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Evaluation of the impact of disease prevention measures: a methodological note on defining incidence rates

Overview of attention for article published in BMC Medical Research Methodology, April 2017
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Title
Evaluation of the impact of disease prevention measures: a methodological note on defining incidence rates
Published in
BMC Medical Research Methodology, April 2017
DOI 10.1186/s12874-017-0350-4
Pubmed ID
Authors

Yin-Bun Cheung, Ying Xu, Matthew Cairns, Paul Milligan

Abstract

In studies of recurrent events, it is common to consider a person who has suffered a disease episode and received curative treatment to be not at risk of suffering a new episode for a duration of time. It is a common practice to deduct this duration from the person's observation time in the statistical analysis of the incidence data. We examined the concepts of incidence and protective efficacy from a real life point of view. We developed simple formulae to show the relationship between the incidence rate and protective efficacy between analyses with and without deducting the curative treatment time from the observation time. We used a malaria chemoprevention and a malaria vaccine study, both previously published, to illustrate the differences. Applying the formulae we derived to a range of disease incidence that covered the two case studies, we demonstrated the divergence of the two sets of estimates when incidence rate is approximately 1 per person-year or higher. In the malaria chemoprevention study, incidence was 5.40 per person-year after the deduction of curative treatment time from observation time but 4.48 per person-year without the deduction. The chemoprevention offered 56.6 and 50.7% protection calculated with and without the deduction, respectively. In the malaria vaccine study, where disease incidence was much lower than one, the results between the two ways of analysis were similar. For answering real life questions about disease burden in the population in a calendar year and the reduction that may be achieved if an intervention is implemented, the definition without deduction of curative treatment time should be used. The practice of deducting curative treatment time from observation time is not wrong, but it is not always the best approach. Investigators should consider the appropriateness of the two analytic procedures in relation to the specific research aims and the intended use of the results.

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Mendeley readers

Mendeley readers

The data shown below were compiled from readership statistics for 41 Mendeley readers of this research output. Click here to see the associated Mendeley record.

Geographical breakdown

Country Count As %
Brazil 1 2%
Unknown 40 98%

Demographic breakdown

Readers by professional status Count As %
Researcher 8 20%
Student > Bachelor 5 12%
Student > Master 5 12%
Student > Ph. D. Student 3 7%
Student > Doctoral Student 2 5%
Other 3 7%
Unknown 15 37%
Readers by discipline Count As %
Medicine and Dentistry 9 22%
Agricultural and Biological Sciences 3 7%
Social Sciences 3 7%
Nursing and Health Professions 2 5%
Immunology and Microbiology 2 5%
Other 6 15%
Unknown 16 39%
Attention Score in Context

Attention Score in Context

This research output has an Altmetric Attention Score of 1. This is our high-level measure of the quality and quantity of online attention that it has received. This Attention Score, as well as the ranking and number of research outputs shown below, was calculated when the research output was last mentioned on 23 April 2017.
All research outputs
#20,660,571
of 25,382,440 outputs
Outputs from BMC Medical Research Methodology
#1,961
of 2,273 outputs
Outputs of similar age
#248,313
of 323,266 outputs
Outputs of similar age from BMC Medical Research Methodology
#31
of 36 outputs
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