Footnotes

• Handling editor Josef S Smolen

• GL and VV contributed equally.

• Collaborators Marco Fornaro, Maria Grazia Giannotta, Elena Silvestri.

• Contributors All authors approved the final version of the letter after being involved in drafting and revising the article for important intellectual content. As the corresponding author, GL had full access to the data and takes responsibility for the accuracy of the performed analysis and the integrity of data. GL, VV and FI were involved in the design of the study. Execution, analysis and writing of the manuscript were performed by GL and VV.

• Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

• Competing interests None declared.

• Ethics approval This study was performed according to the Declaration of Helsinki and obtained the approval by the Ethics Committee in the University of Bari, Italy.

• Provenance and peer review Not commissioned; externally peer reviewed.