## 4 Discussion
According to the available literature, the presence of preoperative depression increased the odds of other adverse outcomes for CABG patients, including a higher incidence of postoperative inflammation, decreased wound healing, and depressed patient resistance, all of which have a negative impact on their postoperative hospital LOS [11; 49; 61]. These adverse outcomes have a strong correlation with the level of CRP and other inflammatory markers [48; 62]. As already stated, inflammation, the key regulator of CRP synthesis, has a prominent role in the etiology of atherosclerotic cardiovascular diseases, including CAD [12; 13]. In the study by [PERSON] et al., (2014) the association of a higher BDI score with increased odds of prolonged hospital stay was partially mediated by elevated early (baseline to 1-3 days post-operatively) and persistent (baseline to 4-8 days post-operatively) CRP response [48]. One increase in early CRP response in their patient cohort resulted in a 1% increase in the greater odds of a more extended hospital stay. In contrast, the same increase in persistent CRP response resulted in 1.3% higher odds. On the contrary, in our CABG cohort, only the persistent CRP levels were associated with a prolonged hospital LOS, with an increase of one unit in persistent CRP resulting in a 1.7% increase in the higher odds for an in-hospital stay greater than one week. Interestingly, separate analysis of gender subgroups within our cohort of CABG patients revealed significant association of persistent CRP change only among the male subgroup while none of CRP measures was associated with prolonged hospital stay in female patient subgroup. Elevated baseline CRP has also been associated with extended postoperative hospital LOS of CABG patients [63]. In the study reported by [PERSON] et al. (2012), elevated baseline CRP levels were identified as an independent predictor for depression (assessed with the PHQ-9 test score) present preoperatively and up to six months after the CABG procedure [50]. However, no such association was detected in our cohort of CABG patients. [PERSON] et al. also reported the lack of association between BDI score and preoperative CRP levels [49]. In our cohort of CABG patients, smoking status was one of the major intensity indicators in early and persistent CRP response. At the same time, the presence of (post)operative infection was statistically associated only with the persistent CRP response. In the present study, smoking status and EuroSCORE-II were associated with a post-operative hospital stay longer than one week. The association between depression and smoking in CABG patients has been reported in several studies [10; 64; 65]. In addition, [PERSON] et al. reported that cigarette smoking was significantly more frequent in depressed young male patients with documented CAD [65]. Most of the variables included in the EuroSCORE-II have been related to anxiety and depression. Thus, EuroSCORE II operational risk values might also be accountable for risks originating from preoperative anxiety and depressive symptoms [66]. This link between baseline depression and patients' EuroSCORE risk stratification should be further explored. Furthermore, [PERSON] et al. (2019) also believe that developing a prognostic screening tool involving emotional, behavioral, social, and functional factors is necessary to complement the risk assessment by EuroSCORE [67]. Although it seems that the BDI-II scale represents a sound path for detecting depression in CABG patients, the need for careful adjustment of cut-off points and evidence-basedinterpretation of score values should be addressed before its usage in clinical decision-making [68]. Our study has several strengths. We examined patients undergoing CABG at a single hospital and removed the influence of inter-hospital variations in discharge policy. The study's design allowed for a temporal relationship between depression, preoperative, and postoperative CRP levels, and length of stay to be analyzed.