The authors reply

I am deeply appreciative of your interest in our recent article entitled “Risk factors and outcomes of acute renal infarction” [1]. Acute renal infarction (RI) is a rare disease, and as such, its long-term clinical outcome is unknown. Acute kidney injury (AKI) is a known risk factor for chronic kidney disease progression. The unexpected findings of AKI and chronic kidney disease in RI patients cannot be explained by the natural course or special characteristics of RI itself. As you have pointed out, it may also be due to the bias inherent in a retrospective cohort study. Our results have adjusted for all relevant risk factors including age, sex, comorbidities, and AKI history, whereupon the remaining factors were found to be statistically significant.

Although Oh et al [2] undertook a large retrospective multicenter study comprising 438 RI patients, information on the causes of death was unavailable to them. Your comment has prompted us to perform further analyses, and we have found several interesting relationships between patients with RI, death, and other risk factors. Only a small proportion of our patients experiences death (8/89, 8.9%). Use of aspirin or other antiplatelet agents [P = 0.03; odds ratio (OR), 5.47; 95% confidence interval (CI), 1.09–27.3], bilateral renal artery involvement (P = 0.03; OR, 5.23; 95% CI, 1.15–23.6), high C-reactive protein (P = 0.002; OR, 1.01; 95% CI, 1.005–1.025), lower high-density lipoprotein level (P = 0.007; OR, 0.9; 95% CI, 0.837–0.972), and higher low-density lipoprotein level (P = 0.009; OR, 1.9; 95% CI, 1.847–1.976) were found to be related to death in RI patients. AKI, together with other lethal comorbid conditions, can also result in a fatal outcome.

We have attempted to reply to another query on the increase in creatinine levels more than 2 times or rehospitalization. However, these data were unavailable. It remained unclear by reviewing medical records whether the second damage was related to the previous RI. Future studies should be designed to investigate this.