TY - JOUR T1 - FORM-2C (Frequency of Renal Monitoring – Creatinine and Cystatin C): An observational cohort study of primary care patients with reduced eGFR JF - British Journal of General Practice JO - Br J Gen Pract DO - 10.3399/BJGP.2020.0940 SP - BJGP.2020.0940 AU - Susannah Fleming AU - Rafael Perera-Salazar AU - Kathryn Taylor AU - Louise Jones AU - FD Richard Hobbs AU - Tim James AU - Chris O'Callaghan AU - Brian Shine AU - Jan Y Verbakel AU - Richard J Stevens AU - Clare Bankhead Y1 - 2021/05/21 UR - http://bjgp.org/content/early/2021/05/21/BJGP.2020.0940.abstract N2 - Background: Monitoring is the mainstay of chronic kidney disease management in primary care. There is little evidence on how best to monitor. Aim: To compare the effectiveness of eGFR derived from creatinine or cystatin C, to predict renal function decline among those with a recent eGFR of 30-89 ml/min/1.73m². Design and setting: Observational cohort study in UK primary care. Method: In 750 adult patients with a recent estimated glomerular filtration rate (eGFR) of 30-89 ml/min/1.73m² both creatinine and cystatin C were measured at seven study visits over two years. The primary outcome was change in eGFR derived from creatinine or cystatin C between 6 and 24 months. Results: Average change in eGFR was 0.51 ml/min/1.73m²/year or -2.35 ml/min/1.73m²/year when estimated by creatinine or cystatin C respectively. The c-statistic for predicting renal decline using creatinine-derived eGFR was 0.495 (95% CI 0.47 to 0.52). The equivalent c-statistic using cystatin C-derived eGFR was 0.497 (95% CI 0.47 to 0.53). Similar results were obtained when restricting analyses to those over or under 75 years, or with eGFR above 60 ml/min/1.73m². In those with eGFR below 60 ml/min/1.73m² cystatin C-derived eGFR was more predictive than creatinine-derived eGFR for future decline. Conclusion: In the primary analysis neither eGFR estimated from creatinine nor cystatin C predicted future change in kidney function, partly due to small changes during two years. In some secondary analyses there was a suggestion that cystatin C to estimate eGFR was a more useful biomarker, especially in those with baseline eGFR < 60 ml/min/1.73m². ER -