Myocardial infarction: an acute respiratory tract infection increased the risk.

Clinical bottom line (level 3b)

Patients who visited their family doctor with an acute respiratory infection were at increased risk of having a myocardial infarction in the next 10 days.

Meier et al: Lancet 1998; 351: 1467-1471

Expires March 2003

The study

Case-control study with objective outcomes, adjusted for confounding factors, not validated in an independent set of patients.

Setting: 400 general practices, UK

9571 patients (aged < 75 (61%: 60 to 75), 75% male) well

Excluded if

history of myocardial infarction, angina, unexplained chest pain, cardiac arrhythmias, congestive heart failure, stroke, intermittent claudication, venous thromboembolism, chronic renal disease, hypertension, hyperlipidaemia, diabetes mellitus
connective tissue disease or cystic fibrosis
known metabolic or cardiovascular conditions predisposing to myocardial infarction
aged > 75

Cases: 1922 patients (75% male, mean age -): acute myocardial infarction
Controls: 7649 patients (75% male, mean age -): matched for age, sex and GP practice

Factors studied:

age, body mass index, smoking, urinary tract infection, respiratory tract infection

Factors summarised:

respiratory tract infection within previous 10 days

A logistic regression analysis was performed to adjust for confounding factors.

Outcomes studied:

myocardial infarction

The evidence

Patient expected event rate for myocardial infarction: 0.1%

risk factor for myocardial infarction	adjusted OR (95% CI)	NNH (95% CI)
respiratory tract infection within previous 10 days	3.0 (2.1 to 4.4)	500 (300 to 910)

Citation

Meier CR, Jick SS, Derby LE, et al: Acute respiratory-tract infections and risk of first-time acute myocardial infarction. Lancet 1998; 351: 1467-1471

Search Terms:
Contributor: Chris Ball and Clare Wotton, February 2000
Reviewer:

_{Clinical Question.}

_Patient	_well
_{Intervention or Exposure}	_{acute respiratory tract infection}
_Outcome	_{myocardial infarction}