Comment on: The Difference in Expression of Autophagy-Related Proteins in Lesional and Perilesional Skin in Adult Patients with Active and Stable Generalized Vitiligo-A Cross-Sectional Pilot Study.

Dear Sir,

We read with interest the article published by Yu et al.: “The Difference in Expression of Autophagy-Related Proteins in Lesional and Perilesional Skin in Adult Patients with Active and Stable Generalized Vitiligo—A Cross-Sectional Pilot Study” published in Indian Journal of Dermatology.[1] The study is plausible and informative and the authors have done a commendable job by investigating the autophagy related protein expression in adult patients with active and stable generalised vitiligo. However, there are a few concerns regarding this study.

It has been mentioned by the authors in the study title that this was a cross sectional study. A cross-sectional study is observational in nature and it involves single examination of a cross-section of population at one point of time.[23] Further in the methods section, the authors have mentioned “mammalian target of rapamycin (mTOR) and p62 in lesional and perilesional vitiligo skin from seven patients with active generalized vitiligo and nine patients with stable generalized vitiligo compared to control skin from six healthy subjects”.[1] Since the study involved two groups (cases & controls) with and without outcome of interest, the study does not appear to be cross-sectional as stated earlier, as cross-sectional studies are prevalence studies and are undertaken in population.[3] The present study does not fit the case control study design too as matching is required for it. With the methods adopted in the present study, the study title and methods should have used the term 'comparative study' not a cross sectional one.