Chronic renal disease is not chronic kidney disease: Implications for use of the QRISK and Joint British Societies risk scores

Abstract

Background. Chronic kidney disease (CKD) is a major risk factor for cardiovascular disease (CVD) and European guidelines advocate assessment of CVD risk. QRISK and JBS3 risk calculators do not use the consensus definition of CKD stages 3-5 but instead use a definition referring to renal pathologies and CKD stages 4 and 5. Consequently, there is potential for doctors to misclassify their patients when using these risk calculators. Objectives. To quantify the number of people who may be affected by such misclassifications. Methods. Database analysis using the Clinical Practice Research Datalink (CPRD).We identified 2 512 053 adults aged 25-84 without prior history of CVD on 1st January 2014. We identified those with 'chronic renal disease' and/or CKD by searching medical event history data. Results. The study population was 48.7% male with mean age of 50.2 years. A total of 80 718 had diagnostic READ codes for CKD stages 3, 4 or 5. Of these, 6585 individuals (8.2%) were classified as having 'chronic renal disease' according to the updated QRISK 2014, up from 3365 according to QRISK 2013. Whilst the updated QRISK definition of 'chronic renal disease' in total identified 62% more people than previously and had improved sensitivity for CKD stages 3 to 5, sensitivity remained poor (8.16%; 95% CI: 7.97-8.35%). Conclusion. Misuse of risk scores by general practitioners could result in clinically important differences in risk estimates. Users of risk scores should recognize the potential for error and developers should aim to label risk factors more clearly.