Following our previous cross-sectional analysis, in this study, we followed-up with the patients for 6 months, 1 year, and over 2 years, and several clinical outcomes were observed. We found that, whether or not multiple factors were adjusted, patients enduring AP with depression symptoms had a significantly high rate of noncardiac readmission and incidence of composite endpoint events while AP patients with anxiety symptoms did not. People with clinical depression and anxiety were found to be at an increased risk of noncardiac readmission and composite endpoint events. Meanwhile, clinical anxiety was found to be associated with MACEs. What we discovered but many other researchers did not keep an eye on was the relationship between the comorbidity of depression and anxiety and prognosis in AP patients, and we elaborated on the fact that this comorbidity might be a predictor of increased risk of noncardiac readmission, MACEs, and composite endpoints.
To our knowledge, this is the first study with an examination of the relationship between depression, anxiety, comorbidity, and noncardiac readmission among AP patients. Current studies underscore the complex relationship between depressive or anxiety symptoms and prognosis in patients with CVD. However, most related studies were focused on populations with myocardial infarction or heart failure, and few medical researchers pay attention to AP. Besides, the endpoint events of many previous studies were normally related to death or reoccurrence of cardiovascular admission instead of noncardiac readmission.
Association of Depression and Prognosis
In our study, patients with clinical depression symptoms were found to have a 3.41-times higher risk of death and 2.32-times higher risk of noncardiac readmission than those who did not suffer from clinical depression. Pederson et al. showed that depression might be an unrecognised and possibly changeable independent risk factor for unexpected readmission or premature death. Depression is difficult to detect in an acute care environment and is often undertreated. Patients with moderate to severe depression symptoms at discharge with no history of depression may face a twofold increase in the risk of short-term hospital readmission or death. Mitchell et al. reported that the risk of hospital readmission or emergency department treatment within 30 days after discharge among patients with PHQ-9 scores of ≥ 5 was increased by 73%. Cancino et al. reported a 49% increase in readmission within 30 days of discharge for patients with mild depression and a 96% increase for patients with moderate to severe depression. Moraska et al. found that high clinical depression scores on the PHQ-9 were associated with increased risk of hospitalisation (adjusted HR: 1.79, 95% CI: 1.30–2.47). In a small study of 144 patients, Kartha et al. found that patients who were diagnosed with severe depression using a standardised scoring algorithm based on PHQ-9 were three times more likely than others to be rehospitalised within 90 days of discharge. We used PHQ-9 scores of < 5, 5–9, and ≥ 10 as the thresholds for non-depression, mild depression, and moderate to severe depression. We also found that both mild and moderate to severe depression symptoms were associated with noncardiac readmission and composite events.
Previous literature has shown that CHD combined with depression symptoms will lead to an increase in mortality and rehospitalisation, thereby aggravating the severity of the disease, medical expenses, and waste of resources. A cumulative number of studies have shown that comorbidity of mental and physical illnesses would increase the severity of the disease, frequencies of readmissions, and medical expenses. Even the presence of isolated psychiatric symptoms might bring the risk of medical comorbidities. People with psychiatric symptoms, but no psychiatric diagnosis, were prone to more lifelong diseases, healthy problems, and length of hospital stay than those without psychiatric diagnosis or symptoms. Our study has shown that both mild depression and moderate to severe depression could be risk factors for hospital readmission.
Association of Anxiety and Prognosis
Previous literature has shown that anxiety is a significant risk factor for recurrent CV events or mortality[3, 13, 35-37]. Although we did not analyse death, revascularisation, or nonfatal myocardial infarction independently due to a lack of valid samples, we summed up cardiac readmission, nonfatal stroke, and all the above as MACEs. Tully et al. found that in patients with confirmed CHD, anxiety was a prognostic risk of subsequent MACEs, such as myocardial infarction, left ventricular failure, and stroke. Another study showed that generalised anxiety disorder increased the MACE risk of acute coronary syndrome outpatients by nearly two times within two years. Similar to previous researchers, we identified an association between clinical anxiety and poor CVD prognoses. Although there are few studies in which the authors analysed the relationship between anxiety and noncardiac readmission, we found a positive correlation between clinical anxiety and noncardiac readmission. We did not observe this association in the anxiety symptom group (GAD-7 scale > 5), possibly because the anxiety symptom is transient and usually triggered by a perceived threat, and once the threat diminishes, the anxiety will diminish too. It has been proven that anxiety is prone to poor quality of life of patients with CHD, especially after an acute coronary syndrome event, and that anxious patients have more disabilities and somatic symptoms than others[40-42].
Association of Comorbidity and Prognosis
The authors of many related studies analysed depression or anxiety as single risk indicators, but we studied them as a comorbid symptom. We discovered that most clinical anxiety patients also have depression symptoms. Denollet and Strik et al.[35, 43] reported that a mixed emotional state consisting of anxiety and depression symptoms, not just depression, was the most common manifestation of patients with myocardial infarction. The author, thus, concluded that anxiety was a common factor of depression after myocardial infarction. A similar symptom overlap was found by Frasure-Smith. Some authors[44, 45] found that this connection was produced by the same dysfunctional biology or that depression and anxiety might be derived from parallel genetic dispositions. Furthermore, Scott et al. showed that comorbid depressive-anxiety disorder increased the risk of a series of physical symptoms occurring at the same time. In a follow-up study of women with suspected myocardial ischemia, depression or anxiety could be used to predict CVD events and death more accurately than the independent symptoms. Phillip et al. demonstrated that even after adjustment, the strongest association between CVD and death from all causes appeared in major depressive disorder and generalised anxiety disorder comorbidities. Similar to previous researchers, we identified a greater risk of MACEs, noncardiac readmission, and composite events among participants with depression and anxiety.
First, due to the small sample size and prognostic events, some statistical analyses in this study may suffer from overfitting. Second, patients with clinical depression or anxiety were categorised into one group because there were only five patients who had anxiety rather than depression, but this did not affect the analysis of comorbidity and prognosis. Although we did not carry out professional psychiatric interviews to confirm the diagnosis of psychiatric symptoms, we used an easy-to-deploy screening tool that has been fully validated. Moreover, our research was conducted in only one hospital specialised in cardiac care, which ensured the consistency of examination tools, methods, and follow-up times and procedures but limited the generalizability of the findings.