Oral Fluoroquinolone and the Risk of Acute Liver Injury: Is It Related to the Antibiotics or the Infection?

To the Editor—We studied with interest the recent article by Nibell and colleagues [1] who found more than 2 times higher risk of acute liver injury (ALI) after use of oral fluoroquinolone compared with amoxicillin. The authors did a register-based propensity score–matched cohort study with 419930 courses of fluoroquinolones and amoxicillin prescriptions. They included patients aged 40–85 years from July 2006 to January 2014, and data were obtained from large national registries in Sweden. ALI was the primary outcome and was defined as toxic liver disease or acute and subacute liver failure using International Classification of Diseases, Tenth Revision, Clinical Modification codes. Ciprofloxacin (79%) followed by norfloxacin (17%) were the most prescribed fluoroquinolones. In total, 18 and 8 ALI events were found, and the incidence rate of ALI was 2.98 and 1.27 per 10000 person-years of follow-up, respectively, after fluoroquinolone and amoxicillin prescriptions. The absolute risk of ALI...