CKD stage-specific utility of two equations for predicting 1-year risk of ESKD.

BACKGROUND: The Kidney Failure Risk Equation (KFRE) and Kaiser Permanente Northwest (KPNW) models have been proposed to predict progression to ESKD among adults with CKD within 2 and 5 years. We evaluated the utility of these equations to predict the 1-year risk of ESKD in a contemporary, ethnically diverse CKD population. METHODS: We conducted a retrospective cohort study of adult members of Kaiser Permanente Northern California (KPNC) with CKD Stages 3-5 from January 2008-September 2015. We ascertained the onset of ESKD through September 2016, and calculated stage-specific estimates of model discrimination and calibration for the KFRE and KPNW equations. RESULTS: We identified 108,091 eligible adults with CKD (98,757 CKD Stage 3; 8,384 CKD Stage 4; and 950 CKD Stage 5 not yet receiving kidney replacement therapy), with mean age of 75 years, 55% women, and 37% being non-white. The overall 1-year risk of ESKD was 0.8% (95%CI: 0.8-0.9%). The KFRE displayed only moderate discrimination for CKD 3 and 5 (c = 0.76) but excellent discrimination for CKD 4 (c = 0.86), with good calibration for CKD 3-4 patients but suboptimal calibration for CKD 5. Calibration by CKD stage was similar to KFRE for the KPNW equation but displayed worse calibration across CKD stages for 1-year ESKD prediction. CONCLUSIONS: In a large, ethnically diverse, community-based CKD 3-5 population, both the KFRE and KPNW equation were suboptimal in accurately predicting the 1-year risk of ESKD within CKD stage 3 and 5, but more accurate for stage 4. Our findings suggest these equations can be used in1-year prediction for CKD 4 patients, but also highlight the need for more personalized, stage-specific equations that predicted various short- and long-term adverse outcomes to better inform overall decision-making.

Dialysis therapy and mortality in older adults with heart failure and advanced chronic kidney disease: A high-dimensional propensity-matched cohort study.

BACKGROUND: Heart failure (HF) and chronic kidney disease (CKD) frequently coexist, and the combination is linked to poor outcomes, but limited data exist to guide optimal management. We evaluated the outcome of dialysis therapy in older patients with HF and advanced CKD. METHODS: We examined adults aged ≥70 years with HF and eGFR ≤20 ml/min/1.73 m2 between 2008-2012 and no prior renal replacement therapy, cancer, cirrhosis or organ transplant. We identified patients who initiated chronic dialysis through 2013 and matched patients who did not initiate dialysis on age, gender, diabetes status, being alive on dialysis initiation date, and a high-dimensional propensity score for starting dialysis. Deaths were identified through 2013. We used Cox regression to evaluate the association of chronic dialysis and all-cause death. RESULTS: Among 348 adults with HF and advanced CKD who initiated dialysis and 947 matched patients who did not start dialysis, mean age was 80±5 years, 51% were women and 33% were Black. The crude rate of death was high overall but lower in those initiating vs. not initiating chronic dialysis (26.1 vs. 32.1 per 100 person-years, respectively, P = 0.02). In multivariable analysis, dialysis was associated with a 33% (95% Confidence Interval:17-46%) lower adjusted rate of death compared with not initiating dialysis. CONCLUSIONS: Among older adults with HF and advanced CKD, dialysis initiation was associated with lower mortality, but absolute rates of death were very high in both groups. Randomized trials should evaluate net outcomes of dialysis vs. conservative management on length and quality of life in this high-risk population.

Timing of AKI after urgent percutaneous coronary intervention and clinical outcomes: a high-dimensional propensity score analysis.

INTRODUCTION: Acute kidney injury is a common complication of percutaneous coronary intervention and has been associated with an increased risk of death and progressive chronic kidney disease. However, whether the timing of acute kidney injury after urgent percutaneous coronary intervention could be used to improve patient risk stratification is not known. METHODS: We conducted a retrospective cohort study in adults surviving an urgent percutaneous coronary intervention between 2008 and 2013 within Kaiser Permanente Northern California, a large integrated healthcare delivery system, to evaluate the impact of acute kidney injury during hospitalization at 12 (±6), 24 (±6) and 48 (±6) hours after urgent percutaneous coronary intervention and subsequent risks of adverse outcomes within the first year after discharge. We used multivariable Cox proportional hazards models with adjustment for a high-dimensional propensity score for developing acute kidney injury after percutaneous coronary intervention to examine the associations between acute kidney injury timing and all-cause death and worsening chronic kidney disease. RESULTS: Among 7250 eligible adults undergoing urgent percutaneous coronary intervention, 306 (4.2%) had acute kidney injury at one or more of the examined time periods after percutaneous coronary intervention. After adjustment, acute kidney injury at 12 (±6) hours was independently associated with higher risks of death (adjusted hazard ratio [aHR] 3.55, 95% confidence interval [CI] 2.19-5.75) and worsening kidney function (aHR 2.40, 95% CI:1.24-4.63). Similar results were observed for acute kidney injury at 24 (±6) hours and death (aHR 3.90, 95% CI:2.29-6.66) and worsening chronic kidney disease (aHR 4.77, 95% CI:2.46-9.23). Acute kidney injury at 48 (±6) hours was associated with excess mortality (aHR 1.97, 95% CI:1.19-3.26) but was not significantly associated with worsening kidney function (aHR 0.91, 95% CI:0.42-1.98). CONCLUSIONS: Timing of acute kidney injury after urgent percutaneous coronary intervention may be differentially associated with subsequent risk of worsening kidney function but not death.

Implication of Trends in Timing of Dialysis Initiation for Incidence of End-stage Kidney Disease.

Importance: In the last 2 decades, there have been notable changes in the level of estimated glomerular filtration rate (eGFR) at which patients initiate long-term dialysis in the US and around the world. How changes over time in the likelihood of dialysis initiation at any given eGFR level in at-risk patients are associated with the population burden of end-stage kidney disease (ESKD) has not been not well defined. Objective: To examine temporal trends in long-term dialysis initiation by level of eGFR and to quantify how these patterns are associated with the number of patients with ESKD. Design, Setting, and Participants: Retrospective cohort study analyzing data obtained from a large, integrated health care delivery system in Northern California from 2001 to 2018 in successive 3-year intervals. Included individuals, ranging in number from as few as 983 122 (2001-2003) to as many as 1 844 317 (2016-2018), were adult members with 1 or more outpatient serum creatinine levels determined in the prior year. Main Outcomes and Measures: One-year risk of initiating long-term dialysis stratified by eGFR levels. Multivariable logistic regression was performed to assess temporal trends in each 3-year cohort with adjustment for age, sex, race, and diabetes status. The potential change in dialysis initiation in the final cohort (2016-2018) was estimated using the relative difference between the standardized risks in the initial cohort (2001-2003) and the final cohort. Results: In the initial 3-year cohort, the mean (SD) age was 55.4 (16.3) years, 55.0% were women, and the prevalence of diabetes was 14.9%. These characteristics, as well as the distribution of index eGFR, were stable across the study period. The likelihood of receiving dialysis at eGFR levels of 10 to 24 mL/min/1.73 m2 generally increased over time. For example, the 1-year odds of initiating dialysis increased for every 3-year interval by 5.2% (adjusted odds ratio, 1.052; 95% CI, 1.004-1.102) among adults with an index eGFR of 20 to 24 mL/min/1.73 m2, by 6.6% (adjusted odds ratio, 1.066; 95% CI, 1.007-1.130) among adults with an eGFR of 16 to 17 mL/min/1.73 m2, and by 5.3% (adjusted odds ratio, 1.053; 95% CI, 1.008-1.100) among adults with an eGFR of 10 to 13 mL/min/1.73 m2, adjusting for age, sex, race, and diabetes. The incidence of new cases of ESKD was estimated to have potentially been 16% (95% CI, 13%-18%) lower if there were no changes in system-level practice patterns or other factors besides timing of initiating long-term dialysis from the initial 3-year interval (2001-2003) to the final interval (2016-2018) assessed in this study. Conclusions and Relevance: The present results underscore the importance the timing of initiating long-term dialysis has on the size of the population of individuals with ESKD.

Kidney Function and Potassium Monitoring After Initiation of Renin-Angiotensin-Aldosterone System Blockade Therapy and Outcomes in 2 North American Populations.

BACKGROUND: Clinical practice guidelines recommend routine kidney function and serum potassium testing within 30 days of initiating ACE (angiotensin-converting enzyme) inhibitor or angiotensin II receptor blocker therapy. However, evidence is lacking about whether follow-up testing reduces therapy-related adverse outcomes. METHODS AND RESULTS: We conducted 2 population-based retrospective cohort studies in Kaiser Permanente Northern California and Ontario, Canada. Patients with outpatient serum creatinine and potassium tests in the 30 days after starting ACE inhibitor or angiotensin II receptor blocker therapy were matched 1:1 to patients without follow-up tests. We evaluated the association of follow-up testing with 30-day all-cause mortality and hospitalization with acute kidney injury or hyperkalemia using Cox regression. We also developed and externally validated a risk score to identify patients at risk of having abnormally high serum creatinine and potassium values in follow-up. We identified 75 251 matched pairs initiating ACE inhibitor or angiotensin II receptor blocker therapy between January 1, 2007, and December 31, 2017, in Kaiser Permanente Northern California. Follow-up testing was not significantly associated with 30-day all-cause mortality in Kaiser Permanente Northern California (hazard ratio, 0.75 [95% CI, 0.54-1.06]) and was associated with higher mortality in 84 905 matched pairs in Ontario (hazard ratio, 1.32 [95% CI, 1.07-1.62]). In Kaiser Permanente Northern California, follow-up testing was significantly associated with higher rates of hospitalization with acute kidney injury (hazard ratio, 1.66 [95% CI, 1.10-2.22]) and hyperkalemia (hazard ratio, 3.36 [95% CI, 1.08-10.41]), as was observed in Ontario. The risk score for abnormal potassium provided good discrimination (area under the curve [AUC], 0.75) and excellent calibration of predicted risks, while the risk score for abnormal serum creatinine provided moderate discrimination (AUC, 0.62) but excellent calibration. CONCLUSIONS: Routine laboratory monitoring after ACE inhibitor or angiotensin II receptor blocker initiation was not associated with a lower risk of 30-day mortality. We identified patient subgroups in which targeted testing may be effective in identifying therapy-related changes in serum potassium or kidney function.

Renin-Angiotensin System Blockade after Acute Kidney Injury (AKI) and Risk of Recurrent AKI.

BACKGROUND AND OBJECTIVES: How to best medically manage patients who survived hospitalized AKI is unclear. Use of renin-angiotensin system blockers in this setting may increase risk of recurrent AKI. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: This is a cohort study of 10,242 members of an integrated health care delivery system in Northern California who experienced AKI and survived a hospitalization between January 1, 2006 and December 31, 2013. All study participants did not have prior heart failure or use of angiotensin-converting enzyme inhibitors (ACE-Is) or angiotensin receptor blockers (ARBs) up to 5 years prior. New receipt and time-updated exposure of ACE-Is/ARBs was identified on the basis of dispensed prescriptions found in outpatient health plan pharmacy databases. The main outcome of interest was subsequent episode of hospitalized AKI after discharge from an initial index hospitalization complicated by AKI. Recurrent AKI episode was defined using acute changes in serum creatinine concentrations. Marginal structural models were used to adjust for baseline and potential time-dependent confounders. RESULTS: Forty-seven percent of the study population had a documented eGFR<60 ml/min per 1.73 m2 or documented proteinuria before hospitalization. With a median of 3 (interquartile range, 1-5) years of follow-up, 1853 (18%) patients initiated use of ACE-Is/ARBs and 2124 (21%) patients experienced recurrent AKI. Crude rate of recurrent AKI was 6.1 (95% confidence interval [95% CI], 5.9 to 6.4) per 100 person-years off ACE-Is/ARBs and 5.7 (95% CI, 4.9 to 6.5) per 100 person-years on ACE-Is/ARBs. In marginal structural causal inference models that adjusted for baseline and potential time-dependent confounders, exposure to ACE-I/ARB use was not associated with higher incidence of recurrent AKI (adjusted odds ratio, 0.71; 95% CI, 0.45 to 1.12). CONCLUSIONS: In this study of AKI survivors without heart failure, new use of ACE-I/ARB therapy was not independently associated with increased risk of recurrent hospitalized AKI.

Trends Associated With Large-scale Expansion of Peritoneal Dialysis Within an Integrated Care Delivery Model.

IMPORTANCE: Despite favorable national trends in the incidence of end-stage renal disease (ESRD) from 2008 to 2011, ESRD incidence has been increasing recently, and less than 10% of patients with ESRD start renal replacement therapy with peritoneal dialysis (PD) in the United States. Given known and potential advantages of PD over hemodialysis, the Kaiser Permanente Northern California integrated health care delivery system implemented a program to expand use of PD. OBJECTIVES: To describe the system-level approach to expansion of PD use and temporal trends in initiation and persistence of PD and its associated mortality. DESIGN, SETTING, AND PARTICIPANTS: This retrospective cohort study included adult members of a large integrated health care delivery system in Northern California who initiated chronic dialysis therapy from January 1, 2008, through December 31, 2018. Data were analyzed from March 1, 2018, through May 31, 2019. EXPOSURE: From 2008 to 2018, Kaiser Permanente Northern California implemented a multidisciplinary, system-wide approach to increase use of PD that included patient and caregiver education, education and support tools for health care professionals, streamlined system-level processes, monitoring, and continuous quality improvement. MAIN OUTCOMES AND MEASURES: Temporal trends in the proportion of patients starting chronic dialysis with PD vs hemodialysis compared with national trends. Secondary outcomes included persistence of PD at 1 year in those initiating it and standardized 1-year mortality rates in those initiating PD or hemodialysis. RESULTS: Among 13 500 eligible health plan members in the study population (7840 men [58.1%] and 5660 women [41.9%]; mean [SD] age, 64.3 [14.4] years), initiation of PD increased from 165 of 1089 all new dialysis patients (15.2%) in 2008 to 486 of 1438 (33.8%) in 2018, which was substantially higher than national trends (6.1% in 2008 and 9.7% in 2016). Among the 2974 patients who initiated PD from 2008 to 2017, 2387 (80.3%) continued PD at 1 year after initiation, with a significant increase in age-, sex-, and race-standardized rates from 2008 (69.1%) to 2017 (84.2%). Age-, sex-, and race-standardized 1-year mortality for patients receiving PD and hemodialysis did not change significantly across this 10-year period (17.3% to 15.5% for hemodialysis, P = 0.89 for trend; and 5.5% to 7.3% for PD, P = 0.12 for trend). CONCLUSIONS AND RELEVANCE: This study suggests that large-scale expansion of PD is feasible using a multidisciplinary, integrated, coordinated care approach; we believe these findings represent a national opportunity to improve outcomes for patients with advanced kidney disease.

Predicting Renal Recovery After Dialysis-Requiring Acute Kidney Injury.

INTRODUCTION: After dialysis-requiring acute kidney injury (AKI-D), recovery of sufficient kidney function to discontinue dialysis is an important clinical and patient-oriented outcome. Predicting the probability of recovery in individual patients is a common dilemma. METHODS: This cohort study examined all adult members of Kaiser Permanente Northern California who experienced AKI-D between January 2009 and September 2015 and had predicted inpatient mortality of <20%. Candidate predictors included demographic characteristics, comorbidities, laboratory values, and medication use. We used logistic regression and classification and regression tree (CART) approaches to develop and cross-validate prediction models for recovery. RESULTS: Among 2214 patients with AKI-D, mean age was 67.1 years, 40.8% were women, and 54.0% were white; 40.9% of patients recovered. Patients who recovered were younger, had higher baseline estimated glomerular filtration rates (eGFR) and preadmission hemoglobin levels, and were less likely to have prior heart failure or chronic liver disease. Stepwise logistic regression applied to bootstrapped samples identified baseline eGFR, preadmission hemoglobin level, chronic liver disease, and age as the predictors most commonly associated with coming off dialysis within 90 days. Our final logistic regression model including these predictors had a correlation coefficient between observed and predicted probabilities of 0.97, with a c-index of 0.64. An alternate CART approach did not outperform the logistic regression model (c-index 0.61). CONCLUSION: We developed and cross-validated a parsimonious prediction model for recovery after AKI-D with excellent calibration using routinely available clinical data. However, the model's modest discrimination limits its clinical utility. Further research is needed to develop better prediction tools.

Risk Factors for Recurrent Acute Kidney Injury in a Large Population-Based Cohort.

RATIONALE & OBJECTIVE: Acute kidney injury (AKI) has numerous sequelae. Repeated episodes of AKI may be an important determinant of adverse outcomes, including chronic kidney disease and death. In a population-based cohort study, we sought to determine the incidence of and predictors for recurrent AKI. STUDY DESIGN: Retrospective cohort study. SETTING & PARTICIPANTS: 38,659 hospitalized members of Kaiser Permanente Northern California who experienced an episode of AKI from 2006 to 2013. PREDICTORS: Demographic, clinical, and laboratory data, including baseline kidney function, proteinuria, hemoglobin level, comorbid conditions, and severity of AKI. OUTCOMES: Incidence and predictors of recurrent AKI. ANALYTICAL APPROACH: Multivariable Cox proportional hazard regression. RESULTS: 11,048 (28.6%) experienced a second hospitalization complicated by AKI during follow-up (11.2 episodes/100 person-years), with the second episode of AKI occurring a median of 0.6 (interquartile range, 0.2-1.9) years after the first hospitalization. In multivariable analyses, older age, black race, and Hispanic ethnicity were associated with recurrent AKI, along with lower estimated glomerular filtration rate, proteinuria, and anemia. Concomitant conditions, including heart failure, acute coronary syndrome, diabetes, and chronic liver disease, were also multivariable predictors of recurrent AKI. Those who had higher acuity of illness during the initial hospitalization were more likely to have recurrent AKI, but greater AKI severity of the index episode was not independently associated with increased risk for recurrent AKI. In multivariable analysis of matched patients, recurrent AKI was associated with an increased rate of death (HR, 1.66; 95% CI, 1.57-1.77). LIMITATIONS: Analyses were based on clinically available data, rather than protocol-driven timed measurements of kidney function. CONCLUSIONS: Recurrent AKI is a common occurrence after a hospitalization complicated by AKI. Based on routinely available patient characteristics, our findings could facilitate identification of the subgroup of patients with AKI who may benefit from more intensive follow-up to potentially avoid recurrent AKI episodes.