Measurement of Change in Estimated Glomerular Filtration Rate in Patients With Renal Insufficiency After Contrast-Enhanced Computed Tomography: A Case-Control Study

Aim: To test the safety of intravenous contrast in patients with renal insufficiency undergoing computed tomography compared with a concurrent group of patients who received no contrast. Materials and Methods: Between October 2006 and February 2007, 106 consecutive patients with renal insufficiency who underwent intravenous contrast computed tomography were retrospectively reviewed. A separate group of 52 patients with renal insufficiency who did not receive intravenous contrast was also reviewed and acted as control group. Baseline and repeat creatinine (in micromole per liter) and estimated glomerular filtration rate (eGFR) levels were obtained for all patients using the modification of diet in renal disease equation within 3.5 days. Mann-Whitney U test was used to determine any statistically significant changes in creatinine and eGFR values. Subgroup analysis involving only patients with eGFR values of less than 60 was also performed. Results: The mean creatinine before and after contrast was 135.45 and 151.37, respectively (P = 0.724.). The mean eGFR before and after contrast was 44.33 and 43.41, respectively (P = 0.824). Subgroup analysis of 63 patients involving patients with eGFR of less than 60 revealed precontrast and postcontrast creatinine mean to be 136.21 and 158.40, respectively (P = 0.248). Estimated GFR mean values in the same group before and after contrast were 43.71 and 40.70, respectively (P = 0.250). Control group showed precontrast and postcontrast eGFR (and creatinine) mean values to be 40 (162.04) and 38 (168.52), respectively (P = 0.641). Conclusions: Estimated GFR (and creatinine) values in patients with renal insufficiency did not show a statistically significant increase after a mean of 3.5 days of receiving intravenous contrast and therefore supports a conservative outpatient-based management approach.