Biomarkers of brain injury after cardiac arrest; a statistical analysis plan from the TTM2 trial biobank investigators

Background

Several biochemical markers in blood correlate with the magnitude of brain injury and may be used to predict neurological outcome after cardiac arrest. We present a protocol for the evaluation of prognostic accuracy of brain injury markers after cardiac arrest. The aim is to define the best predictive marker and to establish clinically useful cut-off levels for routine implementation.

Methods

Prospective international multicenter trial within the Targeted Hypothermia versus Targeted Normothermia after Out-of-Hospital Cardiac Arrest (TTM2) trial in collaboration with Roche Diagnostics International AG. Samples were collected 0, 24, 48, and 72 hours after randomisation (serum) and 0 and 48 hours after randomisation (plasma), and pre-analytically processed at each site before storage in a central biobank. Routine markers neuron-specific enolase (NSE) and S100B, and neurofilament light, total-tau and glial fibrillary acidic protein will be batch analysed using novel Elecsys® electrochemiluminescence immunoassays on a Cobas e601 instrument.

Results

Statistical analysis will be reported according to the Standards for Reporting Diagnostic accuracy studies (STARD) and will include comparisons for prediction of good versus poor functional outcome at six months post-arrest, by modified Rankin Scale (0-3 vs. 4-6), using logistic regression models and receiver operating characteristics curves, evaluation of mortality at six months according to biomarker levels and establishment of cut-off values for prediction of poor neurological outcome at 95-100% specificities.

Conclusions

This prospective trial may establish a standard methodology and clinically appropriate cut-off levels for the optimal biomarker of brain injury which predicts poor neurological outcome after cardiac arrest.

Hypothermic to ischemic ratio and mortality in post-cardiac arrest patients

BACKGROUND

We studied the associations between ischemia and hypothermia duration, that is, the hypothermic to ischemic ratio (H/I ratio), with mortality in patients included in a trial on two durations of targeted temperature management (TTM) at 33°C.

METHODS

The TTH48 (NCT01689077) trial compared 24 and 48 hours of TTM in patients after cardiac arrest. We calculated the hypothermia time from return of spontaneous circulation (ROSC) until the patient reached 37°C after TTM and the ischemic time from CA to ROSC. We compared continuous variables with the Mann-Whitney U test. Using COX regression, we studied the independent association of the logarithmically transformed H/I ratio and time to death as well as interaction between time to ROSC, hypothermia duration, and intervention group. We visualized the predictive ability of variables with receiver operating characteristic curve analysis.

RESULTS

Of the 338 patients, 237 (70%) survived for 6 months. The H/I ratio was 155 (IQR 111-238) in survivors and 114 (IQR 80-169) in non-survivors (P < .001). In a Cox regression model including factors associated with outcome in univariate analysis, the logarithmically transformed H/I ratio was a significant predictor of outcome (hazard ratio 0.52 (0.37-0.72, P = .001)). After removing an outlier, we found no interaction between time to ROSC and intervention group (P = .55) or hypothermia duration in quartiles (P = .07) with mortality. There was no significant difference in the area under the curve (AUC) between time to ROSC and H/I ratio (ΔAUC 0.03 95% CI -0.006-0.07, P = .10).

CONCLUSIONS

We did not find any consistent evidence of a modification of the effect of TTM based on ischemia duration.

Cold fluids for induction of targeted temperature management: A sub-study of the TTH48 trial

BACKGROUND

Pre-intensive care unit (ICU) induction of targeted temperature management (TTM) with cold intravenous (i.v.) fluids does not appear to improve outcomes after in out-of-hospital cardiac arrest (OHCA). We hypothesized that this may be due to ineffective cooling and side effects.

METHODS

A post hoc analysis of a sub-group of patients (n = 352) in the TTH48 trial (NCT01689077) who received or did not receive pre-ICU cooling using cold i.v. fluids. Data collection included patient characteristics, cardiac arrest factors, cooling methods, side effects and continuous core temperature measurements. The primary endpoint was the time to target temperature (TTT, <34 °C), and the secondary endpoints included the incidence of circulatory side effects, abnormal electrolyte levels and hypoxia within the first 24 h of ICU care. A difference of 1 h in the TTT was determined as clinically significant a priori.

RESULTS

Of 352 patients included in the present analysis, 110 received pre-ICU cold fluids. The median time to the return of spontaneous circulation (ROSC) and TTT in the pre-ICU cold fluids group was longer than that of the group that did not receive pre-ICU cold fluids (318 vs. 281 min, p < 0.01). In a linear regression model including the treatment centre, body mass index (BMI), chronic heart failure, diabetes mellitus and time to ROSC, the use of pre-ICU cold i.v. fluids was not associated with a shorter time to the target temperature (standardized beta coefficient: 0.06, 95% CI for B -49 and 16, p  =  0.32). According to the receipt or not of pre-ICU cold i.v. fluids, there was no difference in the proportion of patients with hypoxia on ICU admission (1.8% vs. 3.3%, p =  0.43) or the proportion of patients with electrolyte abnormalities (hyponatremia: 1.8% vs. 2.9% p = 0.54; hypokalaemia: 1.8% vs. 4.5%, p =  0.20). Furthermore, there was no difference in hospital mortality between the groups.

CONCLUSIONS

The initiation of TTM with cold i.v. fluids before ICU arrival did not decrease the TTT. We detected no significant between-group difference in mortality or the incidence of side effects according to the administration or not of pre-ICU cold i.v fluids.

Time-differentiated target temperature management after out-of-hospital cardiac arrest: a multicentre, randomised, parallel-group, assessor-blinded clinical trial (the TTH48 trial): study protocol for a randomised controlled trial

BACKGROUND

The application of therapeutic hypothermia (TH) for 12 to 24 hours following out-of-hospital cardiac arrest (OHCA) has been associated with decreased mortality and improved neurological function. However, the optimal duration of cooling is not known. We aimed to investigate whether targeted temperature management (TTM) at 33 ± 1 °C for 48 hours compared to 24 hours results in a better long-term neurological outcome.

METHODS

The TTH48 trial is an investigator-initiated pragmatic international trial in which patients resuscitated from OHCA are randomised to TTM at 33 ± 1 °C for either 24 or 48 hours. Inclusion criteria are: age older than 17 and below 80 years; presumed cardiac origin of arrest; and Glasgow Coma Score (GCS) <8, on admission. The primary outcome is neurological outcome at 6 months using the Cerebral Performance Category score (CPC) by an assessor blinded to treatment allocation and dichotomised to good (CPC 1-2) or poor (CPC 3-5) outcome. Secondary outcomes are: 6-month mortality, incidence of infection, bleeding and organ failure and CPC at hospital discharge, at day 28 and at day 90 following OHCA. Assuming that 50 % of the patients treated for 24 hours will have a poor outcome at 6 months, a study including 350 patients (175/arm) will have 80 % power (with a significance level of 5 %) to detect an absolute 15 % difference in primary outcome between treatment groups. A safety interim analysis was performed after the inclusion of 175 patients.

DISCUSSION

This is the first randomised trial to investigate the effect of the duration of TTM at 33 ± 1 °C in adult OHCA patients. We anticipate that the results of this trial will add significant knowledge regarding the management of cooling procedures in OHCA patients.

TRIAL REGISTRATION

NCT01689077.

Does spinal surgery improve the quality of life for those with extradural (spinal) osseous metastases? An international multicenter prospective observational study of 223 patients. Invited submission from the Joint Section Meeting on Disorders of the Spine and Peripheral Nerves, March 2007

OBJECT

Opinions vary widely as to the role of surgery (from none to wide margin excision) in the management of spinal metastases. In this study the authors set out to ascertain if surgery improves the quality of remaining life in patients with spinal metastatic and tumor-related systemic disease.

METHODS

The authors included 223 patients in this study who were referred by oncologists and physicians over a 2-year period. All underwent surgery. Surgery was classified according to extent of excision ranging from en bloc excision or debulking to palliative surgery. All patients had a histologically confirmed diagnosis of epithelial spinal metastasis, and an oncology specialist undertook appropriately indicated adjuvant therapy in almost half of the patients.

RESULTS

The mean patient age was 61 years. Excisional en bloc or debulking surgery was performed in 74%; the rest had (minimal) palliative decompression. All patients considered for surgery were included in the study. Patients presented with pain in 92% of cases, paraparesis in 24%, and abnormal urinary sphincter function in 22% (5% were incontinent). Breast, renal, lung, and prostate accounted for 65% of the cancers, and in 60% of patients there were widespread spinal metastases (Tomita Type 6 or 7). The incidence of perioperative death (within 30 days of surgery) was 5.8%. Postoperatively 71% of the entire group had improved pain control, 53% regained or maintained their independent mobility, and 39% regained urinary sphincter function. The median survival for the cohort was 352 days (11.7 months); those who underwent excision survived significantly longer than those in the palliative group (p = 0.003). As with survival results, functional improvement outcome was better in those who underwent excision.

CONCLUSIONS

Surgical treatment was effective in improving quality of life by providing better pain control, enabling patients to regain or maintain mobility, and offering improved sphincter control. Although not a treatment of the systemic cancer, surgery is feasible, has acceptably low mortality and morbidity rates, and for many will improve the quality of their remaining life.

[Estimation of life expectancy for selecting surgical procedure and predicting prognosis of extradural spinal metastases]

BACKGROUND & OBJECTIVE

Clinically, whether and how to make a surgical interventional decision for the patients with spinal metastases is still controversial. Life expectancy is a significant determinant in the selection of surgical procedure for spinal metastases. This study was to evaluate Tomita and Tokuhashi scoring systems in selecting surgical procedure and predicting prognosis of extradural spinal metastases.

METHODS

A total of 169 patients with spinal metastases, treated in the Spine Unit of Aarhus University Hospital, Denmark, from Jan. 2001 to Apr. 2004, were enrolled. The life expectancy was scored according to both Tomita system and Tokuhashi system before operation, the spinal metastases were classified according to Tomita system, and the patients underwent surgery accordingly. Follow-up was done 6, 12, and 24 months after operation. The precise of Tomita system and Tokuhashi system in estimating "death within 3 months", "death within 6 months", and "death within 12 months" was compared using Receiver Operating Characteristic curves (ROC curves). The mean survival time of the patients was calculated by Kaplan-Meier method.

RESULTS

ROC curves of "death within 3 months", "death within 6 months", and "death within 12 months" showed no significant difference between Tomita score and Tokuhashi score in each group (P = 0.16, P = 0.47, and P = 0.38, respectively). Kaplan-Meier survival curves showed that Tomita system overestimated the prognosis in scores from 4 to 7, and Tokuhashi system underestimated the prognosis in scores from 0 to 8.

CONCLUSIONS

Both Tomita and Tokuhashi scoring systems could be used to predict prognosis of spinal metastases after operation. Tokuhashi scoring system can predict early death more accurately, which can be used to avoid major operation for these patients.