Comparative Effectiveness of Dynamic Treatment Strategies for Medication Use and Dosage: Emulating a Target Trial Using Observational Data

BACKGROUND

Availability of detailed data from electronic health records (EHRs) has increased the potential to examine the comparative effectiveness of dynamic treatment strategies using observational data. Inverse probability (IP) weighting of dynamic marginal structural models can control for time-varying confounders. However, IP weights for continuous treatments may be sensitive to model choice.

METHODS

We describe a target trial comparing strategies for treating anemia with darbepoetin in hemodialysis patients using EHR data from the UK Renal Registry 2004 to 2016. Patients received a specified dose (microgram/week) or did not receive darbepoetin. We compared 4 methods for modeling time-varying treatment: (A) logistic regression for zero dose, standard linear regression for log dose; (B) logistic regression for zero dose, heteroscedastic linear regression for log dose; (C) logistic regression for zero dose, heteroscedastic linear regression for log dose, multinomial regression for patients who recently received very low or high doses; and (D) ordinal logistic regression.

RESULTS

For this dataset, method (C) was the only approach that provided a robust estimate of the mortality hazard ratio (HR), with less-extreme weights in a fully weighted analysis and no substantial change of the HR point estimate after weight truncation. After truncating IP weights at the 95th percentile, estimates were similar across the methods.

CONCLUSIONS

EHR data can be used to emulate target trials estimating the comparative effectiveness of dynamic strategies adjusting treatment to evolving patient characteristics. However, model checking, monitoring of large weights, and adaptation of model strategies to account for these is essential if an aspect of treatment is continuous.

Medication Holds in CKD During Acute Volume-Depleting Illnesses: A Randomized Controlled Trial of a "Sick-Day" Protocol

Rationale & Objective

Some drugs prescribed for chronic kidney disease (CKD) may become hazardous on sick days with volume depletion by increasing the risk of acute kidney injury (AKI) and kidney function loss; however, the risks and benefits of their use during intercurrent illness is unknown.

Study Design

6-month pragmatic trial examining a sick-day protocol to determine if withholding prespecified drugs during a volume-depleting illness reduces the incidence AKI or kidney function loss in CKD.

Setting & Participants

315 veterans with stage 3-5 CKD, treated with a renin-angiotensin-aldosterone inhibitor blocker, diuretic, nonsteroidal anti-inflammatory drug, or metformin were randomized into the study with n = 159 and n = 156 in sick-day protocol and usual care groups, respectively.

Intervention

Sick-day protocol administered via interactive voice response system (IVRS) or usual care with 6-month follow-up.

Outcomes

The outcomes of the study are as follows: (1) Change in kidney function, (2) incidence of AKI based on International Classification of Diseases, Tenth Revision codes and ambulatory laboratory testing, (3) urgent service utilizations, and (4) sick days.

Results

The mean age was 70.1 ± 7.4 and 69.2 ± 8.1 years, with a mean baseline glomerular filtration rate (GFR) of 43.1 ± 13.1 and 43.8 ± 13.0 mL/min/1.73 m2, and 112 (70%) and 100 (64%) of participants with diabetes in the sick-day protocol and usual care groups, respectively. The mean change in GFR in the sick-day protocol and usual care groups from baseline to 6-month follow-up, adjusting for baseline GFR, was -0.71 (95% CI, -2.11 to 0.69) and -0.72 (95% CI, -2.12 to 0.68), respectively, with no significant difference, P = 0.99. Hospitalizations in the sick-day protocol and usual care groups were 11.5/100 and 8.4/100 events per person-months, respectively, with the adjusted rate ratio not significantly increased (prevalence ratio, 1.30; 95% CI, 0.96-1.76). Participants interacted with the IVRS in 81% of expected weeks and 19 had one or more qualifying events. In 33 true sick days, participants correctly followed the protocol in only 14.

Limitations

Low incidence of sick days over the 6-month period of the study.

Conclusions

The sick-day protocol was not associated with a significant reduction in AKI episodes or kidney function loss in a high-risk CKD population. Engagement with the IVRS was high, but successful implementation of the sick-day protocol was not optimal.

Trial Registration

ClinicalTrials.gov; NCT03141905.

Abstract 52: KDIGO (Kidney Disease: Improving Global Outcomes) Guideline Update On The Management Of Blood Pressure In Chronic Kidney Disease: What’s New And What’s Different From Other Guidelines

Introduction: In 2012, KDIGO released a guideline on BP management in CKD not receiving dialysis. The emergence of new trials and meta-analyses coupled with wider recognition of the importance of standardized BP measurement protocols have prompted a call to update the 2012 guideline. This summary will outline the changes to the prior recommendations and highlight similarities to guidelines from ACC/AHA and ESC/ESH.

Methods: A systematic review was undertaken to formally assess the following issues: 1) BP measurement; 2) lifestyle interventions; BP management in 3) patients with CKD, with and without diabetes, 4) kidney transplant recipients, and 5) children with CKD.

Results: A total of 6863 citations were screened. Of these, 290 RCTs, 14 observational studies, and 35 systematic reviews were included in the evidence review. A major addition to the KDIGO 2021 guideline is a chapter devoted to BP measurement. KDIGO recommends the use of standardized office BP over routine BP. Out-of-office measurements (ABPM, HBPM) can be used to complement standardized readings. This emphasis on standardized office BP measurement is similar to recommendations from ACC/AHA and ESC/ESH. A systolic BP target of <120 mm Hg is suggested; however, the guidance emphasizes that the target is only applicable when BP is measured using standardized office protocols. RASi are the preferred agents for adults with CKD with increased albuminuria. For lifestyle interventions, dietary sodium intake should be limited to <2 g/day, and ≥150 minutes/week of physical activity is recommended. A BP target of <130/80 mm Hg and use of CCB or ARB are preferred in kidney transplant recipients. BP in children with CKD should be guided by 24-hour MAP using ambulatory monitoring, targeting ≤50th percentile for age, sex, and height. Similar to ACC/AHA and ESC/ESH guidelines, KDIGO also encourages shared-decision making between patients and clinicians in the individualization of BP therapy.

Conclusions: KDIGO has revised its guideline for BP management in CKD based on a rigorous development process and emerging new evidence underscoring the importance of standardized office BP measurement and a lower systolic BP target of <120 mm Hg for achieving potential cardiovascular, kidney, and mortality benefits.

Changes in quality of life (QoL) and other patient-reported outcome measures (PROMs) in living-donor and deceased-donor kidney transplant recipients and those awaiting transplantation in the UK ATTOM programme: a longitudinal cohort questionnaire survey with additional qualitative interviews

OBJECTIVE

To examine quality of life (QoL) and other patient-reported outcome measures (PROMs) in kidney transplant recipients and those awaiting transplantation.

DESIGN

Longitudinal cohort questionnaire surveys and qualitative semi-structured interviews using thematic analysis with a pragmatic approach.

SETTING

Completion of generic and disease-specific PROMs at two time points, and telephone interviews with participants UK-wide.

PARTICIPANTS

101 incident deceased-donor (DD) and 94 incident living-donor (LD) kidney transplant recipients, together with 165 patients on the waiting list (WL) from 18 UK centres recruited to the Access to Transplantation and Transplant Outcome Measures (ATTOM) programme completed PROMs at recruitment (November 2011 to March 2013) and 1 year follow-up. Forty-one of the 165 patients on the WL received a DD transplant and 26 received a LD transplant during the study period, completing PROMs initially as patients on the WL, and again 1 year post-transplant. A subsample of 10 LD and 10 DD recipients participated in qualitative semi-structured interviews.

RESULTS

LD recipients were younger, had more educational qualifications and more often received a transplant before dialysis. Controlling for these and other factors, cross-sectional analyses at 12 months post-transplant suggested better QoL, renal-dependent QoL and treatment satisfaction for LD than DD recipients. Patients on the WL reported worse outcomes compared with both transplant groups. However, longitudinal analyses (controlling for pre-transplant differences) showed that LD and DD recipients reported similarly improved health status and renal-dependent QoL (p<0.01) pre-transplant to post-transplant. Patients on the WL had worsened health status but no change in QoL. Qualitative analyses revealed transplant recipients' expectations influenced their recovery and satisfaction with transplant.

CONCLUSIONS

While cross-sectional analyses suggested LD kidney transplantation leads to better QoL and treatment satisfaction, longitudinal assessment showed similar QoL improvements in PROMs for both transplant groups, with better outcomes than for those still wait-listed. Regardless of transplant type, clinicians need to be aware that managing expectations is important for facilitating patients' adjustment post-transplant.

Obesity, Sex, Race, and Early Onset Hypertension

Investigation for secondary causes is recommended in early onset hypertension. However, obesity is associated with higher blood pressure (BP), so investigation for alternative secondary causes may not be necessary in all obese patients. We sought to define a rational approach to investigation across strata of age, body mass index (BMI) sex and race, based on BP distributions in the US National Health and Nutrition Examination Surveys 2005 to 2016. The majority (71% [95% CI, 59%–79%] and 64% [95% CI, 57%–69%] by European and US definitions respectively) of early onset hypertension cases were attributable to BP distribution shifts accompanying obesity and male sex. Male versus female sex, BMI>40 versus 18.2<BMI≤25 and Black versus White race were accompanied by adjusted mean systolic BP differences of 9 (95% CI, 8–9) mm Hg, 13 (95% CI, 12–15) mm Hg, and 3 (95% CI, 2–4) mm Hg respectively. Normal BMI women above the age cutoff for investigation were less likely to be hypertensive than obese younger men meeting current investigation criteria ( P <0.001). Targeting investigations to combinations of sex, BMI, and age with low hypertension prevalence would reduce the number investigated while still identifying as many secondary cases. Limiting investigations to patients with a BP exceeded by ≤5% of their respective sex/BMI/age category would give investigation thresholds ranging from ≥130/≥80 and ≥140/≥90 for normal BMI women and men, respectively, at age 20 to 30 years, to ≥160/≥100 and ≥170/≥105 for women and men with BMI ≥40 at age 30 to 40 years. In conclusion, we propose refined strategies for investigation of early onset hypertension in the context of an obesity epidemic.

Inequity in Access to Transplantation in the United Kingdom

BACKGROUND AND OBJECTIVES

Despite the presence of a universal health care system, it is unclear if there is intercenter variation in access to kidney transplantation in the United Kingdom. This study aims to assess whether equity exists in access to kidney transplantation in the United Kingdom after adjustment for patient-specific factors and center practice patterns.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In this prospective, observational cohort study including all 71 United Kingdom kidney centers, incident RRT patients recruited between November 2011 and March 2013 as part of the Access to Transplantation and Transplant Outcome Measures study were analyzed to assess preemptive listing (n=2676) and listing within 2 years of starting dialysis (n=1970) by center.

RESULTS

Seven hundred and six participants (26%) were listed preemptively, whereas 585 (30%) were listed within 2 years of commencing dialysis. The interquartile range across centers was 6%-33% for preemptive listing and 25%-40% for listing after starting dialysis. Patient factors, including increasing age, most comorbidities, body mass index >35 kg/m², and lower socioeconomic status, were associated with a lower likelihood of being listed and accounted for 89% and 97% of measured intercenter variation for preemptive listing and listing within 2 years of starting dialysis, respectively. Asian (odds ratio, 0.49; 95% confidence interval, 0.33 to 0.72) and Black (odds ratio, 0.43; 95% confidence interval, 0.26 to 0.71) participants were both associated with reduced access to preemptive listing; however Asian participants were associated with a higher likelihood of being listed after starting dialysis (odds ratio, 1.42; 95% confidence interval, 1.12 to 1.79). As for center factors, being registered at a transplanting center (odds ratio, 3.1; 95% confidence interval, 2.36 to 4.07) and a universal approach to discussing transplantation (odds ratio, 1.4; 95% confidence interval, 1.08 to 1.78) were associated with higher preemptive listing, whereas using a written protocol was associated negatively with listing within 2 years of starting dialysis (odds ratio, 0.7; 95% confidence interval, 0.58 to 0.9).

CONCLUSIONS

Patient case mix accounts for most of the intercenter variation seen in access to transplantation in the United Kingdom, with practice patterns also contributing some variation. Socioeconomic inequity exists despite having a universal health care system.

Health literacy and patient outcomes in chronic kidney disease: a systematic review

Background

Limited health literacy affects 25% of people with chronic kidney disease (CKD), and may reduce self-management skills resulting in poorer clinical outcomes. By disproportionately affecting people with low socio-economic status and non-white ethnicity, limited health literacy may promote health inequity.

Methods

We performed a systematic review of quantitative studies of health literacy and clinical outcomes among adults with CKD.

Results

A total of 29 studies (13 articles; 16 conference abstracts) were included. One included non-USA patients. Of the 29 studies, 5 were cohort studies and 24 were cross-sectional. In all, 18 300 patients were studied: 4367 non-dialysis CKD; 13 202 dialysis; 390 transplant; 341 unspecified. Median study size was 127 [interquartile range (IQR) 92-238)], but 480 (IQR 260-2392) for cohort studies. Median proportion of non-white participants was 48% (IQR 17-70%). Six health literacy measures were used. Outcomes included patient attributes, care processes, clinical/laboratory parameters and 'hard' clinical outcomes. Limited health literacy was significantly, independently associated with hospitalizations, emergency department use, missed dialysis sessions, cardiovascular events and mortality (in cohort studies). Study quality was high (1 study), moderate (3 studies) and poor (25 studies), limited by sampling methods, variable adjustment for confounders and reduced methodological detail given in conference abstracts.

Conclusions

There is limited robust evidence of the causal effects of health literacy on patient outcomes in CKD. Available evidence suggests associations with adverse clinical events, increased healthcare use and mortality. Prospective studies are required to determine the causal effects of health literacy on outcomes in CKD patients, and examine the relationships between socio-economic status, comorbidity, health literacy and CKD outcomes. Intervention development and evaluation will determine whether health literacy is a modifiable determinant of poor outcomes in CKD.

Effect of renin-angiotensin-aldosterone system blockade in adults with diabetes mellitus and advanced chronic kidney disease not on dialysis: a systematic review and meta-analysis

The presumed superiority of renin-angiotensin-aldosterone system (RAAS)-blocking agents over other antihypertensive agents in patients with diabetes to delay development of end-stage kidney disease (ESKD) has recently been challenged. In addition, there is ongoing uncertainty whether RAAS-blocking agents reduce mortality and/or delay ESKD in patients with diabetes and chronic kidney disease (CKD) stages 3-5. In this subgroup, there might be an expedited need for renal replacement therapy (RRT) when RAAS-blocking agents are used. We conducted a meta-analysis of randomized controlled trials (RCTs) of at least 6-months duration in adult patients with diabetes who also have non-dialysis CKD stages 3-5. RCTs comparing single RAAS-blocking agents to placebo or alternative antihypertensive agents were included. Outcomes of interest were all-cause mortality, cardiovascular morbidity, progression of renal function, ESKD and adverse events. A total of nine trials (n = 9797 participants with CKD stages 3-5) fit our inclusion criteria. There was no difference between the RAAS group and control group regarding all-cause mortality {relative risk [RR] = 0.97 [95% confidence interval (CI) 0.85-1.10]}, cardiovascular mortality [RR = 1.03 (95% CI 0.75-1.41)] and adverse events [RR = 1.05 (95% CI 0.89-1.25)]. There was a trend for a favourable effect for non-fatal cardiovascular events [RR = 0.90 (95% CI 0.81-1.00)] and a lower risk of the composite endpoint need for RRT/doubling of serum creatinine [RR = 0.81 (95% CI 0.70-0.92)] in the RAAS-blocking agents group versus the control group. We found evidence that in patients with diabetes mellitus and CKD stages 3-5, treatment with RAAS-blocking agents did not result in a clear survival advantage. The effect on renal outcomes did depend on the selected outcome measure. However, we did not find evidence that the use of RAAS-blocking agents expedited the need for RRT in patients with CKD stages 3-5.

Acute kidney injury and 'nephrotoxins': mind your language

The introduction of the term 'acute kidney injury' (AKI) along with an international classification scheme,1 caused some initial confusion, but most clinicians and many patients now understand that the term 'injury' denotes damage to the internal workings of the kidney, rather than physical trauma. However, of greater concern is the use of the term 'nephrotoxic' to include drugs that are, in most settings, nephroprotective. We argue that this imprecise terminology, unfortunately adopted by the National Institute for Health and Care Excellence (NICE) among others, is potentially harmful, and that the terms 'nephrotoxin' and 'nephrotoxic' should not be used to describe haemodynamically mediated and fully reversible effects of some drugs on excretory function.

Renal albumin excretion in healthy young adults and its association with mortality risk in the US population

Background

Current classification systems do not specify a healthy normal range for urinary albumin excretion. Occult microvascular disease induced by a Western lifestyle may mean that normal values for apparently healthy adults exceed optimal levels defined by mortality risk.

Methods

Using a national population sample [the US Third National Health and Nutrition Examination Survey (NHANES III) cohort; n = 11 887], the distributions of albumin:creatinine ratio (ACR) and fractional excretion of albumin (FEalb) were studied in healthy young adults [ages 20–40 years, without cardiovascular disease (CVD) or risk factors]. The threshold for mortality risk prediction in the whole adult population sample was then studied across ACR/FEalb categories corresponding to quartiles for healthy young adults.

Results

ACR quartiles for healthy young adults were 2.7, 4.2 and 5.9 mg/g in men and 3.8, 6.2 and 9.8 mg/g in women. Increases in ACR below the medians for healthy young adults were not associated with increased mortality or with cardiovascular risk factors when tested in the whole adult population. Increases above this threshold were independently associated with mortality risk [hazard ratio 1.2 (95% confidence interval 1.1–1.4) and 1.8 (1.6–2.0) for Quartiles 3 and 4, respectively]. The prevalence of an optimal ACR below the mortality risk threshold was &lt;25% in the setting of diabetes, hypertension, age &gt;70 years or CVD. Using FEalb to define quartiles of albuminuria gave the same findings.

Conclusion

Based on mortality risk in the whole adult population, there is an optimal range of albumin excretion (ACR &lt; 6 mg/g and 4 mg/g for women and men, respectively). However, only half of even apparently healthy young US adults fall within this range.

Limited health literacy in advanced kidney disease

Limited health literacy may reduce the ability of patients with advanced kidney disease to understand their disease and treatment and take part in shared decision making. In dialysis and transplant patients, limited health literacy has been associated with low socioeconomic status, comorbidity, and mortality. Here, we investigated the prevalence and associations of limited health literacy using data from the United Kingdom-wide Access to Transplantation and Transplant Outcome Measures (ATTOM) program. Incident dialysis, incident transplant, and transplant wait-listed patients ages 18 to 75 were recruited from 2011 to 2013 and data were collected from patient questionnaires and case notes. A score >2 in the Single-Item Literacy Screener was used to define limited health literacy. Univariate and multivariate analyses were performed to identify patient factors associated with limited health literacy. We studied 6842 patients, 2621 were incident dialysis, 1959 were wait-listed, and 2262 were incident transplant. Limited health literacy prevalence was 20%, 15%, and 12% in each group, respectively. Limited health literacy was independently associated with low socioeconomic status, poor English fluency, and comorbidity. However, transplant wait-listing, preemptive transplantation, and live-donor transplantation were associated with increasing health literacy.

Erythropoiesis-stimulating agent dosing, haemoglobin and ferritin levels in UK haemodialysis patients 2005-13

Background: Erythropoiesis-stimulating agents (ESAs) with intravenous iron supplementation are the main treatment for anaemia in patients with chronic kidney disease. Although observational studies suggest better outcomes for patients who achieve higher haemoglobin (Hb) levels, randomized controlled trials comparing higher and lower Hb targets have led to safety concerns over higher targets and to changes in treatment guidelines.

Methods: Quarterly data from 2005 to 2013 were obtained on 28 936 haemodialysis patients from the UK Renal Registry. We examined trends in ESA use and average dose, Hb and ferritin values over time and Hb according to the UK Renal Association guideline range.

Results: The average ESA dose declined over time, with sharper decreases of epoetin seen towards the end of 2006 and from 2009. Average Hb for patients on ESAs was 114.1 g/L [95% confidence interval (CI) 113.7, 114.6] in the first quarter of 2005, which decreased to 109.6 g/L (95% CI 109.3, 109.9) by the end of 2013. Average serum ferritin was 353 µg/L (95% CI 345, 360) at the start of 2005, increasing to 386 µg/L (95% CI 380, 392) in the final quarter of 2013. The percentage of patients with Hb in the range of 100–120 g/L increased from 46.1 at the start of 2005 to 57.6 at the end of 2013.

Conclusions: Anaemia management patterns for haemodialysis patients changed in the UK between 2005 and 2013. These patterns most likely reflect clinician response to emerging trial evidence and practice guidelines. Registries play an important role in continued observation of anaemia management and will monitor further changes as new evidence on optimal care emerges.

What are the risks and benefits of temporarily discontinuing medications to prevent acute kidney injury? A systematic review and meta-analysis

OBJECTIVES

To summarise evidence on temporary discontinuation of medications to prevent acute kidney injury (AKI).

DESIGN

Systematic review and meta-analysis of randomised and non-randomised studies.

PARTICIPANTS

Adults taking diuretics, ACE inhibitors (ACEI), angiotensin receptor blockers (ARB), direct renin inhibitors, non-steroidal anti-inflammatories, metformin or sulfonylureas, experiencing intercurrent illnesses, radiological or surgical procedures.

INTERVENTIONS

Temporary discontinuation of any of the medications of interest.

PRIMARY AND SECONDARY OUTCOME MEASURES

Risk of AKI. Secondary outcome measures were estimated glomerular filtration rate and creatinine post-AKI, urea, systolic and diastolic blood pressure, death, clinical outcomes and biomarkers.

RESULTS

6 studies were included (1663 participants), 3 randomised controlled trials (RCTs) and 3 prospective cohort studies. The mean age ranged from 65 to 73 years, and the proportion of women ranged from 31% to 52%. All studies were in hospital settings; 5 evaluated discontinuation of medication prior to coronary angiography and 1 prior to cardiac surgery. 5 studies evaluated discontinuation of ACEI and ARBs and 1 small cohort study looked at discontinuation of non-steroidal anti-inflammatory drugs. No studies evaluated discontinuation of medication in the community following an acute intercurrent illness. There was an increased risk of AKI of around 15% in those in whom medication was continued compared with those in whom it was discontinued (relative risk (RR) 1.17, 95% CI 0.99 to 1.38; 5 studies). When only results from RCTs were pooled, the increase in risk was almost 50% (RR 1.48, 95% CI 0.84 to 2.60; 3 RCTs), but the CI was wider. There was no difference between groups for any secondary outcomes.

CONCLUSIONS

There is low-quality evidence that withdrawal of ACEI/ARBs prior to coronary angiography and cardiac surgery may reduce the incidence of AKI. There is no evidence of the impact of drug cessation interventions on AKI incidence during intercurrent illness in primary or secondary care.

TRIAL REGISTRATION NUMBER

PROSPERO CRD42015023210.

Development of guidance on the timeliness in response to acute kidney injury warning stage test results for adults in primary care: an appropriateness ratings evaluation

OBJECTIVES

Tackling the harm associated with acute kidney injury (AKI) is a global priority. In England, a national computerised AKI algorithm is being introduced across the National Health Service (NHS) to drive this change. The study sought to maximise its clinical utility and minimise the potential for burden on clinicians and patients in primary care.

DESIGN

An appropriateness ratings evaluation using the RAND/UCLA Appropriateness Method.

SETTING

Clinical scenarios were developed to test the timeliness in (1) communication of AKI warning stage test results from clinical pathology services to primary care, and (2) primary care clinician response to an AKI warning stage test result.

PARTICIPANTS

A 10-person panel was purposively sampled with representation from clinical biochemistry, acute and emergency medicine and general practice. General practitioners (GPs) represented typical practice in relation to rural and urban practice, out of hours care, GP commissioning and those interested in reducing the impact of medicalisation and 'overdiagnosis'.

RESULTS

There was agreement that delivery of AKI warning stage test results through interruptive methods of communication (ie, telephone) from laboratories to primary care was the appropriate next step for patients with an AKI warning stage 3 test result. In the context of acute illness, waiting up to 72 hours to respond to an AKI warning stage test result was deemed an inappropriate action in 62 out of the 65 (94.5%) cases. There was agreement that a clinician response was required within 6 hours, or less, in 39 out of 40 (97.5%) clinical cases relating AKI warning stage test results in the presence of moderate hyperkalaemia.

CONCLUSIONS

The study has informed national guidance to support a timely and calibrated response to AKI warning stage test results for adults in primary care. Further research is needed to support effective implementation, with a view to examine the effect on health outcomes and costs.

CKD Prevalence Varies across the European General Population

CKD prevalence estimation is central to CKD management and prevention planning at the population level. This study estimated CKD prevalence in the European adult general population and investigated international variation in CKD prevalence by age, sex, and presence of diabetes, hypertension, and obesity. We collected data from 19 general-population studies from 13 European countries. CKD stages 1-5 was defined as eGFR<60 ml/min per 1.73 m(2), as calculated by the CKD-Epidemiology Collaboration equation, or albuminuria >30 mg/g, and CKD stages 3-5 was defined as eGFR<60 ml/min per 1.73 m(2) CKD prevalence was age- and sex-standardized to the population of the 27 Member States of the European Union (EU27). We found considerable differences in both CKD stages 1-5 and CKD stages 3-5 prevalence across European study populations. The adjusted CKD stages 1-5 prevalence varied between 3.31% (95% confidence interval [95% CI], 3.30% to 3.33%) in Norway and 17.3% (95% CI, 16.5% to 18.1%) in northeast Germany. The adjusted CKD stages 3-5 prevalence varied between 1.0% (95% CI, 0.7% to 1.3%) in central Italy and 5.9% (95% CI, 5.2% to 6.6%) in northeast Germany. The variation in CKD prevalence stratified by diabetes, hypertension, and obesity status followed the same pattern as the overall prevalence. In conclusion, this large-scale attempt to carefully characterize CKD prevalence in Europe identified substantial variation in CKD prevalence that appears to be due to factors other than the prevalence of diabetes, hypertension, and obesity.

Methodology used in studies reporting chronic kidney disease prevalence: a systematic literature review

Background

Many publications report the prevalence of chronic kidney disease (CKD) in the general population. Comparisons across studies are hampered as CKD prevalence estimations are influenced by study population characteristics and laboratory methods.

Methods

For this systematic review, two researchers independently searched PubMed, MEDLINE and EMBASE to identify all original research articles that were published between 1 January 2003 and 1 November 2014 reporting the prevalence of CKD in the European adult general population. Data on study methodology and reporting of CKD prevalence results were independently extracted by two researchers.

Results

We identified 82 eligible publications and included 48 publications of individual studies for the data extraction. There was considerable variation in population sample selection. The majority of studies did not report the sampling frame used, and the response ranged from 10 to 87%. With regard to the assessment of kidney function, 67% used a Jaffe assay, whereas 13% used the enzymatic assay for creatinine determination. Isotope dilution mass spectrometry calibration was used in 29%. The CKD-EPI (52%) and MDRD (75%) equations were most often used to estimate glomerular filtration rate (GFR). CKD was defined as estimated GFR (eGFR) <60 mL/min/1.73 m² in 92% of studies. Urinary markers of CKD were assessed in 60% of the studies. CKD prevalence was reported by sex and age strata in 54 and 50% of the studies, respectively. In publications with a primary objective of reporting CKD prevalence, 39% reported a 95% confidence interval.

Conclusions

The findings from this systematic review showed considerable variation in methods for sampling the general population and assessment of kidney function across studies reporting CKD prevalence. These results are utilized to provide recommendations to help optimize both the design and the reporting of future CKD prevalence studies, which will enhance comparability of study results.

Access to Transplantation and Transplant Outcome Measures (ATTOM): study protocol of a UK wide, in-depth, prospective cohort analysis

INTRODUCTION

There is significant intercentre variability in access to renal transplantation in the UK due to poorly understood factors. The overarching aims of this study are to improve equity of access to kidney and kidney-pancreas transplantation across the UK and to optimise organ allocation to maximise the benefit and cost-effectiveness of transplantation.

METHODS AND ANALYSIS

6844 patients aged 18-75 years starting dialysis and/or receiving a transplant together with matched patients active on the transplant list from all 72 UK renal units were recruited between November 2011 and March 2013 and will be followed for at least 3 years. The outcomes of interest include patient survival, access to the transplant list, receipt of a transplant, patient-reported outcome measures (PROMs) including quality of life, treatment satisfaction, well-being and health status on different forms of renal replacement therapy. Sociodemographic and clinical data were prospectively collected from case notes and from interviews with patients and local clinical teams. Qualitative process exploration with clinical staff will help identify unit-specific factors that influence access to renal transplantation. A health economic analysis will explore costs and outcomes associated with alternative approaches to organ allocation. The study will deliver: (1) an understanding of patient and unit-specific factors influencing access to renal transplantation in the UK, informing potential changes to practices and policies to optimise outcomes and reduce intercentre variability; (2) a patient-survival probability model to standardise access to the renal transplant list and (3) an understanding of PROMs and health economic impact of kidney and kidney-pancreas transplantation to inform the development of a more sophisticated and fairer organ allocation algorithm.

ETHICS AND DISSEMINATION

The protocol has been independently peer reviewed by National Institute for Health Research (NIHR) and approved by the East of England Research Ethics Committee. The results will be published in peer-reviewed journals and presented at conferences.

Better the donor you know? A qualitative study of renal patients' views on 'altruistic' live-donor kidney transplantation

BACKGROUND

In the UK there is a short-fall between individuals requiring a renal transplant and kidneys available for transplantation. Non-directed 'altruistic' living kidney donation has emerged as a strategy for bridging this gap between supply and demand, with the number increasing each year.

OBJECTIVE

This study aimed to explore the views of potential recipients towards non-directed 'altruistic' live-donor kidney transplantation.

METHODS

Semi-structured interviews with 32 UK deceased-donor kidney transplant recipients were performed. Interviews explored willingness to consider directed and non-directed live-donor kidney transplants (LDKTs). Interviews were recorded, transcribed verbatim and transcripts were analysed using the constant comparison method described in Grounded Theory.

RESULTS

For those not willing to accept a non-directed 'altruistic' LDKT, the following themes were identified: i) Prioritising other recipients above self; ii) Fear of acquiring an unknown donor's characteristics, and iii) Concern for the donor - unnecessary risk. For those willing to accept a non-directed 'altruistic' LDKT the following themes were identified: iv) Prioritising known above unknown persons, v) Belief that they are as deserving as other potential recipients, and vi) Advantages of a LDKT.

CONCLUSIONS

Drawing on 'gift exchange theory', this study contributes to our understanding of the experience of the intended recipient of a gift. The anonymity of the donor-recipient appears to be seen as a benefit of non-directed 'altruistic' live-donor transplants, freeing recipients from the obligations of the gift. However, those who feel unworthy of the 'gifted transplant' are concerned about the donor and by the lack of opportunity for direct reciprocity. Highlighting the 'reciprocal benefits' reported by donors may allow individuals whose preference is a live-donor transplant to accept one if offered. These insights provide the transplant community with targets for intervention, through which the concerns of potential recipients might be addressed.

The risks and benefits of patients temporarily discontinuing medications in the event of an intercurrent illness: a systematic review protocol

BACKGROUND

Acute kidney injury (AKI) is common and often leads to significant morbidity and/or death. The development of AKI, or complications associated with it, may be due to use of certain medications in at-risk patients experiencing an intercurrent illness. Implicated drugs include diuretics, angiotensin-converting enzyme inhibitors/angiotensin receptor blockers/direct renin inhibitors, non-steroidal anti-inflammatory drugs (NSAIDs), metformin and sulfonylureas. Expert consensus opinion (and clinical guidelines) recommend considering discontinuation of diuretics, angiotensin-converting enzyme inhibitors/angiotensin receptor blockers/direct renin inhibitors, NSAIDs, metformin and sulfonylureas in the event of an intercurrent illness to prevent AKI onset or reduce severity or complications. However, the evidence base for these recommendations is very limited. This systematic review aims to address the available evidence for the temporary discontinuation of diuretics, ACE inhibitors, angiotensin receptor blockers, direct renin inhibitors, non-steroidal anti-inflammatories and metformin and sulfonylureas for those at risk of AKI or with newly diagnosed AKI.

METHODS/DESIGN

Randomised controlled trials; non-randomised trials; cohort studies; case-control studies; interrupted time series studies; and before-and-after studies featuring adults aged 18 and over in any setting currently taking diuretics, angiotensin-converting enzyme inhibitors/angiotensin receptor blockers/direct renin inhibitors, NSAIDs and metformin; experiencing an intercurrent illness; or undergoing a radiological/surgical procedure (planned or unplanned) will be searched for. Relevant trial registers and systematic review databases will be searched. Systematic reviews will be assessed for methodological quality using the ROBIS tool, trials will be assessed using the Cochrane risk of bias tool, and observational studies will be assessed using the ACROBAT-NRS tool. If sufficient studies assessing similar populations, study type, settings and outcomes are found, then a formal meta-analysis will be performed to estimate summary measures of effect. If not, a narrative synthesis will be adopted.

DISCUSSION

This review will synthesise evidence for the efficacy of discontinuing diuretics, angiotensin-converting enzyme inhibitors/angiotensin receptor blockers/direct renin inhibitors, NSAIDs, metformin or sulfonylureas to prevent or delay onset of AKI or associated complications. Results will provide guidance on efficacy and safety of this strategy and potentially help to develop an intervention to test the best mechanism of guiding medication discontinuation in at-risk populations.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42015023210.

Clinical and genetic analysis of patients with cystinuria in the United Kingdom

BACKGROUND AND OBJECTIVES

Cystinuria is a rare inherited renal stone disease. Mutations in the amino acid exchanger System b(0,+), the two subunits of which are encoded by SLC3A1 and SLC7A9, predominantly underlie this disease. The work analyzed the epidemiology of cystinuria and the influence of mutations in these two genes on disease severity in a United Kingdom cohort.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Prevalent patients were studied from 2012 to 2014 in the northeast and southwest of the United Kingdom. Clinical phenotypes were defined, and genetic analysis of SLC3A1 and SLC7A9 combining Sanger sequencing and multiplex ligation probe-dependent amplification was performed.

RESULTS

In total, 76 patients (42 men and 34 women) were studied. All subjects had proven cystine stones. Median age of presentation (first stone episode) was 24 years old, but 21% of patients presented after 40 years old. Patients had varied clinical courses, with 37% of patients having ≥10 stone episodes; 70% had evidence of CKD, and 9% had reached ESRD as a result of cystinuria and its complications. Patients with cystinuria received a variety of different therapies, with no obvious treatment consensus. Notably, 20% of patients had staghorn calculi, with associated impaired renal function in 80% of these patients. Genetic analysis revealed that biallelic mutations were present in either SLC3A1 (n=27) or SLC7A9 (n=20); 22 patients had only one mutated allele detected (SLC3A1 in five patients and SLC7A9 in 17 patients). In total, 37 different mutant variant alleles were identified, including 12 novel mutations; 22% of mutations were caused by large gene rearrangements. No genotype-phenotype association was detected in this cohort.

CONCLUSIONS

Patients with cystinuria in the United Kingdom often present atypically with staghorn calculi at ≥40 years old and commonly develop significant renal impairment. There is no association of clinical course with genotype. Treatments directed toward reducing stone burden need to be rationalized and developed to optimize patient care.

A national study of practice patterns in UK renal units in the use of dialysis and conservative kidney management to treat people aged 75 years and over with chronic kidney failure

Background

Conservative kidney management (CKM) is recognised as an alternative to dialysis for a significant number of older adults with multimorbid stage 5 chronic kidney disease (CKD5). However, little is known about the way CKM is delivered or how it is perceived.

Aim

To determine the practice patterns for the CKM of older patients with CKD5, to inform service development and future research.

Objectives

(1) To describe the differences between renal units in the extent and nature of CKM, (2) to explore how decisions are made about treatment options for older patients with CKD5, (3) to explore clinicians’ willingness to randomise patients with CKD5 to CKM versus dialysis, (4) to describe the interface between renal units and primary care in managing CKD5 and (5) to identify the resources involved and potential costs of CKM.

Methods

Mixed-methods study. Interviews with 42 patients aged > 75 years with CKD5 and 60 renal unit staff in a purposive sample of nine UK renal units. Interviews informed the design of a survey to assess CKM practice, sent to all 71 UK units. Nineteen general practitioners (GPs) were interviewed concerning the referral of CKD patients to secondary care. We sought laboratory data on new CKD5 patients aged > 75 years to link with the nine renal units’ records to assess referral patterns.

Results

Sixty-seven of 71 renal units completed the survey. Although terminology varied, there was general acceptance of the role of CKM. Only 52% of units were able to quantify the number of CKM patients. A wide range reflected varied interpretation of the designation ‘CKM’ by both staff and patients. It is used to characterise a future treatment option as well as non-dialysis care for end-stage kidney failure (i.e. a disease state equivalent to being on dialysis). The number of patients in the latter group on CKM was relatively small (median 8, interquartile range 4.5–22). Patients’ expectations of CKM and dialysis were strongly influenced by renal staff. In a minority of units, CKM was not discussed. When discussed, often only limited information about illness progression was provided. Staff wanted more research into the relative benefits of CKM versus dialysis. There was almost universal support for an observational methodology and a quarter would definitely be willing to participate in a randomised clinical trial, indicating that clinicians placed value on high-quality evidence to inform decision-making. Linked data indicated that most CKD5 patients were known to renal units. GPs expressed a need for guidance on when to refer older multimorbid patients with CKD5 to nephrology care. There was large variation in the scale and model of CKM delivery. In most, the CKM service was integrated within the service for all non-renal replacement therapy CKD5 patients. A few units provided dedicated CKM clinics and some had dedicated, modest funding for CKM.

Conclusions

Conservative kidney management is accepted across UK renal units but there is much variation in the way it is described and delivered. For best practice, and for CKM to be developed and systematised across all renal units in the UK, we recommend (1) a standard definition and terminology for CKM, (2) research to measure the relative benefits of CKM and dialysis and (3) development of evidence-based staff training and patient education interventions.

Funding

The National Institute for Health Research Health Services and Delivery Research programme.

Conservative care for ESRD in the United Kingdom: a national survey

BACKGROUND AND OBJECTIVES

Conservative kidney management (CKM) has been developed in the United Kingdom (UK) as an alternative to dialysis for older patients with stage 5 CKD (CKD5) and multiple comorbidities. This national survey sought to describe the current scale and pattern of delivery of conservative care in UK renal units and identify their priorities for its future development.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

A survey on practice patterns of CKM for patients age 75 and older with CKD5 was sent to clinical directors of all 71 adult renal units in the UK in March 2013.

RESULTS

Sixty-seven units (94%) responded. All but one unit reported providing CKM for some patients. Terminology varied, although "conservative management" was the most frequently used term (46%). Lack of an agreed-upon definition of when a patient is receiving CKM made it difficult to obtain meaningful data on the numbers of such patients. Fifty-two percent provided the number of CKM patients age ≥ 75 years in 2012; the median was 45 per unit (interquartile range [IQR], 20-83). The median number of symptomatic CKM patients who would otherwise have started dialysis was eight (IQR, 4.5-22). CKM practice patterns varied: 35% had a written guideline, 23% had dedicated CKM clinics, 45% had dedicated staff, and 50% provided staff training on CKM. Most units (88%) provided primary care clinicians with information/advice regarding CKM. Eighty percent identified a need for better evidence comparing outcomes on CKM versus dialysis, and 65% considered it appropriate to enter patients into a randomized trial.

CONCLUSIONS

CKM is provided in almost all UK renal units, but scale and organization vary widely. Lack of common terminology and definitions hinders the development and assessment of CKM. Many survey respondents expressed support for further research comparing outcomes with conservative care versus dialysis.

Evaluating the contribution of the cause of kidney disease to prognosis in CKD: results from the Study of Heart and Renal Protection (SHARP)

Background

The relevance of the cause of kidney disease to prognosis among patients with chronic kidney disease is uncertain.

Study Design

Observational study.

Settings & Participants

6,245 nondialysis participants in the Study of Heart and Renal Protection (SHARP).

Predictor

Baseline cause of kidney disease was categorized into 4 groups: cystic kidney disease, diabetic nephropathy, glomerulonephritis, and other recorded diagnoses.

Outcomes

End-stage renal disease (ESRD; dialysis or transplantation) and death.

Results

During an average 4.7 years' follow-up, 2,080 participants progressed to ESRD, including 454 with cystic kidney disease (23% per year), 378 with glomerulonephritis (10% per year), 309 with diabetic nephropathy (12% per year), and 939 with other recorded diagnoses (8% per year). By comparison with patients with cystic kidney disease, other disease groups had substantially lower adjusted risks of ESRD (relative risks of 0.28 [95% CI, 0.24-0.32], 0.40 [95% CI, 0.34-0.47], and 0.29 [95% CI, 0.25-0.32] for glomerulonephritis, diabetic nephropathy, and other recorded diagnoses, respectively). Albuminuria and baseline estimated glomerular filtration rate were associated more weakly with risk of ESRD in patients with cystic kidney disease than the 3 other diagnostic categories (P for interaction, <0.001 and 0.01, respectively). Death before ESRD was uncommon in patients with cystic kidney disease, but was a major competing risk for participants with diabetic nephropathy, whose adjusted risk of death was 2-fold higher than that of the cystic kidney disease group (relative risk, 2.35 [95% CI, 1.73-3.18]).

Limitations

Exclusion of patients with prior myocardial infarction or coronary revascularization.

Conclusions

The cause of kidney disease has substantial prognostic implications. Other things being equal, patients with cystic kidney disease are at much higher risk of ESRD (and much lower risk of death before ESRD) than other patients. Patients with diabetic nephropathy are at particularly high risk of death prior to reaching ESRD.

Conservative care in Europe--nephrologists' experience with the decision not to start renal replacement therapy

BACKGROUND

For some patients with end-stage renal disease (ESRD), providing conservative care until death may be an acceptable alternative for renal replacement therapy (RRT). We aimed to estimate the occurrence of conservative care in Europe and evaluated opinions about which factors nephrologists consider important in their decision not to offer RRT.

METHODS

With a web-based survey sent to nephrologists in 11 European countries, we inquired how often RRT was not started in 2009 and how specific factors would influence the nephrologists' decision to provide conservative care. We compared subgroups by nephrologist and facility characteristics using chi-square tests and Mann-Whitney U tests.

RESULTS

We received 433 responses. Nephrologists decided to offer conservative care in 10% of their patients [interquartile range (IQR) 5-20%]. An additional 5% (IQR 2-10%) of the patients chose conservative care as they refused when nephrologists intended to start RRT. Patient preference (93%), severe clinical conditions (93%), vascular dementia (84%) and low physical functional status (75%) were considered extremely or quite important in the nephrologists' decision to provide conservative care. Nephrologists from countries with a low incidence of RRT, not-for-profit centres and public centres more often scored these factors as extremely or quite important than their counterparts from high-incidence countries, for-profit centres and private centres.

CONCLUSIONS

Nephrologists estimated conservative care was provided to up to 15% of their patients in 2009. The presence of severe clinical conditions, vascular dementia and a low physical functional status are important factors in the decision-making not to start RRT. Patient preference was considered as a very important factor, confirming the importance of extensive patient education and shared decision-making.

Association of anaemia in primary care patients with chronic kidney disease: cross sectional study of quality improvement in chronic kidney disease (QICKD) trial data

BACKGROUND

Anaemia is a known risk factor for cardiovascular disease and treating anaemia in chronic kidney disease (CKD) may improve outcomes. However, little is known about the scope to improve primary care management of anaemia in CKD.

METHODS

An observational study (N = 1,099,292) with a nationally representative sample using anonymised routine primary care data from 127 Quality Improvement in CKD trial practices (ISRCTN5631023731). We explored variables associated with anaemia in CKD: eGFR, haemoglobin (Hb), mean corpuscular volume (MCV), iron status, cardiovascular comorbidities, and use of therapy which associated with gastrointestinal bleeding, oral iron and deprivation score. We developed a linear regression model to identify variables amenable to improved primary care management.

RESULTS

The prevalence of Stage 3-5 CKD was 6.76%. Hb was lower in CKD (13.2 g/dl) than without (13.7 g/dl). 22.2% of people with CKD had World Health Organization defined anaemia; 8.6% had Hb ≤ 11 g/dl; 3% Hb ≤ 10 g/dl; and 1% Hb ≤ 9 g/dl. Normocytic anaemia was present in 80.5% with Hb ≤ 11; 72.7% with Hb ≤ 10 g/dl; and 67.6% with Hb ≤ 9 g/dl; microcytic anaemia in 13.4% with Hb ≤ 11 g/dl; 20.8% with Hb ≤ 10 g/dl; and 24.9% where Hb ≤ 9 g/dl. 82.7% of people with microcytic and 58.8% with normocytic anaemia (Hb ≤ 11 g/dl) had a low ferritin (<100 ug/mL). Hypertension (67.2% vs. 54%) and diabetes (30.7% vs. 15.4%) were more prevalent in CKD and anaemia; 61% had been prescribed aspirin; 73% non-steroidal anti-inflammatory drugs (NSAIDs); 14.1% warfarin 12.4% clopidogrel; and 53.1% aspirin and NSAID. 56.3% of people with CKD and anaemia had been prescribed oral iron. The main limitations of the study are that routine data are inevitably incomplete and definitions of anaemia have not been standardised.

CONCLUSIONS

Medication review is needed in people with CKD and anaemia prior to considering erythropoietin or parenteral iron. Iron stores may be depleted in over >60% of people with normocytic anaemia. Prescribing oral iron has not corrected anaemia.

Consensus guidelines for the safe prescription and administration of oral bowel-cleansing agents

Oral bowel-cleansing preparations are used before colonic surgery and endoscopic and radiological assessment of the intestine to minimise faecal contamination. In February 2009, the UK National Patient Safety Agency issued a Rapid Response Report highlighting the potential risk of harm associated with the use of these preparations and instructing local NHS Trusts to implement safeguards to reduce this risk. This guidance has been prepared to help NHS Trusts to respond to these concerns, as the risk of complications is influenced by both individual patient risk factors and the choice of bowel preparation, for which definitive guidance was not previously available. This document provides an outline of the different available oral bowel-cleansing agents and the complications that may arise. This is followed by recommendations for their use in different patient groups and circumstances. The recommendations are based on consensus between the authors, each of whom circulated drafts to members of their specialist society. The evidence for these recommendations has been assessed using the modified GRADE system. The recommendations cover the choice, administration and complications (relative and absolute) of the different oral bowel-cleansing agents, with specific guidance provided for different patient groups.

Confidence and quality in managing CKD compared with other cardiovascular diseases and diabetes mellitus: a linked study of questionnaire and routine primary care data

Background

Much of chronic disease is managed in primary care and chronic kidney disease (CKD) is a recent addition. We are conducting a cluster randomised study of quality improvement interventions in CKD (QICKD) - Clinical Trials Registration: ISRCTN56023731. CKD registers have a lower than expected prevalence and an initial focus group study suggested variable levels of confidence in managing CKD.

Our objective is to compare practitioner confidence and achievement of quality indicators for CKD with hypertension and diabetes.

Method

We validated a new questionnaire to test confidence. We compared confidence with achievement of pay-for-performance indicators (P4P) and implementation of evidence-based guidance. We achieved a 74% (148/201) response rate.

Results

87% (n = 128) of respondents are confident in managing hypertension (HT) compared with 59% (n = 87) in managing HT in CKD (HT+CKD); and with 61% (n = 90) in HT, CKD and diabetes (CKD+HT+DM).

85.2% (P4P) and 62.5% (National targets) of patients with hypertension are at target; in patients with HT and CKD 65.1% and 53.3%; in patients with HT, CKD and DM 67.8% and 29.6%.

Confidence in managing proteinuria in CKD is low (42%, n = 62). 87% of respondents knew BP treatment thresholds in CKD, but only 53% when proteinuria is factored in. Male GPs, younger (< 35 yrs), and older (> 54 yrs) clinicians are more confident than females and 35 to 54 year olds in managing CKD.

84% of patients with hypertension treated with angiotensin modulating drugs achieve achieved P4P targets compared to 67% of patients with CKD.

Conclusions

Practitioners are less likely to achieve management targets where their confidence is low.

The effects of lowering LDL cholesterol with simvastatin plus ezetimibe in patients with chronic kidney disease (Study of Heart and Renal Protection): a randomised placebo-controlled trial

BACKGROUND

Lowering LDL cholesterol with statin regimens reduces the risk of myocardial infarction, ischaemic stroke, and the need for coronary revascularisation in people without kidney disease, but its effects in people with moderate-to-severe kidney disease are uncertain. The SHARP trial aimed to assess the efficacy and safety of the combination of simvastatin plus ezetimibe in such patients.

METHODS

This randomised double-blind trial included 9270 patients with chronic kidney disease (3023 on dialysis and 6247 not) with no known history of myocardial infarction or coronary revascularisation. Patients were randomly assigned to simvastatin 20 mg plus ezetimibe 10 mg daily versus matching placebo. The key prespecified outcome was first major atherosclerotic event (non-fatal myocardial infarction or coronary death, non-haemorrhagic stroke, or any arterial revascularisation procedure). All analyses were by intention to treat. This trial is registered at ClinicalTrials.gov, NCT00125593, and ISRCTN54137607.

FINDINGS

4650 patients were assigned to receive simvastatin plus ezetimibe and 4620 to placebo. Allocation to simvastatin plus ezetimibe yielded an average LDL cholesterol difference of 0·85 mmol/L (SE 0·02; with about two-thirds compliance) during a median follow-up of 4·9 years and produced a 17% proportional reduction in major atherosclerotic events (526 [11·3%] simvastatin plus ezetimibe vs 619 [13·4%] placebo; rate ratio [RR] 0·83, 95% CI 0·74-0·94; log-rank p=0·0021). Non-significantly fewer patients allocated to simvastatin plus ezetimibe had a non-fatal myocardial infarction or died from coronary heart disease (213 [4·6%] vs 230 [5·0%]; RR 0·92, 95% CI 0·76-1·11; p=0·37) and there were significant reductions in non-haemorrhagic stroke (131 [2·8%] vs 174 [3·8%]; RR 0·75, 95% CI 0·60-0·94; p=0·01) and arterial revascularisation procedures (284 [6·1%] vs 352 [7·6%]; RR 0·79, 95% CI 0·68-0·93; p=0·0036). After weighting for subgroup-specific reductions in LDL cholesterol, there was no good evidence that the proportional effects on major atherosclerotic events differed from the summary rate ratio in any subgroup examined, and, in particular, they were similar in patients on dialysis and those who were not. The excess risk of myopathy was only two per 10,000 patients per year of treatment with this combination (9 [0·2%] vs 5 [0·1%]). There was no evidence of excess risks of hepatitis (21 [0·5%] vs 18 [0·4%]), gallstones (106 [2·3%] vs 106 [2·3%]), or cancer (438 [9·4%] vs 439 [9·5%], p=0·89) and there was no significant excess of death from any non-vascular cause (668 [14·4%] vs 612 [13·2%], p=0·13).

INTERPRETATION

Reduction of LDL cholesterol with simvastatin 20 mg plus ezetimibe 10 mg daily safely reduced the incidence of major atherosclerotic events in a wide range of patients with advanced chronic kidney disease.

FUNDING

Merck/Schering-Plough Pharmaceuticals; Australian National Health and Medical Research Council; British Heart Foundation; UK Medical Research Council.

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

BACKGROUND/AIMS

Cases of chronic kidney disease (CKD) are defined by the estimated glomerular filtration rate (eGFR), calculated using the Modified Diet in Renal Disease (MDRD) or, more recently, the CKD Epidemiology Collaboration (CKD-EPI) formula. This study set out to promote a systematic approach to reporting CKD prevalence.

DESIGN, SETTING, PARTICIPANTS AND MEASUREMENTS

The study explores the impact of the way in which eGFR is calculated on the prevalence of CKD. We took into account whether including (1) ethnicity, (2) using a single eGFR, (3) using more than 1 eGFR value or (4) using the CKD-EPI formula affected the estimates of prevalence.

SAMPLE

Of 930,997 registered patients, 36% (332,891) have their eGFR defined (63% of those aged 50-74 years, 81% >75 years).

RESULTS

The prevalence of stage 3-5 CKD is 5.41% (n = 50,331). (1) Not including ethnicity data the prevalence would be 5.49%, (2) just using the latest eGFR 6.4%, (3) excluding intermediary values 5.55% and (4) using the CKD-EPI equation 4.8%. All changes in eGFR (t test) and the proportion with CKD (χ(2) test) were significant (p < 0.001). Using serum-creatinine-calculated eGFR instead of laboratory data reduced the prevalence of stage 3-5 CKD by around 0.01%. Sixty-six percent of people with stage 3-5 disease have cardiovascular disease and 4.0% significant proteinuria using the MDRD formula; the corresponding figures using CKD-EPI are 74 and 4.6%.

CONCLUSIONS

A standardised approach to reporting case finding would allow a better comparison of prevalence estimates. Using a single eGFR tends to inflate the reported prevalence of CKD by ignoring creatinine fluctuation; this effect is greater than the difference between MDRD and CKD-EPI.

Level of renal function in patients starting dialysis: an ERA-EDTA Registry study

BACKGROUND

The aims of this European study were (i) to compare the level of renal function at the start of dialysis between age groups, gender, primary renal disease, comorbid conditions, treatment modality, time periods and countries, and (ii) to determine which baseline characteristics are associated with the level of renal function at the start of dialysis.

METHODS

Renal registries participating in the European Renal Association-European Dialysis and Transplant Association Registry provided data on serum creatinine 0-4 weeks before the start of dialysis in incident dialysis patients in 1999 and 2003. Data were available in 11 472 patients from nine renal registries. Glomerular filtration rate (GFR) was estimated by the four-variable Modification of Diet in Renal Disease equation.

RESULTS

The unadjusted median eGFR at the start of dialysis was 7.0 mL/min/1.73 m(2) in the 1999 data (median serum creatinine 7.5 mg/dL) and 7.7 mL/min/1.73 m(2) in the 2003 data (serum creatinine 7.0 mg/dL). Using linear regression with adjustment for the other covariates, older patients, males, patients with diabetes mellitus, hypertension/renal vascular disease (HT/RVD) as primary renal disease (vs glomerulonephritis), ischaemic heart disease or peripheral vascular disease and patients starting on peritoneal dialysis (PD) initiated dialysis at higher levels of eGFR (range Δ eGFR: 0.1-1.2 mL/min/1.73 m(2)). Using the same analyses, eGFR differed between countries (range: 6.5-8.6 mL/min/1.73 m(2)).

CONCLUSIONS

During 2003, patients started dialysis at somewhat higher eGFR levels than those starting during 1999. There were also international differences in eGFR. Such differences may, at least in part, be explained by differences in creatinine measurement methods between countries and time periods. Finally, older patients, males, patients with HT/RVD or comorbidity and those starting on PD had slightly higher eGFR levels than younger patients, females, those with glomerulonephritis, without comorbidity and those starting on haemodialysis. Further research is needed into other, more clinically related factors affecting the decision to start dialysis.

A method of identifying and correcting miscoding, misclassification and misdiagnosis in diabetes: a pilot and validation study of routinely collected data

AIMS

Incorrect classification, diagnosis and coding of the type of diabetes may have implications for patient management and limit our ability to measure quality. The aim of the study was to measure the accuracy of diabetes diagnostic data and explore the scope for identifying errors.

METHOD

We used two sets of anonymized routinely collected computer data: the pilot used Cutting out Needless Deaths Using Information Technology (CONDUIT) study data (n = 221 958), which we then validated using 100 practices from the Quality Improvement in Chronic Kidney Disease (QICKD) study (n = 760,588). We searched for contradictory diagnostic codes and also compatibility with prescription, demographic and laboratory test data. We classified errors as: misclassified-incorrect type of diabetes; misdiagnosed-where there was no evidence of diabetes; or miscoded-cases where it was difficult to infer the type of diabetes.

RESULTS

The standardized prevalence of diabetes was 5.0 and 4.0% in the CONDUIT and the QICKD data, respectively: 13.1% (n = 930) of CONDUIT and 14.8% (n = 4363) QICKD are incorrectly coded; 10.3% (n = 96) in CONDUIT and 26.2% (n = 1143) in QICKD are misclassified; nearly all of these cases are people classified with Type 1 diabetes who should be classified as Type 2. Approximately 5% of T2DM in both samples have no objective evidence to support a diagnosis of diabetes. Miscoding was present in approximately 7.8% of the CONDUIT and 6.1% of QICKD diabetes records.

CONCLUSIONS

The prevalence of miscoding, misclassification and misdiagnosis of diabetes is high and there is substantial scope for further improvement in diagnosis and data quality. Algorithms which identify likely misdiagnosis, misclassification and miscoding could be used to flag cases for review.

Validation and utility of a computerized South Asian names and group recognition algorithm in ascertaining South Asian ethnicity in the national renal registry

BACKGROUND

The UK Renal Registry (UKRR) reports on equity and quality of renal replacement therapy (RRT). Ethnic origin is a key variable, but it is only recorded for 76% patients overall in the UKRR and there is wide variation in the degree of its completeness between renal centres. Most South Asians have distinctive names.

AIM

To test the relative performance of a computerized name recognition algorithm (SANGRA) in identifying South Asian names using the UKRR database.

DESIGN

Cross-sectional study of patients (n = 27 832) starting RRT in 50 renal centres in England and Wales from 1997 to 2005.

METHODS

Kappa statistics were used to assess the degree of agreement of SANGRA coding with existing ethnicity information in UKRR centres.

RESULTS

In 12 centres outside London (number of patients = 7555) with 11% (n = 747) self-ascribed South Asian ethnicity, the level of agreement between SANGRA and self-ascribed ethnicity was high (kappa=0.91, 95% CI 0.90-0.93). In two London centres (n = 779) with 21% (n = 165) self-ascribed South Asian ethnicity, SANGRA's agreement with self-ascribed ethnicity was lower (kappa=0.60, 95% CI 0.54-0.67), primarily due to difficulties in distinguishing between South Asian ethnicity and other non-White ethnic minorities. Use of SANGRA increased numbers defined as South Asian from 1650 to 2076 with no overall change in percentage of South Asians. Kappa values showed no obvious association with degree of missing data returns to the UKRR.

CONCLUSION

SANGRA's use, taking into account its lower validity in London, allows increased power and generalizability for both ethnic specific analyses and for analyses where adjustment for ethnic origin is important.