DISCUSSION
Psychiatric co-morbidity in the form of depression and anxiety is not uncommon in patients with CAD. The INTERHEART study results have drawn attention to the role of psychosocial factors in CAD(14). Several studies have demonstrated that depression and anxiety are associated with worse outcomes in CAD patients(15–18). These factors may be even more prevalent in patients referred for CABG surgery given the severity of CAD and the anticipated major surgery. This makes identification of depression and anxiety in these patients an essential part of preoperative evaluation. To our knowledge, the present study is the largest Indian study of psychiatric co-morbidity in patients undergoing CABG.
The prevalence of depression and anxiety in our population was 70.5% and 64.6% respectively. Even after exclusion of borderline cases, the prevalence of depression and anxiety remained high at 31.3% and 40.7% respectively. Interestingly, 19% of patients were found to have both depression and anxiety, even after the exclusion of borderline cases. Previous studies have evaluated depression and anxiety in patients being referred for CABG surgery. Different questionnaires which are self-reported by the patient have been used for this purpose(10,19–22). These questionnaires have variable sensitivity and specificity(23). Pirraglia and colleagues studied 237 patients undergoing CABG surgery and found the prevalence of pre-operative depression to be 43.1%. Similarly, other studies have shown a prevalence of pre-operative depression ranging from 27 to 47%(24,25). Pre-operative anxiety has also been evaluated in patients undergoing CABG. Out of 142 patients undergoing CABG surgery, Krannich et al. found preoperative anxiety in 34% of patients(26). Younger patients had more anxiety compared to older patients and showed a decline in symptoms following surgery, in contrast to older patients who did not demonstrate a similar change. In a study of 172 patients, Gallagher et al. reported anxiety in 40.6% patients(27). Data from India on preoperative anxiety and depression is scant. In a small study by Chaudhury et al. from a tertiary hospital in India, preoperative anxiety and depression was reported in 43.3% and 30% before CABG surgery(28). These numbers indicate a significant burden of depression and anxiety in patients undergoing CABG.
Preoperative anxiety and depression are not limited to CABG surgery alone and are frequently diagnosed in patients undergoing elective non-cardiac surgery. Using HADS, Kuzminskaitė and colleagues demonstrated preoperative anxiety in 12.6% of patients undergoing elective non-cardiac surgery(29). The burden of multiple chronic risk factors and previous acute coronary syndromes in a large proportion of patients undergoing CABG surgery may place this subset of patients at a relatively higher risk of preoperative anxiety and depression compared to patients undergoing non-cardiac surgery. Most studies evaluating preoperative anxiety have administered questionnaires on the preoperative day(30,31). Procedure related anxiety related to impending surgery may theoretically be highest on the day preceding surgery. In the present study however, the questionnaires were administered two to seven days prior to elective CABG surgery.
Depressed patients were found to have a worse quality of life compared to those without depression in our study. This was true for all domains measured by the SF-36 questionnaire. We also found that patients with anxiety had a worse quality of life compared to those without anxiety, in the domains of physical functioning, vitality, mental health and general health. Our findings are in agreement with existing literature. In a large study of 1282 patients with stable CAD, Spertus and colleagues found that co-morbid depression was associated with a worse angina-specific functional status, more frequent anginal episodes and a worse quality of life(24). Similar results were demonstrated by Ruo et al., who showed that depressive symptoms were associated with a greater symptom burden, worse health-related quality of life (HRQOL), greater physical limitation and poorer overall health(33). It has been demonstrated previously that depression predicted poor functional improvement after CABG surgery compared to traditional measures of cardiovascular disease severity(34).
We also found that patients with low levels of physical activity were more often depressed and anxious. This was not the case in those with moderate and high levels of physical activity. Patients with multivessel CAD referred for CABG surgery often have limitation of moderate and high levels of physical activity on account of exercise limiting angina. A large proportion of these patients are therefore condemned to low levels of physical activity. The additional burden of psychiatric co-morbidity in the form of depression and anxiety in these patients is associated with worse outcomes if left untreated(35,36).
Preoperative depression and anxiety have been demonstrated previously to increase post-operative morbidity following CABG surgery(6–9,37). Preoperative identification of these patients allows maximization of efforts towards the treatment of depression and anxiety. Early interventions aimed at treatment of these disorders have been associated with a reduction in length of hospital stay, analgesic use, and postsurgical morbidity(38–41).Treatment measures not only include non-pharmacologic measures such as cognitive behavior therapy (CBT) but also pharmacologic therapy in some of these patients. Although, psychosocial interventions constitute an essential component of cardiac rehabilitation programs, patients with depression and anxiety may not be sufficiently motivated to actively take part or continue with these programs in the post-operative period(42). Early identification and treatment of co-morbid depression and anxiety is therefore essential towards improving outcomes post-CABG surgery.
There are a few limitations of our study. Our study included a small number of patients. Since the data was from a single tertiary center, it may not be reflective of the wider population of CAD patients undergoing CABG. Most of the study participants were male patients. Female patients constituted only a small proportion of the study population. This is important because depression and anxiety in patients with cardiovascular disease has been known to affect women more than men(43). Data on income status and pill burden was not collected from the study participants. These factors may have had a bearing on the HADS scores. In the present study we did not follow up patients after CABG surgery. Therefore, the impact of successful CABG surgery on HADS scores could not be assessed.
In conclusion, we found a significant prevalence of anxiety and depression in patients undergoing CABG surgery. In addition, depression and anxiety were associated with a worse quality of life in these patients. There was a high prevalence of depression and anxiety among patients with low level of physical activity who were referred for CABG surgery. It is important to evaluate patients undergoing CABG for co-morbid depression and anxiety. Pre-operative identification of depression and anxiety allows focused efforts to be directed towards treating these disorders, which if untreated have been associated with worse postoperative outcomes.
Acknowledgments: The authors acknowledge the role of highly trained staff nurses (Ms. Jincy Alex and Ms. Pasang Lamo) in data acquisition.
Ethical approval: This study was approved by the ethics committee of All India Institute of Medical Sciences (AIIMS)
Conflict of interest: The authors declare that they do not have any conflicts of interest.