Assessing the Prevalence and Severity of Depression Among Coronary Artery Diseases Patients in Baghdad Using the PHQ-9: A Cross-Sectional Study

Coronary artery disease (CAD) remains one of the leading causes of morbidity and mortality worldwide, with multiple risk factors influencing its onset and progression. Among the psychosocial factors associated with CAD, depression plays a particularly prominent role. Research indicates that while 17% to 27% of patients with CAD have major depression, a significantly larger percentage experience subsyndromal depressive symptoms. This highlights a widespread issue where depressive symptoms, even if not clinically classified as major depression, still contribute to poorer health outcomes in CAD patients. Major depression is not only prevalent among CAD patients but is also linked to an increased risk for developing CAD and higher mortality from the disease. However, the exact mechanisms through which depression impacts cardiovascular health remain unclear.

Coronary heart disease (CHD), a major manifestation of CAD, typically results from the rupture or erosion of an atherosclerotic plaque in the epicardial coronary arteries. Over 60 risk factors and markers have been associated with the initiation and progression of these plaques. When a plaque ruptures, it can stimulate acute thrombosis within the artery, leading to an acute coronary syndrome (ACS), which may present as a myocardial infarction (MI), unstable angina, or even sudden cardiac death. These risk factors can be broadly categorized into three groups: lifestyle, biological, and psychosocial. Depression, as a psychosocial risk factor, not only increases the likelihood of developing CAD but also contributes to worse outcomes in patients who already have the disease.

The impact of depression extends beyond its role in the progression of CAD; it significantly affects the quality of life (QOL) of patients with coronary disease. While treating depression may not necessarily reduce depression's role as a direct risk factor for CAD, improving the quality of life should be considered a primary goal of treatment. Defining and measuring QOL remains a challenge, but recent studies have shown a clear relationship between QOL, depression, and mortality risk in CAD patients. This underscores the importance of addressing both the psychological and physical health of CAD patients in clinical care.

Moreover, the PHQ-9 (Patient Health Questionnaire-9) is a widely used, self-administered tool designed to assess the severity of depression in individuals. Comprising nine simple, straightforward questions, the PHQ-9 evaluates the frequency of common depressive symptoms over the past two weeks, such as feelings of sadness, loss of interest, sleep disturbances, and fatigue. Each response is scored on a scale from 0 to 3, and the total score helps determine the severity of depression, ranging from minimal to severe. Originally developed as a screening tool, the PHQ-9 is now a key instrument in both clinical practice and research for diagnosing major depressive disorder (MDD), monitoring treatment progress, and identifying individuals at risk for worsening symptoms. A meta-analysis conducted in 2015, which included 36 studies with over 21,000 participants, evaluated the sensitivity and specificity of various cut-off scores ranging from 7 to 15. The analysis found that the standard cut-off of 10 had a pooled sensitivity of 0.78 and specificity of 0.87, suggesting it is a reasonably effective screening tool. However, the study also noted significant limitations, such as incomplete reporting on cut-off scores other than 10, which led to misleading results indicating that sensitivity increased with higher cut-off scores, possibly due to selective reporting in some studies.

Despite the well-established connection between depression and CAD in many parts of the world, there is a notable gap in research on this topic within Iraq. This study aims to assess the prevalence and severity of depression among CAD patients in Baghdad using the Patient Health Questionnaire-9 (PHQ-9), a widely recognized tool for diagnosing depression. By exploring the burden of depression in this patient population, this research will provide important insights into the mental health needs of CAD patients in Iraq and contribute to improving both cardiovascular outcomes and quality of life in this underserved region.