This study was conducted to investigate the prevalence of depression in hospitalized patients with chronic diseases in Wuhan, Hubei, China, and to explore its association with polypharmacy behaviors. We found that 40.5% of the patients had depressive symptoms, which was consistent with existing study[23], but higher than the rate that Canoui-Poitrine had found[25]. The possible explanation is that different criteria for depressive symptoms have been adopted in different studies.
Significant associations have been found between polypharmacy behaviors and depression in the multivariate logistic regression model. Compared with non-polypharmacy patients, polypharmacy patients were directly associated with depression (OR = 1.63, 95% CI: 1.12–2.36). After the propensity score weighting approach was applied, patients who had polypharmacy behaviors were more likely to suffer from depression (OR = 1.58, 95%CI: 1.17–2.16), which was consistent with the results of Onder’s study[18]. The possible immediate cause for these associations is that patients taking multiple medications have higher psychological distress, which was proposed in Assari’s study[14], and may eventually evolve into depressive symptoms or even clinical depression. Further, although patients might hope to reduce the number of medications they are taking, their final decision on medication-taking still mainly depends on the prescription issued by physicians. In other words, patients have the problem of high external rely of control, namely that physicians are in control of their health[26]. According to Bramston’s study[27], older adults with a high external locus of control develop depression, which is also a process of learned hopelessness[28] since there is nothing patients can do to change polypharmacy, implying that people’s hopelessness was frequently changing their future, resulting in them suffering from more depressive symptoms[29]. In addition, polypharmacy behaviors have been observed to be associated with a range of negative health outcomes in patients, including falls, frailties and adverse drug events[30], all of which can increase patients' stress and negatively impact their mental health, possibly leading to depression. However, adverse drug reactions were not found to be associated with depression in this study (P = 0.327). On the other hand, it was discovered in a previous study that poorer emotional capability was associated with increased medication use, suggesting that depression might also lead to more medication use[20]. A reasonable explanation could be that depression increases self-medication and the prevalence of polypharmacy behaviors[31]. There were also some researchers who believed that it was multimorbidity that fully mediated the association between polypharmacy behaviors and depression. That is, depression in patients with polypharmacy behaviors might be caused by a higher number of multimorbid conditions[32].
In terms of the physical health status of the participants, hypertension, the number of diseases they had, and their self-rated health status were all found to be risk factors for depressive symptoms in this study. The health status was a significant predictor of depression in a prior study[33]. Perceived health-stress has strong impacts on both depressive symptoms and clinical depression. The worse the self-rated health status of patients with chronic diseases, the higher their self-perceived pressure on health, and the more likely they are to have depressive symptoms and clinical depression[34]. The number of diseases also showed strong associations with patients’ depressive symptoms in this study. In patients with chronic diseases, the probability of developing depressive symptoms increases by 0.27 (0.11–0.47) times for each additional disease. Polypharmacy behaviors are more common in patients with multiple chronic diseases, and they are more likely to develop symptoms of depression. Similar results were shown in relevant studies of Canoui-Poitrine’s[25], which indicated that clinical depression was associated with multimorbidity and polypharmacy behaviors independently. In addition, we also discovered that patients with hypertension were more likely to have depressive symptoms in our study, which is consistent with the findings of the study of Xue[35], namely that patients with uncontrolled hypertension are more likely to develop clinically significant symptoms of depression. The findings of this study support the complex relationships between hypertension and depression. The high proportion of patients who have both hypertension and depression suggests that the two disorders interact, implying that hypertension might be a risk factor for depression. In other relevant studies, this association has also been attributed to the poor lifestyle of patients with depression, somatic symptoms of depression induced by antihypertensive drugs, and increased healthcare utilization of patients with depression to enhance the chance of diagnostic recognition of hypertension[36, 37]. Some other researchers believe that this association might be due to the limitations of self-assessed screening tools for depression. Patients with hypertension might be confused about symptoms of hypertension and depression, such as fatigue symptoms and sleeping disorders. They may consider these symptoms commonly suffered from hypertension as an indication of depression and classify themselves as patients with depression[38]. In addition, we discovered that whether or not patients participate in exercise was related to depressive symptoms in our study. Patients who took exercise were less likely to suffer from depression. Exercise has been demonstrated in previous studies to assist people reduce negative emotions[39] and improve sleep quality[22]. Exercise was found to decrease depression scores significantly[40], even having a stable and robust effect in depression severity among older patients with clinically significant symptoms of depression[41]. On the one hand, physical activities have been demonstrated to upregulate monoamine neurotransmission in animal brains, which might be linked to emotional disorders of human [42]. On the other hand, exercise can also distract people from stressful life events and reduce negative attention biases[43].
Finally, in terms of other medication information, patients taking Chinese medicine to treat chronic diseases were less likely to be depressed (OR = 0.66, 95% CI: 0.48–0.91). At present, there are few international studies on this aspect. The reason might be that the majority of the patients we surveyed are the elderly, and the most of Chinese elderly have a stronger trust in traditional Chinese medicine. The elderly believe that the traditional Chinese medicine has fewer side effects, therefore they pay less attention to the side effects of drugs[44].
Limitations
Our findings should be interpreted cautiously since there were several limitations to this study. Firstly, various definitions of polypharmacy behaviors existed in the literature, we only considered the number of drugs used, namely more than or equal to five drugs as polypharmacy behaviors, so it is difficult to make a distinction between necessary prescribing and polypharmacy behaviors. Secondly, the sample was from eight administrative regions in Wuhan City, so our findings might not be generalizable to other areas. Thirdly, we used no diagnostic assessment of depression, the CES-D 10 scale used in this study could only screen for the presence of depressive symptoms. A complete diagnostic assessment of clinical depression would be better in future researches. Finally, polypharmacy behaviors were measured based on the self-reported number of medications in this study, other sources should be considered to verify the responses.