Warming measures in paediatric cleft surgeries.

Sir,

We read the article by Rajan et al. with great interest which has tried to address a very important research question.[1] However, I would like to point out few issues which need clarification.

This study is a ‘randomised controlled trial’ (RCT) but not a ‘randomised observational study’. It is primarily an interventional/experimental study where randomisation has been done. Here, the intervention is in the form of omission of the standard of care that is, ‘use of active warming measure’. In observational studies, no active intervention is done by the investigator. Any intentional act of ‘commission’ or ‘omission’ by the investigator other than the standard of care constitutes intervention.[2] So actually it is a RCT. There is no mention of the technique used for randomisation, which is considered the heart of any RCT. The ‘closed envelope’ technique as highlighted by the authors is meant for allocation concealment, but not for randomisation.[3] There is no clarity regarding the primary and the secondary outcome. There is no mention of the exact timing (how much time after the start of surgery) when the temperature difference of 0.5°C with a standard deviation of 0.75°C is expected while calculating the sample size.

The intragroup comparison of temperature has been done using paired sample t-test. This test holds true only when there are only two sets of serial values. This test is not applicable when there are more than two serial comparisons within a group because the subsequent values of the variable of interest (temperature in this study) are related to the previous values. Due to this, it needs a specific type of statistical analysis called as ‘longitudinal data/trend’ analyses which take into account the effect of correlation of one set of values to the previous set of values.[4]

Authors have not commented anything upon the blinding, which is an important component of any RCT. Though the intervention can’t be blinded in this case, but there is no information whether the persons collecting and analysing the data were blinded or not to the intervention.[5] Surprisingly, there is a trend towards the difference in the baseline temperature itself which is the primary outcome, though it could not reach statistical significance (P = 0.053). This factor should have been adjusted at the time of analysis. There is no mention about the principle used for the analysis that is, whether it was ‘intention to treat’ or not. Lastly, it would have been better if the authors could have provided the 95% confidence limits apart from the P values.

Despite these limitations, we appreciate the authors for their work, which opens up new arenas of research in the field of strategies to maintain temperature in paediatric patients undergoing cleft lip and cleft palate surgeries.