Creatinine fluctuation has a greater effect than the formula to estimate glomerular filtration rate on the prevalence of chronic kidney disease

Benefits of aldosterone receptor antagonism in chronic kidney disease: the BARACK-D RCT

Background

Chronic kidney disease affects around 10% of the global population and is associated with significant risk of progression to end-stage renal disease and vascular events. Aldosterone receptor antagonists such as spironolactone have shown prognostic benefits in patients with heart failure, but effects on patients with chronic kidney disease are uncertain.

Objectives

To determine the effect of low-dose spironolactone on mortality and cardiovascular outcomes in people with chronic kidney disease stage 3b.

Design

Prospective randomised open blinded end-point trial.

Settings

Three hundred and twenty-nine general practitioner practices throughout the United Kingdom.

Participants

Patients meeting the criteria for chronic kidney disease stage 3b (estimated glomerular filtration rate 30-44 ml/minute/1.73 m2) according to National Institute for Health and Care Excellence guidelines were recruited. Due to the higher than anticipated measurement error/fluctuations, the eligible range was extended to 30-50 ml/minute/1.73 m2 following the initial recruitment period.

Intervention

Participants were randomised 1 : 1 to receive either spironolactone 25 mg once daily in addition to standard care, or standard care only.

Outcome measures

Primary outcome was the first occurring of all-cause mortality, first hospitalisation for heart disease (coronary heart disease, arrhythmia, atrial fibrillation, sudden death, failed sudden death), stroke, heart failure, transient ischaemic attack or peripheral arterial disease, or first occurrence of any condition not listed at baseline. Secondary outcome measures included changes in blood pressure, renal function, B-type natriuretic peptide, incidence of hyperkalaemia and treatment costs and benefits.

Results

One thousand four hundred and thirty-four participants were randomised of the 3022 planned. We found no evidence of differences between the intervention and control groups in terms of effectiveness with the primary combined vascular end points, nor with the secondary clinical outcomes, including progression in renal decline. These results were similar for the total treatment periods or a 3-year follow-up period as originally planned. More adverse events were experienced and more participants discontinued treatment in the intervention group. Two-thirds of participants randomised to spironolactone stopped treatment within six months because they met pre-specified safety stop criteria. The addition of low-dose spironolactone was estimated to have a cost per quality-adjusted life-year gained value above the National Institute for Health and Care Excellence's threshold of £30,000.

Limitations

Main limitations were difficulties in recruiting eligible participants resulting in an underpowered trial with poor ethnic diversity taking twice as long as planned to complete. We have explored the data in secondary analyses that indicate that, despite these difficulties, the findings were reliable.

Conclusions

The benefits of aldosterone receptor antagonism in chronic kidney disease trial found no evidence to support adding low-dose spironolactone (25 mg daily) in patients with chronic kidney disease stage 3b: there were no changes to cardiovascular events during the trial follow-up, either for the combined primary or individual components. There was also no evidence of benefit observed in rates of renal function decline over the trial, but much higher initial creatinine rise and estimated glomerular filtration rate decline, and to a higher percentage rate, in the intervention arm in the first few weeks of spironolactone treatment, which resulted in a high proportion of participants discontinuing spironolactone treatment at an early stage. These higher rates of negative renal change reduced in scale over the study but did not equalise between arms. The addition of 25 mg of spironolactone therefore provided no reno- or cardio-protection and was associated with an increase in adverse events.

Future work

These findings might not be applicable to different mineralocorticoid receptor antagonists.

Study registration

Current Controlled Trials ISRCTN44522369.

Funding

This award was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme (NIHR award ref: 12/01/52) and is published in full in Health Technology Assessment; Vol. 29, No. 5. See the NIHR Funding and Awards website for further award information.

Comment on: Difference between kidney function by cystatin C versus creatinine and association with muscle mass and frailty

See the related reply by O. Alison Potok and Dena E. Rifkin in this issue.

Correlation of Ablation Volume with Renal Function Loss after Cryoablation in Solitary Functioning Kidneys

PURPOSE

To determine the degree of renal function deterioration after renal cryoablation in patients with a solitary functioning kidney on the basis of ablation volume.

MATERIALS AND METHODS

Over a 15-year period, 81 percutaneous cryoablations were performed in solitary functioning kidneys. After exclusion of patients with baseline end-stage renal disease (ESRD) and insufficient follow-up, analysis was performed on 65 procedures in 52 patients (40 men; mean age, 63.5 years). The postcryoablation renal function was based on the lowest serum creatinine within 6 months after procedure. Renal function change was defined as percentage glomerular filtration rate (GFR) change. Volumetric analysis was performed on the target lesion, renal parenchyma, and ablation zone.

RESULTS

The median tumor diameter was 2.0 cm (range, 0.8-4.7 cm). The median baseline GFR decreased from 56.4 mL/min/1.73 m2 (range, 17.5-89.7 mL/min/1.73 m2) to 46.9 mL/min/1.73 m2 (range, 16.5-89.7 mL/min/1.73 m2) at median of 95 days (P < .001), equating to a -7.9% median renal function change (range, -45.0% to +30.7%). All patients had Stage 2 or worse chronic kidney disease, and baseline function did not correlate with renal function change. The median volume of ablated parenchyma was 19.7 mL (range, 2.4-87.3 mL), equating to 8.1% (range, 0.7%-37.2%) of total parenchyma. The volume of parenchymal volume ablated correlated significantly with renal function loss, whereas age, hypertension, and diabetes mellitus did not. No patient developed ESRD within 1 year after cryoablation.

CONCLUSIONS

Cryoablation in solitary functioning kidneys resulted in a modest reduction in renal function, even in patients with chronic kidney disease and ablations of up to 20% of renal parenchymal volume.

Chronic kidney disease: detect, diagnose, disclose-a UK primary care perspective of barriers and enablers to effective kidney care

Chronic kidney disease (CKD) is a global public health problem with major human and economic consequences. Despite advances in clinical guidelines, classification systems and evidence-based treatments, CKD remains underdiagnosed and undertreated and is predicted to be the fifth leading cause of death globally by 2040. This review aims to identify barriers and enablers to the effective detection, diagnosis, disclosure and management of CKD since the introduction of the Kidney Disease Outcomes Quality Initiative (KDOQI) classification in 2002, advocating for a renewed approach in response to updated Kidney Disease: Improving Global Outcomes (KDIGO) 2024 clinical guidelines. The last two decades of improvements in CKD care in the UK are underpinned by international adoption of the KDIGO classification system, mixed adoption of evidence-based treatments and research informed clinical guidelines and policy. Interpretation of evidence within clinical and academic communities has stimulated significant debate of how best to implement such evidence which has frequently fuelled and frustratingly forestalled progress in CKD care. Key enablers of effective CKD care include clinical classification systems (KDIGO), evidence-based treatments, electronic health record tools, financially incentivised care, medical education and policy changes. Barriers to effective CKD care are extensive; key barriers include clinician concerns regarding overdiagnosis, a lack of financially incentivised care in primary care, complex clinical guidelines, managing CKD in the context of multimorbidity, bureaucratic burden in primary care, underutilisation of sodium-glucose co-transporter-2 inhibitor (SGLT2i) medications, insufficient medical education in CKD, and most recently - a sustained disruption to routine CKD care during and after the COVID-19 pandemic. Future CKD care in UK primary care must be informed by lessons of the last two decades. Making step change, over incremental improvements in CKD care at scale requires a renewed approach that addresses key barriers to detection, diagnosis, disclosure and management across traditional boundaries of healthcare, social care, and public health. Improved coding accuracy in primary care, increased use of SGLT2i medications, and risk-based care offer promising, cost-effective avenues to improve patient and population-level kidney health. Financial incentives generally improve achievement of care quality indicators - a review of financial and non-financial incentives in CKD care is urgently needed.

Accuracy of glomerular filtration rate estimation using creatinine and cystatin C for identifying and monitoring moderate chronic kidney disease: the eGFR-C study

Background

Estimation of glomerular filtration rate using equations based on creatinine is widely used to manage chronic kidney disease. In the UK, the Chronic Kidney Disease Epidemiology Collaboration creatinine equation is recommended. Other published equations using cystatin C, an alternative marker of kidney function, have not gained widespread clinical acceptance. Given higher cost of cystatin C, its clinical utility should be validated before widespread introduction into the NHS.

Objectives

Primary objectives were to: (1) compare accuracy of glomerular filtration rate equations at baseline and longitudinally in people with stage 3 chronic kidney disease, and test whether accuracy is affected by ethnicity, diabetes, albuminuria and other characteristics; (2) establish the reference change value for significant glomerular filtration rate changes; (3) model disease progression; and (4) explore comparative cost-effectiveness of kidney disease monitoring strategies.

Design

A longitudinal, prospective study was designed to: (1) assess accuracy of glomerular filtration rate equations at baseline (n = 1167) and their ability to detect change over 3 years (n = 875); (2) model disease progression predictors in 278 individuals who received additional measurements; (3) quantify glomerular filtration rate variability components (n = 20); and (4) develop a measurement model analysis to compare different monitoring strategy costs (n = 875).

Setting

Primary, secondary and tertiary care.

Participants

Adults (≥ 18 years) with stage 3 chronic kidney disease.

Interventions

Estimated glomerular filtration rate using the Chronic Kidney Disease Epidemiology Collaboration and Modification of Diet in Renal Disease equations.

Main outcome measures

Measured glomerular filtration rate was the reference against which estimating equations were compared with accuracy being expressed as P30 (percentage of values within 30% of reference) and progression (variously defined) studied as sensitivity/specificity. A regression model of disease progression was developed and differences for risk factors estimated. Biological variation components were measured and the reference change value calculated. Comparative costs of monitoring with different estimating equations modelled over 10 years were calculated.

Results

Accuracy (P30) of all equations was ≥ 89.5%: the combined creatinine-cystatin equation (94.9%) was superior (p < 0.001) to other equations. Within each equation, no differences in P30 were seen across categories of age, gender, diabetes, albuminuria, body mass index, kidney function level and ethnicity. All equations showed poor (< 63%) sensitivity for detecting patients showing kidney function decline crossing clinically significant thresholds (e.g. a 25% decline in function). Consequently, the additional cost of monitoring kidney function annually using a cystatin C-based equation could not be justified (incremental cost per patient over 10 years = £43.32). Modelling data showed association between higher albuminuria and faster decline in measured and creatinine-estimated glomerular filtration rate. Reference change values for measured glomerular filtration rate (%, positive/negative) were 21.5/-17.7, with lower reference change values for estimated glomerular filtration rate.

Limitations

Recruitment of people from South Asian and African-Caribbean backgrounds was below the study target.

Future work

Prospective studies of the value of cystatin C as a risk marker in chronic kidney disease should be undertaken.

Conclusions

Inclusion of cystatin C in glomerular filtration rate-estimating equations marginally improved accuracy but not detection of disease progression. Our data do not support cystatin C use for monitoring of glomerular filtration rate in stage 3 chronic kidney disease.

Trial registration

This trial is registered as ISRCTN42955626.

Funding

This award was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme (NIHR award ref: 11/103/01) and is published in full in Health Technology Assessment; Vol. 28, No. 35. See the NIHR Funding and Awards website for further award information.

Management of Chronic Kidney Disease in Morocco: A Cost-of-Illness Study

INTRODUCTION

Chronic kidney disease (CKD) is a global public health problem. The aim of this study is to estimate the mean annual direct medical cost per patient with CKD before the start of renal replacement therapy (RRT) in Morocco.

METHODS

This is a cross-sectional cost-of-illness study, using a prevalence approach among adults with CKD before RRT in a Moroccan university hospital. Information on direct medical costs was collected from the patient's report and associated costs were estimated according to national tariff/fee catalogues. We computed annual direct medical costs using society perspective. Costs were then estimated and compared according to CKD stages, health insurance categories, and monthly income.

RESULTS

Eighty-eight participants were included; 63.6% of them were female, their mean age was 61.8±14.0 years, and 76.1% were in stages 4 or 5. The estimated annual direct medical cost of CKD was estimated at $ 2008.80 (95%CI 1528.28-2489.31), Hospitalization, diagnosis, and treatment represented the main expenses of the direct medical cost (32.2%, 29.7%, and 32.2%, respectively). The direct medical cost components were not significantly different between CKD stages.

CONCLUSION

The cost of CKD in Morocco in its early stages is still lower than the cost of RRT, which brings to light the necessity of secondary prevention of CKD to postpone or prevent the progression to end-stage renal disease.

A Long-term Estimated Glomerular Filtration Rate Plot Analysis Permits the Accurate Assessment of a Decline in the Renal Function by Minimizing the Influence of Estimated Glomerular Filtration Rate Fluctuations

Objective Evaluating the rate of decline in the estimated glomerular filtration rate (eGFR) may help identify patients with occult chronic kidney disease (CKD). We herein report that eGFR fluctuation complicates the assessment of the rate of decline and propose a long-term eGFR plot analysis as a solution. Methods In 142 patients with persistent eGFR decline in a single hospital, we evaluated the factors influencing the rate of eGFR decline, calculated over the long term (≥3 years) and short term (<3 years) using eGFR plots, taking into account eGFR fluctuation between visits. Results The difference between the rate of eGFR decline calculated using short- and long-term plots increased as the time period considered in the short-term plots became shorter. A regression analysis revealed that eGFR fluctuation was the only factor that explained the difference and that the fluctuation exceeded the annual eGFR decline in all participants. Furthermore, the larger the eGFR fluctuation, the more difficult it became to detect eGFR decline using a short-term eGFR analysis. Obesity, a high eGFR at baseline, and faster eGFR decline were associated with larger eGFR fluctuations. To circumvent the issue of eGFR fluctuation in the assessment of the rate of eGFR decline, we developed a system that generates a long-term eGFR plot using all eGFR values for a participant, which enabled the detection of occult CKD, facilitating early therapeutic intervention. Conclusion The construction of long-term eGFR plots is useful for identifying patients with progressive eGFR decline, as it minimizes the effect of eGFR fluctuation.

Emergency hospital admissions associated with non-communicable diseases 1998-2018 in England, Wales and Scotland: an ecological study

BACKGROUND

Non-communicable diseases (NCDs) are increasingly prevalent and were responsible for 40.5 million deaths (71%) globally in 2016. We examined the number of NCD-related emergency hospital admissions during the years 1998 to 2018 in the UK.

METHODS

Demographic features for those admitted as an emergency with NCDs as their primary diagnosis were collated for all admissions in England, Wales and Scotland. NCDs recorded as secondary diagnoses for all admissions in England from 2012 to 2018 were additionally recorded.

RESULTS

We identified 120,662,155 emergency episodes of care. From 1998 to 2018 there was an increase from 1,416,233 to 1,892,501 in annual emergency admissions due to NCDs. This, however, represented a fall in the proportion of NCD among all emergency admissions, from 33.4% to 26.9%. Mean age of all patients admitted increased from 46.3 to 53.8 years.

CONCLUSION

Despite a fall in proportion of NCD admissions, the population acutely admitted to hospital was increasingly elderly and increasingly comorbid.

The association of skin autofluorescence with cardiovascular events and all-cause mortality in persons with chronic kidney disease stage 3: A prospective cohort study

BACKGROUND

Tissue advanced glycation end product (AGE) accumulation has been proposed as a marker of cumulative metabolic stress that can be assessed noninvasively by measurement of skin autofluorescence (SAF). In persons on haemodialysis, SAF is an independent risk factor for cardiovascular events (CVEs) and all-cause mortality (ACM), but data at earlier stages of chronic kidney disease (CKD) are inconclusive. We investigated SAF as a risk factor for CVEs and ACM in a prospective study of persons with CKD stage 3.

METHODS AND FINDINGS

Participants with estimated glomerular filtration rate (eGFR) 59 to 30 mL/min/1.73 m2 on two consecutive previous blood tests were recruited from 32 primary care practices across Derbyshire, United Kingdom between 2008 and 2010. SAF was measured in participants with CKD stage 3 at baseline, 1, and 5 years using an AGE reader (DiagnOptics). Data on hospital admissions with CVEs (based on international classification of diseases [ICD]-10 coding) and deaths were obtained from NHS Digital. Cox proportional hazards models were used to investigate baseline variables associated with CVEs and ACM. A total of 1,707 of 1,741 participants with SAF readings at baseline were included in this analysis: The mean (± SD) age was 72.9 ± 9.0 years; 1,036 (60.7%) were female, 1,681 (98.5%) were of white ethnicity, and mean (±SD) eGFR was 53.5 ± 11.9 mL/min/1.73 m2. We observed 319 deaths and 590 CVEs during a mean of 6.0 ± 1.5 and 5.1 ± 2.2 years of observation, respectively. Higher baseline SAF was an independent risk factor for CVEs (hazard ratio [HR] 1.12 per SD, 95% CI 1.03-1.22, p = 0.01) and ACM (HR 1.16, 95% CI 1.03-1.30, p = 0.01). Additionally, increase in SAF over 1 year was independently associated with subsequent CVEs (HR 1.11 per SD, 95% CI 1.00-1.22; p = 0.04) and ACM (HR 1.24, 95% CI 1.09-1.41, p = 0.001). We relied on ICD-10 codes to identify hospital admissions with CVEs, and there may therefore have been some misclassification.

CONCLUSIONS

We have identified SAF as an independent risk factor for CVE and ACM in persons with early CKD. These findings suggest that interventions to reduce AGE accumulation, such as dietary AGE restriction, may reduce cardiovascular risk in CKD, but this requires testing in prospective randomised trials. Our findings may not be applicable to more ethnically diverse or younger populations.

Prevalence of chronic kidney disease in the community using data from OxRen: a UK population-based cohort study

Background

Chronic kidney disease (CKD) is a largely asymptomatic condition of diminished renal function, which may not be detected until advanced stages without screening.

Aim

To establish undiagnosed and overall CKD prevalence using a cross-sectional analysis.

Design and setting

Longitudinal cohort study in UK primary care.

Method

Participants aged ≥60 years were invited to attend CKD screening visits to determine whether they had reduced renal function (estimated glomerular filtration rate [eGFR] <60 ml/min/1.73 m² or albumin:creatinine ratio ≥3 mg/mmol). Those with existing CKD, low eGFR, evidence of albuminuria, or two positive screening tests attended a baseline assessment (CKD cohort).

Results

A total of 3207 participants were recruited and 861 attended the baseline assessment. The CKD cohort consisted of 327 people with existing CKD, 257 people with CKD diagnosed through screening (CKD prevalence of 18.2%, 95% confidence interval [CI] = 16.9 to 19.6), and 277 with borderline/transient decreased renal function. In the CKD cohort, 54.4% were female, mean standard deviation (SD) age was 74.0 (SD 6.9) years, and mean eGFR was 58.0 (SD 18.4) ml/min/1.73 m². Of the 584 with confirmed CKD, 44.0% were diagnosed through screening. Over half of the CKD cohort (51.9%, 447/861) fell into CKD stages 3–5 at their baseline assessment, giving an overall prevalence of CKD stages 3–5 of 13.9% (95% CI = 12.8 to 15.1). More people had reduced eGFR using the Modification of Diet in Renal Disease (MDRD) equation than with CKD Epidemiology Collaboration (CKD-EPI) equation in the 60–75-year age group and more had reduced eGFR using CKD-EPI in the ≥80-year age group.

Conclusion

This study found that around 44.0% of people living with CKD are undiagnosed without screening, and prevalence of CKD stages 1–5 was 18.2% in participants aged >60 years. Follow-up will provide data on annual incidence, rate of CKD progression, determinants of rapid progression, and predictors of cardiovascular events.

Fenestrated-branched endovascular aortic repair in patients with chronic kidney disease

OBJECTIVE

Renal function impairment is a common complication after open repair of complex abdominal aortic aneurysms and thoracoabdominal aortic aneurysms (TAAAs). The purpose of this study was to assess renal perioperative outcomes and renal function deterioration after fenestrated-branched endovascular aneurysm repair (F/BEVAR) in patients with chronic kidney disease (CKD).

METHODS

The study included 186 patients who underwent F/BEVAR between 2013 and 2018 for suprarenal, juxtarenal, and type I to type IV TAAAs. Glomerular filtration rate (GFR) was calculated using the Modification of Diet in Renal Disease (MDRD) study equation. Postoperative acute kidney injury (AKI) and CKD were defined using RIFLE criteria (Risk, Injury, Failure, Loss, and End-stage renal disease) and CKD staging system (stage ≥3, GFR <60 mL/min/1.73 m²), respectively. For those without baseline CKD, renal decline was defined as a drop in GFR <60 mL/min/1.73 m² (ie, progression to CKD stage 3 or higher). For patients with baseline renal dysfunction, GFR decline ≥20% or progression in CKD stage (ie, from stage 3 to stage 4) was considered renal decline.

RESULTS

CKD was present in 83 patients (44.6%). Postoperative AKI was diagnosed in 27 patients (14.5%); 13 (48.1%) had history of CKD and 14 (51.9%) had adequate renal function preoperatively (P = .8). None of these patients required permanent renal replacement therapy. Intraoperative technical success was 100%. Overall 30-day mortality was 1.1%. There was no difference in 30-day mortality in patients with (1.2%) and without (1.0%) CKD (P = .5). During a median follow-up time of 12 months (interquartile range, 6-23 months), renal decline was observed in 21 patients (25.3%) with previous CKD and in 11 patients (10.6%) without CKD (P = .01). Among patients with previous CKD, 18 patients (9%) progressed from stage 3 CKD to stage 4. In patients with progression in CKD stage, two (5%) had renal stent stenosis requiring restenting. Among patients with renal decline, 13 had juxtarenal aneurysms (21.3%), 27 had suprarenal aneurysms (44.3%), and 21 had TAAAs (34.3%; P = .4). Subset analysis of patients who developed AKI in the immediate postoperative period found that patients with a history of CKD were less likely to experience freedom from renal decline.

CONCLUSIONS

F/BEVAR is an effective and safe procedure for patients with complex abdominal aortic aneurysms and TAAAs, even among patients with CKD. The frequency of AKI was not affected by pre-existing CKD. Midterm outcomes demonstrated that progression of CKD was more frequent among patients with pre-existing CKD, but permanent renal replacement therapy was not required. Anatomic extent of aneurysms did not affect CKD progression. CKD patients are susceptible to renal decline over time if they experience AKI in the postoperative period. Therefore, preventing AKI in the postoperative period should be regarded as a priority. Long-term effects of CKD after F/BEVAR remain to be elucidated.

Too much nephrology? The CKD epidemic is real and concerning. A CON view

The prevalence of chronic kidney disease (CKD) clearly depends on its definition, and the definition used most often is the one proposed by the Kidney Disease: Improving Global Outcomes guidelines in 2012: 'CKD is defined as abnormalities of kidney structure or function, present for >3 months, with implications for health.' Abnormality of kidney function is a glomerular filtration rate (GFR) <60 mL/min/1.73 m2, and the most frequently used marker of kidney damage is the presence of albuminuria [albumin excretion rate >30 mg/24 h or albumin/creatinine ratio (ACR) >30 mg/g (or 3 mg/mmol)]. However, two major aspects of this definition could explain why CKD prevalence is, in our view, overstated in most epidemiological studies. First, the fixed threshold at 60 mL/min/1.73 m2 is questionable because normal GFR decreases with age. This and the profound consequence it has on CKD epidemiology will be illustrated. The second aspect of the definition is the criterion of chronicity, which is ignored by the vast majority of epidemiological studies. In other words, confirming CKD (low GFR and/or high ACR) is mandatory. Indeed, a large proportion of subjects with a low first GFR level has a normal GFR level when tested a second time. The prevalence of CKD may hence, in fact, be considerably lower although still neither negligible nor irrelevant.

Impact of a single eGFR and eGFR-estimating equation on chronic kidney disease reclassification: a cohort study in primary care

Background

Chronic kidney disease (CKD) is diagnosed using the estimated glomerular filtration rate (eGFR) and the urinary albumin:creatinine ratio (ACR). The eGFR is calculated from serum creatinine levels using the Modification of Diet in Renal Disease (MDRD) or Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations.

Aim

To compare the performance of one versus two eGFR/ACR measurements, and the impact of equation choice, on CKD diagnosis and classification.

Design and setting

Cohort study in primary care in the Thames Valley region of the UK.

Method

Data were from 485 participants aged >60 years in the Oxford Renal Cohort Study with at least two eGFR tests. The proportion of study participants diagnosed and classified into different CKD stages using one and two positive tests were compared. Prevalence of CKD diagnosis and classification by CKD stage were compared when eGFR was calculated using MDRD and CKD-EPI equations.

Results

Participants included in the analysis had a mean age of 72.1 (±6.8) years and 57.0% were female. Use of a single screening test overestimated the proportion of people with CKD by around 25% no matter which equation was used, compared with the use of two tests. The mean eGFR was 1.4 ml/min/1.73 m² (95% CI = 1.1 to 1.6) higher using the CKD-EPI equation compared with the MDRD equation. More patients were diagnosed with CKD when using the MDRD equation, compared with the CKD-EPI equation, once (64% versus 63%, respectively) and twice (39% versus 38%, respectively), and 16 individuals, all of who had CKD stages 2 or 3A with MDRD, were reclassified as having a normal urinary ACR when using the CKD-EPI equation.

Conclusion

Current guidance to use two eGFR measures to diagnose CKD remains appropriate in an older primary care population to avoid overdiagnosis. A change from MDRD to CKD-EPI equation could result in one in 12 patients with a CKD diagnosis with MDRD no longer having a diagnosis of CKD.

An ontological approach to identifying cases of chronic kidney disease from routine primary care data: a cross-sectional study

Background

Accurately identifying cases of chronic kidney disease (CKD) from primary care data facilitates the management of patients, and is vital for surveillance and research purposes. Ontologies provide a systematic and transparent basis for clinical case definition and can be used to identify clinical codes relevant to all aspects of CKD care and its diagnosis.

Methods

We used routinely collected primary care data from the Royal College of General Practitioners Research and Surveillance Centre. A domain ontology was created and presented in Ontology Web Language (OWL). The identification and staging of CKD was then carried out using two parallel approaches: (1) clinical coding consistent with a diagnosis of CKD; (2) laboratory-confirmed CKD, based on estimated glomerular filtration rate (eGFR) or the presence of proteinuria.

Results

The study cohort comprised of 1.2 million individuals aged 18 years and over. 78,153 (6.4%) of the population had CKD on the basis of an eGFR of < 60 mL/min/1.73m², and a further 7366 (0.6%) individuals were identified as having CKD due to proteinuria. 19,504 (1.6%) individuals without laboratory-confirmed CKD had a clinical code consistent with the diagnosis. In addition, a subset of codes allowed for 1348 (0.1%) individuals receiving renal replacement therapy to be identified.

Conclusions

Finding cases of CKD from primary care data using an ontological approach may have greater sensitivity than less comprehensive methods, particularly for identifying those receiving renal replacement therapy or with CKD stages 1 or 2. However, the possibility of inaccurate coding may limit the specificity of this method.

Probabilistic broken-stick model: A regression algorithm for irregularly sampled data with application to eGFR

In order for clinicians to manage disease progression and make effective decisions about drug dosage, treatment regimens or scheduling follow up appointments, it is necessary to be able to identify both short and long-term trends in repeated biomedical measurements. However, this is complicated by the fact that these measurements are irregularly sampled and influenced by both genuine physiological changes and external factors. In their current forms, existing regression algorithms often do not fulfil all of a clinician's requirements for identifying short-term (acute) events while still being able to identify long-term, chronic, trends in disease progression. Therefore, in order to balance both short term interpretability and long term flexibility, an extension to broken-stick regression models is proposed in order to make them more suitable for modelling clinical time series. The proposed probabilistic broken-stick model can robustly estimate both short-term and long-term trends simultaneously, while also accommodating the unequal length and irregularly sampled nature of clinical time series. Moreover, since the model is parametric and completely generative, its first derivative provides a long-term non-linear estimate of the annual rate of change in the measurements more reliably than linear regression. The benefits of the proposed model are illustrated using estimated glomerular filtration rate as a case study used to manage patients with chronic kidney disease.

Chronic kidney disease is associated with poorer in-hospital outcomes in patients hospitalized with infections: Electronic record analysis from China

Predominantly based on studies from high-income countries, reduced estimated glomerular filtration rate (eGFR) has been associated with increased risk of infections and infection-related hospitalizations (IRHs). We here explore in-hospital outcomes of IRHs in patients with different kidney function. A total of 6,283 adults, not on renal replacement therapy, with a discharge diagnosis of infection, and with an eGFR 1-12 months before index hospitalization, were included from four hospitals in China. We compared in-hospital outcomes (death, intensive care unit (ICU) admission, length of hospital stay (LOHS) and medical expenses), between patients with and without chronic kidney disease (CKD, defined as eGFR ≤ 60 ml/min per 1.73 m2 of body surface area) by mixed-effects logistic regression model or generalized linear model. The odds for in-hospital mortality (adjusted odds ratios (OR) = 1.41; 95% CI 1.02-1.96) and ICU admission (OR = 2.18; 95% CI 1.64-2.91) were higher among patients with CKD. The median LOHS was significantly higher for CKD patients (11 days vs. 10 days in non-CKD, P < 0.001), and inferred costs were 20.0% higher adjusted for inflation rate based on costs in 2012 (P < 0.001). Patients with CKD hospitalized with infections are at increased risk of poorer in-hospital outcomes, conveying higher medical costs.

Cardiovascular morbidity and long term mortality associated with in hospital small increases of serum creatinine

BACKGROUND

The cardiovascular risk associated with an increase in serum creatinine below the acute kidney injury (AKI) threshold, during hospitalization, has not been studied in depth. We assessed patients' features and outcomes associated with these changes.

METHODS

Retrospective cohort study of 12,493 consecutive patients admitted to hospital throughout 12 months. We investigated the patients who had a small creatinine increase (SISCr) between 1.2 and <1.5 times the admission value, and tested the association of creatinine changes with the prevalence of cardiovascular disease (CVD). In a follow-up study, we assessed the all-cause mortality and its relationship with SISCr.

RESULTS

Among patients with two or more creatinine measurements, 14.9% showed a SISCr. Older age, female gender and higher estimated glomerular filtration rate (eGFR) at admission were characteristics of these patients. The prevalence of CVD was 14.6% in patients with SISCr vs. 10.7% in those with stable creatinine (p < 0.001). SISCr was detected in 36, 26.6 and 18.9% of chronic heart failure (CHF), chronic ischemic heart disease (CIHD) and acute myocardial infarction (AMI) patients, respectively. The follow-up was 26.7 ± 10.6 months with 770 all-cause deaths. Serum creatinine increase above 20% was associated with a significant higher mortality compared to changes below 20%, adjusted hazard (HR) ratio 1.577 (p < 0.001). A higher risk was found associated with creatinine increases >1.5 times the baseline: HR 1.704 (p < 0.001).

CONCLUSIONS

In hospitalized patients, increases in serum creatinine below the AKI threshold are associated with CHF, CIHD and long-term mortality.

Demethylzeylasteral ameliorates inflammation in a rat model of unilateral ureteral obstruction through inhibiting activation of the NF‑κB pathway

The present study investigated the pharmacodynamic role and therapeutic mechanism of demethylzeylasteral in the suppression of inflammation in a rat model of unilateral ureteral obstruction and reduction in nuclear factor (NF)‑κB pathway activity. The rats in the unilateral ureteral obstruction model were treated with 30‑120 mg/kg demethylzeylasteral for 8 weeks. The activities of tumor necrosis factor (TNF)‑α, interleukin (IL)‑6 and caspase‑3/9, and the protein expression levels of cyclooxygenase (COX)‑2 and intercellular adhesion molecule‑1 (ICAM‑1) and NF‑κB p65 were analyzed using ELISA kits and western blot analyses, respectively. Compared with the rats in the unilateral ureteral obstruction model group, demethylzeylasteral treatment markedly inhibited the increased concentrations of serum creatinine and blood urea nitrogen, urinary protein/creatinine ratio, and concentrations of high‑density lipoprotein and low‑density lipoprotein cholesterol, and prevented kidney damage. In addition, demethylzeylasteral inhibited the levels of TNF‑α andIL‑6 and suppressed the protein expression levels of COX‑2 and ICAM‑1 in the kidneys of the rats in the unilateral ureteral obstruction model. Demethylzeylasteral also significantly suppressed the protein expression of NF‑κB p65. The results of the present study suggested that demethylzeylasteral unilateral ureteral obstruction and inhibited inflammation via inhibiting the activation of COX‑2, ICAM‑1 and NF‑κB p65, and suppressing the activities of caspase‑3/9 in rats with unilateral ureteral obstruction.

Validity of estimated prevalence of decreased kidney function and renal replacement therapy from primary care electronic health records compared with national survey and registry data in the United Kingdom

BACKGROUND

Anonymous primary care records are an important resource for observational studies. However, their external validity is unknown in identifying the prevalence of decreased kidney function and renal replacement therapy (RRT). We thus compared the prevalence of decreased kidney function and RRT in the Clinical Practice Research Datalink (CPRD) with a nationally representative survey and national registry.

METHODS

Among all people ≥25 years of age registered in the CPRD for ≥1 year on 31 March 2014, we identified patients with an estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m2, according to their most recent serum creatinine in the past 5 years using the Chronic Kidney Disease Epidemiology Collaboration equation and patients with recorded diagnoses of RRT. Denominators were the entire population in each age-sex band irrespective of creatinine measurement. The prevalence of eGFR <60 mL/min/1.73 m2 was compared with that in the Health Survey for England (HSE) 2009/2010 and the prevalence of RRT was compared with that in the UK Renal Registry (UKRR) 2014.

RESULTS

We analysed 2 761 755 people in CPRD [mean age 53 (SD 17) years, men 49%], of whom 189 581 (6.86%) had an eGFR <60 mL/min/1.73 m2 and 3293 (0.12%) were on RRT. The prevalence of eGFR <60 mL/min/1.73 m2 in CPRD was similar to that in the HSE and the prevalence of RRT was close to that in the UKRR across all age groups in men and women, although the small number of younger patients with an eGFR <60 mL/min/1.73 m2 in the HSE might have hampered precise comparison.

CONCLUSIONS

UK primary care data have good external validity for the prevalence of decreased kidney function and RRT.

Improving CKD Diagnosis and Blood Pressure Control in Primary Care: A Tailored Multifaceted Quality Improvement Programme

BACKGROUND

Chronic kidney disease (CKD) is a worldwide public health issue. From 2009 to 2014, the National Institute for Health Research Collaboration for Leadership in Applied Health Research and Care Greater Manchester (NIHR CLAHRC GM) in England ran 4 phased, 12-month quality improvement (QI) projects with 49 primary care practices in GM. Two measureable aims were set - halve undiagnosed CKD in participating practices using modelled estimates of prevalence; and optimise blood pressure (BP) control (<140/90 mm Hg in CKD patients without proteinuria; <130/80 mm Hg in CKD patients with proteinuria) for 75% of recorded cases of CKD. The 4 projects ran as follows: P1 = Project 1 with 19 practices (September 2009 to September 2010), P2 = Project 2 with 11 practices (March 2011 to March 2012), P3 = Project 3 with 12 practices (September 2012 to October 2013), and P4 = Project 4 with 7 practices (April 2013 to March 2014).

METHODS

Multifaceted intervention approaches were tailored based on a contextual analysis of practice support needs. Data were collected from practices by facilitators at baseline and again at project close, with self-reported data regularly requested from practices throughout the projects.

RESULTS

Halving undiagnosed CKD as per aim was exceeded in 3 of the 4 projects. The optimising BP aim was met in 2 projects. Total CKD cases after the programme increased by 2,347 (27%) from baseline to 10,968 in a total adult population (aged ≥18 years) of 231,568. The percentage of patients who managed to appropriate BP targets increased from 34 to 74% (P1), from 60 to 83% (P2), from 68 to 71% (P3), and from 63 to 76% (P4). In nonproteinuric CKD patients, 88, 90, 89, and 91%, respectively, achieved a target BP of <140/90 mm Hg. In proteinuric CKD patients, 69, 46, 48, and 45%, respectively, achieved a tighter target of <130/80 mm Hg. Analysis of national data over similar timeframes indicated that practices participating in the programme achieved higher CKD detection rates.

CONCLUSIONS

Participating practices identified large numbers of "missing" CKD patients with comparator data showing they outperformed non-QI practices locally and nationally over similar timeframes. Improved BP control also occurred through this intervention, but overall achievement of the tighter BP target in proteinuric patients was notably less.

An external validation of models to predict the onset of chronic kidney disease using population-based electronic health records from Salford, UK

BACKGROUND

Chronic kidney disease (CKD) is a major and increasing constituent of disease burdens worldwide. Early identification of patients at increased risk of developing CKD can guide interventions to slow disease progression, initiate timely referral to appropriate kidney care services, and support targeting of care resources. Risk prediction models can extend laboratory-based CKD screening to earlier stages of disease; however, to date, only a few of them have been externally validated or directly compared outside development populations. Our objective was to validate published CKD prediction models applicable in primary care.

METHODS

We synthesised two recent systematic reviews of CKD risk prediction models and externally validated selected models for a 5-year horizon of disease onset. We used linked, anonymised, structured (coded) primary and secondary care data from patients resident in Salford (population ~234 k), UK. All adult patients with at least one record in 2009 were followed-up until the end of 2014, death, or CKD onset (n = 178,399). CKD onset was defined as repeated impaired eGFR measures over a period of at least 3 months, or physician diagnosis of CKD Stage 3-5. For each model, we assessed discrimination, calibration, and decision curve analysis.

RESULTS

Seven relevant CKD risk prediction models were identified. Five models also had an associated simplified scoring system. All models discriminated well between patients developing CKD or not, with c-statistics around 0.90. Most of the models were poorly calibrated to our population, substantially over-predicting risk. The two models that did not require recalibration were also the ones that had the best performance in the decision curve analysis.

CONCLUSIONS

Included CKD prediction models showed good discriminative ability but over-predicted the actual 5-year CKD risk in English primary care patients. QKidney, the only UK-developed model, outperformed the others. Clinical prediction models should be (re)calibrated for their intended uses.

Methodological challenges when carrying out research on CKD and AKI using routine electronic health records

Research regarding chronic kidney disease (CKD) and acute kidney injury (AKI) using routinely collected data presents particular challenges. The availability, consistency, and quality of renal data in electronic health records has changed over time with developments in policy, practice incentives, clinical knowledge, and associated guideline changes. Epidemiologic research may be affected by patchy data resulting in an unrepresentative sample, selection bias, misclassification, and confounding by factors associated with testing for and recognition of reduced kidney function. We systematically explore the issues that may arise in study design and interpretation when using routine data sources for CKD and AKI research. First, we discuss how access to health care and management of patients with CKD may have an impact on defining the target population for epidemiologic study. We then consider how testing and recognition of CKD and AKI may lead to biases and how to potentially mitigate against these. Illustrative examples from our own research within the UK are used to clarify key points. Any research using routine renal data has to consider the local clinical context to achieve meaningful interpretation of the study findings.

Chronic kidney disease among adult participants of the ELSA-Brasil cohort: association with race and socioeconomic position

BACKGROUND

There is increased interest in understanding why chronic kidney disease (CKD) rates vary across races and socioeconomic groups. We investigated the distribution of estimated glomerular filtration rate (eGFR), urinary albumin-creatinine ratio (ACR) and CKD according to these factors in Brazilian adults.

METHODS

Using baseline data (2008-2010) of 14,636 public sector employees (35-74 years) enrolled in the Brazilian Longitudinal Study of Adult Health (ELSA)-Brasil multicentre cohort, we estimated the prevalence of CKD by sex, age, race and socioeconomic factors. CKD was defined as ACR ≥ 30 mg/g and/or eGFR < 60 mL/min/1.73 m(2). GFR was estimated by CKD epidemiology collaboration without correction for race. We used logistic regression to estimate the association of race and socioeconomic position (education, income, social class and occupational nature) with CKD after adjusting for sex, age and several health-related factors.

RESULTS

The prevalence of high ACR or low eGFR, in isolation and combined, increased with age, and was higher in individuals with lower socioeconomic position and among black individuals and indigenous individuals. The overall prevalence of CKD was 8.9%. After full adjustments, it was similar in men and women (OR=0.90; 95% CI 0.79 to 1.02) and increased with age (OR=1.07; 95% CI 1.06 to 1.08). Compared to white individuals, black individuals (OR=1.23; 95% CI 1.03 to 1.47), 'pardos' (OR=1.16; 95% CI 1.00 to 1.35) and Indigenous (OR=1.72; 95% CI 1.07 to 2.76) people had higher odds for CKD. Having high school (OR=1.15; 95% CI 1.00 to 1.34) or elementary education (OR=1.23; 95% CI 1.03 to 1.47) increased the odds for CKD compared to those having a university degree.

CONCLUSIONS

There were marked discrepancies in the increases in reduced eGFR and high ACR with age and race. The higher prevalences of CKD in individuals with lower educational status and in non-whites were not explained by differences in health-related factors.

Effect of shared care on blood pressure in patients with chronic kidney disease: a cluster randomised controlled trial

BACKGROUND

Chronic kidney disease (CKD) is highly prevalent in patients with diabetes or hypertension in primary care. A shared care model could improve quality of care in these patients

AIM

To assess the effect of a shared care model in managing patients with CKD who also have diabetes or hypertension. Design and setting A cluster randomised controlled trial in nine general practices in The Netherlands.

METHOD

Five practices were allocated to the shared care model and four practices to usual care for 1 year. Primary outcome was the achievement of blood pressure targets (130/80 mmHg) and lowering of blood pressure in patients with diabetes mellitus or hypertension and an estimated glomerular filtration rate (eGFR)<60 ml/min/1.73 m(2).

RESULTS

Data of 90 intervention and 74 control patients could be analysed. Blood pressure in the intervention group decreased with 8.1 (95% CI = 4.8 to 11.3)/1.1 (95% CI = -1.0 to 3.2) compared to -0.2 (95% CI = -3.8 to 3.3)/-0.5 (95% CI = -2.9 to 1.8) in the control group. Use of lipid-lowering drugs, angiotensin-system inhibitors and vitamin D was higher in the intervention group than in the control group (73% versus 51%, 81% versus 64%, and 15% versus 1%, respectively, [P = 0.004, P = 0.01, and P = 0.002]).

CONCLUSION

A shared care model between GP, nurse practitioner and nephrologist is beneficial in reducing systolic blood pressure in patients with CKD in primary care.

Exploration of chronic kidney disease prevalence estimates using new measures of kidney function in the health survey for England

BACKGROUND

Chronic kidney disease (CKD) diagnosis relies on glomerular filtration rate (eGFR) estimation, traditionally using the creatinine-based Modification of Diet in Renal Disease (MDRD) equation. The Chronic Kidney Disease Epidemiology Collaboration (CKDEPI) equation performs better in estimating eGFR and predicting mortality and CKD progression risk. Cystatin C is an alternative glomerular filtration marker less influenced by muscle mass. CKD risk stratification is improved by combining creatinine eGFR with cystatin C and urinary albumin to creatinine ratio (uACR). We aimed to identify the impact of introducing CKDEPI and cystatin C on the estimated prevalence and risk stratification of CKD in England and to describe prevalence and associations of cystatin C.

METHODS AND FINDINGS

Cross sectional study of 5799 people in the nationally representative 2009 and 2010 Health Surveys for England.

PRIMARY OUTCOME MEASURES

prevalence of MDRD, CKDEPI and cystatin C-defined eGFR<60 ml/min/1.73 m(2); prevalence of CKD biomarker combinations (creatinine, cystatin C, uACR). Using CKDEPI instead of MDRD reduced the prevalence of eGFR<60 ml/min/1.73 m(2) from 6.0% (95% CI 5.4-6.6%) to 5.2% (4.7-5.8%) equivalent to around 340,000 fewer individuals in England. Those reclassified as not having CKD evidenced a lower risk profile. Prevalence of cystatin C eGFR<60 ml/min/1.73 m(2) was 7.7% and independently associated with age, lack of qualifications, being an ex-smoker, BMI, hypertension, and albuminuria. Measuring cystatin C in the 3.9% people with CKDEPI-defined eGFR<60 ml/min/1.73 m(2) without albuminuria (CKD Category G3a A1) reclassified about a third into a lower risk group with one of three biomarkers and two thirds into a group with two of three. Measuring cystatin C in the 6.7% people with CKDEPI eGFR >60 ml/min/1.73 m(2) with albuminuria (CKD Category G1-2) reclassified almost a tenth into a higher risk group.

LIMITATIONS

Cross sectional study, single eGFR measure, no measured ('true') GFR.

CONCLUSIONS

Introducing the CKDEPI equation and targeted cystatin C measurement reduces estimated CKD prevalence and improves risk stratification.

CKD and the risk of acute, community-acquired infections among older people with diabetes mellitus: a retrospective cohort study using electronic health records

Background

Hospital admissions for community-acquired infection are increasing rapidly in the United Kingdom, particularly among older individuals, possibly reflecting an increasing prevalence of comorbid conditions such as chronic kidney disease (CKD). This study describes associations between CKD (excluding patients treated by dialysis or transplantation) and community-acquired infection incidence among older people with diabetes mellitus.

Study Design

Retrospective cohort study using primary care records from the Clinical Practice Research Datalink linked to Hospital Episode Statistics admissions data.

Setting & Participants

191,709 patients 65 years or older with diabetes mellitus and no history of renal replacement therapy, United Kingdom, 1997 to 2011.

Predictor

Estimated glomerular filtration rate (eGFR) and history of proteinuria.

Outcomes

Incidence of community-acquired lower respiratory tract infections (LRTIs, with pneumonia as a subset) and sepsis, diagnosed in primary or secondary care, excluding hospital admissions from time at risk.

Measurements

Poisson regression was used to calculate incidence rate ratios (IRRs) adjusted for age, sex, smoking status, comorbid conditions, and characteristics of diabetes. Estimates for associations of eGFR with infection were adjusted for proteinuria, and vice versa.

Results

Strong graded associations between lower eGFRs and infection were observed. Compared with patients with eGFRs ≥ 60 mL/min/1.73 m², fully adjusted IRRs for pneumonia among those with eGFRs < 15, 15 to 29, 30 to 44, and 45 to 59 mL/min/1.73 m² were 3.04 (95% CI, 2.42-3.83), 1.73 (95% CI, 1.57-1.92), 1.19 (95% CI, 1.11-1.28), and 0.95 (95% CI, 0.89-1.01), respectively. Associations between lower eGFRs and sepsis were stronger, with fully adjusted IRRs up to 5.56 (95% CI, 3.90-7.94). Those associations with LRTI were weaker but still clinically relevant at up to 1.47 (95% CI, 1.34-1.62). In fully adjusted models, a history of proteinuria remained an independent marker of increased infection risk for LRTI, pneumonia, and sepsis (IRRs of 1.07 [95% CI, 1.05-1.09], 1.26 [95% CI, 1.19-1.33], and 1.33 [95% CI, 1.20-1.47]).

Limitations

Patients without creatinine results were excluded.

Conclusions

Strategies to prevent infection among people with CKD are needed.

Are pre-existing markers of chronic kidney disease associated with short-term mortality following acute community-acquired pneumonia and sepsis? A cohort study among older people with diabetes using electronic health records

Background

We aimed to examine whether pre-existing impaired estimated glomerular filtration rate (eGFR) and proteinuria were associated with mortality following community-acquired pneumonia or sepsis among people aged ≥65 years with diabetes mellitus, without end-stage renal disease.

Methods

Patients were followed up from onset of first community-acquired pneumonia or sepsis episode in a cohort study using large, linked electronic health databases. Follow-up was for up to 90 days, unlimited by hospital discharge. We used generalized linear models with log link, normal distribution and robust standard errors to calculate risk ratios (RRs) for all-cause 28- and 90-day mortality according to two markers of chronic kidney disease: eGFR and proteinuria.

Results

All-cause mortality among the 4743 patients with pneumonia was 29.6% after 28 days and 37.4% after 90 days. Among the 1058 patients with sepsis, all-cause 28- and 90-day mortality were 35.6 and 44.2%, respectively. eGFR <30 mL/min/1.73 m² was a risk marker of higher 28-day mortality for pneumonia (RR 1.27: 95% CI 1.12–1.43) and sepsis (RR 1.32: 95% CI 1.07–1.64), adjusted for age, sex, socio-economic status, smoking status and co-morbidities. Neither moderately impaired eGFR nor proteinuria were associated with short-term mortality following either infection.

Conclusions

People with pre-existing low eGFR but not on dialysis are at higher risk of death following pneumonia and sepsis. This association was not explained by existing co-morbidities. These patients need to be carefully monitored to prevent modifiable causes of death.

Presence of early CKD-related metabolic complications predict progression of stage 3 CKD: a case-controlled study

BACKGROUND

Only a subset of patients who enter stage 3 chronic kidney disease (CKD) progress to stage 4. Identifying which patients entering stage 3 are most likely to progress could improve outcomes, by allowing more appropriate referrals for specialist care, and spare those unlikely to progress the adverse effects and costliness of an unnecessarily aggressive approach. We hypothesized that compared to non-progressors, patients who enter stage 3 CKD and ultimately progress have experienced greater loss of renal function, manifested by impairment of metabolic function (anemia, worsening acidosis and mineral abnormalities), than is reflected in the eGFR at entry to stage 3. The purpose of this case-controlled study was to design a prediction model for CKD progression using laboratory values reflecting metabolic status.

METHODS

Using data extracted from the electronic health record (EHR), two cohorts of patients in stage 3 were identified: progressors (eGFR declined >3 ml/min/1.73 m2/year; n=117) and non-progressors (eGFR declined <1 ml/min/1.713 m2; n=364). Initial laboratory values recorded a year before to a year after the time of entry to stage 3, reflecting metabolic complications (hemoglobin, bicarbonate, calcium, phosphorous, and albumin) were obtained. Average values in progressors and non-progressors were compared. Classification algorithms (Naïve Bayes and Logistic Regression) were used to develop prediction models of progression based on the initial lab data.

RESULTS

At the entry to stage 3 CKD, hemoglobin, bicarbonate, calcium, and albumin values were significantly lower and phosphate values significantly higher in progressors compared to non-progressors even though initial eGFR values were similar. The differences were sufficiently large that a prediction model of progression could be developed based on these values. Post-test probability of progression in patients classified as progressors or non-progressors were 81% (73% - 86%) and 17% (13% - 23%), respectively.

CONCLUSIONS

Our studies demonstrate that patients who enter stage 3 and ultimately progress to stage 4 manifest a greater degree of metabolic complications than those who remain stable at the onset of stage 3 when eGFR values are equivalent. Lab values (hemoglobin, bicarbonate, phosphorous, calcium and albumin) are sufficiently different between the two cohorts that a reasonably accurate predictive model can be developed.

Identification of people with autosomal dominant polycystic kidney disease using routine data: a cross sectional study

Background

Autosomal dominant polycystic kidney disease (ADPKD) causes progressive renal damage and is a leading cause of end-stage renal failure. With emerging therapies it is important to devise a method for early detection. We aimed to identify factors from routine clinical data which can be used to distinguish people with a high likelihood of having ADPKD in a primary health care setting.

Method

A cross-sectional study was undertaken using data from the Quality Intervention in Chronic Kidney Disease trial extracted from 127 primary care practices in England. The health records of 255 people with ADPKD were compared to the general population. Logistic regression was used to identify clinical features which distinguish ADPKD. These clinical features were used to stratify individual risk using a risk score tool.

Results

Renal impairment, proteinuria, haematuria, a diastolic blood pressure over 90 mmHg and multiple antihypertensive medications were more common in ADPKD than the general population and were used to build a regression model (area under the receiver operating characteristic curve; 0.79). Age, gender, haemoglobin and urinary tract infections were not associated with ADPKD. A risk score (range −3 to +10) of ≥0 gave a sensitivity of 70.2% and specificity 74.9% of for detection.

Conclusions

Stratification of ADPKD likelihood from routine data may be possible. This approach could be a valuable component of future screening programs although further longitudinal analyses are needed.

Prevalence and management of chronic kidney disease in primary care patients in the UK

BACKGROUND

This study aimed to estimate the prevalence of chronic kidney disease (CKD) in the UK in 2010 and to assess prevalence, comorbidities and comedications associated with the disease over time, following inclusion of CKD in the Quality and Outcomes Framework (QOF).

METHODS

This was a retrospective, longitudinal study assessing individuals with prevalent or incident CKD (identified using estimated glomerular filtration rate readings and/or Read codes) in the General Practice Research Database (GPRD) in 2010. Individuals were assessed at two time points: in 2010 and at the date of their first classification of CKD in the GPRD.

RESULTS

The prevalence of stage 3-5 CKD in 2010 was 5.9%. In patients with stage 3-5 CKD at first classification, their disease remained stable, progressed or improved by 2010 in approximately 50%, 10-15% and 25-30% of patients, respectively. Diagnoses of cardiovascular-related comorbidities (hypertension, hypercholesterolaemia, diabetes and cardiovascular disease), and treatment with antihypertensives and lipid-modifying therapy (LMT), increased with worsening disease severity. When patients were stratified by diagnosis date, the proportion of patients with stage 3-5 CKD and cardiovascular-related comorbidities decreased with time, and the relative use of LMT and antihypertensives among patients with hypercholesterolaemia and hypertension increased with time.

CONCLUSIONS

Chronic kidney disease is generally stable or progressive, although more patients improve disease stage than previously assumed. Data suggest that the introduction of CKD into the QOF has increased awareness of CKD among physicians in the UK, allowing for earlier intervention and better control of CKD progression.

The need for improved identification and accurate classification of stages 3-5 Chronic Kidney Disease in primary care: retrospective cohort study

Background

Around ten percent of the population have been reported as having Chronic Kidney Disease (CKD), which is associated with increased cardiovascular mortality. Few previous studies have ascertained the chronicity of CKD. In the UK, a payment for performance (P4P) initiative incentivizes CKD (stages 3–5) recognition and management in primary care, but the impact of this has not been assessed.

Methods and Findings

Using data from 426 primary care practices (population 2,707,130), the age standardised prevalence of stages 3–5 CKD was identified using two consecutive estimated Glomerular Filtration Rates (eGFRs) seven days apart. Additionally the accuracy of practice CKD registers and the relationship between accurate identification of CKD and the achievement of P4P indicators was determined. Between 2005 and 2009, the prevalence of stages 3–5 CKD increased from 0.3% to 3.9%. In 2009, 30,440 patients (1.1% unadjusted) fulfilled biochemical criteria for CKD but were not on a practice CKD register (uncoded CKD) and 60,705 patients (2.2% unadjusted) were included on a practice CKD register but did not fulfil biochemical criteria (miscoded CKD). For patients with confirmed CKD, inclusion in a practice register was associated with increasing age, male sex, diabetes, hypertension, cardiovascular disease and increasing CKD stage (p<0.0001). Uncoded CKD patients compared to miscoded patients were less likely to achieve performance indicators for blood pressure (OR 0.84, 95% CI 0.82–0.86 p<0.001) or recorded albumin-creatinine ratio (OR 0.73, 0.70–0.76, p<0.001).

Conclusions

The prevalence of stages 3–5 CKD, using two laboratory reported eGFRs, was lower than estimates from previous studies. Clinically significant discrepancies were identified between biochemically defined CKD and appearance on practice registers, with misclassification associated with sub-optimal care for some people with CKD.

A determination of the current causes of hyperkalaemia and whether they have changed over the past 25 years

OBJECTIVE

Hyperkalaemia is a potentially lethal electrolyte disorder. The objective of this study was to determine if the causes of hyperkalaemia-related visits to the emergency department (ED) have changed since 25 years.

METHODS

All patients presenting to the ED with hyperkalaemia between January 2009 and August 2011 were included in this retrospective, single-centre study. Patients were divided into one of these three categories: mild (5·2≤ K(+)<5·8 mEq/l), moderate (5·8≤K(+)<7·0 mEq/l) or severe hyperkalaemia (K(+)≥7·0 mEq/l). The causes of hyperkalaemia were divided into three groups: renal failure (RF), potassium-increasing drugs (PIDs) or others.

RESULTS

Overall, 139 patients with hyperkalaemia were included in the study (mean K(+) of 6·2 mEq/l): 35% with mild, 49% with moderate and 16% with severe hyperkalaemia. Eighty-three per cent of patients (n = 115) had RF with creatinine levels ≥1·25 mg/dl or estimated glomerular filtration rate (eGFR) levels ≤60 ml/min/1·73 m(2). Serum potassium levels were significantly related with creatinine and eGFR values (P<0·001). The severity of hyperkalaemia was significantly related with creatinine levels ≥1·25 mg/dl (P = 0·002) and eGFR values ≤60 ml/min/1·73 m(2) (P = 0·005). Seventy-five per cent of patients (n = 105) were taking PIDs. Potassium levels were significantly related with PIDs (P<0·001), in particularly spironolactone (P = 0·001) and angiotensin-converting enzyme inhibitors (P = 0·008). The category 'others' included 7% of patients (n = 10).

CONCLUSIONS

RF (83%) and PIDs (75%) remain common causes of hyperkalaemia. Hyperkalaemia is significantly related with four variables: creatinine levels, spironolactone, ACEIs and beta-blocker intake. The causes of hyperkalaemia have not changed in recent years.

Burden of multimorbidity, socioeconomic status and use of health services across stages of life in urban areas: a cross-sectional study

Background

The burden of chronic conditions and multimorbidity is a growing health problem in developed countries. The study aimed to determine the estimated prevalence and patterns of multimorbidity in urban areas of Catalonia, stratified by sex and adult age groups, and to assess whether socioeconomic status and use of primary health care services were associated with multimorbidity.

Methods

A cross-sectional study was conducted in Catalonia. Participants were adults (19+ years) living in urban areas, assigned to 251 primary care teams. Main outcome: multimorbidity (≥2 chronic conditions). Other variables: sex (male/female), age (19–24; 25–44; 45–64; 65–79; 80+ years), socioeconomic status (quintiles), number of health care visits during the study.

Results

We included 1,356,761 patients; mean age, 47.4 years (SD: 17.8), 51.0% women. Multimorbidity was present in 47.6% (95% CI 47.5-47.7) of the sample, increasing with age in both sexes but significantly higher in women (53.3%) than in men (41.7%). Prevalence of multimorbidity in each quintile of the deprivation index was higher in women than in men (except oldest group). In women, multimorbidity prevalence increased with quintile of the deprivation index. Overall, the median (interquartile range) number of primary care visits was 8 (4–14) in multimorbidity vs 1 (0–4) in non-multimorbidity patients. The most prevalent multimorbidity pattern beyond 45 years of age was uncomplicated hypertension and lipid disorder. Compared with the least deprived group, women in other quintiles of the deprivation index were more likely to have multimorbidity than men until 65 years of age. The odds of multimorbidity increased with number of visits in all strata.

Conclusions

When all chronic conditions were included in the analysis, almost 50% of the adult urban population had multimorbidity. The prevalence of multimorbidity differed by sex, age group and socioeconomic status. Multimorbidity patterns varied by life-stage and sex; however, circulatory-endocrine-metabolic patterns were the most prevalent multimorbidity pattern after 45 years of age. Women younger than 80 years had greater prevalence of multimorbidity than men, and women’s multimorbidity prevalence increased as socioeconomic status declined in all age groups. Identifying multimorbidity patterns associated with specific age-related life-stages allows health systems to prioritize and to adapt clinical management efforts by age group.

Benefits of Aldosterone Receptor Antagonism in Chronic Kidney Disease (BARACK D) trial-a multi-centre, prospective, randomised, open, blinded end-point, 36-month study of 2,616 patients within primary care with stage 3b chronic kidney disease to compare the efficacy of spironolactone 25 mg once daily in addition to routine care on mortality and cardiovascular outcomes versus routine care alone: study protocol for a randomized controlled trial

BACKGROUND

Chronic kidney disease (CKD) is common and increasing in prevalence. Cardiovascular disease (CVD) is a major cause of morbidity and death in CKD, though of a different phenotype to the general CVD population. Few therapies have proved effective in modifying the increased CVD risk or rate of renal decline in CKD. There are accumulating data that aldosterone receptor antagonists (ARA) may offer cardio-protection and delay renal impairment in patients with the CV phenotype in CKD. The use of ARA in CKD has therefore been increasingly advocated. However, no large study of ARA with renal or CVD outcomes is underway.

METHODS

The study is a prospective randomised open blinded endpoint (PROBE) trial set in primary care where patients will mainly be identified by their GPs or from existing CKD lists. They will be invited if they have been formally diagnosed with CKD stage 3b or there is evidence of stage 3b CKD from blood results (eGFR 30-44 mL/min/1.73 m2) and fulfil the other inclusion/exclusion criteria. Patients will be randomised to either spironolactone 25 mg once daily in addition to routine care or routine care alone and followed-up for 36 months.

DISCUSSION

BARACK D is a PROBE trial to determine the effect of ARA on mortality and cardiovascular outcomes (onset or progression of CVD) in patients with stage 3b CKD.

TRIAL REGISTRATION

EudraCT: 2012-002672-13ISRTN: ISRCTN44522369.

Impact of multimorbidity: acute morbidity, area of residency and use of health services across the life span in a region of south Europe

Background

Concurrent diseases, multiple pathologies and multimorbidity patterns are topics of increased interest as the world’s population ages. To explore the impact of multimorbidity on affected patients and the consequences for health services, we designed a study to describe multimorbidity by sex and life-stage in a large population sample and to assess the association with acute morbidity, area of residency and use of health services.

Methods

A cross-sectional study was conducted in Catalonia (Spain). Participants were 1,749,710 patients aged 19+ years (251 primary care teams). Primary outcome: Multimorbidity (≥2 chronic diseases). Secondary outcome: Number of new events of each acute disease. Other variables: number of acute diseases per patient, sex, age group (19–24, 25–44, 45–64, 65–79, and 80+ years), urban/rural residence, and number of visits during 2010.

Results

Multimorbidity was present in 46.8% (95% CI, 46.7%-46.8%) of the sample, and increased as age increased, being higher in women and in rural areas. The most prevalent pair of chronic diseases was hypertension and lipid disorders in patients older than 45 years. Infections (mainly upper respiratory infection) were the most common acute diagnoses. In women, the highest significant RR of multimorbidity vs. non-multimorbidity was found for teeth/gum disease (aged 19–24) and acute upper respiratory infection. In men, this RR was only positive and significant for teeth/gum disease (aged 65–79). The adjusted analysis showed a strongly positive association with multimorbidity for the oldest women (80+ years) with acute diseases and women aged 65–79 with 3 or more acute diseases, compared to patients with no acute diseases (OR ranged from 1.16 to 1.99, p < 0.001). Living in a rural area was significantly associated with lower probability of having multimorbidity. The odds of multimorbidity increased sharply as the number of visits increased, reaching the highest probability in those aged 65–79 years.

Conclusions

Multimorbidity is related to greater use of health care services and higher incidence of acute diseases, increasing the burden on primary care services. The differences related to sex and life-stage observed for multimorbidity and acute diseases suggest that further research on multimorbidity should be stratified according to these factors.

Prevalence, awareness, and management of CKD and cardiovascular risk factors in publicly funded health care

BACKGROUND AND OBJECTIVES

It is uncertain how many patients with CKD and cardiovascular risk factors in publicly funded universal health care systems are aware of their disease and how to achieve their treatment targets.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

The CARTaGENE study evaluated BP, lipid, and diabetes profiles as well as corresponding treatments in 20,004 random individuals between 40 and 69 years of age. Participants had free access to health care and were recruited from four regions within the province of Quebec, Canada in 2009 and 2010.

RESULTS

CKD (Chronic Kidney Disease Epidemiology Collaboration equation; <60 ml/min per 1.73 m(2)) was present in 4.0% of the respondents, and hypertension, diabetes, and hypercholesterolemia were reported by 25%, 7.4%, and 28% of participants, respectively. Self-awareness was low: 8% for CKD, 73% for diabetes, and 45% for hypercholesterolemia. Overall, 31% of patients with hypertension did not meet BP goals, and many received fewer antihypertensive drugs than appropriately controlled individuals; 41% of patients with diabetes failed to meet treatment targets. Among those patients with a moderate or high Framingham risk score, 53% of patients had LDL levels above the recommended levels, and many patients were not receiving a statin. Physician checkups were not associated with greater awareness but did increase the achievement of targets.

CONCLUSION

In this population with access to publicly funded health care, CKD and cardiovascular risk factors are common, and self-awareness of these conditions is low. Recommended targets were frequently not achieved, and treatments were less intensive in those patients who failed to reach goals. New strategies to enhance public awareness and reach guideline targets should be developed.

The eGFR-C study: accuracy of glomerular filtration rate (GFR) estimation using creatinine and cystatin C and albuminuria for monitoring disease progression in patients with stage 3 chronic kidney disease--prospective longitudinal study in a multiethnic population

BACKGROUND

Uncertainty exists regarding the optimal method to estimate glomerular filtration rate (GFR) for disease detection and monitoring. Widely used GFR estimates have not been validated in British ethnic minority populations.

METHODS/DESIGN

Iohexol measured GFR will be the reference against which each estimating equation will be compared. The estimating equations will be based upon serum creatinine and/or cystatin C. The eGFR-C study has 5 components: 1) A prospective longitudinal cohort study of 1300 adults with stage 3 chronic kidney disease followed for 3 years with reference (measured) GFR and test (estimated GFR [eGFR] and urinary albumin-to-creatinine ratio) measurements at baseline and 3 years. Test measurements will also be undertaken every 6 months. The study population will include a representative sample of South-Asians and African-Caribbeans. People with diabetes and proteinuria (ACR ≥30 mg/mmol) will comprise 20-30% of the study cohort.2) A sub-study of patterns of disease progression of 375 people (125 each of Caucasian, Asian and African-Caribbean origin; in each case containing subjects at high and low risk of renal progression). Additional reference GFR measurements will be undertaken after 1 and 2 years to enable a model of disease progression and error to be built.3) A biological variability study to establish reference change values for reference and test measures.4) A modelling study of the performance of monitoring strategies on detecting progression, utilising estimates of accuracy, patterns of disease progression and estimates of measurement error from studies 1), 2) and 3).5) A comprehensive cost database for each diagnostic approach will be developed to enable cost-effectiveness modelling of the optimal strategy.The performance of the estimating equations will be evaluated by assessing bias, precision and accuracy. Data will be modelled as a linear function of time utilising all available (maximum 7) time points compared with the difference between baseline and final reference values. The percentage of participants demonstrating large error with the respective estimating equations will be compared. Predictive value of GFR estimates and albumin-to-creatinine ratio will be compared amongst subjects that do or do not show progressive kidney function decline.

DISCUSSION

The eGFR-C study will provide evidence to inform the optimal GFR estimate to be used in clinical practice.

TRIAL REGISTRATION

ISRCTN42955626.

The Oxford Renal (OxRen) cross-sectional study of chronic kidney disease in the UK

INTRODUCTION

Chronic kidney disease (CKD) diagnosed with objective measures of kidney damage and function has been recognised as a major public health burden. Independent of age, sex, ethnicity and comorbidity, strong associations exist between cardiovascular disease, mortality, morbidity and CKD, defined by reduced glomerular filtration rate and increased urinary albumin excretion. Detection of CKD within the population is therefore a priority for health systems.

METHODS AND ANALYSIS

15 000 patients aged 60 years or over meeting the inclusion criteria will be invited to the study. Recruitment will be stratified to represent the distribution of socioeconomic position in the UK general population. Patients will be excluded if terminally ill (expected survival <1 year), or if they have received a solid organ transplant. Patients will attend up to two screening visits, to determine if they have CKD, followed by an assessment visit where demographic and physiological parameters will be recorded alongside questionnaires on exercise, diet, cognitive assessment and quality of life. Blood and urine specimens will be taken for immediate routine assays as well as for freezing pending peptide and genetic studies. Patients will have office and home blood pressure measurements as well as pulse wave velocity assessment. Healthcare costs of screening and subsequent monitoring will be calculated.

ETHICS AND DISSEMINATION

The protocol and related documents have been approved by NRES Committee South Central-Oxford B-Reference 13/SC/0020.

Chronic kidney disease, albuminuria and socioeconomic status in the Health Surveys for England 2009 and 2010

BACKGROUND

Renal replacement therapy rates are inversely related to socioeconomic status (SES) in developed countries. The relationship between chronic kidney disease (CKD) and SES is less clear. This study examined the relationships between SES and CKD and albuminuria in England.

METHODS

Data from the Health Survey for England 2009 and 2010 were combined. The prevalence of CKD 3-5 and albuminuria was calculated, and logistic regression used to determine their association with five individual-level measures and one area-level measure of SES.

RESULTS

The prevalence of CKD 3-5 was 5.2% and albuminuria 8.0%. Age-sex-adjusted CKD 3-5 was associated with lack of qualifications [odds ratio (OR) 2.27 (95% confidence interval 1.40-3.69)], low income [OR 1.50 (1.02-2.21)] and renting tenure [OR 1.36 (1.01-1.84)]. Only tenure remained significant in fully adjusted models suggesting that co-variables were on the causal pathway. Albuminuria remained associated with several SES measures on full adjustment: low income [OR 1.55 (1.14-2.11)], no vehicle [OR 1.38 (1.05-1.81)], renting [OR 1.31 [1.03-1.67)] and most deprived area-level quintile [OR 1.55 (1.07-2.25)].

CONCLUSIONS

CKD 3-5 and albuminuria were associated with low SES using several measures. For albuminuria this was not explained by known measured causal factors.

The effect of rural-to-urban migration on renal function in an Indian population: cross-sectional data from the Hyderabad arm of the Indian Migration Study

Background

Urban migration is associated with an increased risk of hypertension, obesity and diabetes in Indian migrants. This study assessed the relationship between internal migration and renal function in the Hyderabad arm of the Indian Migration Study.

Methods

We assessed 841 subjects; urban non-migrants (n = 158), urban migrants (n = 424) and rural non-migrants (n = 259). Muscle mass was ascertained from DXA scanning. We derived urban life years for urban migrants and rural non-migrants. Multivariable linear regression was used to examine the association between tertiles of urban life years and 4-variable MDRD eGFR using Stata 11.

Results

Mean eGFR was lower in urban non-migrants and urban migrants compared to rural non-migrants. The prevalence of CKD 3-5 was higher in the rural non-migrant population (5.0%) than in the urban non-migrant populations (2.5%) due to a negatively skewed distribution of eGFR in rural non-migrants. As urban life years increased, eGFR declined (p = 0.008) though there was no obvious dose response effect. After adjustment for muscle mass, the association was attenuated and the trend was consistent with chance (p = 0.08). Further adjustment for vascular risk factors weakened the association to a small degree (p = 0.11).

Conclusions

The high prevalence of reduced eGFR in rural areas requires further research. Urbanization was associated with reduced eGFR. This association appears mostly to be due to higher muscle mass with a small contribution from adverse vascular disease risk factors.

Impact on cardiovascular risk follow-up from a shift to the CKD-EPI formula for eGFR reporting: a cross-sectional population-based primary care study

OBJECTIVE

To assess the impact on cardiovascular risk factor management in primary care by the introduction of chronic kidney disease epidemiological collaboration (CKD-EPI) for estimated-glomerular filtration rate (eGFR) reporting.

DESIGN AND SETTING

Cross-sectional study of routine healthcare provision in 47 primary care practices in The Netherlands with Modification of Diet and Renal Disease Study eGFR reporting.

METHODS

eGFR values were recalculated using CKD-EPI in patients with available creatine tests. Patients reclassified from CKD stage 3a to CKD stage 2 eGFR range were compared to those who remained in stage 3a for differences in demographic variables, blood pressure, comorbidity, medication usage and laboratory results.

RESULTS

Among the 60 673 adult patients (37% of adult population) with creatine values, applying the CKD-EPI equation resulted in a 16% net reduction in patients with CKD stage 3 or worse. Patients reclassified from stage 3a to 2 had lower systolic blood pressure (139.7 vs 143.3 mm Hg p<0.0001), higher diastolic blood pressure (81.5 vs 78.4 mm Hg p<0.0001) and higher cholesterol (5.4 vs 5.1 mmol/L p<0.0001) compared to those who remained in stage 3a. Of those reclassified out of a CKD diagnosis 463 (32%) had no comorbidities that would qualify for annual CVD risk factor assessment and 20 (12% of those with sufficient data) had a EuroSCORE CVD risk >20% within 10 years.

CONCLUSIONS

Use of the CKD-EPI equation will result in many patients being removed from CKD registers and the associated follow-up. Current risk factor assessment in this group may be lacking from routine data and some patients within this group are at an increased risk for cardiovascular events.

Association of chronic kidney disease (CKD) and failure to monitor renal function with adverse outcomes in people with diabetes: a primary care cohort study

Background

Chronic kidney disease (CKD) is a known risk factor for cardiovascular events and all-cause mortality. We investigate the relationship between CKD stage, proteinuria, hypertension and these adverse outcomes in the people with diabetes. We also study the outcomes of people who did not have monitoring of renal function.

Methods

A cohort of people with type 1 and 2 diabetes (N = 35,502) from the Quality Improvement in Chronic Kidney Disease (QICKD) cluster randomised trial was followed up over 2.5 years. A composite of all-cause mortality, cardiovascular events, and end stage renal failure comprised the outcome measure. A multilevel logistic regression model was used to determine correlates with this outcome. Known cardiovascular and renal risk factors were adjusted for.

Results

Proteinuria and reduced estimated glomerular filtration rate (eGFR) were independently associated with adverse outcomes in people with diabetes. People with an eGFR <60 ml/min, proteinuria, and hypertension have the greatest odds ratio (OR) of adverse outcome; 1.58 (95% CI 1.36-1.83). Renal function was not monitored in 4460 (12.6%) people. Unmonitored renal function was associated with adverse events; OR 1.35 (95% CI 1.13-1.63) in people with hypertension and OR 1.32 (95% CI 1.07-1.64) in those without.

Conclusions

Proteinuria, eGFR < 60 ml/min, and failure to monitor renal function are associated with cardiovascular and renal events and mortality in people with diabetes.

Progression of chronic kidney disease in a multi-ethnic community cohort of patients with diabetes mellitus

AIMS

Ethnicity is a risk factor for the prevalence of severe chronic kidney disease among patients with diabetes. We studied the effect of ethnicity on progression of chronic kidney disease in people with diabetes managed in community settings.

METHODS

A 5-year retrospective, community-based cohort study of 3855 people with diabetes mellitus of white, black or South Asian ethnicity with an estimated glomerular filtration rate of < 60 ml min⁻¹ 1.73 m⁻² was undertaken. From 135 general practices in east London, all cases with at least 3 years clinical data were included. Using repeated-measures analysis, the annual decline in estimated glomerular filtration rate was calculated. Comparisons between the rate of decline in the three main ethnic groups, with and without proteinuria at baseline, were made.

RESULTS

The annual adjusted decline in estimated glomerular filtration rate for this cohort was 0.85 ml min⁻¹ 1.73 m⁻². The rate of chronic kidney disease progression was significantly greater in South Asian groups (-1.01 ml min⁻¹ 1.73 m⁻²) compared with white groups (-0.70 ml min⁻¹ 1.73 m⁻²) (P = 0.001). For those with proteinuria at baseline, the annual decline was greater at 2.05 ml min⁻¹ 1.73 m⁻², with both South Asian and black groups having a significantly faster rate of decline than white groups.

CONCLUSIONS

For patients with diabetes and chronic kidney disease managed in primary care, the annual decline of renal function is less than previously thought and approximates the age-related annual decline of 1 ml min⁻¹ 1.73 m⁻². Patients with proteinuria and those of South Asian and Black ethnicity need additional monitoring as they are at greater risk of rapid chronic kidney disease progression.

Estimating the glomerular filtration rate in the general population using different equations: effects on classification and association

BACKGROUND/AIMS

Several formulas for glomerular filtration rate (GFR) estimation, based on serum creatinine or cystatin C, have been proposed. We assessed the impact of some of these equations on estimated GFR (eGFR) and chronic kidney disease (CKD) prevalence, and on the association with cardiovascular risk factors, in a general population sample characterized by a young mean age.

METHODS

We studied 1,199 individuals from three Alpine villages enrolled into the MICROS study. eGFR was obtained with the 4- and 6-parameter MDRD study equations, the Virga equation, and with the three CKD-EPI formulas for creatinine, cystatin C, and the combination of creatinine and cystatin C. We assessed the concordance between quantitative eGFR levels, CKD prevalence, and in terms of association with total, LDL, and HDL cholesterol.

RESULTS

The highest and lowest eGFR levels corresponded to the cystatin C-based and MDRD-4 equations, respectively. CKD prevalence varied from 1.8% (Virga) to 5.8% (MDRD-4). The CKD-EPI based on creatinine showed the highest agreement with all other equations. Agreement between methods was higher at lower eGFR levels, older age, and in the presence of diabetes and hypertension. Creatinine-based estimates of eGFR were associated with total and low-density lipoprotein but not high-density lipoprotein cholesterol. The opposite was observed for the cystatin C-based GFR.

CONCLUSION

GFR estimation is strongly affected by the chosen equation. Differences are more pronounced in healthy and younger individuals. To identify CKD risk factors, the choice of the equation is of secondary importance to the choice of the biomarker used in the formula. If eGFR is not calibrated to a gold standard GFR in the general population, reports about CKD prevalence should be considered with caution.

Relationship between body composition and glomerular filtration rate estimates in the general population

BACKGROUND

Differences in body composition may lead to imprecision in estimates of glomerular filtration rate (eGFR) derived from serum creatinine. Our aims were to examine the relationship between eGFR and anthropometric and body composition measures and handgrip strength.

METHODS

We analyzed data from a cross-sectional study comprising 1,630 randomly selected community-dwelling adults. The Modification of Diet in Renal Disease (MDRD) and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations were used to calculate eGFR from IMDS-standardized serum creatinine. Body mass index and body surface area were calculated from measured height and weight. Body composition was determined by dual-energy x-ray absorptiometry, handgrip strength measured by a hand-held dynamometer. Regression analysis was used to examine the association between eGFR and other factors.

RESULTS

In women, eGFR determined by the MDRD equation was inversely associated with height (β = -0.08; p = 0.012), lean mass percentage (β = -0.06; p = 0.047) and handgrip strength (β = -0.15; p < 0.001) and eGFR calculated using the CKD-EPI equation was inversely associated with handgrip strength (β = -0.08; p = 0.001). In men, there was an inverse association between eGFR by the MDRD equation and lean mass percentage (β = -0.10; p = 0.013) and handgrip strength (β = -0.12; p = 0.022) and between eGFR by the CKD-EPI equation and lean mass percentage (β = -0.07; p = 0.018). The R(2) for these variables was <0.02.

CONCLUSIONS

The inverse relationship between eGFR and measures of lean mass percentage and handgrip strength suggests that incorporation of these variables might improve eGFR prediction from serum creatinine in the general population. This effect appears to be small however and needs to be examined in studies that include measured GFR.

Informatics as tool for quality improvement: rapid implementation of guidance for the management of chronic kidney disease in England as an exemplar

Objectives

Chronic kidney disease (CKD) is an important cause of excess cardiovascular mortality and morbidity; as well as being associated with progression to end stage renal disease. This condition was largely unheard of in English primary care prior to the introduction of pay-for-performance targets for management in 2006. A realist review of how informatics has been a mechanism for national implementation of guidance for the improved management of CKD.

Methods

Realist review of context, the English National Health Service with a drive to implement explicit national quality standards; mechanism, the informatics infrastructure and its alignment with policy objectives; and outcomes are describe at the micro-data and messaging, meso-patient care and quality improvement initiatives, and marco-national policy levels.

Results

At the micro-level computerised medical records can be used to reliably identify people with CKD; though differences in creatinine assays, fluctuation in renal function, and errors in diabetes coding were less well understood. At the meso-level more aggressive management of blood pressure (BP) in individual patients appears to slow or reverse decline in renal function; technology can support case finding and quality improvement at the general practice level. At the macro-level informaticians can help ensure that leverage from informatics is incorporated in policy, and ecological investigations inform if there is any association with improved health outcomes.

Conclusions

In the right policy context informatics appears to be an enabler of rapid quality improvement. However, a causal relationship or generalisability of these findings has not been demonstrated.

Engaging primary care in CKD initiatives: the UK experience

Over the last decade, since the introduction of an international classification of chronic kidney disease (CKD) and the development of simple tools to detect people with CKD, primary care has had to adapt to a new paradigm of disease. Significantly, improved identification of CKD, and increased awareness and understanding of the potential associated adverse outcomes, has in turn required the development, implementation and integration of new policies, models and pathways of care. The UK health care system, including primary care, is uniquely positioned to respond to new initiatives. Despite early reservations, CKD has gone from an unheard of condition in primary care prior to 2006 to one where people with this condition are recorded in disease registers and increasingly managed in accordance with evidence-based guidance. National and local initiatives implemented together have contributed to the improved understanding and management of CKD in primary care in the UK and are showing signs of having made significant health gains in CKD.

Audit-based education lowers systolic blood pressure in chronic kidney disease: the Quality Improvement in CKD (QICKD) trial results

Strict control of systolic blood pressure is known to slow progression of chronic kidney disease (CKD). Here we compared audit-based education (ABE) to guidelines and prompts or usual practice in lowering systolic blood pressure in people with CKD. This 2-year cluster randomized trial included 93 volunteer general practices randomized into three arms with 30 ABE practices, 32 with guidelines and prompts, and 31 usual practices. An intervention effect on the primary outcome, systolic blood pressure, was calculated using a multilevel model to predict changes after the intervention. The prevalence of CKD was 7.29% (41,183 of 565,016 patients) with all cardiovascular comorbidities more common in those with CKD. Our models showed that the systolic blood pressure was significantly lowered by 2.41 mm Hg (CI 0.59-4.29 mm Hg), in the ABE practices with an odds ratio of achieving at least a 5 mm Hg reduction in systolic blood pressure of 1.24 (CI 1.05-1.45). Practices exposed to guidelines and prompts produced no significant change compared to usual practice. Male gender, ABE, ischemic heart disease, and congestive heart failure were independently associated with a greater lowering of systolic blood pressure but the converse applied to hypertension and age over 75 years. There were no reports of harm. Thus, individuals receiving ABE are more likely to achieve a lower blood pressure than those receiving only usual practice. The findings should be interpreted with caution due to the wide confidence intervals.

Creatinine-or cystatin C-based equations to estimate glomerular filtration in the general population: impact on the epidemiology of chronic kidney disease

Background

Chronic kidney disease (CKD) is a major issue in public health. Its prevalence has been calculated using estimation of glomerular filtration rate (GFR) by the creatinine-based equations developed in the Modified Diet in Renal Disease (MDRD) and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) study. Recently, new equations based either on cystatin C (CKD-EPI Cys) or both cystatin and creatinine (CKD-EPI mix) have been proposed by the CKD-EPI consortium. The aim of this study was to measure the difference in the prevalence of stage 3 CKD, defined as an estimated GFR less than 60 mL/min/1.73 m², in a population using these four equations.

Methods

CKD screening was performed in the Province of Liège, Belgium. On a voluntary basis, people aged over 50 years have been screened. GFR was estimated by the four equations. Stage 3 CKD was defined as a GFR less than 60 mL/min/1.73 m².

Results

The population screened consisted of 4189 people (47% were men, mean age 63 ± 7y). Their mean serum creatinine and plasma cystatin C levels were 0.88 ± 0.21 mg/dL and 0.85 ± 0.17 mg/L, respectively. The prevalence of CKD in this population using the MDRD, the CKD-EPI, the CKD-EPI Cys and the CKD-EPI mix equations was 13%, 9.8%, 4.7% and 5%, respectively. The prevalence of CKD was significantly higher with the creatinine-based (MDRD and the CKD-EPI) equations compared to the new cystatin C-based equations.

Conclusions

Prevalence of CKD varies strongly depending on the method used to estimate GFR. Such discrepancies are of importance and must be confirmed and explained by additional studies, notably by studies using GFR measured with a reference method.

Trial registration

B70720071509