Fig. 1

Association between cigarette or alcohol consumption and odds ratio of depressive symptoms. Association between A cigarette consumption and B alcohol consumption and odds ratio of depressive symptoms. OR, odds ratio; CI, confidence interval. Odds ratio and 95% confidence interval were estimated by binary logistic regression adjusting for residence, spouse and comorbidity. The smoothing fitting curves and the corresponding equations were obtained by interpolation analysis with 2nd order Lagrange polynomials. The dots indicate the adjusted odds ratio of depressive symptoms estimated via binary logistic regression adjusting for residence, spouse and comorbidity. Bars indicate the upper and lower limit of 95% confidence interval of odds ratio