Author contribution: Rakhmanov RS — developing the study concept and design, manuscript writing; Bogomolova ES — editing, approval of the final version of the article; Narutdinov DA — primary data acquisition; Razgulin SA — literature review; Istomin AV — statistical data processing and data interpretation; Shurkin DA — statistical data processing.

Compliance with ethical standards: the study was approved by the Ethics Committee of the Privolzhsky Research Medical University (protocol № 4 of 14 March 2022), it was carried out in accordance with the ethical principles stipulated in the Declaration of Helsinki of the World Medical Association; all servicemen submitted the informed consent to participation in the study.