Introduction: Prevalence is the most frequently used health indicator in order to assess the magnitude of a disease in a public health environment. It is a fraction that relates the number of screened disease cases divided by the total number of screened cases. When comparing two different study populations it is not possible to predict the proportions of old and new cases. This, when combined with variations in the health care delivery systems, makes the comparison of prevalence within two populations questionable. The objective of this study was to discuss the validity of the comparison of prevalence between two different populations.
Methodology: Mathematical derivatives were presented to express the prevalence of a disease in a given population. Further fragmentation of the equations led to various probabilities pertaining to the number of old versus new cases that contributes to the prevalence of any existing disease. These calculations were applied to a theoretical example and final confirmation of its applicability was completed using various published scenarios from the Scientific Database at Blue Skies Services.
Results: The decomposition of the formula of prevalence to probabilities that measure new, old and normal case probabilities out of the screened individuals will lead to the fact that, not all the parts of these formula are comparable, due either to different settings, health systems or even the time of exposure to a given impairment.
Conclusion: It is concluded that the prevalence of a disease between two different populations is unlikely to be comparable.
Keywords: Prevalence, Prevalence comparison, Health indicators, Dubai Healthcare city
Authors: Amar Hassan Khamis, Maanas Shah