The role of inflammation in contrast-induced nephropathy

Objective: Global incidence of contrast-induced nephropathy (CIN) is 2-5%, but a recent Kenyan study highlighted a local incidence of 12-14% without offering an explanation for the higher incidence. This study proposes that inflammatory states confer a higher relative risk for development of CIN. Our objective was to determine the risk of developing CIN given the presence of an inflammatory state in patients in Kenya. Methods: Prospective cohort study of patients undergoing a contrast-enhanced CT (CECT) scan in a private university teaching hospital in Kenya and having no known risk factors for CIN. 423 patients were recruited and grouped into those without inflammation (unexposed) having serum C-reactive protein (CRP) levels <= 5mg dl(-1) and those with evidence of inflammation having CRP levels >5mg dl(-1). Serum creatinine (SCr) was measured before the CECT and 48 h following the CECT with CIN diagnosed by an increase of >25% in the SCr from the baseline. Relative risk was determined and multiple logistic regression analysis performed on biophysical variables and contrast volume to assess their effect on development of CIN. Results: Patients with high CRP levels had a relative risk of developing CIN of 2.16 compared with those with normal levels of CRP (p=0.016). No statistically significant association was seen between biophysical variables or volume of contrast and development of CIN. Conclusion: Ongoing inflammation doubles the likelihood of development of CIN. Advances in knowledge: This study highlights the importance of inflammation as a risk factor in the development of CIN.