Dietary inflammatory index and acute myocardial infarction in a large Italian case–control study

Background: Diet and inflammation have been implicated to play a role in the incidence of acute myocardial infarction (AMI). Methods: In this Italian case-control study conducted between 1995 and 2003, we explored the association between the dietary inflammatory index (DIITM) and AMI. Cases were 760 patients, below age 79 years, with a first episode of nonfatal AMI and controls were 682 patients admitted to hospital for acute conditions unrelated to diet. The DII was computed based on dietary intake assessed using a reproducible and validated 78-item food frequency questionnaire. Odds ratios (OR) were estimated through logistic regression models adjusting for age, sex, total energy intake, tobacco, body mass index, hypertension, hyperlipidemia and other recognized confounding factors. Results: Higher DII scores (i.e., indicating a more pro-inflammatory diet) were associated with increased likelihood of AMI when expressed both as continuous (ORcontinuous=1.14, 95% confidence interval, CI:1.05, 1.24; one-unit increase in DII score corresponding to ≈9% of the range of DII) and as quartiles (ORQuartile4vs1= 1.60, 95%, CI 1.06, 2.41; P-trend = 0.02). Stratified analyses produced slightly stronger associations between DII and AMI among women, ≥60 years, never smokers, subjects with history of hypertension and subjects with no family history of AMI, however, in the absence of heterogeneity across strata. Conclusion: A pro-inflammatory diet as indicated by higher DII scores is associated with increased likelihood of AMI.