<h3>Background:</h3> Rheumatoid arthritis (RA) is systemic autoimmune disease that targets the synovial joints and potentially resulting in the permanent destruction of cartilage and bone if not adequately treated. Numerous cohort studies have highlighted an increased risk of chronic kidney disease in RA patients compared to healthy controls. This risk may be influenced by medications and accelerated atherosclerosis due to the increased inflammatory burden. However, data on this risk are not yet well-characterized. <h3>Objectives:</h3> To evaluate the decline of glomerular filtration rate (eGFR) among RA patients during follow up. <h3>Methods:</h3> A cohort study was conducted involving RA patients followed for a minimum of one year in Medicarte SAS, a Colombian center for immune-mediated diseases. The eGFR was calculated using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation (2), this result was rounded to the nearest whole number. A mixed linear regression model was carried out using the 'lmer' function from the 'lme4' package in R software (3). The model considered the relationship between the dependent variable eGFR, time and other factors including hypertension (HT) and diabetes mellitus (DM). To assess stability, a bootstrap simulation (comprising 1000 iterations) was conducted. Interquartile range (IQR) was calculated for both the simulated and observed values. Finally, the adjusted values were generated and the correlation matrix of the variance-covariance of the random effects was calculated. <h3>Results:</h3> A total 1,971 RA patients were included, with 89.3% (n= 1730) being female. The median age at baseline was 5.4 years (IQR= 2.1-6.8). The median follow-up duration was 5.04 years (IQR= 2.2-6.8). Initially, 20% (n=396) of individuals had HT and 4.2% (n=84) had DM. The statistical model revealed that, on average, in RA patients each unit increase in time was associated with a decrease in eGFR by 0.97 ml/min/1.73m². A Patients with DM showed a significant decrease in eGFR of 2.9. Individuals with HT had a decrease of 6.8, and those with both conditions experienced a reduction in eGFR of 7.5 ml/min/1.73m². The model reports considerable variability among individuals, suggesting personal differences in baseline levels of CKD-EPI, Table 1. <h3>Conclusion:</h3> In our cohort, RA patients exhibited a decline in eGRF by 0.97 ml/min/1.73m², comparable to eGFR decline observed in healthy individuals (4). Notably, RA patients with HT and DM exhibited a more pronounced decline in eGFR, suggesting an elevated risk of chronic kidney disease and associated mortality. Further investigation is warranted to validate these findings. <b>Table 1.</b> Summary of Model <h3>REFERENCES:</h3> <b>NIL.</b> <h3>Acknowledgements:</h3> <b>NIL.</b> <h3>Disclosure of Interests:</h3> <b>None declared.</b>