Prevalence and associations of depression among patients with cardiac diseases in a public health institute in Trinidad and Tobago

During the 5-month period from November 1, 2015 to March 31, 2016, all patients admitted to the hospital for cardiac diseases were examined for eligibility for participation in the study. The medical ward admission books were used to identify patients with a cardiac diagnosis. The identified patients with cardiac disease were approached for discussion on the nature of the study and their willingness to grant consent for participation. The eligibility criteria were stable cardiac disease for a minimum of 3 months, age 18 years or older, absence of confusion (ability to understand, think clearly, and produce meaningful understandable statements), and ability to communicate in the native English language for approximately 20 min and recall experiences without difficulty. The exclusion criteria were severe cardiac illness (i.e. patients who are unstable, very short of breath, or exhausted), and accompanying major debilitating comorbidities such as dialysis, terminal stage of cancer (cancer that has spread to various parts of the body), acquired immune deficiency syndrome (AIDS) (i.e. patients who were symptomatic: weak, emaciated, and likely to have opportunistic infections), or stage 1 V heart failure (i.e. patients who were very symptomatic at rest or minimal exertion). Medical students acted as research assistants and were trained on the identification of patients with cardiac disease, the conduction of interviews, and the collection of data. Through convenience sampling, patients with cardiac disease, identified from the patient records and whose diagnoses were confirmed by the treating physicians, were selected for possible participation in the study. Potential participants were briefed on the nature of study, and their willingness to participate was ascertained. They were also informed of their rights (freedom of choice to participate, discontinue, or refuse to participate). Patients whose verbal consent was acquired were interviewed. Interviews were stopped and resumed if the interviewees were in the meantime needed for medical examinations, consultations, or investigations. Face to face interviews were conducted at the patient’s bedside 3 to 5 days after admission. This would allow time for patient stabilisation and would avoid interference with medical interventions. Since the average length of stay for medical patients, including those with cardiac diseases, is 5.6 days, most patients were available for interview 3 days after admission. A sample size of 388 was determined to be sufficient using a 5% margin of error and a prevalence of 50% in the population.

The data collection instrument was a questionnaire that contained survey items related to patient demographics and a depression diagnostic tool. Data collected included socio-demographic variables (age, sex, height, weight, ethnicity, level of education (primary, secondary, or tertiary), current employment status, and religion), self-reported medical and lifestyle history (hypercholesterolemia, current smoking (i.e. smoking up to within 30 days of the interview), diabetes mellitus, hypertension, abdominal obesity, stressful life, depression, daily consumption of substantial fruits and vegetables, exercise (at least 3 times per week for 20 min), regular alcohol consumption, and family history of ischaemic heart disease (female parent or siblings younger than 65 years old and male parent or siblings younger than 55 years old reported to have or treated for heart disease)), other medical history (chronic obstructive pulmonary disease, cancer, end-stage renal disease, peripheral vascular disease, stroke/transient ischaemic attack, and psychosis), specialised examinations/treatment (angiography, angioplasty, and coronary artery bypass grafting), and others such as social support (source of support and care). Patients were guided on the interpretation of social support (receiving the required help in daily chores), of exercise (exercising regularly for 20 min at least 3 times per week), feeling stressed – anxious, irritable, and depressed – ‘down’, sad, or dejected. The type and duration of cardiac disease were also recorded.

The PHQ-9 was selected to measure depression among the commonly used instruments. The PHQ-9 has been widely used among patients with cardiac disease with good sensitivity and specificity and it is easy to administer. A cut-off score of ≥5 for minor depression had sensitivity of 0.91 and specificity of 0.81 for a Sri Lankan population [34]. The PHQ-9 has a sensitivity of 54% and specificity of 90% for scores ≥10 in a United States and Canada population [35]. Overall, the PHQ-9 was reported to have 94% sensitivity and 84% specificity for scores > 8 and achieved greater accuracy than the depression component of the Hospital Anxiety and Depression score (cut-off of 5, sensitivity = 81%; specificity = 77%) [36]. The PHQ-9 comprises nine questions: ‘little interest or pleasure in doing things’, ‘feeling down, depressed, or hopeless’, ‘trouble falling or staying asleep or sleeping too much’, ‘feeling tired or having little energy’, ‘poor appetite or overeating’, ‘feeling bad about yourself or that you are a failure or have let yourself or your family down’, ‘trouble concentrating on things such as reading the newspaper or watching television’, ‘moving or speaking so slowly that other people could have noticed or the opposite – being so fidgety or restless that you have been moving around a lot more than usual’, and ‘thoughts that you would be better off dead or of hurting yourself in some way’. The questions are scored using a scale of 0 to 3: not at all (0), several days (1), more than half the days (2), and nearly every day (3). The PHQ-9 scores classify depression as mild (score: 5–9), moderate (10–14), moderately severe (15–19), and severe (20–27) [37]. While most studies have used a score signifying higher than moderate depression as warranting intervention, even mild depression should be identified because of its role in worsening CAD. A study with hospitalised patients with cardiac disease utilised depression with a cut-off of 5 or non-minimal depression (PHQ-9 ≥ 5) [38] to determine depression prevalence. In this study, tests of association and strength of association were conducted utilising PHQ-9 ≥ 5. For this, depression scores were dichotomised into less than mild depression (PHQ-9 < 5) or depression (PHQ-9 ≥ 5). In addition, a significant clinical depression score (PHQ-9 > 9) was calculated to compare the prevalence among various studies, since most of these used a cut-off for depression of PHQ-9 > 9.

Data collected were entered and stored in a password-secured computer. SPSS, Version 21 (IBM Corp., Armonk, NY) was used to analyse the data through both descriptive and inferential statistical methods. Descriptive methods included frequency and percentage distributions tables, bar graphs, and summary statistics. Inferential methods included forming 95% confidence intervals (CIs), and chi-square tests of association as was required for this cross-sectional study. Odds ratios as opposed to relative risks were used to determine the strength of the associations, since the cross-sectional sample had a high prevalence of depression [39].

Ethical approval was granted by the ethics committee of the South West Regional Authority on October 21, 2015.

Age showed no association with non-minimal depression (PHQ-9 ≥ 5) in this study. This study also found no significant association with diabetes mellitus and non-minimal depression. This was unexpected. Increased depression among diabetics was identified by Anderson et al. who found that in controlled studies, the odds of depression in the diabetic group were twice as high as those in the non-diabetic comparison group (OR = 2.0, 95% CI 1.8–2.2) [56]. Al-Ghamdi et al. also concluded that depression is more common among diabetics (34%) than among non-diabetics (13%, p < 0.001) [57].

In this study, patients who had undergone open heart surgery intervention experienced more depression (83.3%, p = 0.49), than did those who had undergone angioplasty (72.4%, p = 0.42), both of which were not significantly associated with depression (Table 2). This contradicts the findings of Chaudhury et al. who reported that before and after receiving percutaneous transluminal coronary angioplasty, 32.1% and 3.6% of patients respectfully had clinically significant depression [58]. This may relate to other interventions that may accompany surgical procedures such as counselling and cardiac rehabilitation. Cardiac rehabilitation in Trinidad and Tobago is absent in the public health institutes. Some studies have identified higher depression levels among patients who subsequently became unemployed [59] and those with income, relationship, and participation restrictions [60, 61]. The absence of association between depression and age, ethnicity, monthly income, or religious affiliation in this study is in line with findings of Munga who showed that age, sex, and marital and socioeconomic statuses did not significantly affect the development of depression in patients with cardiac diseases [62].

There was a high correlation between self-reported stress and the depression score obtained from the PHQ-9. Patients with self-reported depression were four times more likely to be depressed (PHQ-9 > 9). There may be a case for treating those that self-report feelings of depression without elaborate screening for depression. However, this method may neglect cases of an occult nature that may be in greater need of assistance, since many of these patients may even be suicidal [63] and unwilling to share their feelings. Depression among patients with self-reported stress was twice as common as among those without self-reported stress. These findings are corroborated by Schrader et al. who showed that self-reported history of depression, anxiety, or stress [64] were useful predictors of mild or moderate to severe level of depressive symptoms at hospitalisation.

Social support, while not robustly examined, did not significantly impact depression prevalence in this study. This may be related to the high percentage (at least 80%) of patients who had some form of support and is comparable to previous findings of 79.9% of patients receiving support from a spouse or relative [55]. Social support refers to the various types of support that people receive from others and is generally classified into two or three major categories: emotional, instrumental, and (sometimes) informational support [65]. Low social support infers that the emotional, instrumental, and informational assistance/help that people receive from others is lacking. Low social support is a robust risk factor for major depressive disorder [66]. Higher depression levels were also found in those living alone [67] or those who experienced social neglect at the work place [59]. Freidmann et al. found that depression and social isolation predicted mortality in heart failure patients [68].

A multitude of other factors such as those pertaining to personality may also be related to depression. Individuals with negative illness beliefs [69] and those with high neuroticism and low extraversion scores were found to be more vulnerable to depression [70] as was reported by a study conducted among older CHD patients. Living alone, alcohol abuse, perception of medical care as being a substantial economic burden, and health status were identified as predictors of developing depressive symptoms [71].

This study found that employment and exercising at least three times per week for 20 min provided additional protective benefits, since these patients were 50% less likely to develop depression compared to those who were unemployed or exercised less following MI [72]. In fact, regular exercise can be used as an instrument to reduce depression in patients after CAD events [73]. Similarly, another study reported increased levels of depression associated with adverse changes in employment after experiencing an MI [74].

In this study, four patients or 1% reported receiving formal help from a psychiatrist or psychologist. This is despite at least 40.0% having clinical depression (moderate, moderately severe, or severe depression) based on PHQ-9 > 9. A large percentage of untreated patients has been reported in other studies; Smolderen et al. found that 528 (69.6%) patients had untreated depression [44]. Because of the high incidence of disease complications and the increased mortality associated with depressed patients with cardiac disease [3, 5], patients with depression must be identified and treated in an appropriate manner e.g. with counselling, psychotherapy, and/or pharmacotherapy [75] to improve their quality of life.

This was a single-centre study with non-debilitated patients with cardiac disease with a relatively small convenience sample. Convenience sampling has a degree of bias, although efforts were made to select all eligible patients during the study period. The exclusion of patients with severe health illnesses has led to underestimation of the prevalence of depression among patients with cardiac disease, since those with high disease severity may be more likely to be depressed. Conversely, there is a potential to spuriously inflate somatic symptoms after admission and thus, artificially inflate depression prevalence. Interviewing patients 3–5 days after admission may exclude some patients that had been discharged by that time. However, with an average length of stay of 5.6 days, most patients were available for interview. This study primarily depended on recall, which can be difficult for many patients. Certain questions may not have been sufficient to provide an adequate evaluation of variables such as social support, stress, or depression, since self-reports were used in the study. Though patients were willing to share their feelings, many responses could have been exaggerated or under-reported. The population was mainly Indo/Afro Trinidadian of lower socioeconomic status who sought support in the public healthcare system. Although generalisation would be difficult, this study produced findings that could be extrapolated to similar populations. Psychosocial issues such as divorce, suicide, unemployment, and crime, which may influence the extent and effect of depression in patients with cardiac disease, have not been addressed. Although the research assistants would inform the attending physician of patients with suicidal ideation, the patients were not identified, and no formal report could be conducted.