4 | DISCUSSION
In this study, we investigated the prognostic value of CAR in patients with OHCA. The main finding of our study was that CAR was significantly higher in non-survivor group compared to in survivor group. Also, CAR was an independent predictor of in-hospital mortality. To our knowledge, this is the first study demonstrating the independent relationship between CAR and in hospital mortality in patients with OHCA.
The extensive ischemia during CA leads to the activation of systemic inflammation.4 After that, some complex pathophysiological changes occur such as free oxygen radical production, increased vascular permeability and disruption of the blood-brain barrier. All these changes cause systemic ischemia and multi organ failure.4,11 Therefore, it is very important to assess the prognosis after CPR and to predict survival early and accurately in patients who survived from CA.
After cardiac arrest, lactate accumulation occurs due to interruption of blood flow to metabolically active tissues and decreased tissue oxygenation.12 Therefore, serum lactate level, an easily obtainable marker from blood gas analysis, was used in several studies for predicting poor outcomes in patients with OHCA.12-15 It was found that higher lactate level on admission was associated with unfavorable outcomes and poor prognosis. Similar to these studies, we also found that serum lactate level on admission was significantly higher in non-survivor group compared to survivor group. In addition, we detected that serum lactate level was an independent predictor of mortality. These results suggest that on admission serum lactate level may be used as a beneficial tool for predicting in-hospital mortality in patients with OHCA.
Because a widely inflammatory process is triggered in patients with cardiac arrest, previous studies have frequently investigated the importance of inflammatory markers.16-20 NLR, a cheap and an easily detectable marker from complete blood cell, is a combination of two independent markers of systemic inflammation.5 It was demonstrated that NLR is a stronger parameter that other white blood cell subtypes for evaluating the inflammatory process.21 Therefore, it is one of the most used inflammatory markers in daily practice. Weiser et al.6 found that NLR at admission predicted mortality independently in patients with OHCA. Similar to this study, we also found that NLR at hospital admission was an independent predictor of mortality in these patients. These results suggest that in hospital prognosis may be poorer in patients with OHCA where a more intense inflammatory process is triggered.
CRP and albumin are biochemical markers of systemic inflammation. The clinical usefulness of them have been investigated in previous studies.22,23 Increased level of CRP and decreased level of albumin were found to be associated with poor outcomes in patients with CA. CAR is a novel marker of systemic inflammation and can be obtained easily from biochemical analysis.7 It reflects the balance between CRP and albumin and has been found that the combination of these two markers are stronger and more consistent than CRP or albumin alone for predicting outcomes.10Although previous studies separately investigated the CRP and albumin levels in patients with CA.22,23 To our knowledge, there is no study evaluating CAR in patients with OHCA. In the present study, we investigated the CAR level in addition to the NLR in patients with OHCA. We found that CAR was significantly higher in non-survivor group compared to survivor group. Also, CAR was an independent predictor of in-hospital mortality. Moreover, we found that the AUC of CAR was significantly higher than both the AUCs of CRP and albumin for predicting in-hospital mortality. These results suggest that CAR has a better prognostic role than either CRP or albumin alone for predicting poor outcomes in patients with OHCA. In addition, it can be concluded that CAR is a good clinical marker for predicting in-hospital mortality after surviving from OHCA.