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.