#1321 Long term outcomes in people with fluctuating criteria for the diagnosis of chronic kidney disease

Abstract

Abstract Background and Aims The diagnostic criteria for chronic kidney disease (CKD) recognise that measures of kidney function may fluctuate in the short term by requiring that abnormalities must persist for at least 90 days to support the diagnosis. Nevertheless, studies have reported that even people who meet the diagnostic criteria may have transient or prolonged improvement in kidney function in the absence of specific treatment. In this study we used the opportunity afforded by long term follow-up of a cohort recruited from primary care to assess the impact on outcomes of fluctuations in CKD diagnostic criteria. Method Participants with confirmed CKD stage 3 were recruited from primary care practices in 2008-2010. Clinical assessment and protocol laboratory tests were performed at baseline, 1 and 5 year study visits. In 2019-20, information on deaths and latest available outpatient estimated GFR (eGFR) and urine albumin to creatinine ratio (UACR) values was obtained from electronic records. Participants with eGFR ≥60 ml/min/1.73 m2 and UACR <3 mg/mmol were regarded as being in “remission” at each time point. CKD progression was defined as a decline in eGFR of ≥25% and progression to a more advanced stage (KDIGO definition). Results The cohort included 1741 participants with median (IQR) age 74 (67-79) years, eGFR 53.8 (45.3-61.7) ml/min/1.73 m2 and UACR 0.3 (0.001-1.5) mg/mmol at baseline. During a median observation period of 9.8 (9.2-10.0) years, 680 participants (39.1%) died and CKD progression was observed in 430 of 1402 (30.6%) but only 24 (1.4%) progressed to CKD stage 5. The prevalence of remission was 495/1737 (28.5%) at baseline, 424/1618 (26.2%) at year 1, 335/1236 (27.1%) at year 5 and 176/1190 (14.8%) at year 10. Remission was present at all three visits in 15.4%, two visits in 13.0% and one visit in 15.8%. Participants with diabetes and those treated with a renin-angiotensin system inhibitor evidenced a lower prevalence of remission at all time points. Blood pressure control to <130/80 mmHg was not associated with remission. Evidence of remission at 1, 2 or 3 study visits was associated with progressively lower incidence of persistent CKD, CKD progression and death at 10 years (Table, p < 0.001 for all trends). No participants with an episode of remission had progressed to CKD stage 5 at 10 years. Conclusion A substantial minority of people diagnosed with CKD in primary care exhibit fluctuating diagnostic criteria. People with one or more episodes of remission appear to have a better prognosis than those with persistent CKD but remain at risk of CKD progression. They can therefore be reassured that an episode of remission is associated with an improved prognosis but long-term monitoring of kidney function is still warranted.