Global burden of non-communicable diseases - why prevalence is not a comprehensive measure

Abstract

Background: The prevalence is a common epidemiological measure to describe the morbidity and burden of a non-communicabledisease in a population. Often it is used to compare various populations with respect to the disease, e.g. in different countries. However, comparing the prevalence in different populations may lead to erroneous conclusions about the disease specific situation, because the prevalence is a result of a complex interplay between incidence and mortality. In this article, we show how distinctivelydifferent population based interventions against type 2 diabetes mellitus (T2DM) lead to the same age-specific prevalence of thedisease. By comparing the prevalences of T2DM, the impact of the interventions would be rated as being equivalent – which theyare not.

Methods: Based on data from the National Health Interview Surveys (NHIS) and the National Health and Nutrition ExaminationSurveys (NHANES), we calculate the effects of two hypothetical prevention programs against T2DM in the United States. Thefirst prevention program is based on a pharmacological intervention, which is assumed to affect the incidence of diabetes only. The second program is a lifestyle intervention affecting both, incidence of diabetes and the mortality in the population.

Results: Choosing plausible participation rates, both prevention programs have the same impact on the age-specific prevalence ofdiabetes. Considering the prevalence alone would erroneously indicate a similar effect of both programs although the lifestyle intervention is superior in terms of the mortality in the population.

Conclusion: A comprehensive description of the burden of a chronic disease in a population should not rely on the prevalencealone, but include further measures, such as the incidence and the mortality rates. This is especially important in setting upsurveillance systems for chronic diseases as requested e.g. by the United Nations’ resolution against chronic diseases.