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

Diagnosis codes underestimate chronic kidney disease incidence compared with eGFR-based evidence: a retrospective observational study of patients with type 2 diabetes in UK primary care

BACKGROUND

Type two diabetes (T2D) is a leading cause of both chronic kidney disease (CKD) and onward progression to end-stage renal disease. Timely diagnosis coding of CKD in patients with T2D could lead to improvements in quality of care and patient outcomes.

AIM

To assess the consistency between estimated glomerular filtration rate (eGFR)-based evidence of CKD and CKD diagnosis coding in UK primary care.

DESIGN & SETTING

A retrospective analysis of electronic health record data in a cohort of people with T2D from 60 primary care centres within England between 2012 and 2022.

METHOD

We estimated the incidence rate of CKD per 100 person-years using eGFR-based CKD and diagnosis codes. Logistic regression was applied to establish which attributes were associated with diagnosis coding. Time from eGFR-based CKD to entry of a diagnosis code was summarised using the median and interquartile range.

RESULTS

The overall incidence of CKD was 2.32 (95% confidence interval [CI] = 2.24 to 2.41) and significantly higher for eGFR-based criteria than diagnosis codes: 1.98 (95% CI = 1.90 to 2.05) versus 1.06 (95% CI = 1.00 to 1.11), respectively; P<0.001. Only 45.4% of CKD incidences identified using eGFR-based criteria had a corresponding diagnosis code. Patients who were younger, had a higher CKD stage (G4), had an observed urine albumin-to-creatinine ratio (A1), or no observed HbA1c in the past year were more likely to have a diagnosis code.

CONCLUSION

Diagnosis coding of patients with eGFR-based evidence of CKD in UK primary care is poor within patients with T2D, despite CKD being a well-known complication of diabetes.

Chronic kidney disease recognition amongst physicians and advanced practice providers

Objective

Chronic kidney disease is a worldwide public health issue, with increasing prevalence resulting in high morbidity and mortality. As a result, recognizing and treating it early can lead to improved outcomes. We hypothesized that some providers might be more comfortable making this diagnosis than others.

Methods

Retrospective study of 380 patients with chronic kidney disease seen between 2012 and 2016 in an outpatient setting.

Results

Three hundred and sixteen patients were treated by physicians and sixty-four by advanced practice providers. Chronic kidney disease was identified by the primary care providers in 318 patients (83.6%). Patients recognized with chronic kidney disease were older, 76 ± 8.8 vs 72 ± 7.45 years, p = 0.001; had lower GFR, 37 [29, 46] vs 57 [37, 76] ml/min/1.73 m², p < 0.0001 and were more likely to be seen by a physician compared to an advanced practice provider: 272/316 (86%) vs 46/64 (71.8%), p = 0.008. In multivariate analyses, care by a physician, OR = 2.27 (1.13–4.58), p = 0.02 was associated with increased recognition of chronic kidney disease. On the other hand, higher GFR was associated with decreased diagnosis of chronic kidney disease, OR = 0.95 (0.93–0.96), p < 0.0001.

Conclusion

The odds of chronic kidney disease recognition were higher amongst physicians in comparison to non-physician providers.

CKD Prevalence in the Military Health System: Coded Versus Uncoded CKD

Rationale & Objective

Chronic kidney disease (CKD) is common but often goes unrecorded.

Study Design

Cross-sectional.

Setting & Participants

Military Health System (MHS) beneficiaries aged 18 to 64 years who received care during fiscal years 2016 to 2018.

Predictors

Age, sex, active duty status, race, diabetes, hypertension, and numbers of kidney test results.

Outcomes

We defined CKD by International Classification of Diseases, Tenth Revision (ICD-10) code and/or a positive result on a validated electronic phenotype that uses estimated glomerular filtration rate and measures of proteinuria with evidence of chronicity. We defined coded CKD by the presence of an ICD-10 code. We defined uncoded CKD by a positive e-phenotype result without an ICD-10 code.

Analytical Approach

We compared coded and uncoded populations using 2-tailed t tests (continuous variables) and Pearson χ² test for independence (categorical variables).

Results

The MHS population included 3,330,893 beneficiaries. Prevalence of CKD was 3.2%, based on ICD code and/or positive e-phenotype result. Of those identified with CKD, 63% were uncoded. Compared with beneficiaries with coded CKD, those with uncoded CKD were younger (aged 45 ± 13 vs 52 ± 11 years), more often women (54.4% vs 37.6%) and active duty (20.2% vs 12.5%), and less often of Black race (18.5% vs 31.5%) or with diabetes (23.5% vs 43.5%) or hypertension (46.6% vs 77.1%; P < 0.001). Beneficiaries with coded (vs uncoded) CKD had greater numbers of kidney test results (P < 0.001).

Limitations

Use of cross-sectional administrative data prevents inferences about causality. The CKD e-phenotype may fail to capture CKD in individuals without laboratory data and may underestimate CKD.

Conclusions

The prevalence of CKD in the MHS is ~3.2%. Beneficiaries with well-known CKD risk factors, such as older age, male sex, Black race, diabetes, and hypertension, were more likely to be coded, suggesting that clinicians may be missing CKD in groups traditionally considered lower risk, potentially resulting in suboptimal care.

Impact of Using Risk-Based Stratification on Referral of Patients With Chronic Kidney Disease From Primary Care to Specialist Care in the United Kingdom

Introduction

The externally validated Kidney Failure Risk Equation (KFRE) for predicting risk of end-stage renal disease (ESRD) has been developed, but its potential impact in a population on referrals for patients with chronic kidney disease (CKD) from primary to specialty nephrology care is not known.

Methods

A cross-sectional population-based study of individuals in United Kingdom primary care registered in The Health Improvement Network database was conducted. National Institute of Health and Care Excellence (NICE) 2014 CKD guidelines versus the 4-variable KFRE set at a >3% risk of ESRD at 5 years were applied to patients identified with CKD stage 3-5 between January 1, 2016, and March 31, 2017.

Results

In all, 39,476 (36.6%) of 107,962 adults with CKD stage 3-5 had a urine albumin:creatinine ratio (ACR) available and entered into the primary analysis. Of that, 7566 (19.2%) patients fulfilled NICE criteria for referral, 2386 (31.5%) of whom had a ≤3% 5-year risk of ESRD. Also 8663 (21.9%) patients had a >3% 5-year risk of ESRD, 3483 (40.2%) of whom did not fulfill NICE criteria; this represents 8.8% of the primary population. By using the KFRE threshold rather than NICE criteria for referral, 5869 patients (14.9% of the primary analysis population) would have been reallocated between primary and specialist care. Imputational analysis was used for missing ACR measurements and showed similar results.

Conclusions

A risk-based referral approach would lead to a substantial reallocation of patients between primary care and specialist nephrology care with only a small increase in numbers eligible, ensuring those at higher risk of progression are identified.

The risk of new fragility fractures in patients with chronic kidney disease and hip fracture-a population-based cohort study in the UK

Chronic kidney disease (CKD) is a risk factor for fractures. However, in hip fracture patients, CKD G3-G5 was associated with a higher mortality risk and not associated with a higher risk of subsequent non-hip fractures compared to eGFR > 60 ml/min. The higher mortality risk may, as competing risk, explain our findings.

INTRODUCTION

Chronic kidney disease (CKD) is a known risk factor for fragility fractures. Patients aged 50+ with a recent fragility fracture have an increased risk of subsequent fractures. Our aim was to evaluate the association between CKD stages G3-G5 versus estimated glomerular filtration rate (eGFR) > 60 ml/min and the risk of a new non-hip fracture or fragility fracture in patients with a first hip fracture.

METHODS

Population-based cohort study using the UK general practices in the Clinical Practice Research Datalink. Associations between CKD stage and first subsequent fracture were determined using Cox proportional hazard analyses to estimate hazard ratios (HRs). To explore the potential competing risk of mortality, cause-specific (cs) HRs for mortality were estimated.

RESULTS

CKD G3-G5 was associated with a lower risk of any subsequent non-hip fracture (HR: 0.90, 95%CI: 0.83-0.97), but not with the risk of subsequent major non-hip fragility fracture. CKD G3-G5 was associated with a higher mortality risk (cs-HR: 1.05, 95%CI: 1.01-1.09). Mortality risk was 1.5- to 3-fold higher in patients with CKD G4 (cs-HR: 1.50, 95%CI: 1.38-1.62) and G5 (cs-HR: 2.93, 95%CI: 2.48-3.46) compared to eGFR > 60 ml/min.

CONCLUSIONS

The risk of a subsequent major non-hip fragility fractures following hip fracture was not increased in patients with CKD G3-G5 compared to eGFR > 60 ml/min. Mortality risk was higher in both hip fracture and non-hip fracture patients with CKD G4 and G5. The higher mortality risk may, as competing risk, explain our main finding of no increased or even decreased subsequent fracture risk after a hip fracture in patients with CKD G3-G5.

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.

Approaches for the identification of chronic kidney disease in CPRD-HES-linked studies

Aim: There are different methods to identify chronic kidney disease (CKD) in Clinical Practice Research Datalink (CPRD)-Hospital Episode Statistics (HES). Methods: Using CPRD-HES, nonvalvular atrial fibrillation patients were classified according to CKD category. Results: Using glomerular filtration rate/estimated glomerular filtration rate tests only to identify patients with CKD resulted in 3.5% stage 2, 2.7% stage 3, 0.3% stage 4 and 0.03% stage 5. Using data from diagnostic codes to identify patients with CKD resulted in 1.4% stage 3, 0.4% stage 4 and 0.3% stage 5. Using test records and codes resulted in 3.5% stage 2, 4.0% stage 3, 0.6% stage 4 and 0.4% stage 5. Conclusion: To identify CKD status in CPRD-HES, a combination of test records and codes should be used. Using diagnostic codes only significantly underestimates CKD prevalence.

Direct medical costs of end-stage kidney disease and renal replacement therapy: a cohort study in Guangzhou City, southern China

BACKGROUND

Renal replacement therapy was a lifesaving yet high-cost treatment for people with end-stage kidney disease (ESKD). This study aimed to estimate the direct medical costs per capita of ESKD by different treatment strategies: haemodialysis (HD); peritoneal dialysis (PD); kidney transplantation (KT) (in the first year); KT (in the second year), and by two urban health insurance schemes.

METHODS

This was a retrospective observational cohort study. Data were obtained from outpatient and inpatient claims database of two urban health insurance from Guangzhou City, Southern China. Adult patients with HD (n = 3765; mean age 58 years), PD (n = 1237; 51 years), KT (first year) (n = 117; 37 years) and KT (second year) (n = 41; 39 years) were identified between 2010 and 2012. The primary outcome was the annual per patient medical costs in 2013 Chinese Yuan (CNY) incurred in the outpatient and inpatient sectors. Secondary outcomes were annual outpatient visits and inpatient admissions, length of stay per admission. Generalized linear regression and bootstrapping statistical methods were used for analysis.

RESULTS

The estimated average annual medical costs for patients on HD were CNY 94,760.5 (US$15,066.0), 95% Confidence Interval (CI): CNY85,166.6-106,972.2, which was higher than those for patients on PD [CNY80,762.9 (US$12,840.5), 95% CI: CNY 76,249.8-85,498.9]. The estimated annual cost ratio of HD versus PD was 1.17 (95% CI: 1.12-1.25). Among the transplanted patients, the estimated average annual medical costs in the first year were CNY132,253.0 (US$21,026.9), 95%CI: CNY114,009.9-153,858.6, and in the second year were CNY93,155.3 (US$14,810.8), 95%CI: CNY61,120.6-101,989.1. The mean annual medical costs for dialysis patients under Urban Employee-based Basic Medical Insurance scheme were significantly higher than those for patients under Urban Resident-based Basic Medical Insurance scheme (P < 0.001).

CONCLUSIONS

The direct medical costs of ESKD patients were high and different by types of renal replacement therapy and insurance. The findings can be used to conduct cost-effectiveness research on different types of RRT for ESKD patients that provides economic evidence for health policy design in China.

Incidence of chronic kidney disease hospitalisations and mortality in Espírito Santo between 1996 to 2017

INTRODUCTION

Chronic kidney disease (CKD) has a set of clinical and laboratory abnormalities where renal function loss is noted. The high prevalence of comorbidity of people living with CKD, its economic impact and its prognosis have made it a public health problem, justifying the need to implement preventive measures.

OBJECTIVE

To analyse the mortality and incidence of hospital admissions for CKD.

METHODS

Ecological study with a time series design using secondary microdata of deaths and hospital admissions from patients with CKD from 1996 to 2017 in the State of Espírito Santo, Brazil.

RESULTS

The average mortality rate of CKD during the studied years was 2.92 per 100,000 inhabitants per year. During this period global mortality was a stationary phenomenon. In women, the trend of mortality from 2005 on increased 7,87% per year. Between 2008 and 2017, the average incidence hospital admissions due to CKD per year was 45.76 per 100,000 inhabitants. It was observed that the overall hospital admission increased by the equivalent of 6.23% per year. More than a half of mortality and hospitalisations correspond to male patients over 50 years of age. In terms of mortality, 32.99% corresponded to Caucasian patients, while 35.13% of hospitalisations were mixed race.

CONCLUSION

We found that age and gender are factors associated with deaths and hospitalisations for chronic kidney disease. While hospitalisation increases 6.23% per year, global mortality remains stationary. However, from 2005 onwards a trend towards increasing of 7.87%/annual in mortality was observed in women.

How do primary care doctors in England and Wales code and manage people with chronic kidney disease? Results from the National Chronic Kidney Disease Audit

Background

In the UK, primary care records are electronic and require doctors to ascribe disease codes to direct care plans and facilitate safe prescribing. We investigated factors associated with coding of chronic kidney disease (CKD) in patients with reduced kidney function and the impact this has on patient management.

Methods

We identified patients meeting biochemical criteria for CKD (two estimated glomerular filtration rates <60 mL/min/1.73 m² taken >90 days apart) from 1039 general practitioner (GP) practices in a UK audit. Clustered logistic regression was used to identify factors associated with coding for CKD and improvement in coding as a result of the audit process. We investigated the relationship between coding and five interventions recommended for CKD: achieving blood pressure targets, proteinuria testing, statin prescription and flu and pneumococcal vaccination.

Results

Of 256 000 patients with biochemical CKD, 30% did not have a GP CKD code. Males, older patients, those with more severe CKD, diabetes or hypertension or those prescribed statins were more likely to have a CKD code. Among those with continued biochemical CKD following audit, these same characteristics increased the odds of improved coding. Patients without any kidney diagnosis were less likely to receive optimal care than those coded for CKD [e.g. odds ratio for meeting blood pressure target 0.78 (95% confidence interval 0.76–0.79)].

Conclusion

Older age, male sex, diabetes and hypertension are associated with coding for those with biochemical CKD. CKD coding is associated with receiving key primary care interventions recommended for CKD. Increased efforts to incentivize CKD coding may improve outcomes for CKD patients.

Predictors of late presentation to renal dialysis: a cohort study of linked primary and secondary care records in East London

OBJECTIVES

The outcomes and experience of care for patients who start renal replacement therapy (RRT) in an unplanned manner are worse than for those who have planned care. The objective of this study was to examine the primary care predictors of unplanned starts to RRT.

DESIGN

Retrospective cohort study with linked primary care and hospital data.

SETTING

128 general practices in East London with a combined population of 1 043 346 people.

PARTICIPANTS

999 consecutive patients starting dialysis at Barts Health National Health Service Trust between September 2014 and August 2017.

PRIMARY OUTCOME MEASURES

Unplanned versus a planned start to dialysis among the cohort of 389 patients with a linked primary care record. An unplanned start to dialysis is defined as receiving nephrology care in the low clearance clinic (or equivalent) for less than 90 days. A planned start is defined as access to pre-dialysis counselling and care for at least 90 days prior to commencing dialysis.

RESULTS

The adjusted logistic regression analysis showed that the most important modifiable risk factors for unplanned dialysis were the absence of a chronic kidney disease (CKD) code in the general practice (GP) record (OR 8.02, 95% CI 3.65 to 17.63) and the absence of prescribed lipid lowering medication (OR 2.37, 95% CI 1.05 to 5.34). Other contributing factors included male gender and a greater number of long-term conditions.

CONCLUSIONS

Improving CKD coding in primary care and the additional review and clinical scrutiny associated with this may contribute to a further reduction in unplanned RRT rates.

Improving coding and primary care management for patients with chronic kidney disease: an observational controlled study in East London

BACKGROUND

The UK national chronic kidney disease (CKD) audit in primary care shows diagnostic coding in the electronic health record for CKD averages 70%, with wide practice variation. Coding is associated with improvements to risk factor management; CKD cases coded in primary care have lower rates of unplanned hospital admission.

AIM

To increase diagnostic coding of CKD (stages 3-5) and primary care management, including blood pressure to target and prescription of statins to reduce cardiovascular disease risk.

DESIGN AND SETTING

Controlled, cross-sectional study in four East London clinical commissioning groups (CCGs).

METHOD

Interventions to improve coding formed part of a larger system change to the delivery of renal services in both primary and secondary care in East London. Quarterly anonymised data on CKD coding, blood pressure values, and statin prescriptions were extracted from practice computer systems for 1-year pre- and post-initiation of the intervention.

RESULTS

Three intervention CCGs showed significant coding improvement over a 1 year period following the intervention (regression for post-intervention trend P<0.001). The CCG with highest coding rates increased from 76-90% of CKD cases coded; the lowest coding CCG increased from 52-81%. The comparison CCG showed no change in coding rates. Combined data from all practices in the intervention CCGs showed a significant increase in the proportion of cases with blood pressure achieving target levels (difference in proportion P<0.001) over the 2-year study period. Differences in statin prescribing were not significant.

CONCLUSION

Clinically important improvements to coding and management of CKD in primary care can be achieved by quality improvement interventions that use shared data to track and monitor change supported by practice-based facilitation. Alignment of clinical and CCG priorities and the provision of clinical targets, financial incentives, and educational resource were additional important elements of the intervention.

Cardiovascular, thromboembolic and renal outcomes in IgA vasculitis (Henoch-Schönlein purpura): a retrospective cohort study using routinely collected primary care data

BACKGROUND

IgA vasculitis (IgAV, Henoch-Schönlein purpura) is a small-vessel vasculitis most common in children but also occurring in adults. Case series have suggested that IgAV may be associated with cardiovascular disease and venous thromboembolism, but this has not been evaluated in population-based studies. Renal disease and hypertension are possible complications of the disease with unknown incidence.

METHODS

Using a large UK primary care database, we conducted an open retrospective matched cohort study of cardiovascular, venous thrombotic and renal outcomes in adult-onset and childhood-onset IgAV. Control participants were selected at a 2:1 ratio, matched for age and sex. Adjusted HRs (aHRs) were calculated using Cox proportional hazards models.

RESULTS

2828 patients with adult-onset IgAV and 10 405 patients with childhood-onset IgAV were compared with age-matched and sex-matched controls. There was significantly increased risk of hypertension (adult-onset aHR 1.42, 95% CI 1.19 to 1.70, p < 0.001; childhood-onset aHR 1.52, 95% CI 1.22 to 1.89, p < 0.001) and stage G3-G5 chronic kidney disease (adult-onset aHR 1.54, 95% CI 1.23 to 1.93, p < 0.001; childhood-onset aHR 1.89, 95% CI 1.16 to 3.07, p=0.010). There was no evidence of association with ischaemic heart disease, cerebrovascular disease or venous thromboembolism. All-cause mortality was increased in the adult-onset IgAV cohort compared with controls (aHR 1.27, 95% CI 1.07 to 1.50, p=0.006).

CONCLUSIONS

Patients with IgAV are at increased risk of hypertension and chronic kidney disease (CKD) compared with individuals without IgAV; analysis restricted to adult-onset IgAV patients showed increased mortality. Appropriate surveillance and risk factor modification could improve long-term outcomes in these patients.

Risk of chronic kidney disease in patients with gout and the impact of urate lowering therapy: a population-based cohort study

Background

An association between gout and renal disease is well-recognised but few studies have examined whether gout is a risk factor for subsequent chronic kidney disease (CKD). Additionally, the impact of urate-lowering therapy (ULT) on development of CKD in gout is unclear. The objective of this study was to quantify the risk of CKD stage ≥ 3 in people with gout and the impact of ULT.

Methods

This was a retrospective cohort study using data from the Clinical Practice Research Datalink (CPRD). Patients with incident gout were identified from general practice medical records between 1998 and 2016 and randomly matched 1:1 to patients without a diagnosis of gout based on age, gender, available follow-up time and practice. Primary outcome was development of CKD stage ≥ 3 based on estimated glomerular filtration rate (eGFR) or recorded diagnosis. Absolute rates (ARs) and adjusted hazard ratios (HRs) were calculated using Cox regression models. Risk of developing CKD was assessed among those prescribed ULT within 1 and 3 years of gout diagnosis.

Results

Patients with incident gout (n = 41,446) were matched to patients without gout. Development of CKD stage ≥ 3 was greater in the exposed group than in the unexposed group (AR 28.6 versus 15.8 per 10,000 person-years). Gout was associated with an increased risk of incident CKD (adjusted HR 1.78 95% CI 1.70 to 1.85). Those exposed to ULT had a greater risk of incident CKD, but following adjustment this was attenuated to non-significance in all analyses (except on 3-year analysis of women (adjusted HR 1.31 95% CI 1.09 to 1.59)).

Conclusions

This study has demonstrated gout to be a risk factor for incident CKD stage ≥ 3. Further research examining the mechanisms by which gout may increase risk of CKD and whether optimal use of ULT can reduce the risk or progression of CKD in gout is suggested.

Electronic supplementary material

The online version of this article (10.1186/s13075-018-1746-1) contains supplementary material, which is available to authorized users.

Serum free light chain levels and renal function at diagnosis in patients with multiple myeloma

Background

Renal impairment (RI) is common in multiple myeloma (MM) and is associated with poor survival. This study reports the associations between renal function and disease characteristics including serum free light chain (FLC) level at diagnosis in patients with MM.

Methods

Using data from the Medical Research Council Myeloma IX trial, a multicentre, randomized, open-label, phase III and factorial-design trial, we assessed the relationships between renal function, demographic, and disease characteristics, including serum FLC levels, in 1595 newly diagnosed MM patients. Multivariable linear regression was utilised to identify factors that were associated with renal function at diagnosis. A receiver operating characteristic curve (ROC) was used to identify the optimal threshold for serum FLC level at diagnosis to predict severe RI.

Results

52.8% of patients had an estimated glomerular filtration rate (eGFR) ≥60 ml/min/1.73 m² (no RI), 37.3% an eGFR 30–59 ml/min/1.73 m² (mild to moderate RI), and 9.8% an eGFR < 30 ml/min/1.73 m² (severe RI). In a multivariable analysis, factors independently and negatively associated with eGFR at diagnosis were: higher serum FLC level, female gender, and older age. Elevated serum FLC level at diagnosis, irrespective of the paraprotein type, was strongly associated with severe RI. Receiver operating characteristic curve analysis showed a serum FLC level of > 800 mg/L as the optimal cut-off associated with severe RI (area under curve 0.86, 95% confidence interval 0.77–0.84).

Conclusion

There was a strong relationship between higher serum FLC levels at diagnosis and the severity of RI that was irrespective of the paraprotein type. We report an increased risk of severe RI in patients presenting with serum FLC levels above 800 mg/L at diagnosis.

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.

Economic evaluation of a pre-ESRD pay-for-performance programme in advanced chronic kidney disease patients

Background

The National Health Insurance Administration in Taiwan initiated a nationwide pre-end-stage renal disease (ESRD) pay-for-performance (P4P) programme at the end of 2006 to improve quality of care for chronic kidney disease (CKD) patients. This study aimed to examine this programme's effect on patients' clinical outcomes and its cost-effectiveness among advanced CKD patients.

Methods

We conducted a longitudinal observational matched cohort study using two nationwide population-based datasets. The major outcomes of interests were incidence of dialysis, all-cause mortality, direct medical costs, life years (LYs) and incremental cost-effectiveness ratio comparing matched P4P and non-P4P advanced CKD patients. Competing-risk analysis, general linear regression and bootstrapping statistical methods were used for the analysis.

Results

Subdistribution hazard ratio (95% confidence intervals) for advanced CKD patients enrolled in the P4P programme, compared with those who did not enrol, were 0.845 (0.779-0.916) for incidence of dialysis and 0.792 (0.673-0.932) for all-cause mortality. LYs for P4P and non-P4P patients who initiated dialysis were 2.83 and 2.74, respectively. The adjusted incremental CKD-related costs and other-cause-related costs were NT$114 704 (US$3823) and NT$32 420 (US$1080) for P4P and non-P4P patients who initiated dialysis, respectively, and NT$-3434 (US$114) and NT$45 836 (US$1572) for P4P and non-P4P patients who did not initiate dialysis, respectively, during the 3-year follow-up period.

Conclusions

P4P patients had lower risks of both incidence of dialysis initiation and death. In addition, our empirical findings suggest that the P4P pre-ESRD programme in Taiwan provided a long-term cost-effective use of resources and cost savings for advanced CKD patients.

Health-Related Quality of Life Impacts Mortality but Not Progression to End-Stage Renal Disease in Pre-Dialysis Chronic Kidney Disease: A Prospective Observational Study

BACKGROUND

Chronic kidney disease (CKD) is associated with reduced health-related quality of life (HRQL). However, the relationship between pre-dialysis CKD, HRQL and clinical outcomes, including mortality and progression to end-stage renal disease (ESRD) is unclear.

METHODS

All 745 participants recruited into the Renal Impairment In Secondary Care study to end March 2014 were included. Demographic, clinical and laboratory data were collected at baseline including an assessment of HRQL using the Euroqol EQ-5D-3L. Health states were converted into an EQ-5Dindex score using a set of weighted preferences specific to the UK population. Multivariable Cox proportional hazards regression and competing risk analyses were undertaken to evaluate the association of HRQL with progression to ESRD or all-cause mortality. Regression analyses were then performed to identify variables associated with the significant HRQL components.

RESULTS

Median eGFR was 25.8 ml/min/1.73 m2 (IQR 19.6-33.7ml/min) and median ACR was 33 mg/mmol (IQR 6.6-130.3 mg/mmol). Five hundred and fifty five participants (75.7%) reported problems with one or more EQ-5D domains. When adjusted for age, gender, comorbidity, eGFR and ACR, both reported problems with self-care [hazard ratio 2.542, 95% confidence interval 1.222-5.286, p = 0.013] and reduced EQ-5Dindex score [hazard ratio 0.283, 95% confidence interval 0.099-0.810, p = 0.019] were significantly associated with an increase in all-cause mortality. Similar findings were observed for competing risk analyses. Reduced HRQL was not a risk factor for progression to ESRD in multivariable analyses.

CONCLUSIONS

Impaired HRQL is common in the pre-dialysis CKD population. Reduced HRQL, as demonstrated by problems with self-care or a lower EQ-5Dindex score, is associated with a higher risk for death but not ESRD. Multiple factors influence these aspects of HRQL but renal function, as measured by eGFR and ACR, are not among them.

Understanding tensions and identifying clinician agreement on improvements to early-stage chronic kidney disease monitoring in primary care: a qualitative study

OBJECTIVES

Since 2006, general practitioners (GPs) in England, UK, have been incentivised to keep a register and monitor patients with chronic kidney disease (CKD) stages 3-5. Despite tensions and debate around the merit of this activity, there has been little qualitative research exploring clinician perspectives on monitoring early-stage CKD in primary care. This study aimed to examine and understand a range of different healthcare professional views and experiences of identification and monitoring in primary care of early-stage CKD, in particular stage 3.

DESIGN

Qualitative design using semistructured interviews.

SETTING

National Health Service (NHS) settings across primary and secondary care in South West England, UK.

PARTICIPANTS

25 clinicians: 16 GPs, 3 practice nurses, 4 renal consultants and 2 public health physicians.

RESULTS

We identified two related overarching themes of dissonance and consonance in clinician perspectives on early-stage CKD monitoring in primary care. Clinician dissonance around clinical guidelines for CKD monitoring emanated from different interpretations of CKD and different philosophies of healthcare and moral decision-making. Clinician consonance centred on the need for greater understanding of renal decline and increasing proteinuria testing to reduce overdiagnosis and identify those patients who were at risk of progression and further morbidity and who would benefit from early intervention. Clinicians recommended adopting a holistic approach for patients with CKD representing a barometer of overall health.

CONCLUSIONS

The introduction of new National Institute for Health and Care Excellence (NICE) CKD guidelines in 2014, which focus the meaning and purpose of CKD monitoring by increased proteinuria testing and assessment of risk, may help to resolve some of the ethical and moral tensions clinicians expressed regarding the overmedicalisation of patients with a CKD diagnosis.

Results and lessons from the Spironolactone To Prevent Cardiovascular Events in Early Stage Chronic Kidney Disease (STOP-CKD) randomised controlled trial

OBJECTIVES

To determine whether low-dose spironolactone can safely lower arterial stiffness in patients with chronic kidney disease stage 3 in the primary care setting.

DESIGN

A multicentre, prospective, randomised, placebo-controlled, double-blinded study.

SETTING

11 primary care centres in South Birmingham, England.

PARTICIPANTS

Adult patients with stage 3 chronic kidney disease. Main exclusion criteria were diagnosis of diabetes mellitus, chronic heart failure, atrial fibrillation, severe hypertension, systolic blood pressure < 120 mm Hg or baseline serum potassium ≥ 5 mmol/L.

INTERVENTION

Eligible participants were randomised to receive either spironolactone 25 mg once daily, or matching placebo for an intended period of 40 weeks.

OUTCOME MEASURES

The primary end point was the change in arterial stiffness as measured by pulse wave velocity. Secondary outcome measures included the rate of hyperkalaemia, deterioration of renal function, barriers to participation and expected recruitment rates to a potential future hard end point study.

RESULTS

From the 11 practices serving a population of 112,462, there were 1598 (1.4%) patients identified as being eligible and were invited to participate. Of these, 134 (8.4%) attended the screening visit of which only 16 (1.0%) were eligible for randomisation. The main reasons for exclusion were low systolic blood pressure (<120 mm Hg: 40 patients) and high estimated glomerular filtration rate (≥ 60 mL/min/1.73 m(2): 38 patients). The trial was considered unfeasible and was terminated early.

CONCLUSIONS

We highlight some of the challenges in undertaking research in primary care including patient participation in trials. This study not only challenged our preconceptions, but also provided important learning for future research in this large and important group of patients.

TRIAL REGISTRATION NUMBER

ISRCTN80658312.

Early chronic kidney disease: diagnosis, management and models of care

Chronic kidney disease (CKD) is prevalent in many countries, and the costs associated with the care of patients with end-stage renal disease (ESRD) are estimated to exceed US$1 trillion globally. The clinical and economic rationale for the design of timely and appropriate health system responses to limit the progression of CKD to ESRD is clear. Clinical care might improve if early-stage CKD with risk of progression to ESRD is differentiated from early-stage CKD that is unlikely to advance. The diagnostic tests that are currently used for CKD exhibit key limitations; therefore, additional research is required to increase awareness of the risk factors for CKD progression. Systems modelling can be used to evaluate the impact of different care models on CKD outcomes and costs. The US Indian Health Service has demonstrated that an integrated, system-wide approach can produce notable benefits on cardiovascular and renal health outcomes. Economic and clinical improvements might, therefore, be possible if CKD is reconceptualized as a part of primary care. This Review discusses which early CKD interventions are appropriate, the optimum time to provide clinical care, and the most suitable model of care to adopt.

Timeliness in chronic kidney disease and albuminuria identification: a retrospective cohort study

Background

Chronic kidney disease (CKD) is predominantly managed in primary care in the UK, but there is evidence of under-identification leading to lack of inclusion on practice chronic disease registers, which are necessary to ensure disease monitoring. Guidelines for CKD patients recommend urinary albumin to creatinine ratio (uACR) testing to identify albuminuria to stratify risk and guide management. This study aimed to describe the pattern and associations of timely CKD registration and uACR testing.

Methods

A retrospective cohort of individuals with incident CKD 3–5 (two estimated glomerular filtration rates (eGFR) <60 ml/min/1.73 m² ≥ three months apart) between 2007 and 2013 was identified from a linked database containing primary and secondary care data. Descriptive statistics and Cox proportional hazards models were used to identify associations with patient characteristics of timely CKD registration and uACR testing (within a year of first low eGFR).

Results

12,988 people with CKD 3–5 were identified from 88 practices and followed for median 3.3 years. During this time period, 3235 (24.9%) were CKD-registered and 4638/12,988 (35.7%) had uACR testing (median time to CKD registration 307 days and to uACR test 379 days). 1829 (14.1%) were CKD-registered and 2229 (17.2%) had uACR testing within one year. Amongst people whose CKD was registered within a year, 676/1829 (37.0%) had uACR testing within a year (vs. 1553/11,159 (13.9%) of those not registered (p < 0.001)). Timely uACR testing varied by year, with a sharp rise in proportion in 2009 (when uACR policy changed). Timely CKD registration was independently associated with lower eGFR, being female, earlier year of joining the cohort, having diabetes, hypertension, or cardiovascular disease but not with age. Timely uACR testing was associated with timely CKD registration, younger age, having diabetes, higher baseline eGFR and later year of joining the cohort.

Conclusions

Better systems are needed to support timely CKD identification, registration and uACR testing in primary care in order to facilitate risk stratification and appropriate clinical management.

Electronic supplementary material

The online version of this article (doi:10.1186/s12875-015-0235-8) contains supplementary material, which is available to authorized users.