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.