One of the more overlooked implications of antibiotic overexposure is the possibility that it may increase risk of cardiovascular disease (CVD). A recent study in European Heart Journal looked at associations between life-stage and duration of antibiotic exposure during adulthood and subsequent CVD events.
The Nurses’ Health Study (NHS) began gathering information on antibiotic use in 2004. After excluding women with prior histories of myocardial infarction (MI), angina pectoris, stroke or cancer, the study included 36,429 women aged ≥ 60 years and initially free of CVD and cancer. Participants were asked how long, in total, they used antibiotics. Duration was broken into eight time periods, ranging from none to 5+ years and time periods for usage were ages 20 to 39, 40 to 59 and 60+. The authors categorized participants into four groups based on their usage: none, < 15 days, 15 days to 2 months, and 2 months or more.
During an average 7.6 years of follow-up, 1056 participants developed CVD. After adjusting for covariates, the authors observed that women with who had used antibiotics for at least 2 months when they were age 60 or older had a significantly higher risk of CVD (HR 1.32, 95% CI 1.03-1.70). The authors also noted that longer-term antibiotic use between ages 40 to 59 also had a higher risk of CVD (P trend = 0.003). Antibiotic usage at ages 20 to 39 was not associated with a higher risk of CVD.
The authors offered several potential explanations for why antibiotic usage may be associated with increased CVD risk. Antibiotic treatment may induce prolongation of the QT interval and Torsades do Pointes, and sudden cardiac death. Antibiotics can also stimulate proliferation and activity of macrophages, which may induce accumulation of lipids and atherosclerosis over the long term. One other possibility is that antibiotic exposure may influence the abundance and composition of gut microbiota, which could have an effect on CVD heath. The authors believe that their findings reinforce the notion that antibiotics should be used sparingly and especially so in women older than age 60.