Validation of the Pittsburgh Cardiac Arrest Category illness severity score

doi:10.1016/j.resuscitation.2015.01.020

Resuscitation

Volume 89, April 2015, Pages 86-92

https://doi.org/10.1016/j.resuscitation.2015.01.020 Get rights and content

Abstract

Background

The purpose of this study was to validate the ability of an early post-cardiac arrest illness severity classification to predict patient outcomes.

Methods

The Pittsburgh Cardiac Arrest Category (PCAC) is a 4-level illness severity score that was found to be strongly predictive of outcomes in the initial derivation study. We assigned PCAC scores to consecutive in and out-of-hospital cardiac arrest subjects treated at two tertiary care centers between January 2011 and September 2013. We made assignments prospectively at Site 1 and retrospectively at Site 2. Our primary outcome was survival to hospital discharge. Inter-rater reliability of retrospective PCAC assessments was assessed. Secondary outcomes were favorable discharge disposition (home or acute rehabilitation), Cerebral Performance Category (CPC) and modified Rankin Scale (mRS) at hospital discharge. We tested the association of PCAC with each outcome using unadjusted and multivariable logistic regression.

Results

We included 607 cardiac arrest patients during the study (393 at Site 1 and 214 at Site 2). Site populations differed in age, arrest location, rhythm, use of hypothermia and distribution of PCAC. Inter-rater reliability of retrospective PCAC assignments was excellent (κ = 0.81). PCAC was associated with survival (unadjusted odds ratio (OR) for Site 1: 0.33 (95% confidence interval (CI) 0.27–0.41)) Site 2: 0.32 (95% CI 0.24–0.43) even after adjustment for other clinical variables (adjusted OR Site 1: 0.32 (95% CI 0.25–0.41) Site 2: 0.31 (95% CI 0.22–0.44)). PCAC was predictive of secondary outcomes.

Conclusions

Our results confirm that PCAC is strongly predictive of survival and good functional outcome after cardiac arrest.

Introduction

Over 500,000 Americans suffer a cardiac arrest annually.¹ Among those with return of spontaneous circulation (ROSC) admitted to the hospital, 50–70% die before discharge. Accurate prognostication of survival, good functional outcome and complications after ROSC can inform medical management, surrogate decision-making and resource allocation. Furthermore, a measure that controls for illness severity using early clinical characteristics would allow prospective stratification or retrospective adjustment in research that examines post-resuscitation care in this heterogeneous population. A number of illness severity scores have been developed for use after cardiac arrest, but rely on information that is not readily available to clinicians in the early hours after ROSC.2, 3, 4 Further, these scores are intended for use in either in-hospital cardiac arrest (IHCA) or out-of-hospital cardiac arrest (OHCA), but not both.2, 3, 4 We previously derived an illness severity scale, the Pittsburgh Cardiac Arrest Category (PCAC), that was strongly associated with survival to hospital discharge and good functional outcome in both IHCA and OHCA.⁵ This scale was derived for simplicity, focus on objective physical findings, and relevance to post-arrest patients.

The present study was intended to validate the PCAC. We hypothesized that the PCAC would independently predict survival and functional outcome in two populations of patients hospitalized after cardiac arrest even after adjustment for other variables. Since neurological prognostication may lead to a “self-fulfilling prophecy” whereby care is withdrawn based on perceived prognosis,⁶ we assigned the PCAC prospectively at the center where it had been derived and retrospectively at another center. Thus, our study was intended to prospectively validate the PCAC in a population similar to the derivation cohort while simultaneously providing external validation to avoid the possibility of bias.

Section snippets

Methods

The University of Pittsburgh Institutional Review Board approved this study.

Results

A total of 607 subjects with cardiac arrest were admitted during the study period (393 at Site 1 and 214 at Site 2). Subjects at Site 2 tended to be older, with a higher prevalence of PEA, IHCA, and received therapeutic hypothermia less frequently (Table 1). Baseline characteristics were similar across PCAC levels (Table 1). The frequency of IHCA and VF/VT decreased across PCAC levels while use of hypothermia increased. Inter-rater reliability of retrospective PCAC assignment yielded a kappa

Discussion

We demonstrate that PCAC is strongly associated with survival to hospital discharge and good functional outcome. This association is similar regardless of whether PCAC was assigned prospectively or retrospectively. Importantly, we have confirmed reproducibility of this association in two different hospital settings with demographically distinct patient populations and care practices. Finally, we have demonstrated excellent inter-rater reliability when PCAC is retrospectively assigned. Although

Conclusion

PCAC, an illness severity score derived in a previous cohort of IHCA and OHCA patients, predicted survival and functional recovery in two different cohorts. This score can be calculated in all cardiac arrest survivors early after ROSC using information readily available to clinicians. PCAC is a useful method for making early estimates of prognosis and can be used to adjust for injury severity in future studies of post-resuscitation care.

Conflict of interest statement

None.

Funding source

None.

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Cited by (114)

Simple approach to quantify hypoxic-ischemic brain injury severity from computed tomography imaging files after cardiac arrest
2024, Resuscitation
Grey-white ratio (GWR) can estimate severity of cytotoxic cerebral edema secondary to hypoxic-ischemic brain injury after cardiac arrest and predict progression to death by neurologic criteria (DNC). Current approaches to calculating GWR are not standardized and have variable interrater reliability. We tested if measures of variance of brain density on early computed tomographic (CT) imaging after cardiac arrest could predict DNC.
We performed a retrospective cohort study, identifying post-arrest patients treated between 2011 and 2020 at our single center. We extracted demographic data from our registry and Digital Imaging and Communication in Medicine (DICOM) files for each patient’s first brain CT. We analyzed slices 15–20 of each DICOM, corresponding to the level of the basal ganglia while accommodating differences in patient anatomy. We extracted pixel arrays and converted the radiodensities to Hounsfield units (HU). To focus on brain tissue densities, we excluded HU > 60 and < 10. We calculated the variance of each patient’s HU distribution and the difference between the means of a two-group Gaussian finite mixture model. We compared these novel metrics to existing measures of cerebral edema, then randomly divided our data into 80% training and 20% test sets and used logistic regression to predict DNC.
Of 1,133 included subjects, 457 (40%) were female, mean (standard deviation) age was 58 (16) years, and 115 (10%) progressed to DNC. CTs were obtained a median [interquartile range] of 4.2 [2.8–5.7] hours post-arrest. Our novel measures correlated weakly with GWR. HU variance, but not difference between mixture model means, differed significantly between subjects with and without sulcal or cistern effacement. GWR outperformed our novel measures in predicting progression to DNC with an area under the receiver operating characteristic curve (AUC) of 0.82, compared to HU variance (AUC = 0.73) and the difference between mixture model means (AUC = 0.56).
There are differences in the distribution of HU on post-arrest CT in patients with qualitative measures of cerebral edema. Current methods to quantify cerebral edema outperform simple measures of attenuation variance on early brain CT. Further analyses could investigate if these measures of variance, or other distributional characteristics of brain density, have improved predictive performance on brain CTs obtained later in the clinical course or derived from discrete regions of anatomical interest.
Brain computed tomography after resuscitation from in-hospital cardiac arrest
2024, Resuscitation
Few data characterize the role of brain computed tomography (CT) after resuscitation from in-hospital cardiac arrest (IHCA). We hypothesized that identifying a neurological etiology of arrest or cerebral edema on brain CT are less common after IHCA than after resuscitation from out-of-hospital cardiac arrest (OHCA).
We included all patients comatose after resuscitation from IHCA or OHCA in this retrospective cohort analysis. We abstracted patient and arrest clinical characteristics, as well as pH and lactate, to estimate systemic illness severity. Brain CT characteristics included quantitative measurement of the grey-to-white ratio (GWR) at the level of the basal ganglia and qualitative assessment of sulcal and cisternal effacement. We compared GWR distribution by stratum (no edema ≥1.30, mild-to-moderate <1.30 and >1.20, severe ≤1.20) and newly identified neurological arrest etiology between IHCA and OHCA groups.
We included 2,306 subjects, of whom 420 (18.2%) suffered IHCA. Fewer IHCA subjects underwent post-arrest brain CT versus OHCA subjects (149 (35.5%) vs 1,555 (82.4%), p < 0.001). Cerebral edema for IHCA versus OHCA was more often absent (60.1% vs. 47.5%) or mild-to-moderate (34.3% vs. 27.9%) and less often severe (5.6% vs. 24.6%). A neurological etiology of arrest was identified on brain CT in 0.5% of IHCA versus 3.2% of OHCA.
Although severe edema was less frequent in IHCA relative to OHCA, mild-to-moderate or severe edema occurred in one in three patients after IHCA. Unsuspected neurological etiologies of arrest were rarely discovered by CT scan in IHCA patients.
Blood-brain barrier permeability for the first 24 hours in hypoxic-ischemic brain injury following cardiac arrest
2024, Resuscitation
This study aimed to explore the changes in blood–brain barrier (BBB) permeability and intracranial pressure (ICP) for the first 24 h after the return of spontaneous circulation (ROSC) and their association with injury severity of cardiac arrest.
This prospective study analysed the BBB permeability assessed using the albumin quotient (Qa) and ICP every 2 h for the first 24 h after ROSC. The injury severity of cardiac arrest was assessed using Pittsburgh Cardiac Arrest Category (PCAC) scores. The primary outcome was the time course of changes in the BBB permeability and ICP for the first 24 h after ROSC and their association with injury severity (PCAC scores of 1–4).
Qa and ICP were measured 274 and 197 times, respectively, in 32 enrolled patients. Overall, the BBB permeability increased progressively over time after ROSC, and then it increased significantly at 18 h after ROSC compared with the baseline. In contrast, the ICP revealed non-significant changes for the first 24 h after ROSC. The Qa in the PCAC 2 group was < 0.01, indicating normal or mild BBB disruption at all time points, whereas the PCAC 3 and 4 groups showed a significant increase in BBB permeability at 14 and 22 h, and 12 and 14 h after ROSC, respectively.
BBB permeability increased progressively over time for the first 24 h after ROSC despite post-resuscitation care, whereas ICP did not change over time. BBB permeability has an individual pattern when stratified by injury severity.
Diagnostic yield of computed tomography after non-traumatic out-of-hospital cardiac arrest
2023, Resuscitation
Determine the frequency with which computed tomography (CT) after out-of-hospital cardiac arrest (OHCA) identifies clinically important findings.
We included non-traumatic OHCA patients treated at a single center from February 2019 to February 2021. Clinical practice was to obtain CT head in comatose patients. Additionally, CT of the cervical spine, chest, abdomen, and pelvis were obtained if clinically indicated. We identified CT imaging obtained within 24 hours of emergency department (ED) arrival and summarized radiology findings. We used descriptive statistics to summarize population characteristics and imaging results, report their frequencies and, post hoc, compared time from ED arrival to catheterization between patients who did and did not undergo CT.
We included 597 subjects, of which 491 (82.2%) had a CT obtained. Time to CT was 4.1 hours [2.8–5.7]. Most (n = 480, 80.4%) underwent CT head, of which 36 (7.5%) had intracranial hemorrhage and 161 (33.5%) had cerebral edema. Fewer subjects (230, 38.5%) underwent a cervical spine CT, and 4 (1.7%) had acute vertebral fractures. Most subjects (410, 68.7%) underwent a chest CT, and abdomen and pelvis CT (363, 60.8%). Chest CT abnormalities included rib or sternal fractures (227, 55.4%), pneumothorax (27, 6.6%), aspiration or pneumonia (309, 75.4%), mediastinal hematoma (18, 4.4%) and pulmonary embolism (6, 3.7%). Significant abdomen and pelvis findings were bowel ischemia (24, 6.6%) and solid organ laceration (7, 1.9%). Most subjects that had CT imaging deferred were awake and had shorter time to catheterization.
CT identifies clinically important pathology after OHCA.
Duration of cardiopulmonary resuscitation and phenotype of post-cardiac arrest brain injury
2023, Resuscitation
Patients resuscitated from cardiac arrest have variable severity of primary hypoxic ischemic brain injury (HIBI). Signatures of primary HIBI on brain imaging and electroencephalography (EEG) include diffuse cerebral edema and burst suppression with identical bursts (BSIB). We hypothesize distinct phenotypes of primary HIBI are associated with increasing cardiopulmonary resuscitation (CPR) duration.
We identified from our prospective registry of both in-and out-of-hospital CA patients treated between January 2010 to January 2020 for this cohort study. We abstracted CPR duration, neurological examination, initial brain computed tomography gray to white ratio (GWR), and initial EEG pattern. We considered four phenotypes on presentation: awake; comatose with neither BSIB nor cerebral edema (non-malignant coma); BSIB; and cerebral edema (GWR ≤ 1.20). BSIB and cerebral edema were considered as non-mutually exclusive outcomes. We generated predicted probabilities of brain injury phenotype using localized regression.
We included 2,440 patients, of whom 545 (23%) were awake, 1,065 (44%) had non-malignant coma, 548 (23%) had BSIB and 438 (18%) had cerebral edema. Only 92 (4%) had both BSIB and edema. Median CPR duration was 16 [IQR 8–28] minutes. Median CPR duration increased in a stepwise manner across groups: awake 6 [3–13] minutes; non-malignant coma 15 [8–25] minutes; BSIB 21 [13–31] minutes; cerebral edema 32 [22–46] minutes. Predicted probability of phenotype changes over time.
Brain injury phenotype is related to CPR duration, which is a surrogate for severity of HIBI. The sequence of most likely primary HIBI phenotype with progressively longer CPR duration is awake, coma without BSIB or edema, BSIB, and finally cerebral edema.
Validation of the rCAST score and comparison to the PCAC and FOUR scores for prognostication after out-of-hospital cardiac arrest
2023, Resuscitation
Early, accurate outcome prediction after out-of-hospital cardiac arrest (OHCA) is critical for clinical decision-making and resource allocation. We sought to validate the revised post-Cardiac Arrest Syndrome for Therapeutic hypothermia (rCAST) score in a United States cohort and compare its prognostic performance to the Pittsburgh Cardiac Arrest Category (PCAC) and Full Outline of UnResponsiveness (FOUR) scores.
This is a single-center, retrospective study of OHCA patients admitted between January 2014-August 2022. Area under the receiver operating curve (AUC) was computed for each score for predicting poor neurologic outcome at discharge and in-hospital mortality. We compared the scores’ predictive abilities via Delong’s test.
Of 505 OHCA patients with all scores available, the medians [IQR] for rCAST, PCAC, and FOUR scores were 9.5 [6.0, 11.5], 4 [3, 4], and 2 [0, 5], respectively. The AUC [95% confidence interval] of the rCAST, PCAC, and FOUR scores for predicting poor neurologic outcome were 0.815 [0.763–0.867], 0.753 [0.697–0.809], and 0.841 [0.796–0.886], respectively. The AUC [95% confidence interval] of the rCAST, PCAC, and FOUR scores for predicting mortality were 0.799 [0.751–0.847], 0.723 [0.673–0.773], and 0.813 [0.770–0.855], respectively. The rCAST score was superior to the PCAC score for predicting mortality (p = 0.017). The FOUR score was superior to the PCAC score for predicting poor neurological outcome (p < 0.001) and mortality (p < 0.001).
The rCAST score can reliably predict poor outcome in a United States cohort of OHCA patients regardless of TTM status and outperforms the PCAC score.

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^☆: A Spanish translated version of the abstract of this article appears as Appendix in the final online version at http://dx.doi.org/10.1016/j.resuscitation.2015.01.020.

¹: The list of Post Cardiac Arrest Service researchers are listed in Appendix A.

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Clinical PaperValidation of the Pittsburgh Cardiac Arrest Category illness severity score☆

Abstract

Background

Methods

Results

Conclusions

Introduction

Section snippets

Methods

Results

Discussion

Conclusion

Conflict of interest statement

Funding source

Resuscitation

Resuscitation

Resuscitation

Lancet

Resuscitation

J Crit Care

Resuscitation

Resuscitation

Resuscitation

Resuscitation

Emerg Med Clin N Am

Resuscitation

Heart disease and stroke statistics – 2012 update: a report from the American Heart Association

Circulation

Predicting survival with good neurological recovery at hospital admission after successful resuscitation of out-of-hospital cardiac arrest: the OHCA score

Eur Heart J

A validated prediction tool for initial survivors of in-hospital cardiac arrest

Arch Intern Med

Get with the guidelines-resuscitation I. Development and validation of the Good Outcome Following Attempted Resuscitation (GO-FAR) score to predict neurologically intact survival after in-hospital cardiopulmonary resuscitation

JAMA Intern Med

Clinical Paper
Validation of the Pittsburgh Cardiac Arrest Category illness severity score☆