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ARTICLE:
M. Luz Garcia Garcia, Ulrich Wahn, Leen Gilles, Arlene Swern, Carol A. Tozzi, and Peter Polos
Montelukast, Compared With Fluticasone, for Control of Asthma Among 6- to 14-Year-Old Patients With Mild Asthma: The MOSAIC Study
Pediatrics 2005; 116: 360-369 [Abstract] [Full text] [PDF]
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[Read eLetters] Randomisation across continents, could be a confounding factor for biased results.
Dinkar Bakshi   (2 September 2005)

Randomisation across continents, could be a confounding factor for biased results. 2 September 2005
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Dinkar Bakshi,
Paediatrician
Leeds Teaching Hospitals NHS Trust, UK

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Re: Randomisation across continents, could be a confounding factor for biased results.

dinkarbakshi{at}hotmail.co.uk Dinkar Bakshi

Given the difficulties in conducting research in children, The MOSAIC study seems to have been planned and executed rather well. However, the paper has not listed the countries involved in the study. It is well known, that asthmatic attacks are more common in winter, and have an association with the pollution index of industrial towns. Although the study was done over a period of one year, and one would expect the differences due to climatic changes to be ironed out, as it would complete a cycle of seasons, it would have been relevant to know which countries were involved in the study. Latitudnal differences in the geographical locations of countries, can lead to differences in the incidence of asthma, and this could also be affected by the pollution levels of some industrial towns, especially in developing countries. Also, if patients were randomised to the two groups, without taking into account the geographical locations, it could introduce an element of bias, to the results. For example, if more children were randomised to receive Montelukast, in a developing country, with a generally cold climate, and high levels of pollution, it could skew the results of the secondary end points, in favour of Fluticasone. Although, it is understandable that there are logistic difficulties and no study can be perfect, it would be helpful to know whether the number of subjects, allocated to either group, in all the countries, was similar.

Conflict of Interest:

None declared