Table 1 Characteristics of included studies.

From: Protective effect of influenza vaccination on cardiovascular diseases: a systematic review and meta-analysis

Study design First author Published year Country Age range Matching Definition of case (number of participants) Definition of control Outcomes
RCT Dokainish32 2019 Multicenter  ≥ 18 1:1 Vaccinated patients with heart failure and NYHA functional class II, III, and IV (n = 2500) Unvaccinated patients with heart failure and NYHA functional class II, III, and IV (n = 2500) Cardiovascular death, non-fatal myocardial infarction, non-fatal stroke, and hospitalizations for heart failure
Kuanprasert5 2011 Thailand  ≥ 65 1:1, sex, age Vaccinated patients with the acute coronary syndrome (n = 221) Unvaccinated patients with the acute coronary syndrome (n = 218) Coronary ischemic events, stroke, heart failure, and vascular death
Bilińska133 2010 Poland 51–69 1:1, sex, age Vaccinated patients with stable angina (n = 242) Unvaccinated patients with stable angina (n = 259) Coronary ischemic events
Bilińska233 2010 Poland 51–67 1:1, sex, age Vaccinated patients with acute coronary syndrome (n = 83) Unvaccinated patients with acute coronary syndrome (n = 74) Coronary ischemic events
Bilinska334 2008 Poland 32–80 1:1, sex, age Vaccinated patients with coronary artery disease (n = 335) Unvaccinated patients with coronary artery disease (n = 333) Coronary ischemic events
de la Fuente123 2004 Argentina  ≥ 21 1:1, sex, age Vaccinated patients with MI or planned stenting (n = 145) Unvaccinated patients with MI or planned stenting (n = 147) Coronary ischemic events and vascular deaths
de la Fuente235 2002 Argentina  ≥ 21 1:1, sex, age Vaccinated patients with MI or planned stenting (n = 151) Unvaccinated patients with MI or planned stenting (n = 150) Coronary ischemic events and vascular deaths
Cohort Thomsen36 2019 Denmark  ≥ 65 1:1.5, sex Vaccinated ICU survivors (n = 28,353) Unvaccinated ICU survivors (n = 44,984) Coronary ischemic events, stroke, and heart failure
Hsin Wu37 2019 Taiwan 76 ± 6a 1:1, sex, age Vaccinated patients with diagnoses of acute MI (n = 4253) Unvaccinated patients with diagnoses of acute MI(n = 4219) Heart failure
Lavallée7 2014 Multicenter  ≥ 31 1:3, sex, age Vaccinated patients with stroke or TIA (n = 5672) Unvaccinated patients with stroke or TIA (n = 16,901) Coronary ischemic events, stroke, vascular deaths
Loeb38 2012 Multicenter  ≥ 55 1:1.5 Vaccinated patients with vascular disease or diabetes mellitus (n = 40,130) Unvaccinated patients with vascular disease or diabetes mellitus (n = 61,621) Cardiovascular death, nonfatal myocardial infarction, and nonfatal stroke
de la Fuente39 2004 Argentina  ≥ 65 1:1, sex, age Vaccinated patients with myocardial infarction (n = 114) Unvaccinated patients with myocardial infarction (n = 108) Coronary ischemic events
Case–control MacIntyre40 2013 Australia  ≥ 40 1:1 Patients admitted with an acute myocardial infarction (n = 275) Patients in orthopedic or ophthalmic outpatient clinics (n = 284) Coronary ischemic events
Heckbert41 2006 USA  ≥ 72 1:2.5, sex, age Patients with myocardial infarction (n = 750) Patients without myocardial infarction (n = 1735) Coronary ischemic events
Barlas42 2000 USA 63 ± 12a 1:1, sex, age CHD Patients With New MI (n = 109) CHD Patients Without New MI (n = 109) Coronary ischemic events
Beahm43 2004 USA 70a 1:1.5, sex, age Patients with myocardial infarction (n = 335) Patients with bone fractures (n = 199) Coronary ischemic events
Hsien Chiang44 2017 Taiwan  ≥ 65 1:1, sex, age Patients who hospitalized with MACE (n = 80,363) Patients with no previous MACE (n = 80,363) Coronary ischemic events and stroke
Siriwardena25 2010 UK  ≥ 40 1:4, sex, age Patients with acute myocardial infarction (n = 16,012) Patients without acute myocardial infarction (n = 62,694) Coronary ischemic events
  1. aThese studies did not report age range, so the mean (± standard deviation) was reported.