Risk of infections in patients treated with ticagrelor vs. clopidogrel: a systematic review and meta-analysis

Aims: Ticagrelor has been shown to reduce the risk of pneumonia and improve lung function, but the findings across studies were inconsistent. The objective is to investigate the relative safety of ticagrelor vs. clopidogrel on infection outcomes in patients with cardiovascular diseases.

Methods and results: We searched MEDLINE, Embase, Cochrane Library, and ClinicalTrials.gov up to 15 October 2019. Randomized controlled trials comparing ticagrelor and clopidogrel that reported infection outcomes were included. The primary outcome was pneumonia. Secondary outcomes were upper respiratory tract infection (URTI), urinary tract infection (UTI), and sepsis. Study quality was assessed using the Cochrane Risk of Bias tool. Study selection, data extraction, and quality assessment were conducted by independent authors. Random-effects model was used for data synthesis. Relative risks (RRs) and 95% confidence intervals (CIs) were pooled with a random-effects model. Out of 5231 citations, 10 trials with altogether 37 514 patients were included. Ticagrelor was associated with a lower risk of pneumonia (RR 0.80, 95% CI 0.67-0.95) compared to clopidogrel. There were no statistically significant differences for URTI (RR 0.71, 95% CI 0.34-1.48), UTI (RR 1.06, 95% CI 0.73-1.64), or sepsis (RR 0.79, 95% CI 0.50-1.26).

Conclusion: Compared to clopidogrel, ticagrelor reduces the risk of pneumonia, but not URTI, UTI, or sepsis. Our study provides further evidence for recommending ticagrelor to patients with acute coronary syndrome at risk of pneumonia, although the mechanism by which ticagrelor reduces the risk of pneumonia merits further research.