Associations between metabolic score for visceral fat and adult lung functions from NHANES 2007-2012.

Background: Obesity is a significant part of the factors affecting lung function, and the assessment of obesity using the Metabolic Score for Visceral Fat (METS-VF) is more precise than other indicators like waist circumference and body mass index. This study investigated the relationship between lung function and METS-VF in The National Health and Nutrition Examination Survey (NHANES) database from 2007 to 2012.

Method: The data utilized in this study was obtained from National Health and Nutrition Examination Survey spanning the years 2007 to 2012. A multivariate linear regression analysis was employed to investigate the association between METS-VF and lung function, followed by subgroup analysis to identify populations that may exhibit heightened sensitivity. Nonlinear correlations were assessed by fitting a restricted cubic spline, with validation of results conducted via threshold effect analysis.

Result: In a study involving 4,356 participants, a weighted multiple linear regression model revealed a significant negative association between the METS-VF and forced expiratory volume in the first second (FEV1), forced vital capacity (FVC), FEV1/FVC ratio, and forced expiratory flow between 25 and 75% of FVC (FEF25-75%). However, no association was observed with peak expiratory flow rate (PEF). When dividing the METS-VF into thirds, participants in the highest third exhibited significantly decreased levels of FEV1 (: -342, 95%CI: -440, -245,  < 0.001), FVC (: -312, 95%CI: -431, -192,  < 0.001), FEV1/FVC (: -0.020, 95%CI: -0.030, -0.010,  < 0.001), and FEF25-75% (: -424, 95%CI: -562, -285,  < 0.001). However, there was no significant relationship with PEF (: -89, 95%CI: -325, 147,  = 0.446). RCS curve indicated a nonlinear negative correlation between METS-VF and FEV1, FVC, and FEV1/FVC. For FEV1, a significant negative correlation was found when the METS-VF < 6.426 ( = -158.595, 95%CI: -228.183, -89.007). This negative association became more pronounced when the METS-VF > 6.426 ( = -314.548, 95%CI: -387.326, -241.770). For FVC, a negative association was observed when the METS-VF < 6.401, ( = -5.477, 95%CI: -91.655, 80.702), but it did not reach statistical significance. However, METS-VF > 6.401, METS VF and lung function show a significant negative correlation ( = -399.288, 95%CI: -486.187, -312.388). FEV1/FVC showed a negative correlation only before the inflection point (METS-VF < 6.263) ( = -0.040, 95%CI: -0.047, -0.032), after the inflection point (METS-VF > 6.263), no correlation was found, but there was no statistical significance ( = 0.000; 95%CI: -0.006, 0.007), and METS-VF had a linear negative correlation with FEF25-75%. Subgroup analysis showed that the association was consistent across a variety of demographic factors, including age, sex, race, hypertension, and coronary heart disease. In addition, we found a stronger association between men under 40 and lung function.

Conclusion: METS-VF showed a linear negative correlation with FEF25-75%, and a nonlinear negative correlation with FEV1, FVC, FEV1/FVC, and FEF25-75%, but was not associated with PEF, particularly among males under the age of 40. These findings offer valuable insights into managing lung function by controlling visceral fat.