COMMUNITY DENTISTRY
Cite this article:
Khamis AH. Is Comparison
of the Prevalence of Disease
Appropriate as Health
Indicator between
two Populations?
Stoma Edu J. 2014;1(2):
92-96.
IS COMPARISON OF THE PREVALENCE
OF DISEASE APPROPRIATE
AS HEALTH INDICATOR BETWEEN
TWO POPULATIONS?
Amar Hassan Khamis1a*,
Maanas Shah2b
1. Biostatistics and Research Unit,
Hamdan Bin Mohammed College
of Dental Medicine (HBMCDM),
Dubai, United Arab Emirates
2. Department of Periodontology,
Hamdan Bin Mohammed College
of Dental Medicine (HBMCDM),
Dubai, United Arab Emirates
a. PhD, DEA, MSc, BSc, Associate Professor
b. BDS, MSD, CAGS, Clinician
Abstract
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.
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 to the time of exposure to a
given impairment.
Conclusion: The conclusion is that the prevalence of a disease between two
different populations is unlikely to be comparable.
Keyword: prevalence, prevalence comparison, health indicators,
Dubai healthcare city.
Introduction
Received: 24 September 2014
Accepted: 06 October 2014
* Corresponding author:
Associate Professor Amar Hassan Khamis,
PhD, DEA, MSc, BSc
Head of Biostatistics and Research Unit
Hamdan Bin Mohammed College of Dental
Medicine (HBMCDM)
34, Al Zahrawi Building
Dubai, PO – 505097
United Arab Emirates
Tel/Fax: +97144248787
e-mail: [email protected]
92
The recent definition of the word disease in the Oxford English dictionary is: a condition
of the body or some part or organ of the body, in which its functions are disturbed or
deranged; morbid physical conditions; a departure from state of health, especially when
caused by structural change (1). This definition identifies a wide spectrum of the concept of
the word disease from influenza to arthritis and from tuberculosis to cancer. In epidemiology
and in biostatistics, despite the above-mentioned definition, a disease is considered as a
dichotomous variable (yes or no) regardless of the status of the illness or the different states
of the patient.
The prevalence or prevalence proportion is an indicator that is frequently used in
epidemiology to describe the number of people with a disease in a given population. The
proportion of a population found to have a condition (typically a disease) is derived by
STOMA.EDUJ (2014) 1 (2)