Maidstone RJ, Turner J, Vetter C, et al. Night shift work is associated with an increased risk of asthma. Thorax 2021;76:53-60.
The authors regrettably note that smoking pack years was recorded in the UK Biobank dataset as not available for ‘never smokers’, which resulted in ‘missing data’ being recorded in the statistical programme ‘R’ for ‘never smokers’. Ultimately, this led to ‘never smokers’ being inadvertently excluded from the analysis. Model 1 (adjusted for age and sex) was unaffected, but Models 2 and 3 (supposedly adjusted for smoking) did not include ‘never smokers’.
The following differences were identified:
The authors no longer find an association between permanent night shift workers and all asthma in Models 2 and 3, in contrast to findings in the original manuscript.
The chronotype re-analysis generated similar findings in all asthma as reported in the original manuscript, but for moderate-severe asthma the association with both extreme chronotypes remained statistically significant in both Models 2 and 3, whereas in the original manuscript the association with evening chronotype attenuated to the null in Models 2 and When the authors assessed the likelihood of moderate-severe asthma in individuals with a particular chronotype by shift work pattern the re-analysis shows no strong evidence of associations between shift work pattern and the likelihood of moderate-severe asthma in any particular chronotype. However, in the original manuscript the authors had shown that in participants who were definitely morning chronotypes, there were higher odds of moderate/severe asthma in those shift workers working irregular shifts, including nights.
After excluding cases of COPD, emphysema and chronic bronchitis the authors still found an association between both moderate-severe asthma and all asthma and shift workers who never or rarely undertook night shifts in Model 1. However, the association between permanent night shift workers and asthma/moderate-severe asthma (which was only found in Models 2 and 3 originally) was no longer significant.
The online article has been updated.