The present study found a higher prevalence of depressive and anxious symptoms among patients with COPD in China compared to a matched healthy control group without the condition, while the scores for anxious and depressive symptoms were higher among the patients with COPD than among the controls. Previous studies have reported anxiety symptoms ranging from 9.57–49%, and depressive symptoms ranging from 22.8–52%, using the HADS as the screening tool [12, 26, 27]. Our findings confirmed a higher frequency of anxious (18.3%) and depressive symptoms (35.7%) in stable COPD patients. Higher percentages of patients with COPD than of controls reported symptoms of depression, while anxiety was also more common in the patients than in the controls. These high rates stress the importance of screening and treatment of depression and anxiety in patients with COPD to maintain health-related quality of life .
Of importance was our result that more COPD patients with anxiety had depression than COPD patients with depression had anxiety. Given that there was a significant correlation between anxiety and depression, our result should remind general practitioners that when patients have symptoms of anxiety or depression, the other condition should be suspected as well. The prevalence of anxious and depressive symptoms increased with the GOLD stage and BODE index, as established in previous studies [29–31]. These corresponding increases suggest that when the general practitioner detects poorer health status in patients with COPD, they should consider giving psychological guidance along with medical treatment.
The present study showed a correlation between depressive or anxious symptoms and age, sex, education level, household income, history of smoking, BODE index, SGRQ and co-morbid anxious or depressive symptoms, which was partially consistent with the results of previous studies [27, 31–33]. This is of relevance for practice: general practitioners need to be aware that anxiety and depression are common conditions in COPD patients. The present result found that patients who were younger, females, a higher education level, lower household income, higher BODE index, higher SGRQ scores and a history of smoking suffered from anxious or depressive symptoms more frequently. The relationship of age to anxiety and depression in patients with COPD has been investigated by Cleland et al.. A previous study has reported susceptibility to depression in female patients with COPD . Consistent with this result, our data confirmed that the frequency of depression in female patients with COPD differed significantly from that in male patients with COPD, unlike the report from Cleland et al.. This is likely due to different study populations. The majority of women in rural areas in China are housewives, and when they become ill, it means that the family has no food to eat, which may produce more anxiety and depression. The increase in anxiety and depression with advancing educational level could be due to the lower education level of our participants; they were all junior high school level. Their understanding of COPD is less, so they may be more prone to anxiety and depression. The COPD patients who had low family income tended to suffer from anxiety and depression, perhaps because there were no local medical treatment safeguard measures. Patients with a higher degree of airflow limitation reported more symptoms of depression and increased risk for depression, and pulmonary functioning was found to be a predictor of depression [34, 35]. However, FEVl alone was not capable of predicting the presence of anxiety or depression . In the present study, the FEVl had no clear relation with anxiety or depression scores. The BODE index had a stronger association with anxious and depressive symptoms than did the FEVl in our study, consistent with the results of previous studies [21, 26, 27, 35]. Our results also confirmed that the SGRQ was related to anxiety and depression in the patients with COPD. This revealed that the decline in the quality of life can lead to the generation of anxiety and depression, and vice versa, anxiety and depression can lead to reduced quality of life.
We found a strong positive correlation between BODE index and GOLD stage. Although considerable overlap between stages was also found within BODE quartiles, the BODE index can indeed be used to discern groups of COPD patients. This suggest that the BODE index could better reflect the anxiety and depression status of patients with COPD .
Our data indicated that subjects who were anxious and depressive walked a shorter six-minute walking distance (6MWD), had more dyspnea, a higher BODE index, and lower SGRQ. The anxiety and depression scores and the prevalence of anxious and depressive symptoms increased as BODE quartiles increased. From the binary logistic regression results, the BODE index was an independent predictor for anxious and depressive symptoms after being adjusted for other confounders. To explore the association between anxious and depressive symptoms and the components of the BODE index, a binary logistic regression model was used to analyze the relation. The results showed that anxiety was associated with shorter distances walked (6MWD)and dyspnea (MRC); however, depression was associated with FEV1% and more dyspnea (MRC).
Although this is, to date, the largest study to evaluate the frequency and risk factors associated with depression and anxiety in Chinese patients with COPD, it has certain limitations. Although we used a reliable and valid measure of anxiety and depression, our measure was not a clinical diagnosis of a generalized anxiety and depression disorder. We were also not able to evaluate changes in anxiety and depression over time. In addition, there is the possibility of misclassification of COPD, although we took rigorous steps to avoid this.