Identification of patients undergoing chronic kidney replacement therapy in primary and secondary care data: validation study based on OpenSAFELY and UK Renal Registry

Objective

To validate primary and secondary care codes in electronic health records to identify people receiving chronic kidney replacement therapy based on gold standard registry data.

Design

Validation study using data from OpenSAFELY and the UK Renal Registry, with the approval of NHS England.

Setting

Primary and secondary care electronic health records from people registered at 45% of general practices in England on 1 January 2020, linked to data from the UK Renal Registry (UKRR) within the OpenSAFELY-TPP platform, part of the NHS England OpenSAFELY covid-19 service.

Participants

38 745 prevalent patients (recorded as receiving kidney replacement therapy on 1 January 2020 in UKRR data, or primary or secondary care data) and 10 730 incident patients (starting kidney replacement therapy during 2020), from a population of 19 million people alive and registered with a general practice in England on 1 January 2020.

Main outcome measures

Sensitivity and positive predictive values of primary and secondary care code lists for identifying prevalent and incident kidney replacement therapy cohorts compared with the gold standard UKRR data on chronic kidney replacement therapy. Agreement across the data sources overall, and by treatment modality (transplantation or dialysis) and personal characteristics.

Results

Primary and secondary care code lists were sensitive for identifying the UKRR prevalent cohort (91.2% (95% confidence interval (CI) 90.8% to 91.6%) and 92.0% (91.6% to 92.4%), respectively), but not the incident cohort (52.3% (50.3% to 54.3%) and 67.9% (66.1% to 69.7%)). Positive predictive values were low (77.7% (77.2% to 78.2%) for primary care data and 64.7% (64.1% to 65.3%) for secondary care data), particularly for chronic dialysis (53.7% (52.9% to 54.5%) for primary care data and 49.1% (48.0% to 50.2%) for secondary care data). Sensitivity decreased with age and index of multiple deprivation in primary care data, but the opposite was true in secondary care data. Agreement was lower in children, with 30% (295/980) featuring in all three datasets. Half (1165/2315) of the incident patients receiving dialysis in UKRR data had a kidney replacement therapy code in the primary care data within three months of the start date of the kidney replacement therapy. No codes existed whose exclusion would substantially improve the positive predictive value without a decrease in sensitivity.

Conclusions

Codes used in primary and secondary care data failed to identify a small proportion of prevalent patients receiving kidney replacement therapy. Codes also identified many patients who were not recipients of chronic kidney replacement therapy in UKRR data, particularly dialysis codes. Linkage with UKRR kidney replacement therapy data facilitated more accurate identification of incident and prevalent kidney replacement therapy cohorts for research into this vulnerable population. Poor coding has implications for any patient care (including eligibility for vaccination, resourcing, and health policy responses in future pandemics) that relies on accurate reporting of kidney replacement therapy in primary and secondary care data.

Epidemiology of childhood acute kidney injury in England using e-alerts

Background

Few studies describe the epidemiology of childhood acute kidney injury (AKI) nationally. Laboratories in England are required to issue electronic (e-)alerts for AKI based on serum creatinine changes. This study describes a national cohort of children who received an AKI alert and their clinical course.

Methods

A cross-section of AKI episodes from 2017 are described. Hospital record linkage enabled description of AKI-associated hospitalizations including length of stay (LOS) and critical care requirement. Risk associations with critical care (hospitalized cohort) and 30-day mortality (total cohort) were examined using multivariable logistic regression.

Results

In 2017, 7788 children (52% male, median age 4.4 years, interquartile range 0.9-11.5 years) experienced 8927 AKI episodes; 8% occurred during birth admissions. Of 5582 children with hospitalized AKI, 25% required critical care. In children experiencing an AKI episode unrelated to their birth admission, Asian ethnicity, young (<1 year) or old (16-<18 years) age (reference 1-<5 years), and high peak AKI stage had higher odds of critical care. LOS was higher with peak AKI stage, irrespective of critical care admission. Overall, 30-day mortality rate was 3% (n = 251); youngest and oldest age groups, hospital-acquired AKI, higher peak stage and critical care requirement had higher odds of death. For children experiencing AKI alerts during their birth admission, no association was seen between higher peak AKI stage and critical care admission.

Conclusions

Risk associations for adverse AKI outcomes differed among children according to AKI type and whether hospitalization was related to birth. Understanding the factors driving AKI development and progression may help inform interventions to minimize morbidity.

Understanding the perspectives of recruiters is key to improving randomised controlled trial enrolment: a qualitative evidence synthesis

Background

Recruiting patients to randomised controlled trials (RCTs) is often reported to be challenging, and the evidence base for effective interventions that could be used by staff (recruiters) undertaking recruitment is lacking. Although the experiences and perspectives of recruiters have been widely reported, an evidence synthesis is required in order to inform the development of future interventions. This paper aims to address this by systematically searching and synthesising the evidence on recruiters’ perspectives and experiences of recruiting patients into RCTs. 

Methods

A qualitative evidence synthesis (QES) following Thomas and Harden’s approach to thematic synthesis was conducted. The Ovid MEDLINE, CINAHL, EMBASE, PsycInfo, Cochrane Central Register of Controlled Trials, ORRCA and Web of Science electronic databases were searched. Studies were sampled to ensure that the focus of the research was aligned with the phenomena of interest of the QES, their methodological relevance to the QES question, and to include variation across the clinical areas of the studies. The GRADE CERQual framework was used to assess confidence in the review findings.

Results

In total, 9316 studies were identified for screening, which resulted in 128 eligible papers. The application of the QES sampling strategy resulted in 30 papers being included in the final analysis. Five overlapping themes were identified which highlighted the complex manner in which recruiters experience RCT recruitment: (1) recruiting to RCTs in a clinical environment, (2) enthusiasm for the RCT, (3) making judgements about whether to approach a patient, (4) communication challenges, (5) interplay between recruiter and professional roles.

Conclusions

This QES identified factors which contribute to the complexities that recruiters can face in day-to-day clinical settings, and the influence recruiters and non-recruiting healthcare professionals have on opportunities afforded to patients for RCT participation. It has reinforced the importance of considering the clinical setting in its entirety when planning future RCTs and indicated the need to better normalise and support research if it is to become part of day-to-day practice.

Trial registration

PROSPERO CRD42020141297 (registered 11/02/2020).

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-022-06818-4.

Advanced chronic kidney disease among UK children

The UK Renal Registry currently collects information on UK children with kidney failure requiring long-term kidney replacement therapy (KRT), which supports disease surveillance and auditing of care and outcomes; however, data are limited on children with chronic kidney disease (CKD) not on KRT.

METHODS

In March 2020, all UK Paediatric Nephrology centres submitted data on children aged <16 years with severely reduced kidney function as of December 2019, defined as an estimated glomerular filtration rate <30 mL/min/1.73 m2.

RESULTS

In total, 1031 children had severe CKD, the majority of whom (80.7%) were on KRT. The overall prevalence was 81.2 (95% CI 76.3 to 86.3) per million of the age-related population.

CONCLUSIONS

The prevalence of severe CKD among UK children is largely due to a high proportion of children on long-term KRT. Expanding data capture to include children with CKD before reaching failure will provide greater understanding of the CKD burden in childhood.

Increasing trends in hemodialysis and living donor kidney transplantation for children and young people in the United Kingdom

BACKGROUND

The UK Renal Registry is responsible for the national collection and reporting of data on all children receiving long-term kidney replacement therapy [KRT], including kidney transplantation.

METHODS

All 13 UK pediatric nephrology centers contributed to providing individual patient data from the pediatric population incident to and prevalent to KRT as per the date 31 December 2018. Data for children aged 16-<18 years were presented separately as some were managed under adult care settings with different methods of data collection. Demographics and biochemical data, including kidney function and prevalence of cardiovascular risk factors [hypertension, hypercholesterolemia, BMI] were reported.

RESULTS

Eight hundred and twenty-six children (65.4 per million age-related population [pmarp]) and 199 young people (139.4pmarp) in the United Kingdom were prevalent to KRT on 31 December 2018. Overall, the incidence of KRT during 2018 was 9.1 pmarp and 12.6 pmarp in children and young people, respectively. Congenital anomalies of the kidney and urinary tract (CAKUT) were the most prevalent primary diagnoses (52%). Living and deceased donor transplantation was the most common treatment modality (78%). Patients on dialysis had lower age standardized mean height and weight ranges recorded in comparison to transplant patients [median height z score -1.8 vs. -1.1]. 73.1% patients had one or more cardiovascular disease risk factors.

CONCLUSIONS

This study highlights increasing prevalence of hemodialysis and living donor transplantation as modalities for KRT. Of those incident to KRT, the highest patient survival was seen among 8-12 years and lowest <2 years. Moreover, there was a demographic shift from Caucasian toward Asian/other ethnicity and from CAKUT to other primary kidney diseases.

Acute kidney injury identification for pharmacoepidemiologic studies: Use of laboratory electronic acute kidney injury alerts versus electronic health records in Hospital Episode Statistics

PURPOSE

A laboratory-based acute kidney injury (AKI) electronic-alert (e-alert) system, with e-alerts sent to the UK Renal Registry (UKRR) and collated in a master patient index (MPI), has recently been implemented in England. The aim of this study was to determine the degree of correspondence between the UKRR-MPI and AKI International Classification Disease-10 (ICD-10) N17 coding in Hospital Episode Statistics (HES) and whether hospital N17 coding correlated with 30-day mortality and emergency re-admission after AKI.

METHODS

AKI e-alerts in people aged ≥18 years, collated in the UKRR-MPI during 2017, were linked to HES data to identify a hospitalised AKI population. Multivariable logistic regression was used to analyse associations between absence/presence of N17 codes and clinicodemographic features. Correlation of the percentage coded with N17 and 30-day mortality and emergency re-admission after AKI were calculated at hospital level.

RESULTS

In 2017, there were 301 540 adult episodes of hospitalised AKI in England. AKI severity was positively associated with coding in HES, with a high degree of inter-hospital variability-AKI stage 1 mean of 48.2% [SD 14.0], versus AKI stage 3 mean of 83.3% [SD 7.3]. N17 coding in HES depended on demographic features, especially age (18-29 years vs. ≥85 years OR 0.22, 95% CI 0.21-0.23), as well as sex and ethnicity. There was no evidence of association between the proportion of episodes coded for AKI with short-term AKI outcomes.

CONCLUSION

Coding of AKI in HES is influenced by many factors that result in an underestimation of AKI. Using e-alerts to triangulate the true incidence of AKI could provide a better understanding of the factors that affect hospital coding, potentially leading to improved coding, patient care and pharmacoepidemiologic research.

The incidence of and risk factors for late presentation of childhood chronic kidney disease: A systematic review and meta-analysis

BACKGROUND

When detected early, inexpensive measures can slow chronic kidney disease progression to kidney failure which, for children, confers significant morbidity and impacts growth and development. Our objective was to determine the incidence of late presentation of childhood chronic kidney disease and its associated risk factors.

METHODS

We searched MEDLINE, Embase, PubMed, Web of Science, Cochrane Library and CINAHL, grey literature and registry websites for observational data describing children <21 years presenting to nephrology services, with reference to late presentation (or synonyms thereof). Independent second review of eligibility, data extraction, and risk of bias was undertaken. Meta-analysis was used to generate pooled proportions for late presentation by definition and investigate risk factors. Meta-regression was undertaken to explore heterogeneity.

RESULTS

Forty-five sources containing data from 30 countries were included, comprising 19,339 children. Most studies (37, n = 15,772) described children first presenting in kidney failure as a proportion of the chronic kidney disease population (mean proportion 0.43, 95% CI 0.34-0.54). Using this definition, the median incidence was 2.1 (IQR 0.9-3.9) per million age-related population. Risk associations included non-congenital disease and older age. Studies of hospitalised patients, or from low- or middle-income countries, that had older study populations than high-income countries, had higher proportions of late presentation.

CONCLUSIONS

Late presentation is a global problem among children with chronic kidney disease, with higher proportions seen in studies of hospitalised children or from low/middle-income countries. Children presenting late are older and more likely to have non-congenital kidney disease than timely presenting children. A consensus definition is important to further our understanding and local populations should identify modifiable barriers beyond age and disease to improve access to care.

Sociodemographic features and mortality of individuals on haemodialysis treatment who test positive for SARS-CoV-2: A UK Renal Registry data analysis

Kidney disease is a recognised risk factor for poor COVID-19 outcomes. Up to 30 June 2020, the UK Renal Registry (UKRR) collected data for 2,385 in-centre haemodialysis (ICHD) patients with COVID-19 in England and Wales. Overall unadjusted survival at 1 week after date of positive COVID-19 test was 87.5% (95% CI 86.1-88.8%); mortality increased with age, treatment vintage and there was borderline evidence of Asian ethnicity (HR 1.16, 95% CI 0.94-1.44) being associated with higher mortality. Compared to the general population, the relative risk of mortality for ICHD patients with COVID-19 was 45.4 and highest in younger adults. This retrospective cohort study based on UKRR data supports efforts to protect this vulnerable patient group.

P1627KIDNEY TRANSPLANT OUTCOMES FOR CHILDREN AND YOUNG ADULTS IN THE UK

Background and Aims

Multiple international studies report young adulthood is associated with kidney transplant loss. However, there are few published UK graft survival data for children and young adults. To our knowledge, no studies assess initial transplant function or examine declining function, when interventions may improve outcomes.

We aimed to report graft survival for UK children and young adults and to explore the importance of donor and recipient variables on graft loss and rate of decline.

Method

Retrospective cohort study using UK Renal Registry and NHS Blood and Transplant data, including patients aged &lt;30 years who underwent kidney transplantation between 1998-2016. Univariate analyses included Kaplan-Meier survival curves and log-rank tests. Multivariable analyses used Cox proportional hazards to investigate variables associated with death-censored graft failure in a conditional risk-set model for multiple failure data. Age group was time-varying. We used the Efron method for ties, stratification by graft number and clustering at participant level.

We calculated estimated glomerular filtration rate (eGFR) using the Schwartz formula if aged &lt;18 years and the 4-variable Modification of Diet in Renal Disease formula otherwise. For participants with ≥4 values outside the first 6 months, individual regressions of eGFR against time were performed. We undertook multivariable linear regression to establish associations with eGFR slope gradients.

Results

We studied 5121 individuals. Of these, 371 received a further transplant during the study period. There were 1371 graft failures and 145 deaths with a functioning graft over a 39541-year risk period. The cohort was 61% male and 80% white. Most (36%) had structural kidney problems, followed by glomerulonephritides (29%). Live donation occurred in 48%, donation after brainstem death in 46% and after circulatory death in 6%. Mean initial eGFR was 62 mls/min/1.73m2.

Median graft survival was 7 years. One-year survival was 94.4% (95% confidence interval (CI) 93.7, 95.0), 5-year survival 84.0% (95% CI 82.9, 85.0), 10-year survival 71.1% (95% CI 69.6, 72.5), 15-year survival 60.2% (95% CI 58.1, 62.3) and 20-year survival 51.2% (47.6, 54.7). Survival at 15 years was least at 54.4% (95% CI 49.9, 58.7) in those transplanted at age 15-19 years and most in those transplanted at age 0-4 years at 71.7% (95% CI 63.4, 78.5).

Figure 1 displays hazard ratios for graft loss. Protective associations were male gender (p=0.04), living donation (p=0.02) and higher initial eGFR (p&lt;0.0001). Risk associations included adverse human leucocyte mismatches (p=0.001), black ethnicity (p=0.001), young adulthood and glomerulonephritides. Risk associations for faster eGFR decline included female gender (p&lt;0.0001), age group 15-19 years (p=0.04), higher initial eGFR (p&lt;0.0001), additional graft (p=0.003) and transplants during 2011-2014 (p=0.03).

Conclusion

This study reports long-term graft survival for UK children and young adults and evaluates associations with declining transplant function. It contributes up to 20 years of follow-up and considers initial graft function in addition to established co-variates. Graft survival was ≈60% at 15 years. The study highlights the changing survival by age group over time. Those aged &lt;5 years at transplant had the least initial survival, but best long-term graft survival relative to other age groups. Initial transplant function is strongly associated with graft performance. Similar associations with gender, ethnicity and age group are seen compared with other studies. Young adulthood is a high-risk period for UK patients and interventions are needed to improve outcomes during transition and young adulthood.