<?xml version='1.0' encoding='UTF-8'?><xml><records><record><source-app name="HighWire" version="7.x">Drupal-HighWire</source-app><ref-type name="Journal Article">17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Fleming, Susannah</style></author><author><style face="normal" font="default" size="100%">Perera-Salazar, Rafael</style></author><author><style face="normal" font="default" size="100%">Taylor, Kathryn S</style></author><author><style face="normal" font="default" size="100%">Jones, Louise</style></author><author><style face="normal" font="default" size="100%">Hobbs, FD Richard</style></author><author><style face="normal" font="default" size="100%">James, Tim</style></author><author><style face="normal" font="default" size="100%">O’Callaghan, Chris A</style></author><author><style face="normal" font="default" size="100%">Shine, Brian</style></author><author><style face="normal" font="default" size="100%">Verbakel, Jan Y</style></author><author><style face="normal" font="default" size="100%">Stevens, Richard</style></author><author><style face="normal" font="default" size="100%">Bankhead, Clare</style></author></authors><secondary-authors></secondary-authors></contributors><titles><title><style face="normal" font="default" size="100%">Frequency of Renal Monitoring — Creatinine and Cystatin C (FORM-2C): an observational cohort study of patients with reduced eGFR in primary care</style></title><secondary-title><style face="normal" font="default" size="100%">British Journal of General Practice</style></secondary-title></titles><dates><year><style  face="normal" font="default" size="100%">2021</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2021-09-01 00:00:00</style></date></pub-dates></dates><pages><style  face="normal" font="default" size="100%">e677-e684</style></pages><doi><style  face="normal" font="default" size="100%">10.3399/BJGP.2020.0940</style></doi><volume><style face="normal" font="default" size="100%">71</style></volume><issue><style face="normal" font="default" size="100%">710</style></issue><abstract><style  face="normal" font="default" size="100%">Background Monitoring is the mainstay of chronic kidney disease management in primary care; however, there is little evidence about the best way to do this.Aim To compare the effectiveness of estimated glomerular filtration rate (eGFR) derived from serum creatinine and serum cystatin C to predict renal function decline among those with a recent eGFR of 30–89 ml/min/1.73 m2.Design and setting Observational cohort study in UK primary care.Method Serum creatinine and serum cystatin C were both measured at seven study visits over 2 years in 750 patients aged ≥18 years with an eGFR of 30–89 ml/min/1.73 m2 within the previous year. The primary outcome was change in eGFR derived from serum creatinine or serum cystatin C between 6 and 24 months.Results Average change in eGFR was 0.51 ml/min/1.73 m2/year when estimated by serum creatinine and −2.35 ml/min/1.73 m2/year when estimated by serum cystatin C. The c-statistic for predicting renal decline using serum creatininederived eGFR was 0.495 (95% confidence interval [CI] = 0.471 to 0.519). The equivalent c-statistic using serum cystatin C-derived eGFR was 0.497 (95% CI = 0.468 to 0.525). Similar results were obtained when restricting analyses to those aged ≥75 or &lt;75 years, or with eGFR ≥60 ml/min/1.73 m2. In those with eGFR &lt;60 ml/min/1.73 m2, serum cystatin C-derived eGFR was more predictive than serum creatinine-derived eGFR for future decline in kidney function.Conclusion In the primary analysis neither eGFR estimated from serum creatinine nor from serum cystatin C predicted future change in kidney function, partly due to small changes during 2 years. In some secondary analyses there was a suggestion that serum cystatin C was a more useful biomarker to estimate eGFR, especially in those with a baseline eGFR &lt;60 ml/min/1.73 m2.</style></abstract></record></records></xml>