Glomerular filtration rate assessed by using creatinine and cystatin in patients treated with dabigatran

Dabigatran (DAB) is 80 % renally excreted. Glomerular filtration rate (GFR) estimation is recommended to evaluate the kidney function for DAB dosage adjusting. In this paper we report same results about evaluation of creatinine (CRE) GFR and cystatin-C (CYS) GFR in comparison with drug concentration in a group of patients treated with DAB. We considered 77 patients in which an evaluation of kidney function using CRE and CYS based GFR was performed. After GFR-CRE and GFR-CYS calculation these patients were classified as recommended by KDIGO guidelines. Moreover we evaluated the relationship between trough DAB concentration and GFR-CRE or GFR-CYS. We observed a satisfactory correlation between GFR-CRE and GFR-CYS ( $R=0.85$ ). Following KDIGO criteria, patients’ classification performed by using GFR-CRE or GFR-CYS was concordant in 52 (68 %) subjects and discordant in 25 (32 %). We observed an inverse relationship between trough DAB concentration versus GFR-CRE ( $R=-0.71$ ) and GFR-CYS ( $R=-0.79$ ). Results obtained in this study, although preliminary, suggested that, in this particular subset of patients, the determination of GFR-CYS can be a better renal function indicator than GFR-CRE. Moreover, we observed that GFR evaluation alone is not able to explain in a satisfactory manner, individual responses to dabigatran etexilate evaluated as a trough DAB concentration.