Spss statistical software package version 17

Univariate and multivariate Cox regression analyses were used identify significant risk factors for CSS and OS. Multivariable analyses examined factors that were significantly associated with CSS and OS in the univariate analyses. The optimal cut-off point for the LNR was determined from the receiver operating characteristic (ROC) curve. Calculation of survival rates were plotted by the Kaplan-Meier method, and compared using the log-rank test. All data were analyzed using the SPSS statistical software package, version 17.0 (IBM Corporation, Armonk, NY, USA). A P-value less than 0.05 was considered statistically significant.

All data are expressed as the mean ± standard deviation. One-way analysis of variance followed by Duncan’s test were performed to compare the significant differences (p < 0.05) between different treatments and controls using SPSS statistical software package version 17.0 (IBM Corp., Armonk, NY, USA).

We used the chi-square test for comparative analysis based on the alcohol consumption status, while the Student’s t-test analysis was performed to compare each variable between men and women. A linear-by-linear association test was performed for comparative analysis based on the amount of smoking. Regression analysis was performed by considering FEV1, FVC, FEF25–75%, FEV1/FVC, PEV, and FEV6 as dependent variables to evaluate the effect of each item on each pulmonary function value. In addition, Cohen's D in t-test result and F-squared values in linear regression analysis were used to measure the effect size. And, the method used is described in the supplementary file. (Supplemental method) We used SPSS statistical software package version 17 (SPSS Inc., Chicago, USA) for all analyses and a p value < 0.05 was considered statistically significant.