterns of Kidney Function Decline in Autosomal Dominant Polycystic Kidney Disease: A Post Hoc Analysis From the HALT-PKD Trials

BACKGROUND

Previous clinical studies of autosomal dominant polycystic kidney disease (ADPKD) reported that loss of kidney function usually follows a steep and relentless course. A detailed examination of individual patterns of decline in estimated glomerular filtration rate (eGFR) has not been performed.

STUDY DESIGN

Longitudinal post hoc analysis of data collected during the Halt Progression of Polycystic Kidney Disease (HALT-PKD) trials.

SETTING & PARTICIPANTS

494 HALT-PKD Study A participants (younger; preserved eGFR) and 435 Study B participants (older; reduced eGFR) who had more than 3 years of follow-up and 7 or more eGFR assessments.

MEASUREMENTS

Longitudinal eGFR assessments using the CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) creatinine equation.

PREDICTORS

Demographic, clinical, laboratory, and imaging features of participants.

OUTCOMES

Probability of linear and nonlinear decline patterns or of stable eGFR calculated for each participant from a Bayesian model of individual eGFR trajectories.

RESULTS

Most (62.5% in Study A and 81% in Study B) participants had a linear decline in eGFR during up to 8 years of follow-up. A proportion (22% in Study A and 13% in Study B) of progressors had a nonlinear pattern. 15.5% of participants in Study A and 6% in Study B had a prolonged (≥4.5 years) period of stable eGFRs. These individuals (Study A) had significantly smaller total kidney volumes, higher renal blood flows, lower urinary albumin excretion, and lower body mass index at baseline and study end. In Study B, participants with reduced but stable eGFRs were older than the progressors. Two-thirds of nonprogressors in both studies had PKD1 mutations, with enrichment for weak nontruncating mutations.

LIMITATIONS

Relatively short follow-up of a clinical trial population.

CONCLUSIONS

Although many individuals with ADPKD have a linear decline in eGFR, prolonged intervals of stable GFRs occur in a substantial fraction. Lower body mass index was associated with more stable kidney function in early ADPKD.

BP in Dialysis: Results of a Pilot Study

The optimal BP target for patients receiving hemodialysis is unknown. We randomized 126 hypertensive patients on hemodialysis to a standardized predialysis systolic BP of 110-140 mmHg (intensive arm) or 155-165 mmHg (standard arm). The primary objectives were to assess feasibility and safety and inform the design of a full-scale trial. A secondary objective was to assess changes in left ventricular mass. Median follow-up was 365 days. In the standard arm, the 2-week moving average systolic BP did not change significantly during the intervention period, but in the intensive arm, systolic BP decreased from 160 mmHg at baseline to 143 mmHg at 4.5 months. From months 4-12, the mean separation in systolic BP between arms was 12.9 mmHg. Four deaths occurred in the intensive arm and one death occurred in the standard arm. The incidence rate ratios for the intensive compared with the standard arm (95% confidence intervals) were 1.18 (0.40 to 3.33), 1.61 (0.87 to 2.97), and 3.09 (0.96 to 8.78) for major adverse cardiovascular events, hospitalizations, and vascular access thrombosis, respectively. The intensive and standard arms had similar median changes (95% confidence intervals) in left ventricular mass of -0.84 (-17.1 to 10.0) g and 1.4 (-11.6 to 10.4) g, respectively. Although we identified a possible safety signal, the small size and short duration of the trial prevent definitive conclusions. Considering the high risk for major adverse cardiovascular events in patients receiving hemodialysis, a full-scale trial is needed to assess potential benefits of intensive hypertension control in this population.

Intravenous iron administration strategies and anemia management in hemodialysis patients

Background

The effect of maintenance intravenous (IV) iron administration on subsequent achievement of anemia management goals and mortality among patients recently initiating hemodialysis is unclear.

Methods

We performed an observational cohort study, in adult incident dialysis patients starting on hemodialysis. We defined IV administration strategies over a 12-week period following a patient's initiation of hemodialysis; all those receiving IV iron at regular intervals were considered maintenance, and all others were considered non-maintenance. We used multivariable models adjusting for demographics, clinical and treatment parameters, iron dose, measures of iron stores and pro-infectious and pro-inflammatory parameters to compare these strategies. The outcomes under study were patients' (i) achievement of hemoglobin (Hb) of 10-12 g/dL, (ii) more than 25% reduction in mean weekly erythropoietin stimulating agent (ESA) dose and (iii) mortality, ascertained over a period of 4 weeks following the iron administration period.

Results

Maintenance IV iron was administered to 4511 patients and non-maintenance iron to 8458 patients. Maintenance IV iron administration was not associated with a higher likelihood of achieving an Hb between 10 and 12 g/dL {adjusted odds ratio (OR) 1.01 [95% confidence interval (CI) 0.93-1.09]} compared with non-maintenance, but was associated with a higher odds of achieving a reduced ESA dose of 25% or more [OR 1.33 (95% CI 1.18-1.49)] and lower mortality [hazard ratio (HR) 0.73 (95% CI 0.62-0.86)].

Conclusions

Maintenance IV iron strategies were associated with reduced ESA utilization and improved early survival but not with the achievement of Hb targets.

Antihypertensive medications and risk of death and hospitalizations in US hemodialysis patients: Evidence from a cohort study to inform hypertension treatment practices

Antihypertensive medications are commonly prescribed to hemodialysis patients but the optimal regimens to prevent morbidity and mortality are unknown. The goal of our study was to compare the association of routinely prescribed antihypertensive regimens with outcomes in US hemodialysis patients.We used 2 datasets for our analysis. Our primary cohort (US Renal Data System [USRDS]) included adult patients initiating in-center hemodialysis from July 1, 2006 to June 30, 2008 (n = 33,005) with follow-up through December 31, 2009. Our secondary cohort included adult patients from Dialysis Clinic, Inc. (DCI), a national not-for-profit dialysis provider, initiating in-center hemodialysis from January 1, 2003 to June 30, 2008 (n = 11,291) with follow-up through December 31, 2008. We linked the USRDS cohort with Medicare part D prescriptions-fill data and the DCI cohort with USRDS data. Unique aspect of USRDS cohort was pharmacy prescription-fill data and for DCI cohort was detailed clinical data, including blood pressure, weight, and ultrafiltration. We classified prescribed antihypertensives into the following mutually exclusive regimens: β-blockers, renin-angiotensin system blocking drugs-containing regimens without a β-blocker (RAS), β-blocker + RAS, and others. We used marginal structural models accounting for time-updated comorbidities to quantify each regimen's association with mortality (both cohorts) and cardiovascular hospitalization (DCI-Medicare Subcohort).In the USRDS and DCI cohorts there were 9655 (29%) and 3200 (28%) deaths, respectively. In both cohorts, RAS compared to β-blockers regimens were associated with lower risk of death; (hazard ratio [HR]) (95% confidence interval [CI]) for all-cause mortality, (0.90 [0.82-0.97] in USRDS and 0.87 [0.76-0.98] in DCI) and cardiovascular mortality (0.84 [0.75-0.95] in USRDS and 0.88 [0.71-1.07] in DCI). There was no association between antihypertensive regimens and the risk of cardiovascular hospitalizations.In hemodialysis patients undergoing routine care, renin-angiotensin system blocking drugs-containing regimens were associated with a lower risk of death compared with β-blockers-containing regimens but there was no association with cardiovascular hospitalizations. Pragmatic clinical trials are needed to specifically examine the effectiveness of these commonly used antihypertensive regimens in dialysis patients.

Total Kidney Volume Is a Prognostic Biomarker of Renal Function Decline and Progression to End-Stage Renal Disease in Patients With Autosomal Dominant Polycystic Kidney Disease

Introduction

Autosomal dominant polycystic kidney disease is the most common hereditary kidney disease. TKV is a promising imaging biomarker for tracking and predicting the natural history of autosomal dominant polycystic kidney disease. The prognostic value of TKV was evaluated, in combination with age and eGFR, for the outcomes of 30% decline in eGFR and progression to ESRD. Observational data including 2355 patients with TKV measurements were available.

Methods

Multivariable Cox models were developed to assess the prognostic value of age, TKV, height-adjusted TKV, eGFR, sex, race, and genotype for the probability of a 30% decline in eGFR or ESRD.

Results

TKV was the most important prognostic term for 30% decline in eGFR in autosomal dominant polycystic kidney disease patients with and without preserved baseline eGFR. For a 40-year-old subject with preserved eGFR (70 ml/min per 1.73 m²), the adjusted hazard ratios for a 30% decline in eGFR were 1.86 (95% CI, 1.65-2.10) for a 2-fold larger TKV (600 vs. 1200 ml) and 2.68 (95% CI, 2.22-3.24) for a 3-fold larger TKV (600 vs. 1800 ml), respectively. Hazard ratios for progression to ESRD for 2- and 3-fold larger TKV were 1.72 (95% CI, 1.49-1.99) and 2.36 (95% CI, 1.88-2.97), respectively.

Discussion

The capability to predict 30% decline in eGFR is a novel aspect of this study. TKV was formally qualified, both by FDA and EMA, as a prognostic enrichment biomarker for selecting patients at high risk for a progressive decline in renal function for inclusion in interventional clinical trials.

Vascular imaging for hemodialysis vascular access planning

INTRODUCTION

Central venous catheters (CVC) increase risks associated with hemodialysis (HD), but may be necessary until an arteriovenous fistula (AVF) or graft (AVG) is achieved. The impact of vascular imaging on achievement of working AVF and AVG has not been firmly established.

METHODS

Retrospective cohort of patients initiating HD with CVC in 2010-2011, classified by exposure to venography or Doppler vein mapping, and followed through December 31, 2012. Standard and time-dependent Cox models were used to determine hazard ratios (HRs) of death, working AVF, and any AVF or AVG. Logistic regression was used to assess the association of preoperative imaging with successful AVF or AVG among 18,883 individuals who had surgery. Models were adjusted for clinical and demographic factors.

FINDINGS

Among 33,918 patients followed for a median of 404 days, 39.1% had imaging and 55.7% had surgery. Working AVF or AVG were achieved in 40.6%; 46.2% died. Compared to nonimaged patients, imaged patients were more likely to achieve working AVF (HR = 1.45 [95% confidence interval [CI] 1.36, 1.55], P < 0.001]), any AVF or AVG (HR = 1.63 [1.58, 1.69], P > 0.001), and less likely to die (HR = 0.88 [0.83-0.94], P < 0.001). Among patients who had surgery, the odds ratio for any successful AVF or AVG was 1.09 (1.02-1.16, P = 0.008).

DISCUSSION

Fewer than half of patients who initiated HD with a CVC had vascular imaging. Imaged patients were more likely to have vascular surgery and had increased achievement of working AV fistulas and grafts. Outcomes of surgery were similar in patients who did and did not have imaging.

Peripherally Inserted Central Catheters and Hemodialysis Outcomes

BACKGROUND AND OBJECTIVES

Use of peripherally inserted central catheters has expanded rapidly, but the consequences for patients who eventually require hemodialysis are undefined.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Our national, population-based analysis included 33,918 adult Medicare beneficiaries from the US Renal Data System who initiated hemodialysis with central venous catheters as their sole vascular access in 2010 and 2011. We used linked Medicare claims to identify peripherally inserted central catheter exposures and evaluate the associations of peripherally inserted central catheter placement with transition to working arteriovenous fistulas or grafts and patient survival using a Cox model with time-dependent variables.

RESULTS

Among 33,918 individuals initiating hemodialysis with a catheter as sole access, 12.6% had received at least one peripherally inserted central catheter. Median follow-up was 404 days (interquartile range, 103-680 days). Among 6487 peripherally inserted central catheters placed, 3435 (53%) were placed within the 2 years before hemodialysis initiation, and 3052 (47%) were placed afterward. Multiple peripherally inserted central catheters were placed in 30% of patients exposed to peripherally inserted central catheters. Recipients of peripherally inserted central catheters were more likely to be women and have comorbid diagnoses and less likely to have received predialysis nephrology care. After adjustment for clinical and demographic factors, peripherally inserted central catheters placed before or after hemodialysis initiation were independently associated with lower likelihoods of transition to any working fistula or graft (hazard ratio for prehemodialysis peripherally inserted central catheter, 0.85; 95% confidence interval, 0.79 to 0.91; hazard ratio for posthemodialysis peripherally inserted central catheter, 0.81; 95% confidence interval, 0.73 to 0.89).

CONCLUSIONS

Peripherally inserted central catheter placement was common and associated with adverse vascular access outcomes. Recognition of potential long-term adverse consequences of peripherally inserted central catheters is essential for clinicians caring for patients with CKD.

Comparison of Prescribed and Measured Dialysate Sodium: A Quality Improvement Project

BACKGROUND

There is controversy regarding the optimal dialysate sodium concentration for hemodialysis patients. Dialysate sodium concentrations of 134 to 138 mEq/L may decrease interdialytic weight gain and improve hypertension control, whereas a higher dialysate sodium concentration may offer protection to patients with low serum sodium concentrations and hypotension. We conducted a quality improvement project to explore the hypothesis that prescribed and delivered dialysate sodium concentrations may differ significantly.

STUDY DESIGN

Cross-sectional quality improvement project.

SETTING & PARTICIPANTS

333 hemodialysis treatments in 4 facilities operated by Dialysis Clinic, Inc.

QUALITY IMPROVEMENT PLAN

Measure dialysate sodium to assess the relationships of prescribed and measured dialysate sodium concentrations.

OUTCOMES

Magnitude of differences between prescribed and measured dialysate sodium concentrations.

MEASUREMENTS

Dialysate sodium measured pre- and late dialysis.

RESULTS

The least square mean of the difference between prescribed minus measured dialysate sodium concentration was -2.48 (95% CI, -2.87 to -2.10) mEq/L. Clinics with a greater number of different dialysate sodium prescriptions (clinic 1, n=8; clinic 2, n=7) and that mixed dialysate concentrates on site had greater differences between prescribed and measured dialysate sodium concentrations. Overall, 57% of measured dialysate sodium concentrations were within ±2 mEq/L of the prescribed dialysate sodium concentration. Differences were greater at higher prescribed dialysate sodium concentrations.

LIMITATIONS

We only studied 4 facilities and dialysate delivery machines from 2 manufacturers. Because clinics using premixed dialysate used the same type of machine, we were unable to independently assess the impact of these factors. Pressures in dialysate delivery loops were not measured.

CONCLUSIONS

There were significant differences between prescribed and measured dialysate sodium concentrations. This may have beneficial or deleterious effects on clinical outcomes, as well as confound results from studies assessing the relationships of dialysate sodium concentrations to outcomes. Additional studies are needed to identify factors that contribute to differences between prescribed and measured dialysate sodium concentrations. Quality assurance and performance improvement (QAPI) programs should include measurements of dialysate sodium.

Ergocalciferol Supplementation in Hemodialysis Patients With Vitamin D Deficiency: A Randomized Clinical Trial

Locally produced 1,25-dihydroxyvitamin D3 may have pleiotropic effects outside of bone. Experimental and observational studies suggest that nutritional vitamin D may enhance erythropoiesis in settings of 25-hydroxy vitamin D (25(OH)D) deficiency. We conducted a double-blind, placebo-controlled, randomized clinical trial to assess the effects of supplementation with ergocalciferol on epoetin utilization and other secondary outcomes in patients on hemodialysis with serum 25(OH)D <30 ng/ml. In all, 276 patients were randomized to 6 months of ergocalciferol or placebo. Mean±SD serum 25(OH)D increased from 16.0±5.9 ng/ml at baseline to 39.2±14.9 ng/ml in the ergocalciferol arm and did not change (16.9±6.4 ng/ml and 17.5±7.4 ng/ml, respectively) in the placebo arm. There was no significant change in epoetin dose over 6 months in the ergocalciferol or placebo arms (geometric mean rate 0.98 [95% confidence interval (95% CI), 0.94 to 1.02] versus 0.99 [95% CI, 0.95 to 1.03], respectively) and no difference across arms (P=0.78). No change occurred in serum calcium, phosphorus, intact parathyroid hormone, or C-reactive protein levels, cinacalcet use, or phosphate binder or calcitriol dose in either study arm. Rates of all-cause, cardiovascular, and infection-related hospitalizations did not differ by study arm, although statistical power was limited for these outcomes. In conclusion, 6 months of supplementation with ergocalciferol increased serum 25(OH)D levels in patients on hemodialysis with vitamin D insufficiency or deficiency, but had no effect on epoetin utilization or secondary biochemical and clinical outcomes.

Closeout of the HALT-PKD trials

BACKGROUND

The HALT Polycystic Kidney Disease Trials Network consisted of two randomized, double blind, placebo-controlled trials among patients with autosomal dominant polycystic kidney disease. The trials involved 5-8years of participant follow-up with interventions in blood pressure and antihypertensive therapy. We provide a framework for designing and implementing closeout near the end of a trial while ensuring patient safety and maintaining scientific rigor and study morale.

METHODS

We discuss issues and resolutions for determining the last visit, tapering medications, and unblinding of participants to study allocation and results. We also discuss closure of clinical sites and Data Coordinating Center responsibilities to ensure timely release of study results and meeting the requirements of regulatory and funding authorities.

RESULTS

Just over 90% of full participants had a 6-month study visit prior to their last visit preparing them for trial closeout. Nearly all patients wanted notification of study results (99%) and treatment allocation (99%). All participants were safely tapered off study and open label blood pressure medications. Within 6months, the trials were closed, primary papers published, and 805 letters distributed to participants with results and allocation. DCC obligations for data repository and clinicaltrials.gov reporting were completed within 12months of the last study visit.

CONCLUSIONS

Closeout of our trials involved years of planning and significant human and financial resources. We provide questions for investigators to consider when planning closeout of their trials with focus on (1) patient safety, (2) dissemination of study results and (3) compliance with regulatory and funding responsibilities.

Satisfaction with Care of Patients on Hemodialysis

BACKGROUND AND OBJECTIVES

Little is known about patients receiving dialysis who respond to satisfaction and experience of care surveys and those who do not respond, nor is much known about the corollaries of satisfaction. This study examined factors predicting response to Dialysis Clinic, Inc. (DCI)'s patient satisfaction survey and factors associated with higher satisfaction among responders.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENT

A total of 10,628 patients receiving in-center hemodialysis care at 201 DCI facilities between January 1, 2011, and December 31, 2011, aged ≥18 years, treated during the survey administration window, and at the facility for ≥3 months before survey administration. Primary outcome was response to at least one of the nine survey questions; secondary outcome was overall satisfaction with care.

RESULTS

Response rate was 77.3%. In adjusted logistic regression (odds ratios with 95% confidence intervals), race other than black (white race, 1.23 [1.10 to 1.37]), missed treatments (1.16 [1.02 to 1.32]) or shortened treatments (≥5 treatments, 1.40 [1.22 to 1.60]), more hospital days (>3 days in the last 3 months, 1.89 [1.66 to 2.15]), and lower serum albumin (albumin level <3.5 g/dl, 1.4 [1.28 to 1.73]) all independently predicted nonresponse. In adjusted linear regression, the following were more satisfied with care: older patients (age ≥63 years, 1.84 [1.78 to 1.90]; age <63 years, 1.91 [1.86 to 1.97]; P<0.001), white patients (1.76 [1.71 to 1.81]) versus black patients (1.93 [1.88 to 1.99]) or those of other race (1.93 [1.83 to 2.03]) (P<0.001), patients with shorter duration of dialysis (≤2.5 years, 1.79 [1.73 to 1.84]; >2.5 years, 1.96 [1.91 to 2.02]; P<0.001), patients who had missed one or fewer treatments (1.83 [1.78 to 1.88]) versus those who had missed more than one treatment (1.92 [1.85 to 1.98]; P=0.002) and those who had shortened treatment (for one treatment or less, 1.84 [1.77 to 1.90]; for two to four treatments, 1.87 [1.81 to 1.93]; for five or more treatments, 1.92 [1.87 to 1.98]; P=0.004).

CONCLUSIONS

Survey results represent healthier and more adherent patients on hemodialysis. Shorter survey administration windows were associated with higher response rates. Older, white patients with shorter dialysis vintage were more satisfied.

Angiotensin blockade in late autosomal dominant polycystic kidney disease

BACKGROUND

Hypertension develops early in patients with autosomal dominant polycystic kidney disease (ADPKD) and is associated with disease progression. The renin-angiotensin-aldosterone system (RAAS) is implicated in the pathogenesis of hypertension in patients with ADPKD. Dual blockade of the RAAS may circumvent compensatory mechanisms that limit the efficacy of monotherapy with an angiotensin-converting-enzyme (ACE) inhibitor or angiotensin II-receptor blocker (ARB).

METHODS

In this double-blind, placebo-controlled trial, we randomly assigned 486 patients, 18 to 64 years of age, with ADPKD (estimated glomerular filtration rate [GFR], 25 to 60 ml per minute per 1.73 m(2) of body-surface area) to receive an ACE inhibitor (lisinopril) and placebo or lisinopril and an ARB (telmisartan), with the doses adjusted to achieve a blood pressure of 110/70 to 130/80 mm Hg. The composite primary outcome was the time to death, end-stage renal disease, or a 50% reduction from the baseline estimated GFR. Secondary outcomes included the rates of change in urinary aldosterone and albumin excretion, frequency of hospitalizations for any cause and for cardiovascular causes, incidence of pain, frequency of ADPKD-related symptoms, quality of life, and adverse study-medication effects. Patients were followed for 5 to 8 years.

RESULTS

There was no significant difference between the study groups in the incidence of the composite primary outcome (hazard ratio with lisinopril-telmisartan, 1.08; 95% confidence interval, 0.82 to 1.42). The two treatments controlled blood pressure and lowered urinary aldosterone excretion similarly. The rates of decline in the estimated GFR, urinary albumin excretion, and other secondary outcomes and adverse events, including hyperkalemia and acute kidney injury, were also similar in the two groups.

CONCLUSIONS

Monotherapy with an ACE inhibitor was associated with blood-pressure control in most patients with ADPKD and stage 3 chronic kidney disease. The addition of an ARB did not alter the decline in the estimated GFR. (Funded by the National Institute of Diabetes and Digestive and Kidney Diseases and others; HALT-PKD [Study B] ClinicalTrials.gov number, NCT01885559.).

Blood pressure in early autosomal dominant polycystic kidney disease

BACKGROUND

Hypertension is common in autosomal dominant polycystic kidney disease (ADPKD) and is associated with increased total kidney volume, activation of the renin-angiotensin-aldosterone system, and progression of kidney disease.

METHODS

In this double-blind, placebo-controlled trial, we randomly assigned 558 hypertensive participants with ADPKD (15 to 49 years of age, with an estimated glomerular filtration rate [GFR] >60 ml per minute per 1.73 m(2) of body-surface area) to either a standard blood-pressure target (120/70 to 130/80 mm Hg) or a low blood-pressure target (95/60 to 110/75 mm Hg) and to either an angiotensin-converting-enzyme inhibitor (lisinopril) plus an angiotensin-receptor blocker (telmisartan) or lisinopril plus placebo. The primary outcome was the annual percentage change in the total kidney volume.

RESULTS

The annual percentage increase in total kidney volume was significantly lower in the low-blood-pressure group than in the standard-blood-pressure group (5.6% vs. 6.6%, P=0.006), without significant differences between the lisinopril-telmisartan group and the lisinopril-placebo group. The rate of change in estimated GFR was similar in the two medication groups, with a negative slope difference in the short term in the low-blood-pressure group as compared with the standard-blood-pressure group (P<0.001) and a marginally positive slope difference in the long term (P=0.05). The left-ventricular-mass index decreased more in the low-blood-pressure group than in the standard-blood-pressure group (-1.17 vs. -0.57 g per square meter per year, P<0.001); urinary albumin excretion was reduced by 3.77% with the low-pressure target and increased by 2.43% with the standard target (P<0.001). Dizziness and light-headedness were more common in the low-blood-pressure group than in the standard-blood-pressure group (80.7% vs. 69.4%, P=0.002).

CONCLUSIONS

In early ADPKD, the combination of lisinopril and telmisartan did not significantly alter the rate of increase in total kidney volume. As compared with standard blood-pressure control, rigorous blood-pressure control was associated with a slower increase in total kidney volume, no overall change in the estimated GFR, a greater decline in the left-ventricular-mass index, and greater reduction in urinary albumin excretion. (Funded by the National Institute of Diabetes and Digestive and Kidney Diseases and others; HALT-PKD [Study A] ClinicalTrials.gov number, NCT00283686.).

Effect of intravenous iron use on hospitalizations in patients undergoing hemodialysis: a comparative effectiveness analysis from the DEcIDE-ESRD study

BACKGROUND

Intravenous iron use in hemodialysis patients has greatly increased over the last decade, despite limited studies on the safety of iron.

METHODS

We studied the association of receipt of intravenous iron with hospitalizations in an incident cohort of hemodialysis patients. We examined 9544 patients from Dialysis Clinic, Inc. (DCI). We ascertained intravenous iron use from DCI electronic medical record and USRDS data files, and hospitalizations through Medicare claims. We examined the association between iron exposure accumulated over 1-, 3- or 6-month time windows and incident hospitalizations in the follow-up period using marginal structural models accounting for time-dependent confounders. We performed sensitivity analyses including recurrent events models for multiple hospitalizations and models for combined outcome of hospitalization and death.

RESULTS

There were 22 347 hospitalizations during a median follow-up of 23 months. Higher cumulative dose of intravenous iron was not associated with all-cause, cardiovascular or infectious hospitalizations [HR 0.97 (95% CI: 0.77-1.22) for all-cause hospitalizations comparing >2100 mg versus 0-900 mg of iron over 6 months]. Findings were similar in models examining the risk of hospitalizations in 1- and 3-month windows [HR 0.88 (95% CI: 0.79-0.99) and HR 0.88 (95% CI: 0.74-1.03), respectively] or the risk of combined outcome of hospitalization and death in the 6-month window [HR 0.98 (95% CI: 0.78-1.23)].

CONCLUSIONS

Higher cumulative dose of intravenous iron may not be associated with increased risk of hospitalizations in hemodialysis patients. While clinical trials are needed, employing higher iron doses to reduce erythropoiesis-stimulating agents does not appear to increase morbidity in routine clinical care.

Intravenous iron exposure and mortality in patients on hemodialysis

BACKGROUND AND OBJECTIVES

Clinical trials assessing effects of larger cumulative iron exposure with outcomes are lacking, and observational studies have been limited by assessment of short-term exposure only and/or failure to assess cause-specific mortality. The associations between short- and long-term iron exposure on all-cause and cause-specific mortality were examined.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

The study included 14,078 United States patients on dialysis initiating dialysis between 2003 and 2008. Intravenous iron dose accumulations over 1-, 3-, and 6-month rolling windows were related to all-cause, cardiovascular, and infection-related mortality in Cox proportional hazards models that used marginal structural modeling to control for time-dependent confounding.

RESULTS

Patients in the 1-month model cohort (n=14,078) were followed a median of 19 months, during which there were 27.6% all-cause deaths, 13.5% cardiovascular deaths, and 3% infection-related deaths. A reduced risk of all-cause mortality with receipt of >150-350 (hazard ratio, 0.78; 95% confidence interval, 0.64 to 0.95) or >350 mg (hazard ratio, 0.79; 95% confidence interval, 0.62 to 0.99) intravenous iron compared with >0-150 mg over 1 month was observed. There was no relation of 1-month intravenous iron dose with cardiovascular or infection-related mortality and no relation of 3- or 6-month cumulative intravenous iron dose with all-cause or cardiovascular mortality. There was a nonstatistically significant increase in infection-related mortality with receipt of >1050 mg intravenous iron in 3 months (hazard ratio, 1.69; 95% confidence interval, 0.87 to 3.28) and >2100 mg in 6 months (hazard ratio, 1.59; 95% confidence interval, 0.73 to 3.46).

CONCLUSIONS

Among patients on incident dialysis, receipt of ≤ 1050 mg intravenous iron in 3 months or 2100 mg in 6 months was not associated with all-cause, cardiovascular, or infection-related mortality. However, nonstatistically significant findings suggested the possibility of infection-related mortality with receipt of >1050 mg in 3 months or >2100 mg in 6 months. Randomized clinical trials are needed to assess the safety of exposure to greater cumulative intravenous iron doses.

An instrumental variable approach finds no associated harm or benefit with early dialysis initiation in the United States

The estimated glomerular filtration rate (eGFR) at dialysis initiation has been rising. Observational studies suggest harm, but may be confounded by unmeasured factors. As instrumental variable methods may be less biased we performed a retrospective cohort study of 310,932 patients starting dialysis between 2006 to 2008 and registered in the United States Renal Data System in order to describe geographic variation in eGFR at dialysis initiation and determine its association with mortality. Patients were grouped into 804 health service areas by zip code. Individual eGFR at dialysis initiation averaged 10.8 ml/min/1.73m² but varied geographically. Only 11% of the variation in mean health service areas-level eGFR at dialysis initiation was accounted for by patient characteristics. We calculated demographic-adjusted mean eGFR at dialysis initiation in the health service areas using the 2006 and 2007 incident cohort as our instrument and estimated the association between individual eGFR at dialysis initiation and mortality in the 2008 incident cohort using the 2 stage residual inclusion method. Among 89,547 patients starting dialysis in 2008 with eGFR 5 to 20 ml/min/1.73m², eGFR at initiation was not associated with mortality over a median of 15.5 months [hazard ratio 1.025 per 1 ml/min/1.73m² for eGFR 5 to 14 ml/min/1.73m²; and 0.973 per 1 ml/min/1.73m² for eGFR 14 to 20 ml/min/1.73m²]. Thus, there was no associated harm or benefit from early dialysis initiation in the United States.

Comparative effectiveness of early versus conventional timing of dialysis initiation in advanced CKD

BACKGROUND

Previous observational studies examining outcomes associated with the timing of dialysis therapy initiation in the United States have often been limited by lead time and survivor bias.

STUDY DESIGN

Retrospective cohort study comparing the effectiveness of early versus later (conventional) dialysis therapy initiation in advanced chronic kidney disease (CKD). The analysis used inverse probability weighting to account for an individual's contribution to different exposure groups over time in a pooled logistic regression model. Patients contributed risk to both exposure categories (early and later initiation) until there was a clear treatment strategy (ie, dialysis therapy was initiated early or estimated glomerular filtration rate [eGFR] decreased to <10mL/min/1.73m(2)).

SETTING & PARTICIPANTS

Patients with CKD who had at least one face-to-face outpatient encounter with a Cleveland Clinic health care provider as of January 1, 2005, and at least 3 eGFRs in the range of 20-30mL/min/1.73m(2) measured at least 180 days apart.

PREDICTORS

Timing of dialysis therapy initiation as determined using model-based interpolation of eGFR trajectories over time. Timing was defined as early (interpolated eGFR at dialysis therapy initiation≥10mL/min/1.73m(2)) or later (eGFR < 10mL/min/1.73m(2)) and was time-varying.

OUTCOMES

Death from any cause occurring from the time that eGFR was equal to 20mL/min/1.73m(2) through September 15, 2009.

RESULTS

The study population consisted of 652 patients meeting inclusion criteria. Most (71.3%) of the study population did not initiate dialysis therapy during follow-up. Patients who did not initiate dialysis therapy (n=465) were older, more likely to be white, and had more favorable laboratory profiles than those who started dialysis therapy. Overall, 146 initiated dialysis early and 80 had eGFRs decrease to <10mL/min/1.73m(2). Many participants (n=426) were censored prior to attaining a clear treatment strategy and were considered undeclared. There was no statistically significant survival difference for the early compared with later initiation strategy (OR, 0.85; 95% CI, 0.65-1.11).

LIMITATIONS

Interpolated eGFR, moderate sample size, and likely unmeasured confounders.

CONCLUSIONS

In patients with advanced CKD, timing of dialysis therapy initiation was not associated with mortality when accounting for lead time bias and survivor bias.

Predialysis systolic BP variability and outcomes in hemodialysis patients

BP variability (BPV) is an important predictor of outcomes in the general population, but its association with clinical outcomes in hemodialysis patients is not clear. We identified 11,291 patients starting dialysis in 2003-2008 and followed them through December 31, 2008 (median=22 months). Predialysis systolic BPV was assessed over monthly intervals. Outcomes included factors associated with BPV, mortality (all-cause and cardiovascular), and first cardiovascular event (cardiovascular death or hospitalization). Patients' mean age was 62 years, 55% of patients were men, and 58% of patients were white. Modifiable factors associated with higher BPV included obesity, higher calcium-phosphate product levels, and lower hemoglobin concentration; factors associated with lower BPV included greater fluid removal, achievement of prescribed dry weight during dialysis, higher hemoglobin concentration, and antihypertensive regimens without β-blockers or renin-angiotensin system blocking agents. In total, 3200 deaths occurred, including 1592 cardiovascular deaths. After adjustment for demographics, comorbidities, and clinical factors, higher predialysis BPV was associated with increased risk of all-cause mortality (hazard ratio [HR], 1.18; 95% confidence interval [95% CI] per 1 SD increase in BPV, 1.13 to 1.22), cardiovascular mortality (HR, 1.18; 95% CI, 1.12 to 1.24), and first cardiovascular event (HR, 1.11; 95% CI, 1.07 to 1.15). Results were similar when BPV was categorized in tertiles and patients were stratified by baseline systolic BP. In summary, predialysis systolic BPV is an important, potentially modifiable risk factor for death and cardiovascular outcomes in incident hemodialysis patients. Studies of BP management in dialysis patients should focus on both absolute BP and BPV.

Trends in anemia management in US hemodialysis patients 2004-2010

BACKGROUND

There have been major changes in the management of anemia in US hemodialysis patients in recent years. We sought to determine the influence of clinical trial results, safety regulations, and changes in reimbursement policy on practice.

METHODS

We examined indicators of anemia management among incident and prevalent hemodialysis patients from a medium-sized dialysis provider over three time periods: (1) 2004 to 2006 (2) 2007 to 2009, and (3) 2010. Trends across the three time periods were compared using generalized estimating equations.

RESULTS

Prior to 2007, the median proportion of patients with monthly hemoglobin >12 g/dL for patients on dialysis 0 to 3, 4 to 6 and 7 to 18 months, respectively, was 42%, 55% and 46% declined to 41%, 54%, and 40% after 2007, and declined more sharply in 2010 to 34%, 41%, and 30%. Median weekly Epoeitin alpha doses over the same periods were 18,000, 12,400, and 9,100 units before 2007; remained relatively unchanged from 2007 to 2009; and decreased sharply in the patients 3-6 and 6-18 months on dialysis to 10,200 and 7,800 units, respectively in 2010. Iron doses, serum ferritin, and transferrin saturation levels increased over time with more pronounced increases in 2010.

CONCLUSION

Modest changes in anemia management occurred between 2007 and 2009, followed by more dramatic changes in 2010. Studies are needed to examine the effects of declining erythropoietin use and hemoglobin levels and increasing intravenous iron use on quality of life, transplantation rates, infection rates and survival.

Patterns in blood pressure medication use in US incident dialysis patients over the first 6 months

BACKGROUND

Several observational studies have evaluated the effect of a single exposure window with blood pressure (BP) medications on outcomes in incident dialysis patients, but whether BP medication prescription patterns remain stable or a single exposure window design is adequate to evaluate effect on outcomes is unclear.

METHODS

We described patterns of BP medication prescription over 6 months after dialysis initiation in hemodialysis and peritoneal dialysis patients, stratified by cardiovascular comorbidity, diabetes, and other patient characteristics. The cohort included 13,072 adult patients (12,159 hemodialysis, 913 peritoneal dialysis) who initiated dialysis in Dialysis Clinic, Inc., facilities January 1, 2003-June 30, 2008, and remained on the original modality for at least 6 months. We evaluated monthly patterns in BP medication prescription over 6 months and at 12 and 24 months after initiation.

RESULTS

Prescription patterns varied by dialysis modality over the first 6 months; substantial proportions of patients with prescriptions for beta-blockers, renin angiotensin system agents, and dihydropyridine calcium channel blockers in month 6 no longer had prescriptions for these medications by month 24. Prescription of specific medication classes varied by comorbidity, race/ethnicity, and age, but little by sex. The mean number of medications was 2.5 at month 6 in hemodialysis and peritoneal dialysis cohorts.

CONCLUSIONS

This study evaluates BP medication patterns in both hemodialysis and peritoneal dialysis patients over the first 6 months of dialysis. Our findings highlight the challenges of assessing comparative effectiveness of a single BP medication class in dialysis patients. Longitudinal designs should be used to account for changes in BP medication management over time, and designs that incorporate common combinations should be considered.

Health-related quality of life in patients with autosomal dominant polycystic kidney disease and CKD stages 1-4: a cross-sectional study

BACKGROUND

In people with early autosomal dominant polycystic kidney disease (ADPKD), average total kidney volume (TKV) is 3 times normal and increases by an average of 5% per year despite a seemingly normal glomerular filtration rate (GFR). We hypothesized that increased TKV would be a source of morbidity and diminished quality of life that would be worse in patients with more advanced disease.

STUDY DESIGN

Cross-sectional.

SETTING & PARTICIPANTS

1,043 patients with ADPKD, hypertension, and a baseline estimated GFR (eGFR)> 20mL/min/1.73m(2).

PREDICTORS

(1) eGFR, (2) height-adjusted TKV (htTKV) in patients with eGFR> 60mL/min/1.73m(2).

OUTCOMES

36-Item Short Form Health Survey (SF-36) and the Wisconsin Brief Pain Survey.

MEASUREMENTS

Questionnaires were self-administered. GFR was estimated from serum creatinine using the CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equation. htTKV was measured by magnetic resonance imaging.

RESULTS

Back pain was reported by 50% of patients, and 20% experienced it "often, usually, or always." In patients with early disease (eGFR> 60mL/min/1.73m(2)), there was no association between pain and htTKV, except in patients with large kidneys (htTKV> 1,000mL/m). Comparing across eGFR levels and including patients with eGFRs< 60mL/min/1.73m(2), patients with eGFRs of 20-44mL/min/1.73m(2) were significantly more likely to report that pain impacted on their daily lives and had lower SF-36 scores than patients with eGFRs of 45-60 and ≥60mL/min/1.73m(2). Symptoms relating to abdominal fullness were reported by 20% of patients and were related significantly to lower eGFRs in women, but not men.

LIMITATIONS

TKV and liver volume were not measured in patients with eGFR < 60mL/min/1.73m(2). The number of patients with eGFRs< 30mL/min/1.73m(2) is small. Causal inferences are limited by cross-sectional design.

CONCLUSIONS

Pain is a common early symptom in the course of ADPKD, although it is not related to kidney size in early disease (eGFR> 60mL/min/1.73m(2)), except in individuals with large kidneys (htTKV> 1,000 mL/m). Symptoms relating to abdominal fullness and pain are greater in patients with more advanced (eGFR, 20-45mL/min/1.73m(2)) disease and may be due to organ enlargement, especially in women. More research about the role of TKV in quality of life and outcomes of patients with ADPKD is warranted.

Predialysis health, dialysis timing, and outcomes among older United States adults

Studies of dialysis initiation timing have not accounted for predialysis clinical factors that could impact postdialysis outcomes. We examined the association of predialysis health with timing of dialysis initiation in older adult patients in the United States and contrasted morbidity and mortality outcomes among patients with early [estimated GFR (eGFR)≥10 ml/min per 1.73 m(2)] versus later (eGFR<10 ml/min per 1.73 m(2)) initiation. We included all patients from the US Renal Data System who initiated dialysis between 2006 and 2008, were ≥67 years old, and had ≥2 years of prior Medicare coverage (n=84,654). We calculated patients' propensity to initiate dialysis early and matched patients by propensity scores. Cox models were used to compare risks of mortality and hospitalization among initiation groups. The majority (58%) of patients initiated dialysis early. Early initiators were more likely to have had AKI, multiple congestive heart failure admissions, and other hospitalizations preceding initiation. Among propensity-matched patients (n=61,930), early initiation associated with greater all-cause (hazard ratio [HR], 1.11; 95% confidence interval [95% CI], 1.08 to 1.14), cardiovascular (CV; HR, 1.13; 95% CI, 1.09 to 1.17), and infectious (HR, 1.13; 95% CI, 1.06 to 1.22) mortality and greater all-cause (HR, 1.03; 95% CI, 1.01 to 1.05) and infectious (HR, 1.10; 95% CI, 1.07 to 1.13) hospitalizations. There was no difference in CV hospitalizations. Among these older adults, early dialysis initiation associates with greater mortality and hospitalizations, even after accounting for predialysis clinical factors. These findings do not support the common practice of early dialysis initiation in the United States.

Comparative effectiveness studies to improve clinical outcomes in end stage renal disease: the DEcIDE patient outcomes in end stage renal disease study

BACKGROUND

Evidence is lacking to inform providers' and patients' decisions about many common treatment strategies for patients with end stage renal disease (ESRD).

METHODS/DESIGN

The DEcIDE Patient Outcomes in ESRD Study is funded by the United States (US) Agency for Health Care Research and Quality to study the comparative effectiveness of: 1) antihypertensive therapies, 2) early versus later initiation of dialysis, and 3) intravenous iron therapies on clinical outcomes in patients with ESRD. Ongoing studies utilize four existing, nationally representative cohorts of patients with ESRD, including (1) the Choices for Healthy Outcomes in Caring for ESRD study (1041 incident dialysis patients recruited from October 1995 to June 1999 with complete outcome ascertainment through 2009), (2) the Dialysis Clinic Inc (45,124 incident dialysis patients initiating and receiving their care from 2003-2010 with complete outcome ascertainment through 2010), (3) the United States Renal Data System (333,308 incident dialysis patients from 2006-2009 with complete outcome ascertainment through 2010), and (4) the Cleveland Clinic Foundation Chronic Kidney Disease Registry (53,399 patients with chronic kidney disease with outcome ascertainment from 2005 through 2009). We ascertain patient reported outcomes (i.e., health-related quality of life), morbidity, and mortality using clinical and administrative data, and data obtained from national death indices. We use advanced statistical methods (e.g., propensity scoring and marginal structural modeling) to account for potential biases of our study designs. All data are de-identified for analyses. The conduct of studies and dissemination of findings are guided by input from Stakeholders in the ESRD community.

DISCUSSION

The DEcIDE Patient Outcomes in ESRD Study will provide needed evidence regarding the effectiveness of common treatments employed for dialysis patients. Carefully planned dissemination strategies to the ESRD community will enhance studies' impact on clinical care and patients' outcomes.

Analysis of baseline parameters in the HALT polycystic kidney disease trials

HALT PKD consists of two ongoing randomized trials with the largest cohort of systematically studied patients with autosomal dominant polycystic kidney disease to date. Study A will compare combined treatment with an angiotensin-converting inhibitor and receptor blocker to inhibitor alone and standard compared with low blood pressure targets in 558 early-stage disease patients with an eGFR over 60 ml/min per 1.73 m(2). Study B will compare inhibitor-blocker treatment to the inhibitor alone in 486 late-stage patients with eGFR 25-60 ml/min per 1.73 m(2). We used correlation and multiple regression cross-sectional analyses to determine associations of baseline parameters with total kidney, liver, or liver cyst volumes measured by MRI in Study A and eGFR in both studies. Lower eGFR and higher natural log-transformed urine albumin excretion were independently associated with a larger natural log-transformed total kidney volume adjusted for height (ln(HtTKV)). Higher body surface area was independently associated with a higher ln(HtTKV) and lower eGFR. Men had larger height-adjusted total kidney volume and smaller liver cyst volumes than women. A weak correlation was found between the ln(HtTKV) and natural log-transformed total liver volume adjusted for height or natural log liver cyst volume in women only. Women had higher urine aldosterone excretion and lower plasma potassium. Thus, our analysis (1) confirms a strong association between renal volume and functional parameters, (2) shows that gender and other factors differentially affect the development of polycystic disease in the kidney and liver, and (3) suggests an association between anthropomorphic measures reflecting prenatal and/or postnatal growth and disease severity.

Both patient and facility contribute to achieving the Centers for Medicare and Medicaid Services' pay-for-performance target for dialysis adequacy

The Centers for Medicare and Medicaid Services (CMS) designated the achieved urea reduction ratio (URR) as a pay-for-performance measure, but to what extent this measure reflects patient characteristics and adherence instead of its intent to reflect facility performance is unknown. Here, we quantified the contributions of patient case-mix and adherence to the variability in achieving URR targets across dialysis facilities. We found that 92% of 10,069 hemodialysis patients treated at 173 facilities during the last quarter of 2004 achieved the target URR ≥65%. Mixed-effect models with random intercept for dialysis facility revealed a significant facility effect: 11.5% of the variation in achievement of target URR was attributable to the facility level. Adjusting for patient case-mix reduced the proportion of variation attributable to the facility level to 6.7%. Patient gender, body surface area, dialysis access, and adherence with treatment strongly associated with achievement of the URR target. We could not identify specific facility characteristics that explained the remaining variation between facilities. These data suggest that if adherence is not a modifiable patient characteristic, providers could be unfairly penalized for caring for these patients under current CMS policy. These penalties may have unintended consequences.

Cardiac magnetic resonance assessment of left ventricular mass in autosomal dominant polycystic kidney disease

BACKGROUND AND OBJECTIVES

Autosomal dominant polycystic kidney disease (ADPKD) is associated with a substantial cardiovascular disease burden including early onset hypertension, intracranial aneurysms, and left ventricular hypertrophy (LVH). A 41% prevalence of LVH has been reported in ADPKD, using echocardiographic assessment of LV mass (LVM). The HALT PKD study was designed to assess the effect of intensive angiotensin blockade on progression of total kidney volume and LVM. Measurements of LVM were performed using cardiac magnetic resonance (MR).

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Five hundred forty-three hypertensive patients with GFR >60 ml/min per 1.73 m(2) underwent MR assessment of LVM at baseline. LVM was adjusted for body surface area and expressed as LVM index (LVMI; g/m(2)).

RESULTS

Baseline BP was 125.1 ± 14.5/79.3 ± 11.6 mmHg. Average duration of hypertension was 5.79 years. Prior use of angiotensin-converting enzyme inhibitors or angiotensin receptor blockers was present in 59.5% of patients. The prevalence of LVH assessed using nonindexed LVM (g) was 3.9% (n = 21, eight men and 13 women) and 0.93% (n = 5, one man and four women) using LVMI (g/m(2)). In exploratory analyses, the prevalence of LVH using LVM indexed to H(2.7), and the allometric index ppLVmass(HW), ranged from 0.74% to 2.23% (n = 4 to 12). Multivariate regression showed significant direct associations of LVMI with systolic BP, serum creatinine, and albuminuria; significant inverse associations with LVMI were found with age and female gender.

CONCLUSIONS

The prevalence of LVH in hypertensive ADPKD patients <50 years of age with short duration of hypertension, and prior use of angiotensin-converting enzyme inhibitors/angiotensin receptor blockers is low. Early BP intervention in ADPKD may have decreased LVH and may potentially decrease cardiovascular mortality.