A snapshot of European registries on chronic kidney disease patients not on kidney replacement therapy

BACKGROUND

Traditionally, renal registries collect and report population-based epidemiological data on patients with kidney failure who are treated by kidney replacement therapy (KRT), i.e. dialysis or transplantation. Over the past decade, a number of these registries have started to widen the inclusion of patients to those with kidney failure treated with comprehensive conservative management and in some cases to earlier stages of chronic kidney disease (CKD), leading to, for example, CKD Stages 4–5 registries. As a result, they are increasing their value by not only providing numbers on those receiving or refraining from extremely expensive therapies, but also to stages of CKD in which kidney failure may still be prevented.

The European Renal Association (ERA) Registry currently collects data on patients treated by KRT and uses them for comparison and collaborative research. In this article we report the current status of CKD registries in Europe in relation to their data collection on patients not on KRT so that in the future we may investigate to what extent their data may be used for similar purposes, such as collaborative research on CKD trajectories and patient outcomes.

CKD REGISTRIES IN EUROPE

Information was collected from six existing CKD registries and one in preparation. Most had been started by the boards of the national KRT registry with which they formed one registry, but in Romania the CKD registry was separate from that on KRT (Table 1). The Czech registry was fully funded by non-governmental sources, whereas five others—those in French-speaking Belgium, France, Norway, Romania and Sweden—managed to secure at least partial funding from their ministries of health or other healthcare system authorities, mostly for the set-up or maintenance of their web-based data collection platforms. In the majority of cases, data collection was voluntary.

RESEARCH OBJECTIVES AND PATIENT POPULATIONS COVERED

While most registries aimed to conduct epidemiological and clinical research now or in the future, health economics research was also among their objectives. Four registries—those from French-speaking Belgium, Czech Republic, Norway and Sweden—specifically aimed for quality improvement making use of benchmarking.

Patient inclusion was mostly restricted to CKD Stages 4 and 5 patients from nephrology departments. In Norway, however, the inclusion was limited to CKD Stage 5 patients, whereas in French-speaking Belgium and Romania the registry was set up to include all stages of CKD. With an estimated 75%, the coverage of the CKD patients treated by nephrologists was highest in Sweden, followed by Norway, which also included more than half of the patients. Undoubtedly the difficulty in reaching full coverage is caused by the relatively high number of patients suffering from this condition and by the fact that a substantial number of them may be followed by non-nephrologists or in whom the condition may go unrecognized. This may result in a risk of selection bias, e.g. in epidemiological research.

DATA COLLECTION

All registries collected demographic data, primary renal disease (PRD), comorbidities and height and weight at baseline, but in France and Norway this was extended to information on care plans (Table 2). Most collected medications, often accompanied by their Anatomical Therapeutic Chemical codes. Additionally, all registries gathered baseline and follow-up data on estimated glomerular filtration rate (eGFR). In contrast, only three registries collected data on urinary albumin:creatinine ratio. All countries with functioning registries collected at least some laboratory test results (Table 3), frequently by linkage to national or regional laboratory databases.

The outcomes studied included CKD progression, dialysis and transplantation (including pre-emptive transplantation), date and cause of death, sometimes supplemented with data on (pre-emptive) transplant waitlisting, hospitalization and complications. The Swedish registry also collected patient-reported outcomes in the form of RAND-36 data.

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CONCLUSION

Given the importance of obtaining knowledge on patients with advanced CKD, it is not unexpected but still disappointing that the results of this inventory show that in Europe only six countries or large regions have engaged in routine data collection on patients with CKD Stages 4–5 who are under the care of nephrologists and Finland is making preparations to do so. Most are collecting data on a growing number of patients while facing challenging issues in registry management, such as the efforts needed for data collection. As a next step, we will explore whether the data quality and potential differences in methods and definitions used by the countries will allow collaboration in a European CKD registry under the umbrella of the ERA Registry with the purpose of joint scientific analyses to advance our knowledge of treatments and outcomes in advanced CKD.

FUNDING

The ERA Registry is funded by the ERA.

AUTHORS’ CONTRIBUTIONS

This article was written by K.J.J., A.Å., F.C., C.C., M.E., P.F., I.P., I.R. and Z.A.M. on behalf of the ERA Registry, which is an official body of the ERA.

CONFLICT OF INTEREST STATEMENT

The results presented in this article have not been published previously in whole or part. K.J.J. reports grants from the ERA. F.C. reports lecture fees from Baxter, Fresenius Medical Care and Vifor.