Letter to the editor

Abstract

The authors reply: We thank Hsu and Lai 1 Hsu C-K Lai C-C Infection indication and severity, Kidney Int. https://doi.org/10.1016/j.kint.2022.08.010 Google Scholar for their interest in our study. 2 Assimon M.M. Pun P.H. Wang L. et al. Azithromycin use increases the risk of sudden cardiac death in patients with hemodialysis-dependent kidney failure. Kidney Int. 2022; 102: 894-903 Abstract Full Text Full Text PDF Scopus (2) Google Scholar They suggest that confounding by infection indication and severity may have influenced the results. 1 Hsu C-K Lai C-C Infection indication and severity, Kidney Int. https://doi.org/10.1016/j.kint.2022.08.010 Google Scholar We agree that these are important considerations, and, to the extent possible, we controlled for these factors. First, recognizing that azithromycin, levofloxacin, and amoxicillin-based antibiotics are used to treat nonrespiratory infections, we included other infection types (i.e., skin/soft tissue, genitourinary) in our propensity score models for confounding control. The authors are correct that we did not control for recent ear, eye, or sexually transmitted infections. However, we excluded otic and ophthalmic antibiotics. Second, to minimize confounding from illness severity, we studied oral, outpatient antibiotics and excluded patients who were hospitalized or in a skilled nursing facility during the 30 days before study antibiotic initiation. We also excluded antibiotic prescriptions with therapeutic durations typical of more severe infections (i.e., >5 days for azithromycin and >10 days for comparator antibiotics). Finally, our negative control outcome analyses produced null results, suggesting minimal bias. 3 Dusetzina S.B. Brookhart M.A. Maciejewski M.L. Control outcomes and exposures for improving internal validity of nonrandomized studies. Health Serv Res. 2015; 50: 1432-1451 Crossref PubMed Scopus (30) Google Scholar Azithromycin use increases the risk of sudden cardiac death in patients with hemodialysis-dependent kidney failureKidney InternationalVol. 102Issue 4PreviewAzithromycin is an antibiotic with QT-prolonging potential commonly prescribed to individuals receiving hemodialysis. Hemodialysis patients have a high prevalence of clinical conditions, such as structural heart disease, that can enhance the pro-arrhythmic effects azithromycin, but were excluded from prior investigations evaluating the cardiac safety of azithromycin. Using data from the United States Renal Data System (2007-2017), we conducted two cohort studies to examine the cardiac safety of azithromycin relative to amoxicillin-based antibiotics (amoxicillin, amoxicillin/clavulanic acid) and levofloxacin (a fluoroquinolone antibiotic known to prolong the QT-interval) in the hemodialysis population. Full-Text PDF Infection indication and severityKidney InternationalVol. 102Issue 5PreviewWe read with great interest a recent study that investigated the association between the use of azithromycin and the risk of sudden cardiac death in patients with hemodialysis-dependent kidney failure.1 Based on the findings of 2 cohort studies, azithromycin versus amoxicillin-based antibiotic (amoxicillin, amoxicillin/clavulanic acid) was associated with a higher risk of sudden cardiac death but azithromycin versus levofloxacin was associated with a lower risk of sudden cardiac death. Although many confounding factors have been adjusted in this study, we have a serious concern about the confounding effect of infection indication and severity. Full-Text PDF