Low-Osmolar vs. Iso-Osmolar Contrast Media on the Risk of Contrast-Induced Acute Kidney Injury: A Propensity Score Matched Study

OBJECTIVE: Among the various risk factors associated with contrast-induced acute kidney injury (CI-AKI), the importance of osmolality and viscosity is emerging among the characteristics of contrast media (CM) itself. High osmolality CM (HOCM) is deprecated and low osmotic pressure (LOCM) and iso-osmotic pressure (IOCM) are mainly used in clinical situations where the results of studies on their effect on the development of CI-AKI are contradictory. We evaluated the association between the type of CM and the risk of CI-AKI. MATERIALS AND METHODS: A retrospective observational cohort study to analyze the effect of the type of CM on the development of CI-AKI. Using propensity score (PS) matching, 2,263 LOCM and IOCM groups were paired for analysis from 5,267 patients and fulfilled the inclusion criteria among 12,742 patients who underwent CAG between 1 January 2007, and 31 December 2016. LOCM included iopromide and iopamidol, IOCM was iodixanol. CI-AKI, which was the primary endpoint, was defined based on the Kidney Disease Improving Global Outcomes criteria within 48 h after exposure to the CM. A multivariable logistic regression analysis was used in the unmatched and matched cohorts, respectively. In addition, a stratified model on clinically important variables, including a high Mehran score (≥ 6), was also used in the matched cohort. RESULTS: LOCM users showed an increased incidence of CI-AKI (11.7% vs. 9.3%; p = 0.006), but it lost statistical significance after PS matching (9.9% vs. 9.5%, p = 0.725). In multivariable analyses, the adjusted odds ratio for CI-AKI in the LOCM group were 1.059 [95% confidence interval (CI) = 0.875–1.282; p = 0.555] in unmatched cohort and 0.987 (95% CI = 0.803–1.214; p = 0.901) in matched cohort. These results were also consistent with the high-risk (high Mehran score) group. CONCLUSIONS: Although the role of CM types in the development of CI-AKI has been debated, our observation shows that the selection between LOCM and IOCM during CAG has no influence on the incidence of CI-AKI.