The role of inflammation in contrast induced nephropathy
Date of Award
Master of Medicine (MMed)
Imaging and Diagnostic Radiology (East Africa)
Background: Intravenously administered iodinated contrast media are widely and liberally used in daily diagnostic radiological investigations. Contrast-induced nephropathy (CIN) is notable as the third commonest cause of hospital-acquired renal injury.
Justification: The global prevalence of CIN from various studies ranges from 2-5% but an incidence of CIN of 12-14% in Kenya was highlighted by a recent study without an explanation for the markedly increased incidence. Intravascular contrast has been demonstrated to commonly cause renal vasoconstriction. However, the low incidence of CIN in the general population infers that contrast alone cannot be a causative insult. This study proposes that inflammatory states, which are prothrombotic, when coupled with renal vasoconstriction may confer a higher relative risk for development of CIN. Objective: To determine the risk of developing CIN given the presence of an inflammatory state in patients presenting to a private university hospital in Kenya.
Study design: Prospective cohort study of patients undergoing a contrast- enhanced CT scan (CECT) in Aga Khan University Hospital, Nairobi (AKUHN) Radiology department and who have no known risk factors for CIN.
Methodology: A total of 423 patients were recruited over a period of 4 months. The patients were grouped into those without inflammation (unexposed) having serum C-reactive protein (CRP) levels ≤5mg/dL and those with inflammation(exposed) having CRP levels >5mg/dl. Serum creatinine (SCr) was measured before the CECT and 48 hours following the CECT with CIN diagnosed when there was an increase of >25% in the SCr from the baseline value. Relative risk was determined and multiple logistic regression analysis performed on the biophysical variables (age, weight, sex) and contrast volume to assess their effect on development of CIN.
Results: CIN was present in 42 (9.92%) patients. Of the exposed group (elevated CRP), 29 out of 215 patients (13.5%) developed CIN. In the unexposed group, 13 out of 208 patients (6.25%) developed CIN. This gave arelative risk of developing CIN of 2.16(1.15 to 4.04, P=0.016).The attributable risk percentage is 7.24% (1.1% to 12.2%). No statistically significant association was seen between the biophysical variables and volume of contrast and development of CIN.
Conclusion: Inflammation doubles the likelihood of development of CIN. Therefore a patient presenting with inflammation and any other risk factor for CIN should have a risk-benefit analysis to assess the need for administration of iodinated intravenous contrast.
Kwasa, E. A. (2013). The role of inflammation in contrast induced nephropathy (Unpublished master's dissertation). Aga Khan University, East Africa.