Measures of frequency in epidemiological studies
Journal Title: Αρχεία Ελληνικής Ιατρικής - Year 2014, Vol 31, Issue 6
Abstract
In epidemiological studies, measures of frequency are used for the measurement of the frequency of the occurrence of the outcomes, while measures of association are used for the estimation of the relation between determinants and frequency of the occurrence of the outcomes. Measures of frequency are empirical and theoretical. In epidemiological studies, empirical measures of frequency can be calculated, while theoretical measures of frequency cannot be calculated but are estimated with the empirical measures of frequency. Empirical measures of frequency are measures of incidence and measures of prevalence. Empirical measures of incidence include incidence-proportion and incidence-density, while measures of prevalence include point prevalence and period prevalence. Outcomes in measures of incidence are events, while in measures of prevalence are states. Theoretical measures of frequency are incidence-proportion, incidence-density, point prevalence, period prevalence, risk and odds. The value of a theoretical measure of frequency cannot be calculated but has a priori a specific and unknown value that is estimated with the respective empirical measure of frequency in a specific study population. At first, the determinant, the outcome and the study population are defined and then the appropriate measures of frequency are calculated. In closed populations, incidence-proportion, incidence-density and prevalence are calculated, while risk is estimated with incidence- proportion. In open populations, incidence-density and prevalence are calculated. When the outcome under study is the death and the study population consists of healthy people, then the incidence of the death is called mortality. In closed populations, mortality is calculated as incidence-proportion or incidence-density, while in open populations, mortality is calculated as incidence-density. When the study population is closed and consists of patients with a specific disease and the outcome under study is the death from this disease, then incidence-proportion of death or case fatality rate is calculated. Key
Authors and Affiliations
P. GALANIS
Keywords
Related Articles
- EP ID EP147802
- DOI -
- Views 128
- Downloads 0
«Απο-ασυλοποίηση», «απο-ιδρυματοποίηση» και ετερότητα<br />
In vivo nephrogenesis in Lewis rats from endothelial cells of syngeneic liver grafts transplanted into partially excised kidney: The role of transforming growth factor (TGF)-β1 and Thy-1 (CD90)
OBJECTIVE In vitro nephrogenesis using the own tissues is an ideal substitute for allogeneic whole-kidney transplantation. METHOD Adult Lewis rats were transplanted syngeneic liver structure grafts, from which hepatoc...
The design of the object of prognostic therapeutic intervention studies
Prognostic intervention studies can be either preventive intervention studies or therapeutic intervention studies. The formulation of prognosis about the progress of the health of an individual is one of the most importa...
Immunology: Past, present and future
No abstract available
Comparison of costs of hemoglobin A1c determination by point-of-care testing (POCT) and standard hemoglobin A1c analyzer
OBJECTIVE The use of the levels of hemoglobin A1c for the monitoring of glycemic control in patients with diabetes mellitus (DM) is an accepted method of clinical usefulness. A study was performed to assess the relative...