Background As one of the critical indicators of obesity, the interaction between visceral fat content and lung disease is the focus of current research. However, the exact relationship between Visceral adipose index (VAI) and lung function is not fully understood. The purpose of this study was to evaluate the relationship between VAI and lung function, Methods Our study included all participants from the baseline survey population in Xinjiang in the Natural Population Cohort Study in Northwest China. A field survey was conducted in rural areas of Moyu County, Xinjiang, China, between 35 and 74 years old from June to December 2018. We collected standard questionnaires and completed physical examinations, visceral fat tests, and lung function measurements. Results The study included 2367 participants with a mean VAI of 10.35 ± 4.35, with males having a significantly higher VAI than females: 13.17 ± 3.91 vs. 7.58 ± 2.65. The piecewise linear spline models indicated a significant threshold effect between lung function and VAI in the general population and the males population, showing an inverted U-shaped curve. But there was no significant association between VAI and lung function in females. FEV1% predicted and FVC% predicted increased with the increase of VAI (β 0.76; 95% CI 0.30, 1.21) and (β 0.50; 95% CI 0.06, 0.94) in males with VAI ≤ 14, while FEV1% predicted and FVC% predicted decreased with the increase of VAI (β − 1.17; 95% CI − 1.90, − 0.45) and (β − 1.36; 95% CI − 2.08, − 0.64) in males with VAI ≥ 15. Conclusions The relationship between lung function and VAI in male participants showed an inverted U-shaped curve, with the turning point of VAI between 14 and 15. The association between visceral fat and lung function was more robust in males than in females.

Objective This study aimed to construct and evaluate a clinical predictive model for the development of COPD in northwest China’s rural areas. Methods A cross-sectional study of a natural population was performed in rural northwest China. After assessing demographic and disease characteristics, a clinical prediction model was developed. First, we used the least absolute shrinkage and selection operator regression model to screen possible factors influencing COPD. Then construct a logistic regression model and draw a nomogram. The discriminability of the model was further evaluated by the calibration diagram, C-index and ROC curve system. Clinical benefit was analyzed using the decision curve. Finally, the 1000 bootstrap resamples and Harrell’s C-index was used for internal verification of the nomogram. Results Among 3249 patients in the local rural natural population, 394 (12.13%) were diagnosed with COPD. The LASSO regression model was used to find the optimal combination of parameters, and the screened influencing factors included age, gender, barbeque, smoking, passive smoking, energy type, ventilation system and Post-Bronchodilator FEV1. These predictors are used to construct a nomogram. C index is 0.81 (95% confidence interval:0.79–0.83). The combination of the calibration curve and ROC curve indicates that the model has high discriminability. The decision curve shows benefits in clinical practice when the threshold probability is >6% and <58%, respectively. The internal verification results using Harrell’s C-Index were 0.80 (95% confidence interval: 0.78–0.83). Conclusion Combining information such as age, sex, barbeque, smoking, passive smoking, type of energy, ventilation systems, and Post-Bronchodilator FEV1 can be easily used to predict the risk of COPD in local rural areas.

Objective: Pulmonary tuberculosis (PTB)is a significant risk factor for COPD, and Xinjiang, China, has a high incidence of pulmonary tuberculosis. The effects of tuberculosis history on airflow restriction, clinical symptoms, and acute episodes in COPD patients have not been reported in the local population. Besides, the exact relationship between lung function changes in people with a history of tuberculosis and COPD's risk was not clear. Methods: This study is based on the Xinjiang baseline survey data in the Natural Population Cohort Study in Northwest China from June to December 2018. Subjects' questionnaires, physical examination, and lung function tests were obtained through a face-to-face field survey. To analyze the impact of previous pulmonary tuberculosis on local COPD. Furthermore, we clarify the specific relationship between pulmonary function decline and the probability of developing COPD in people with a history of tuberculosis. Results: A total of 3249 subjects were eventually enrolled in this study, including 87 with a history of tuberculosis and 3162 non-TB. The prevalence of COPD in the prior TB group was significantly higher than that in the control group (p-value = 0.005). First, previous pulmonary tuberculosis is an essential contributor to airflow limitation in the general population and patients with COPD: In all subjects included, Pulmonary function, FEV1% predicted (p-value < 0.001) and FEV1/FVC (%) (p-value < 0.001) was significantly lower in the prior TB group than in the control group. Compared with non-TB group, FEV1% Prediction (p-value = 0.019), FEV1/FVC (%) (p-value = 0.016) was significantly reduced, and airflow restriction (p-value = 0.004) was more severe in prior TB group among COPD patients. Second, COPD patients in the Prior TB Group had more severe clinical symptoms: Compared with no history of tuberculosis, mMRC (p-value = 0.001) and CAT (p-value = 0.002) scores were higher in the History of tuberculosis group among COPD patients. Third, Compared with the non-TB group, the number of acute exacerbations per year(p-values＝0.008), the duration of each acute exacerbation(p-values＝0.004), and hospitalization/patient/year(p-values＜0.001) were higher in the History of tuberculosis among COPD patients. Finally, there was a dose-response relationship between FEV1/FVC (%) and the Probability of developing COPD in people with previous pulmonary TB: when FEV1/FVC (%) < 80.8, the risk of COPD increased by 13.5% per unit decrease in lung function [0.865(0.805, 0.930)]. Conclusion: COPD patients with previous pulmonary tuberculosis have more severe airflow limitations and clinical symptoms and are at higher risk for acute exacerbations in the local population. Furthermore, lung function changes in people with a history of tuberculosis were associated with a dose-response relationship with the probability of developing COPD.