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