Table 4. Predictive factors for depression in patients with chronic airway lung diseases Factors Odds ratio (95% CI) p value Age 1.017 (0.978 - 1.059) 0.395 Female gender 1.792 (0.579 - 5.547) 0.311 Body mass index 0.974 (0.865 - 1.095) 0.656 Current or ex-smoker 3.894 (1.269 - 11.952) 0.018 Post-bronchodilator FVC, % predicted 0.990 (0.961 - 1.020) 0.522 Post-bronchodilator FEV1, % predicted 0.972 (0.947 - 0.997) 0.027 CI, confidence interval; FVC, forced vital capacity; FEV1, forced expiratory volume one second. or serum albumin level. Compared to patients without depression (BDI < 16), patients with depression (BDI ≥ 16) had significantly higher median scores for both subscales of the STAI (p < 0.0001), and their symptoms of depression were positively correlated with both state- anxiety (r = 0.644, p < 0.0001) and trait-anxiety (r = 0.597, p < 0.0001). A bivariate analysis identified four variables related to increased risk for clinically relevant depression (p < 0.05): BMI (OR, 0.9; p = 0.023), history of smoking (current or ex-smoker; OR, 2.8; p = 0.004), predicted value of post- bronchodilator FVC (OR, 0.972; p = 0.002), and predicted value of post-bronchodilator FEV1 (OR, 0.966; p < 0.0001). Age and sex were added to these four factors in a multivariate logistic analysis, revealing that the predicted value of post-bronchodilator FEV1 (OR, 0.972; p = 0.027) and smoking (current or ex-smoker) (OR, 3.894; p = 0.018) were independently associated with the development of depression in patients with chronic airway lung diseases, irrespective of individual diagnosis (Table 4). DISCUSSION The present study found a higher prevalence of depression among patients with chronic airway lung diseases than among those in the healthy control group, but found no significant difference with respect to the frequency of anxiety, even though the scores for anxiety symptoms were higher among the patients with chronic airway lung diseases than among the controls. Clinically significant depression was strongly correlated with more severe airflow limitations and a history of smoking (current or ex-smokers), which were independent risk factors for depression in patients with chronic airway lung diseases. Ryu YJ, et al. Depression and anxiety in chronic airway lung diseases 55 Previous studies have reported a tendency toward depression in patients with COPD [4-7], and our findings confirmed a higher frequency of depression in these patients. In the present study, 70% of patients with severe to very severe COPD exhibited depression. Higher percentages of patients with COPD and bronchiectasis than of controls reported symptoms of depression, although anxiety was not more common in the patients than in the controls. Previous studies have reported susceptibility to depression in patients with other chronic respiratory conditions [17,22]. Indeed, bronchiectasis manifests as a chronic and progressive disease with multiple exacerbations resulting in altered lung functioning, including irreversible airflow obstruction, progressive dyspnea, and greatly reduced quality of life [14]. Contrary to the results of previous studies [17,22], our data showed that the scores for and frequency of depression in patients with asthma did not differ significantly from those in members of the control group. However, irrespective of the specific pulmonary diagnosis, clinically significant levels of depression were more common in patients who were smokers and/or those with airflow limitations that altered lung functioning. As established in previous studies [4,22], our results also showed a significant correlation between anxiety and depression. The state-anxiety scale evaluates a momentary condition in which the intensity of unpleasant feelings depends on the situation. Thus, because state-anxiety anxiety represents symptoms at the moment of evaluation, the groups with chronic airway lung diseases would be expected to have higher state-anxiety scores than would those in the control group [17]. The trait- anxiety scores of patients and healthy controls, however, did not differ significantly, and the frequency of trait- anxiety in patients and controls was similar. This finding can be attributed to the fact that the trait-anxiety scale measures a lasting personality trait-anxiety related to how an individual responds to potentially threatening situations over the course of a lifetime. The dearth of studies with adequate sample sizes and the variability in the instruments and threshold scores used to measure depression and anxiety have been recognized as difficulties in developing strategies to manage Korean patients with chronic airway lung diseases. A BDI score of 21 has been suggested as the optimal cutoff score for the diagnosis of major depression because it is 1 standard deviation from the mean in a Korean cohort [20]. However, a recent study reported that a cutoff score