Background: In recent years, the importance of circulating levels of proinsulin and apolipoproteins as risk factors for myocardial infarction (MI) has been highlighted. The aims of the current study were to investigate whether introduction of these new markers of coronary risk could improve the performance of a risk prediction score and to compare this new score with traditional scoring schemes, such as the Framingham Study and the Prospective Cardiovascular Munster (PROCAM) Study schemes.
Methods: From 1970 to 1973 all 50-year-old men in Uppsala, Sweden, were invited to participate in a health survey aimed at identifying risk factors for cardiovascular disease (the Uppsala Longitudinal Study of Adult Men [ULSAM] cohort). The current study investigated metabolic characteristics at baseline and the incidence of fatal and nonfatal MI (n = 251) during 28.7 years of follow-up in 1108 men who were free of coronary heart disease at baseline.
Results: The risk prediction score was derived from one half of the population sample from the ULSAM cohort and included systolic blood pressure, smoking, family history of MI, serum proinsulin, and the ratio between apolipoprotein B and apolipoprotein A1. The score was highly predictive for future MI (hazard ratio, 1.77 for a 1 SD increase; 95% CI, 1.49 to 2.10, P <.0001) in the other half of the population that was not used for generating the score. The ULSAM score performed slightly better than the Framingham and PROCAM scores (evaluated as areas under the receiver operating curves; Framingham, 61%; PROCAM, 63%; ULSAM, 66%; P =.08).
Conclusions: A risk prediction score for MI including proinsulin and the ratio between apolipoprotein B and apolipoprotein A1 was developed in middle-aged men. This score was highly predictive for future fatal and nonfatal MI and proved to be at least as good as the Framingham and the PROCAM scores, being based on traditional risk factors.