Determinants of plasma interleukin-6 levels among survivors of myocardial infarction.

Background: We identify determinants of plasma interleukin-6 (IL-6) levels in a multicenter panel study of myocardial infarction (MI) survivors, using repeated measurements to evaluate both baseline and time-varying factors.

Design And Methods: Survivors of MI (N= 1003) recruited in six European cities had repeated measurements (median: 6/patient) of IL-6. At baseline, participants' behaviour and medical histories were determined by interview, and blood pressure, anthropometry, cholesterol and N-terminal B-type natriuretic peptide (NT-proBNP) were measured. Short-term exposures and medication intake were recorded at each visit. Generalized additive mixed models were used to analyze associations of IL-6 with baseline and time-varying risk factors, taking into account repeated measurements.

Results: Age, hour of blood withdrawal, body mass index, pack-years of smoking, NT-proBNP, systolic blood pressure, high-density lipoprotein cholesterol, persistent cough/phlegm and statin use were significantly and independently associated with IL-6 after adjustment for city, recurrent MI, baseline alcohol intake, current active smoking, tea consumption and extreme anger or stress.

Conclusion: Among MI survivors, IL-6 levels are associated with many traditional cardiovascular risk factors. Patients with elevated NT-proBNP, respiratory symptoms or obesity had higher IL-6 concentrations and may potentially be at greater risk for coronary artery disease progression.