A new way of stratifying acute chest pain: the clinical – chemistry score
Emergency Department, Policlinico Umberto I, “Sapienza” University, Rome
In our study, carried out in the Emergency Department of the Policlinico Umberto I in Rome, we tested a new diagnostic score: The Clinical – Chemistry Score (CCS) (2018).
We selected 143 patients with acute chest pain without signs of STEMI, analyzing the data acquired from the first value of high sensitivity cardiac troponin, from the result obtained from the scores that we selected and from the diagnosis and outcome data. We took the HEART score as a reference and comparison to the CCS.
Comparing the two scores, we have demonstrated the validity of the CCS (76% concordance index), the non-inferiority in the “rule-in” and the superiority of the CCS in the “rule-out”.
In our study we have for the first time highlighted the capability of CCS compared to the HEART score to reduce patients in the so-called gray zone, bringing patients to the “extremes” of the risk classification.
Clinical – Chemistry Score (CCS) – Acute Chest Pain – Stratification of Risk
Acute chest pain management is one of the greatest challenges of the Emergency Departments (ED) worldwide. 
Chest pain is one of the most common and complex symptoms for which patients approach to the Emergency Departments; according to some published studies, it causes 5-9%  of the total accesses.
Several documents in literature, both at national and international level, have deal over years with the problem of risk stratification in patients that show up to ED with chest pain, proposing a series of implementation strategies. [3,4,5,6,7,8,9,10]
However, this doesn’t lead to data that allow us to have in 100% of cases a correct diagnosis and a short time of observation of the patients “rule-out” for ACS (Acute Coronary Syndrome).
This situation leads to inappropriate hospitalizations, up to 25-50% of patients presenting with chest pain and to inappropriate discharges of 2-8% of patients, with important forensic implications  (the erroneous discharge of patients with MI (Myocardial Infarction) accounts for 20% of the forensic expenses against the doctors in the USA Emergency Departments [ 12]). Also give rise to a prolongation of the examination times with a consequent increase in the number of patients under observation and the reduction of the reception capacity of the ED.
For these reasons, the research has focused on new strategies employing both the use of increasingly faster biochemical markers (hs-cTn, High-sensitivity Cardiac Troponin) and the use of diagnostic algorithms and their implementation with scores that define the probability of risk.
The essential concept that drives the medical research to compare the value of troponin with other elements is that troponins do not express only the damage from MI but, in general, they express myocardial damage, even as from different causes. The diagnostic scores rise to support the clinical picture, the EKG and the troponins so to be helpful for a correct classification of the patient.
The Clinical – Chemistry Score is a diagnostic score develop by a Canadian medical team in collaboration with German, Australian and New Zealand doctors and whose primary results were published on 20 August 2018. 
The score was studied on 4245 patients in the ED of Hamilton (Canada), Hamburg (Germany), Brisbane (Australia) and Christchurch (New Zealand) and the first results showed a greater sensitivity and specificity in the stratification “rule-in / rule- out”, compared to the use of the only ultrasensitive troponins.
In this study we examine the CCS as a new score to be tested in the ED of Policlinico Umberto I in Rome, make a comparison with the HEART score and test its validity.
The data collected in this study constitute the first experimentation in Italy of this new score.
- Both sexes
- Age³18 years
- At least one determination of cardiac troponin
- Informed and written consent
- Chest pain (or angina pain) of suspected cardiac origin and negative EKG for ACS – STE as normal EKG, non-diagnostic / nonspecific EKG or ECG with other ischemic changes (negative T-waves or ST-segment depression).
- Refusal to provide informed consent;
- ST segment elevation to the EKG;
- Pregnancy or breastfeeding;
- Any other clinical condition not judged by the investigator compatible with participation in the TROCAR study.
- HIGH risk patients to CCS (4-5 pt.) and HEART score (7-10 pt.) and ACS +;
- HIGH risk patients to CCS and HEART score and ACS -;
- HIGH risk patients to CCS and LOW / INTERMEDIATE risk to HEART score and ACS +;
- LOW/ INTERMEDIATE risk patients to CCS and HIGH risk to HEART score and ACS +;
- LOW/ INTERMEDIATE risk patients to CCS and HEART score and ACS +;
- LOW/ INTERMEDIATE risk patients risk to CCS and HEART score and ACS -.
- discharged at home, at affiliated and / or ambulatory facilities for further investigations;
- hospitalized with ACS – diagnosis;
- performed coronarography that excluded the diagnosis of ACS.
40 patients with LOW risk to HEART score and ACS -;
2 patients with LOW risk to HEART score and ACS +;
48 patients with INTERMEDIATE to HEART score and ACS -;
14 patients with INTERMEDIATE to HEART score and ACS +;
23 patients with HIGH risk to HEART score and ACS +;
9 patients with HIGH risk to HEART score and ACS -.
Figure 1 – Comparison between HEART score and outcome related to diagnosis
- 69 patients with LOW risk to CCS and ACS -;
- 4 patients with LOW risk to CCS and ACS +;
- 17 patients with INTERMEDIATE to CCS and ACS -;
- 9 patients with INTERMEDIATE to CCS and ACS +;
- 26 patients with HIGH risk to CCS and ACS +;
- 11 patients with HIGH risk to CCS and ACS -.
Figure 1 – Comparison between CCS and outcome related to diagnosis
- 14 patients with a score of 0 to CCS, which 12 discharged and 2 hospitalized (chest pain of unknow cause);
- 29 patients with score of 1 to CCS, which 22 discharged and 7 hospitalized (chest pain of unknow cause);
- 30 patients with a score of 2 to CCS, including 15 discharges, 11 hospitalizations (chest pain of unknow cause) and 4 patients diagnosed with ACS +.
- CCS sensitivity: 0.9 (IC95% 0.82-0.98);
- CCS specificity: 0.71 (IC95% 0.62-0.79);
- Positive predictive Value (PPV): 0.56 (IC95% 0.438-0.682);
- Negative predictive value (NPV): 0.95 (IC95% 0.902-0.998);
- Validity of the test: 0.76.
- Sensitivity: 0.86 (IC95% 0.736-0.984);
- Specificity: 0.86 (IC95% 0.799-0.921);
- Positive Predictive Value (PPV): 0.7 (IC95% 0.562-0.838);
- Negative Predictive Value (NPV: 0.95 (IC95% 0.902-0.998).
- Validity of the test: 0.86.
Figure 3. Comparison of HEART score – CCS. Correlation between risk in relation to positive diagnosis for ACS
The capability of Clinical – Chemistry Score to reduce the numbers of patients in the gray area and to bring them to the “extremes” of stratification is the most important data of our study.
Often the gray areas are the weak point of the scores, which make the case of difficult interpretation and, therefore, the reliability of the score in the medical evaluation.
Moreover, it is quite the gray area that limits the direction to make the choice about “rule-out” patients.
In our experience the CCS as compared to HEART has the ability to reduce the number of patients in the gray area by directing them mainly towards “rule-out” and this is an important strength of this new score. Regarding “rule-in” the data of the CCS are similar to the HEART.
The judgment on this score will be validated by expanding the case study, but our preliminary results allow us to see a greater accuracy of this new score.
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