Coronary disease surveillance: a public health imperative

Abstract

Coronary heart disease (CHD) is the leading cause of death in the Western world, thereby constituting an immense public health problem. While CHD mortality declined in the last four decades, the use of age-adjusted rates to describe CHD mortality obscures the fact that the decline largely represents the postponement of CHD deaths until older age. In fact, the burden of CHD is increasing in parallel with the increase in life expectancy.1 As the burden of prevalent CHD is increasing, identifying persons with CHD, measuring its incidence and outcome and how these vary over time and across populations is essential to understand the determinants of the trends in CHD. This in turn is crucial to define the relative contributions of risk factor reduction and therapeutic improvements, which is necessary to design effective interventions to reduce CHD. The monitoring (otherwise termed surveillance) of CHD requires several conditions. The availability of a defined population is indispensable to generate incidence rates, and valid definitions that actually measure the intended event are essential. The definitions should be standardized to enable reliable data collection and comparisons across studies. The definitions should also be relatively immune to temporal changes so that time trends in the occurrence of CHD can be appraised. Despite their apparent simplicity, these requirements are rarely met. Indeed, hospital discharges, while constituting an intuitive indicator of the occurrence of CHD, are event based, not person based, and allow for multiple hospitalizations for the same individual to be counted. The diagnoses are not standardized such that they may reflect different entities depending on care delivery patterns, themselves depending on insurance coverage, medical practice habits, etc. As they do not differentiate between first and subsequent admission for a given condition, hospital discharges cannot measure incidence. Finally, shifts in discharge … Corresponding author. Tel: +1 507 284 0519; fax: +1 507 266 0228. E-mail address: roger.veronique{at}mayo.edu