[Measurement of chronic conditions in a single person as a mortality predictor].

The presence of multiple chronic diseases in a single individual has become an increasing public health problem for two reasons: population aging and the growing prevalence of chronic conditions in the elderly. This article aims to review the various measures of chronic conditions used in different morbidity studies and to provide an example of their application. We present definitions and characteristics of distinct morbidity measures, as well as their advantages and disadvantages, and provide an example of their calculation using real data. The presence of multiple chronic diseases in a single individual can be measured in multiple ways. Thus, morbidity can be expressed as multi-morbidity, co-morbidity, or as a co-morbidity index. Researchers have to select the best option according to the research objectives, study design, information resources, and the main outcome variable selected.