Editorial
Copyright ©The Author(s) 2018. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Respirol. Nov 26, 2018; 8(1): 1-12
Published online Nov 26, 2018. doi: 10.5320/wjr.v8.i1.1
Classical regression equations of spirometric parameters are not applicable for diagnosing spirometric abnormalities in adipotic adults
Kazuhiro Yamaguchi, Hisamitsu Omori, Takao Tsuji, Kazutetsu Aoshiba
Kazuhiro Yamaguchi, Takao Tsuji, Department of Respiratory Medicine, Tokyo Medical University, Tokyo 160-0023, Japan
Hisamitsu Omori, Department of Biomedical Laboratory Sciences, Kumamoto University, Kumamoto 860-8556, Japan
Kazutetsu Aoshiba, Department of Respiratory Medicine, Tokyo Medical University, Ibaraki Medical Center, Ibaraki 300-0395, Japan
Author contributions: All authors contributed conception and designation of the study; they contributed acquisition, analysis and interpretation of the data; they expressed the final approval of the version of the article.
Conflict-of-interest statement: The authors have no conflict of interest to declare. There were no supportive foundations to the present study.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Kazuhiro Yamaguchi, FCCP, MD, PhD, Professor, Department of Respiratory Medicine, Tokyo Medical University, 6-7-1 Nishi-Shinjuku, Shinjuku-ku, Tokyo 160-0023, Japan. yamaguc@sirius.ocn.ne.jp
Telephone: +81-3-34215402 Fax: +81-3-34215402
Received: July 24, 2018
Peer-review started: July 24, 2018
First decision: August 30, 2018
Revised: September 29, 2018
Accepted: November 13, 2018
Article in press: November 14, 2018
Published online: November 26, 2018
Processing time: 135 Days and 12.5 Hours
Abstract

The prevalence of overweighing and obese adults (defined as “adipotic” adults), has markedly increased over the world. A remarkable increase in the adipotic population urgently needs developing the regression equations for predicting spirometric parameters (SPs), which are specifically applicable to adipotic adults. Unfortunately, however, the reliable equations suitable for adipotic adults have not been reported to date. Recently, Yamaguchi et al have proposed the quantitative method to estimate the effects of adiposity on deciding the SPs incorporating with age-specific contributions of various explanatory, independent variables such as age (A), standing height (H), body weight (BW), and fat fraction of body mass (F). Extending the method proposed by Yamaguchi et al, we attempted to elaborate the novel regression equations applicable for diagnosing the spirometric abnormality in adipotic adults. For accomplishing this purpose, never-smoking, adipotic adults with body mass index (BMI) over 25 kg/m2 and no respiratory illness were recruited from the general population in Japan (n = 3696, including men: 1890 and women: 1806). Introducing the four explanatory variables of A, H, BW, and F, gender-specific and age-dependent regression equations that allowed for prescribing the SPs in adipotic adults were constructed. Comparing the results obtained for non-adipotic adults (i.e., those with normal BMI), the negative or positive impact of height on SPs was preserved in adipotic adults, as well. However, the negative impact of age on SPs was blunted in adipotic men and the positive effect of BW on SPs was impeded in adipotic men and women. The fat fraction of body mass-elicited negative impact on SPs vanished in adipotic women. These results indicate that the regression equations of SPs for adipotic adults differ significantly from those for non-adipotic adults, leading to the conclusion that the regression equations for non-adipotic adults should not be used while judging the spirometric abnormalities in adipotic adults.

Keywords: Spirometric parameters; Reference mean; Lower limit of normal; Overweight; Obesity; Body weight; Fat fraction of body mass

Core tip: The impacts of age and a variety of anthropometric factors, including standing height, body weight, and fat fraction body mass, on decision of the spirometric parameters (SPs) differ significantly between non-adipotic adults [i.e., normal body mass index (BMI)] and adipotic adults (i.e., increased BMI). Therefore, if the reference means and lower limits of normal of SPs estimated from the regression equations established for non-adipotic adults are used, substantial errors will emerge while diagnosing the lung function abnormalities in adipotic adults.