Table 3

Summary table of case–control studies of the association between RTI and AMI

StudyStudy locationStudy design and study periodParticipant age
Mean (range)*
Prior AMI in study participantsRTI in cases
n/N (%)
RTI in controls n/N (%)OR (95% CI)Adjusted confoundersVaccine coverageaOR (95% CI)Risk of bias score
Clayton et al31Kansas, USAProspective hospital-based study; influenza season(s) unknown63 (NNR)Exclusion criteria not reported177/335 (52.8)126/199 (63.3)1.0 (0.5 to 1.9)Gender, age, BMI, area deprivation score, smoking status and history of anginaNot reported0.92 (0.60 to 1.42)High
Clayton et al32UKRetrospective GP database study; 1994–1996, not restricted to influenza season72 (SD 13)Cases/controls: prior MI excluded84/11 155 (0.8)†34/11 155 (0.3)†2.48 (1.67 to 3.70)‡Hypertension, hyperlipidaemia, diabetes, CVA, coronary heart disease in first-degree relatives, peripheral vascular disease and chronic obstructive pulmonary disease, smoking status and BMI35.6% cases
31.7% controls
2.55 (1.71 to 3.80)Moderate
MacIntyre et al27Sydney, AustraliaProspective hospital-based study; 2009–2010 influenza seasons§Aged ≥40 yearsCases: prior AMI eligible. (NNR)
Controls: 12-month history of AMI, TIA or stroke excluded
52/275 (31.1)32/284 (18.6)1.98 (1.2 to 3.3)Age, gender, smoking, high cholesterol33.5% cases
64.8% controls
Not calculatedLow
Meier et al33UKRetrospective GP database study; 1994–1996, not restricted to influenza seasonAged ≤75 yearsCases/controls: prior MI, angina pectoris and other cardiovascular conditions excluded54/1922 (2.8)¶72/7649 (0.94)¶3.0 (2.1 to 4.4)Smoking status, BMI, history of asthma, calendar year, fatal AMINot reported3.0 (2.1 to 4.4)High
Penttinen and Valonen34FinlandNested case–control study; 1980–1992 not restricted to influenza seasonNNR (38–61)Cases: exclusion criteria not reported
Controls: prior MI excluded
50/83 (60.3)115/249 (46.1)1.77 (1.07 to 2.93)‡Age, smoking status, social status and county of residenceNot reportedNot calculatedHigh
Spodick et al35Massachusetts, USAProspective hospital-based study; influenza season(s) unknownCases: males 63 (SD 13), females 73 (SD 11)
Controls: males 63 (SD 13), females 73 (SD 11)
Exclusion criteria not reported42/150 (28)23/150 (15.3)2.15 (1.22 to 3.80)‡GenderNot reportedNot calculatedHigh
Warren-Gash et al28London, EnglandProspective hospital-based study; 2009–2010 influenza seasonAged ≥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)
17/70 (24.3)12/64 (18.8)1.39 (0.60 to 3.19)Influenza vaccination, personal and family history of AMI42.9% cases
45.3% controls
1.39 (0.56 to 3.47)Low
  • *Unless otherwise reported.

  • †RTI occurring 1–7 days before AMI. ‡Calculated from included data (not reported in original paper).

  • §RTI questionnaires conducted over the 2009 and 2010 influenza seasons only.

  • ¶RTI occurring 1–10 days before AMI.

  • AMI, acute myocardial infarction; BMI, body mass index; CVA, cerebrovascular accident; IQR, interquartile range; MI, myocardial infarction; NNR, number not reported; RTI, respiratory tract infection; TIA, transient ischaemic attack; SD, standard deviation.