Summary table of case–control studies of the association between ILI and AMI
| Study | Study location | Study design and study period | Participant age Mean (range)* | Prior AMI in study participants | ILI in cases n/N (%) | ILI in controls n/N (%) | OR (95% CI) | Adjusted confounders | Vaccine coverage | aOR (95% CI) | Risk of bias score |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Mattila30 | Helsinki, Finland | Prospective hospital-based study; influenza season(s) unknown | Cases: 44.5 (34–50) Controls without CHD: 41 (28–50) Controls with CHD: 39.1 (30–50) | Cases: exclusion criteria not reported Controls: 30/71 chronic CHD admitted for angiography | 11/40 (28) | 8/71 (11.3) | 2.99 (1.09 to 8.21)† | No adjustment | Not reported | Not calculated | High |
| Ponka et al26 | Helsinki, Finland | Prospective hospital-based study; 1980 influenza season | Cases: 63 (36–82) Controls: 68 (33–89) | Exclusion criteria not reported | 6/49 (12.2) | 4/37 (10.8) | 1.15 (0.30 to 4.41)† | Date of hospital admission | Not reported | Not calculated | High |
| Warren-Gash et al28 | London, England | Prospective hospital-based study; 2009–2010 influenza season | Aged ≥40 years 63.6 (IQR 53.3–72.6 | Cases: prior AMI eligible (14/70) Controls: 1-month history of AMI excluded (5/64 prior AMI) | 10/71 (14.3) | 3/64 (4.7) | 3.39 (0.89 to 12.92) | Influenza vaccination, personal and family history of myocardial infarction | 42.9% cases 45.3% controls | 3.17 (0.61 to 16.47) | Low |
*Unless otherwise reported.
†Calculated from included data (not reported in original paper).
AMI, acute myocardial infarction; CHD, coronary heart disease; ILI, influenza-like illness.