Renal function trajectory is more important than chronic kidney disease stage for managing patients with chronic kidney disease

Stage 5-CKD under nephrology care: to dialyze or not to dialyze, that is the question

Appropriate timing of starting chronic dialysis in patients with advanced chronic kidney disease (CKD) under nephrology care still is undefined. We systematically reviewed the most recent studies that have compared outcomes of stage 5-CKD under conservative versus substitutive treatment. Eleven studies, most in elderly patients, were identified. Results indicate no advantage of dialysis over conservative management in terms of survival, hospitalization or quality of life. This information is integrated with a case report on a middle-aged CKD patient followed in our clinic who has remained for 15 years in stage 5 despite severe disease. The patient is a diabetic woman who underwent right nephrectomy in 1994 because of renal tuberculosis. In 1999, she commenced regular nephrology care in our clinic and, since 2000, when she was 53 years old, her estimated glomerular filtration rate (eGFR) has been ≤15 ml/min/1.73 m(2). Over the last decade, despite, several episodes of acute kidney injury and placement of permanent percutaneous nephrostomy in 2001, renal function has remained remarkably stable, though severely impaired (eGFR 7.7-5.6 ml/min/1.73 m(2)). Our systematic analysis of the literature and this case report highlight the need for further studies, not limited exclusively to elderly patients, to verify the efficacy of non-dialysis treatment in stage 5-CKD patients. Meanwhile, nephrologists may consider that their intervention can safely prolong for several years the dialysis-free condition in ESRD independently of age.

Estimated glomerular filtration rate progression in UK primary care patients with type 2 diabetes and diabetic kidney disease: a retrospective cohort study

AIMS

To examine the rates of diabetic kidney disease (DKD) progression and associated factors, we undertook a study of estimated glomerular filtration rate (eGFR) in a historical cohort of UK primary care patients with type 2 diabetes mellitus (T2DM) and associated DKD from the Clinical Practice Research Datalink.

METHODS

Our eligible population were patients with definitive T2DM from a recorded diagnostic code with either a diagnosis of chronic kidney disease (CKD) or renal function test values and renal abnormalities consistent with a CKD diagnosis, identified between 1 October 2006 and 31 December 2011. Only patients with albuminuria results reported in mg/l were used for the longitudinal statistical analyses of the eGFR rate of change using multilevel models.

RESULTS

We identified 111,030 patients with T2DM. Among them 58.6% (95% confidence interval (CI): 58.3-58.9) had CKD and 37.2% (95% CI: 36.9-37.5%) had presumed DKD at baseline. Only 19.4% of patients had urinary albumin test results expressed as mg/l in the year prior to index date. Almost two-thirds (63.8%) of patients with T2DM and presumed DKD received prescriptions for angiotensin-converting enzyme (ACE) inhibitors or angiotensin type 1 receptor blockers (ARB) or both. Time-dependent variables that predict subsequent eGFR decline include increased albuminuria, time from index date and older age.

CONCLUSION

Only a minority of diabetic patients with DKD had quantitative albuminuria assessments. The relatively low proportion of DKD patients with ACEi or ARB prescriptions suggests a gap between healthcare practice and available scientific evidence during the study period. Increased albuminuria and older age were the most consistent predictors of subsequent eGFR decline.

Maintenance Dialysis throughout the World in Years 1990 and 2010

Rapidly rising global rates of chronic diseases portend a consequent rise in ESRD. Despite this, kidney disease is not included in the list of noncommunicable diseases (NCDs) targeted by the United Nations for 25% reduction by year 2025. In an effort to accurately report the trajectory and pattern of global growth of maintenance dialysis, we present the change in prevalence and incidence from 1990 to 2010. Data were extracted from the Global Burden of Disease 2010 epidemiologic database. The results are on the basis of an analysis of data from worldwide national and regional renal disease registries and detailed systematic literature review for years 1980-2010. Incidence and prevalence estimates of provision of maintenance dialysis from this database were updated using a negative binomial Bayesian meta-regression tool for 187 countries. Results indicate substantial growth in utilization of maintenance dialysis in almost all world regions. Changes in population structure, changes in aging, and the worldwide increase in diabetes mellitus and hypertension explain a significant portion, but not all, of the increase because increased dialysis provision also accounts for a portion of the rise. These findings argue for the importance of inclusion of kidney disease among NCD targets for reducing premature death throughout the world.

Time-dependent risk factors associated with the decline of estimated GFR in CKD patients

Background

Targeting the modifiable risk factors may help halt the progression of CKD, thus risk factor analysis is better performed using the parameters in the follow-up. This study aimed to examine the time-dependent risk factors for CKD progression using time-averaged values and to investigate the characteristics of rapid progression group.

Methods

This is a retrospective cohort study enrolling 770 patients of CKD stage 3–4. Time-dependent parameters were calculated as time-averaged values by a trapezoidal rule. % decline of estimated GFR (eGFR) per year from entry was divided to three groups: <10 % (stable), 10–25 % (moderate progression), and ≥25 % (rapid progression). Multivariate regression analyses were employed for the baseline and the time-averaged datasets.

Results

eGFR decline was 2.83 ± 4.04 mL/min/1.73 m²/year (8.8 ± 12.9 %) in male and 1.66 ± 3.23 mL/min/1.73 m²/year (5.4 ± 11.0 %) in female (p < 0.001). % decline of eGFR was associated with male, proteinuria, phosphorus, and systolic blood pressure as risk factors and with age, albumin, and hemoglobin as protective factors using either dataset. Baseline eGFR and diabetic nephropathy appeared in the baseline dataset, while uric acid appeared in the time-averaged dataset. The rapid progression group was associated with proteinuria, phosphorus, albumin, and hemoglobin in the follow-up.

Conclusion

These results suggest that time-averaged values provide insightful clinical guide in targeting the risk factors. Rapid decline of eGFR is strongly associated with hyperphosphatemia, proteinuria, and anemia indicating that these risk factors should be intervened in the follow-up of CKD.

Recalibration of blood analytes over 25 years in the atherosclerosis risk in communities study: impact of recalibration on chronic kidney disease prevalence and incidence

BACKGROUND

Equivalence of laboratory tests over time is important for longitudinal studies. Even a small systematic difference (bias) can result in substantial misclassification.

METHODS

We selected 200 Atherosclerosis Risk in Communities Study participants attending all 5 study visits over 25 years. Eight analytes were remeasured in 2011-2013 from stored blood samples from multiple visits: creatinine, uric acid, glucose, total cholesterol, HDL cholesterol, LDL cholesterol, triglycerides, and high-sensitivity C-reactive protein. Original values were recalibrated to remeasured values with Deming regression. Differences >10% were considered to reflect substantial bias, and correction equations were applied to affected analytes in the total study population. We examined trends in chronic kidney disease (CKD) pre- and postrecalibration.

RESULTS

Repeat measures were highly correlated with original values [Pearson r > 0.85 after removing outliers (median 4.5% of paired measurements)], but 2 of 8 analytes (creatinine and uric acid) had differences >10%. Original values of creatinine and uric acid were recalibrated to current values with correction equations. CKD prevalence differed substantially after recalibration of creatinine (visits 1, 2, 4, and 5 prerecalibration: 21.7%, 36.1%, 3.5%, and 29.4%, respectively; postrecalibration: 1.3%, 2.2%, 6.4%, and 29.4%). For HDL cholesterol, the current direct enzymatic method differed substantially from magnesium dextran precipitation used during visits 1-4.

CONCLUSIONS

Analytes remeasured in samples stored for approximately 25 years were highly correlated with original values, but 2 of the 8 analytes showed substantial bias at multiple visits. Laboratory recalibration improved reproducibility of test results across visits and resulted in substantial differences in CKD prevalence. We demonstrate the importance of consistent recalibration of laboratory assays in a cohort study.

Time to re-evaluate effects of renin-angiotensin system inhibitors on renal and cardiovascular outcomes in diabetic nephropathy

The use of renin-angiotensin system (RAS) inhibitors, such angiotensin converting enzyme inhibitors/angiotensin-II receptor blockers, to slow progression of chronic kidney disease (CKD) in a large group dominated by elderly people in the real world is not supported by available evidence. Large-scale clinical trials had many faults, among them a lack of focus on the elderly. However, it would be difficult to conduct clinical trials of a similar scale in elderly CKD patients. Besides, progression of kidney disease is often slow in elderly persons, and the vast majority of older adults with CKD will die before reaching end stage renal disease. Moreover, since it is not clear that progression of kidney disease, and even of proteinuric diabetic nephropathy, is not inhibited through the use of RAS inhibitors, the most patient-centric goal of therapy for many elderly individuals should be individualized.

Parental history of premature cardiovascular disease, estimated GFR, and rate of estimated GFR decline: results from the Aerobics Center Longitudinal Study

BACKGROUND

Despite cardiovascular disease (CVD) and chronic kidney disease sharing similar causes and interplay, it is unknown if a broader relationship between these diseases exists across generations. We investigated the association between parental CVD history and estimated glomerular filtration rate (eGFR) in the community.

STUDY DESIGN

Cross-sectional and longitudinal analyses.

SETTING & PARTICIPANTS

13,241 community-based adults with serum creatinine measurement and follow-up visits (from 1-8 visits ~2 years apart) from the Aerobics Center Longitudinal Study.

PREDICTORS

Premature parental CVD history (before age 50 years).

OUTCOMES

eGFR, decreased eGFR (<60 mL/min/1.73 m(2)), and rate of eGFR decline.

MEASUREMENTS

Information for parental history was collected by protocol-standardized questionnaires. eGFR was assessed with serum creatinine.

RESULTS

3,339 (25.2%) participants reported a history of parental CVD. Individuals with parental CVD had significantly lower eGFRs compared with those without parental CVD (69.4 ± 12.9 vs 74.8 ± 14.2 mL/min/1.73 m(2); P<0.001). After multivariable adjustment, parental CVD was associated independently with higher odds of having decreased eGFR (adjusted OR, 1.68; 95% CI, 1.52-1.86). Random-coefficient models showed that individuals with parental CVD had a faster decline in eGFR compared with those without parental CVD (sex- and ethnicity-adjusted annual change of -0.47 vs -0.41 mL/min/1.73 m(2); P=0.06).

LIMITATIONS

~70% of participants did not attend a second examination.

CONCLUSIONS

Parental history of CVD was associated with lower baseline eGFR, higher odds of decreased eGFR, and a nominally faster rate of eGFR decline in the offspring. Such findings may imply previously unrecognized cross-generational links between both diseases and be of support in community screening programs.

Will incremental hemodialysis preserve residual function and improve patient survival?

The progressive loss of residual renal function in peritoneal dialysis patients is associated with increased mortality. It has been suggested that incremental dialysis may help preserve residual renal function and improve patient survival. Residual renal function depends upon both patient related and dialysis associated factors. Maintaining patients in an over-hydrated state may be associated with better preservation of residual renal function but any benefit comes with a significant risk of cardiovascular consequences. Notably, it is only observational studies that have reported an association between dialysis patient survival and residual renal function; causality has not been established for dialysis patient survival. The tenuous connections between residual renal function and outcomes and between incremental hemodialysis and residual renal function should temper our enthusiasm for interventions in this area.

Illness trajectories and their relevance to the care of adults with kidney disease

PURPOSE OF REVIEW

Existing practice guidelines for chronic kidney disease advocate a stage-based approach to management, in which treatment recommendations are based largely on the severity of kidney disease, and future risk for adverse health outcomes. However, the course of kidney disease can vary widely among patients with similar levels of kidney function, and each patient will experience their illness in unique ways.

RECENT FINDINGS

We summarize recent studies of patterns of kidney function over time among patients with chronic kidney disease, and discuss these findings in the context of relevant conceptual models of illness and communication. Although knowledge of disease severity can provide useful information on life expectancy and risk for future health events, an understanding of each patient's illness trajectory and their unique experience of illness is essential in supporting patient-centered care for patients with kidney disease. This information can be helpful in setting realistic expectations for the future, in communicating about prognosis and in aligning treatment decisions with each patient's goals and preferences.

SUMMARY

We here explain how an understanding of illness trajectories may be useful in predicting and guiding care and decision-making in patients with kidney disease. We highlight the importance of competing disease trajectories, the heterogeneity in renal function trajectories among patients with kidney disease, and the variability in these trajectories over time in individual patients. We discuss how individual disease trajectories can shape each patient's experience of illness. Finally, we explain how an understanding of an individual patient's illness trajectory and experience of illness may be useful in guiding discussions about prognosis and treatment decisions and in supporting a patient-centered approach to care.

Regression methods for investigating risk factors of chronic kidney disease outcomes: the state of the art

Background

Chronic kidney disease (CKD) is a progressive and usually irreversible disease. Different types of outcomes are of interest in the course of CKD such as time-to-dialysis, transplantation or decline of the glomerular filtration rate (GFR). Statistical analyses aiming at investigating the association between these outcomes and risk factors raise a number of methodological issues. The objective of this study was to give an overview of these issues and to highlight some statistical methods that can address these topics.

Methods

A literature review of statistical methods published between 2002 and 2012 to investigate risk factors of CKD outcomes was conducted within the Scopus database. The results of the review were used to identify important methodological issues as well as to discuss solutions for each type of CKD outcome.

Results

Three hundred and four papers were selected. Time-to-event outcomes were more often investigated than quantitative outcome variables measuring kidney function over time. The most frequently investigated events in survival analyses were all-cause death, initiation of kidney replacement therapy, and progression to a specific value of GFR. While competing risks were commonly accounted for, interval censoring was rarely acknowledged when appropriate despite existing methods. When the outcome of interest was the quantitative decline of kidney function over time, standard linear models focussing on the slope of GFR over time were almost as often used as linear mixed models which allow various numbers of repeated measurements of kidney function per patient. Informative dropout was accounted for in some of these longitudinal analyses.

Conclusions

This study provides a broad overview of the statistical methods used in the last ten years for investigating risk factors of CKD progression, as well as a discussion of their limitations. Some existing potential alternatives that have been proposed in the context of CKD or in other contexts are also highlighted.

Timing of dialysis initiation in the geriatric population: toward a patient-centered approach

Over the last 10-15 years, the incidence of treated end-stage renal disease (ESRD) among older adults has increased and dialysis is being initiated at progressively higher levels of estimated glomerular filtration rate (eGFR). Average life expectancy after dialysis initiation among older adults is quite limited, and many experience an escalation of care and loss of independence after starting dialysis. Available data suggest that treatment decisions about dialysis initiation in older adults in the United States are guided more by system- than by patient-level factors. Stronger efforts are thus needed to ensure that treatment decisions for older adults with advanced kidney disease are optimally aligned with their goals and preferences. There is growing interest in more conservative approaches to the management of advanced kidney disease in older patients who prefer not to initiate dialysis and those for whom the harms of dialysis are expected to outweigh the benefits. A number of small single center studies, mostly from the United Kingdom report similar survival among the subset of older adults with a high burden of comorbidity treated with dialysis vs. those managed conservatively. However, the incidence of treated ESRD in older US adults is several-fold higher than in the United Kingdom, despite a similar prevalence of chronic kidney disease, suggesting large differences in the social, cultural, and economic context in which dialysis treatment decisions unfold. Thus, efforts may be needed to adapt conservative care models developed outside the United States to optimally meet the needs of US patients. More flexible approaches toward dialysis prescription and better integration of treatment decisions about conservative care with those related to modality selection will likely be helpful in meeting the needs of individual patients. Regardless of the chosen treatment strategy, time can often be a critical ally in centering care on what matters most to the patient, and a flexible and iterative approach of re-evaluation and redirection may often be needed to ensure that treatment strategies are fully aligned with patient priorities.

Dialysis initiation: what's the rush?

The recent trend to early initiation of dialysis (at eGFR >10 ml/min/1.73 m(2) ) appears to have been based on conventional wisdoms that are not supported by evidence. Observational studies using administrative databases report worse comorbidity-adjusted dialysis survival with early dialysis initiation. Although some have concluded that the IDEAL randomized controlled trial of dialysis start provided evidence that patients become symptomatic with late dialysis start, there is no definitive support for this view. The potential harms of early start of dialysis, including the loss of residual renal function (RRF), have been well documented. The rate of RRF loss (renal function trajectory) is an important consideration for the timing of the dialysis initiation decision. Patients with low glomerular filtration rate (GFR) may have sufficient RRF to be maintained off dialysis for years. Delay of dialysis start until a working arterio-venous access is in place seems prudent in light of the lack of harm and possible benefit of late dialysis initiation. Prescribing frequent hemodialysis is not recommended when dialysis is initiated early. The benefits of early initiation of chronic dialysis after episodes of congestive heart failure or acute kidney injury require further study. There are no data to show that early start benefits diabetics or other patient groups. Preemptive start of dialysis in noncompliant patients may be necessary to avoid complications. The decision to initiate dialysis requires informed patient consent and a joint decision by the patient and dialysis provider. Possible talking points for obtaining informed consent are provided.

Has the yearly increase in the renal replacement therapy population ended?

The recent decline in the number of new patients undergoing dialysis and transplantation in the United States may be linked to a reduction in the incidence of early-start dialysis, defined as the initiation of renal replacement therapy (RRT) at an estimated GFR ≥10 ml/min per 1.73 m(2). We examined the most recent data from the U.S. Renal Data System to determine how this trend will affect the future incidence of ESRD in the United States. The percentage of early dialysis starts grew from 19% to 54% of all new starts between 1996 and 2009 but remained stable between 2009 and 2011. Similarly, the incident RRT population increased substantially in all age groups between 1996 and 2005, with the largest increase occurring in patients aged ≥75 years. Early dialysis starts accounted for most of the increase in the incident RRT population in all age groups during this time period, and between 2005 and 2010, the increase slowed dramatically. Although the future incident RRT population will be determined in part by population growth, these results suggest that later dialysis starts and greater use of conservative and palliative care, which may improve quality of life for elderly patients with advanced renal failure, will continue to attenuate the increase observed in previous years.