Psychological distress, physical illness and risk of myocardial infarction in the Caerphilly study

Studies have found associations between psychological distress (PD) and increased risk of myocardial infarction (MI). However, it is not clear whether the relationship reflects the subtle influence of pre-existing illness on both PD and MI. This study examines the association between PD and MI in a prospective epidemiological study of 1864 middle-aged men to examine if the association is explained by existing illness.

This study was a prospective cohort study modelling the association between PD, measured using the 30-item General Health Questionnaire (GHQ) and non-fatal myocardial infarction (NFMI) and fatal/non-fatal myocardial infarction (FNFMI). The relationship was modelled in a series of logistic regression models adjusted for age, then cigarette smoking, then social position, and finally for all sociodemographic characteristics, coronary heart disease (CHD) risk factors, and baseline CHD.

PD was associated with a 70% and 68% increased risk of NFMI and FNFMI in fully adjusted analysis. However, PD was not associated with an increased risk of NFMI and FNFMI in analyses excluding those with baseline CHD. Further, being psychologically distressed and physically ill was associated with a greater than twofold risk of NFMI and FNFMI, 2.37 (95% CI 1.33-4.20) and 2.33 (95% CI 1.32-4.12) respectively.

This study suggests that PD is a moderator of the increased risk of MI associated with existing physical illness. PD in men who are physically ill is a marker of an underlying chronic physical illness. The prospective association of PD with MI is not independent of baseline physical illness.