open access

Vol 70, No 3 (2019)
DEVELOPMENT IN MARITIME MEDICINE Review article
Published online: 2019-10-03
Submitted: 2019-05-16
Accepted: 2019-08-06
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How to calculate incidence rates from proportionate data

Olaf Chresten Jensen, Agnes Flores, Despena Andrioti Bygvraa, Fereshteh Baygi, George Charalambous
DOI: 10.5603/IMH.2019.0029
·
Pubmed: 31617934
·
International Maritime Health 2019;70(3):187-192.

open access

Vol 70, No 3 (2019)
DEVELOPMENT IN MARITIME MEDICINE Review article
Published online: 2019-10-03
Submitted: 2019-05-16
Accepted: 2019-08-06

Abstract

This paper describes the methodological aspects of calculation of incidence rates from incomplete data in occupational epidemiology. Proportionate measures in epidemiological studies are useful e.g. to describe the proportion of slips, trips and falls compared to other types of injury mechanisms within single age-strata. However, a comparison of proportions of slips, trips and falls among the different age-strata gives no meaning and can hamper the conclusions. Examples of a constructed example and some selected studies show how estimates of incidence rates can be calculated from the proportionate data by applying estimates of denominators available from other information. The calculated examples show how the risks based on the incidence rates in some cases differ from the risks based on the proportionate rates with the consequence of hampering the conclusions and the recommendations for prevention. In some cases the proportionate rates give good estimates of the incidence rates, but in other studies this might cause errors. It is recommended that estimates of the incidence rates should be used, where this is possible, by estimation of the size of the population. The paper is intended to be useful for students and teachers in epidemiology by using the attached Excel training file. 

Abstract

This paper describes the methodological aspects of calculation of incidence rates from incomplete data in occupational epidemiology. Proportionate measures in epidemiological studies are useful e.g. to describe the proportion of slips, trips and falls compared to other types of injury mechanisms within single age-strata. However, a comparison of proportions of slips, trips and falls among the different age-strata gives no meaning and can hamper the conclusions. Examples of a constructed example and some selected studies show how estimates of incidence rates can be calculated from the proportionate data by applying estimates of denominators available from other information. The calculated examples show how the risks based on the incidence rates in some cases differ from the risks based on the proportionate rates with the consequence of hampering the conclusions and the recommendations for prevention. In some cases the proportionate rates give good estimates of the incidence rates, but in other studies this might cause errors. It is recommended that estimates of the incidence rates should be used, where this is possible, by estimation of the size of the population. The paper is intended to be useful for students and teachers in epidemiology by using the attached Excel training file. 

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Keywords

epidemiology; injury; occupational; proportionate; maritime

About this article
Title

How to calculate incidence rates from proportionate data

Journal

International Maritime Health

Issue

Vol 70, No 3 (2019)

Pages

187-192

Published online

2019-10-03

DOI

10.5603/IMH.2019.0029

Pubmed

31617934

Bibliographic record

International Maritime Health 2019;70(3):187-192.

Keywords

epidemiology
injury
occupational
proportionate
maritime

Authors

Olaf Chresten Jensen
Agnes Flores
Despena Andrioti Bygvraa
Fereshteh Baygi
George Charalambous

References (14)
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