Safety and Effectiveness of the High-Sensitivity Cardiac Troponin HEART Pathway in Patients With Possible Acute Coronary Syndrome

BACKGROUND

The HEART Pathway (History, Electrocardiogram, Age, Risk factors, Troponin) can be used with high-sensitivity cardiac troponin to risk stratify emergency department patients with possible acute coronary syndrome. However, data on whether a high-sensitivity HEART Pathway (hs-HP) are safe and effective is lacking.

METHODS

An interrupted time series study was conducted at 5 North Carolina sites in 26 126 adult emergency department patients being investigated for possible acute coronary syndrome and without ST-segment-elevation myocardial infarction. Patients were accrued into 16-month preimplementation and postimplementation cohorts with a 6-month wash-in phase. Preimplementation (January 2019 to April 2020), the traditional HEART Pathway was used with 0- and 3-hour contemporary troponin measures (Siemens). In the postimplementation period (November 2020 to February 2022), a modified hs-HP was used with 0- and 2-hour high-sensitivity cardiac troponin (Beckman Coulter) measures. The primary safety and effectiveness outcomes were 30-day all-cause death or myocardial infarction and 30-day hospitalizations. These outcomes and early discharge rate (emergency department discharge without stress testing or coronary angiography) were determined from health records and death index data. Outcomes were compared preimplementation versus postimplementation using χ2 tests and multivariable logistic regression to adjust for potential confounders.

RESULTS

Preimplementation and postimplementation cohorts included 12 317 and 13 809 patients, respectively, of them 52.7% (13 767/26 126) were female with a median age of 54 years (interquartile range, 42-66). Rates of 30-day death or MI were 6.8% (945/13 809) postimplementation and 7.7% (948/12 317) preimplementation (adjusted odds ratio, 1.00 [95% CI, 0.90-1.11]). hs-HP implementation was associated with 19.9% (95% CI, 18.7%-21.1%) higher early discharges (post versus pre: 63.6% versus 43.7%; adjusted odds ratio, 2.22 [95% CI, 2.10-2.35]). The hs-HP was also associated with 16.1% (95% CI, 14.9%-17.3%) lower 30-day hospitalizations (postimplementation versus preimplementation, 31.4% versus 47.5%; adjusted odds ratio, 0.51 [95% CI, 0.48-0.54]). Among early discharge patients, death or myocardial infarction occurred in 0.5% (41/8780) postimplementation versus 0.4% (22/5383) preimplementation (P=0.61).

CONCLUSIONS

hs-HP implementation is associated with increased early discharges without increasing adverse events. These findings support the use of a modified hs-HP to improve chest pain care.

Sex and race differences in the performance of the European Society of Cardiology 0/1-h algorithm with high-sensitivity troponin T

The diagnostic performance of the high-sensitivity troponin T (hs-cTnT) European Society of Cardiology (ESC) 0/1-h algorithm in sex and race subgroups of US Emergency Department (ED) patients is unclear. A pre-planned subgroup analysis of the STOP-CP cohort study was conducted. Participants with 0- and 1-h hs-cTnT measures from eight US EDs (1/2017 to 9/2018) were stratified into rule-out, observation, and rule-in zones using the hs-cTnT ESC 0/1 algorithm. The primary outcome was adjudicated 30-day cardiac death or MI. The proportion with the primary outcome in each zone was compared between subgroups with Fisher's exact tests. The negative predictive value (NPV) of the ESC 0/1 rule-out zone for 30-day CDMI was calculated and compared between subgroups using Fisher's exact tests. Of the 1422 patients enrolled, 54.2% (770/1422) were male and 58.1% (826/1422) white with a mean age of 57.6 ± 12.8 years. At 30 days, cardiac death or myocardial infarction (MI) occurred in 12.9% (183/1422) of participants. Among patients stratified to the rule-out zone, 30-day cardiac death or MI occurred in 1.1% (5/436) of women versus 2.1% (8/436) of men (p = .40) and 1.2% (4/331) of non-white patients versus 1.8% (9/490) of white patients (p = .58). The NPV for 30-day cardiac death or MI was similar among women versus men (98.9% [95% confidence interval, CI: 97.3-99.6] vs. 97.9% [95% CI: 95.9-99.1]; p = .40) and among white versus non-white patients (98.8% [95% CI: 96.9-99.7] vs. 98.2% [95% CI: 96.5-99.2]; p = .39). NPVs <99% in each subgroup suggest the hs-cTnT ESC 0/1-h algorithm may not be safe for use in US EDs. Trial Registration: High-Sensitivity Cardiac Troponin T to Optimize Chest Pain Risk Stratification (STOP-CP; ClinicalTrials.gov: NCT02984436; https://clinicaltrials.gov/ct2/show/NCT02984436).

Rural and socioeconomic differences in the effectiveness of the HEART Pathway accelerated diagnostic protocol

BACKGROUND

The HEART Pathway is a validated accelerated diagnostic protocol (ADP) for patients with possible acute coronary syndrome (ACS). This study aimed to compare the safety and effectiveness of the HEART Pathway based on patient rurality (rural vs. urban) or socioeconomic status (SES).

METHODS

We performed a preplanned subgroup analysis of the HEART Pathway Implementation Study. The primary outcomes were death or myocardial infarction (MI) and hospitalization at 30 days. Proportions were compared by SES and rurality with Fisher's exact tests. Logistic regression evaluated for interactions of ADP implementation with SES or rurality and changes in outcomes within subgroups.

RESULTS

Among 7245 patients with rurality and SES data, 39.9% (2887/7245) were rural and 22.2% were low SES (1607/7245). The HEART Pathway identified patients as low risk in 32.2% (818/2540) of urban versus 28.1% (425/1512) of rural patients (p = 0.007) and 34.0% (311/915) of low SES versus 29.7% (932/3137) high SES patients (p = 0.02). Among low-risk patients, 30-day death or MI occurred in 0.6% (5/818) of urban versus 0.2% (1/425) rural (p = 0.67) and 0.6% (2/311) with low SES versus 0.4% (4/932) high SES (p = 0.64). Following implementation, 30-day hospitalization was reduced by 7.7% in urban patients (adjusted odds ratio [aOR] 0.76, 95% confidence interval [CI] 0.66-0.87), 10.6% in low SES patients (aOR 0.68, 95% CI 0.54-0.86), and 4.5% in high SES patients (aOR 0.83, 95% CI 0.73-0.94). However, rural patients had a nonsignificant 3.3% reduction in hospitalizations.

CONCLUSIONS

HEART Pathway implementation decreased 30-day hospitalizations regardless of SES and for urban patients but not rural patients. The 30-day death or MI rate was similar among low-risk patients.

Derivation and validation of a high sensitivity troponin-T HEART pathway

BACKGROUND

The HEART Pathway is widely used for chest pain risk stratification but has yet to be optimized for high sensitivity troponin T (hs-cTnT) assays.

METHODS

We conducted a secondary analysis of STOP-CP, a prospective cohort study enrolling adult ED patients with symptoms suggestive of acute coronary syndrome at 8 sites in the United States (US). Patients had a 0- and 1-hour hs-cTnT measured and a HEAR score completed. A derivation set consisting of 729 randomly selected participants was used to derive a hs-cTnT HEART Pathway with rule-out, observation, and rule-in groups for 30-day cardiac death or myocardial infarction (MI). Optimal baseline and 1-hour troponin cutoffs were selected using generalized cross validation to achieve a negative predictive value (NPV) >99% for rule out and positive predictive value (PPV) >60% or maximum Youden index for rule-in. Optimal 0-1-hour delta values were derived using generalized cross validation to maximize the NPV for the rule-out group and PPV for the rule-in group. The hs-cTnT HEART Pathway performance was validated in the remaining cohort (n = 723).

RESULTS

Among the 1452 patients, 30-day cardiac death or MI occurred in 12.7% (184/1452). Within the derivation cohort the optimal hs-cTnT HEART Pathway classified 36.5% (266/729) into the rule-out group, yielding a NPV of 99.2% (95% CI: 98.2-100) for 30-day cardiac death or MI. The rule-in group included 15.4% (112/729) with a PPV of 55.4% (95% CI: 46.2-64.6). In the validation cohort, the hs-cTnT HEART Pathway ruled-out 37.6% (272/723), of which 2 had 30-day cardiac death or MI, yielding a NPV of 99.3% (95% CI: 98.3-100). The rule-in group included 14.5% (105/723), yielding a PPV of 57.1% (95% CI: 47.7-66.6).

CONCLUSIONS

A novel hs-cTnT HEART Pathway with serial 0- and 1-hour hs-cTnT measures has high NPV and moderate PPV for 30-day cardiac death or MI.

Prehospital Comparison of the HEAR and HE-MACS Scores for 30-Day Adverse Cardiac Events

OBJECTIVE

The History, Electrocardiogram (ECG), Age, and Risk factor (HEAR) and History and ECG-only Manchester Acute Coronary Syndromes (HE-MACS) risk scores can risk stratify chest pain patients without troponin measures. The objective of this study was to determine if either risk score could achieve the ≥99% negative predictive value (NPV) required to rule out major adverse cardiovascular events (MACE; a composite of all-cause death, myocardial infarction, or coronary revascularization) at 30 days or the ≥50% positive predictive value (PPV) indicative of a patient possibly needing interventional cardiology.

METHODS

We performed a pre-planned secondary analysis of the prospective multisite PARAHEART (n = 462, 12/2016-1/2018) and RESCUE (n = 767, 4/2018-1/2019) trials, which accrued adults ≥21 years old with acute non-traumatic chest pain transported by emergency medical services (EMS). Paramedics prospectively completed risk assessment forms. Very low risk was defined by a HEAR score of 0-1 or HE-MACS probability <4%. The primary outcome was 30-day MACE, which was determined by adjudication (PARAHEART) or electronic record review (RESCUE). NPV and PPV with exact 95% confidence intervals (95%CI) for 30-day MACE were calculated for each risk score and compared using McNemar's tests.

RESULTS

Among the PARAHEART and RESCUE cohorts, 30-day MACE occurred in 18.8% (87/462) and 6.9% (53/767) of patients, respectively. In PARAHEART, 7.8% (36/462) were very low risk by HEAR score vs. 7.8% (36/462) by HE-MACS (p = 1.0). The HEAR score had a NPV of 97.2% (95%CI 91.9-100.0) vs. 91.7% (95%CI 82.6-100.0) for HE-MACS (p = 0.15). The HEAR and HE-MACS PPVs were similar [46.4% (95%CI 28.0-64.9) vs. 33.3% (95%CI 13.2-53.5) (p = 0.26)]. In RESCUE, the HEAR score identified 14.2% (109/767) as low risk compared to 8.3% (64/767) by HE-MACS (p < 0.001). In this cohort, the HEAR and HE-MACS scores had similar NPVs [98.2% (95%CI 95.7-100.0) vs. 98.4% (95%CI 95.4-100.0) (p = 0.89)] and PPVs [16.2% (95%CI 6.2-32.0) vs. 22.6% (95%CI 12.3-36.2) (p = 0.41)].

CONCLUSIONS

In two prehospital chest pain cohorts, neither the HEAR score nor HE-MACS achieved sufficient NPV or PPV to rule out or rule in 30-day MACE.

Age and the European Society of Cardiology 0/1-hour high sensitivity troponin T algorithm for the evaluation of patients with possible acute myocardial infarction: results from the STOP-CP study

Background

The European Society of Cardiology (ESC) 0/1-hour high sensitivity troponin (hs-cTn) algorithm is widely used in the evaluation of patients presenting to the Emergency Department (ED) with symptoms suspicious for non ST-segment elevation myocardial infarction (NSTEMI). The effect of increasing patient age with its use has not been studied in any detail.

Purpose

The objective of this secondary analysis of the STOP-CP (High Sensitivity Cardiac Troponin T to Optimize Chest Pain Risk Stratification) United States (US) multicenter study was to evaluate the efficacy and safety of use of the ESC 0/1-hour hs-cTnT algorithm in younger, middle-aged, and older patients.

Methods

Patients (≥21 years old) presenting to the (ED) with symptoms suggestive of NSTEMI were enrolled (1/25/2017–9/6/2018) at 8 US medical centers. The ESC hs-cTnT 0/1-hour hs-cTnT algorithm was used to place patients into rule-out, observe, and rule-in NSTEMI zones. Algorithm performance for rapid NSTEMI rule-out and 30-day adverse outcomes was studied in 3 patient age (years) intervals: younger (21–45). middle aged (46–64) and older (≥65). Major adverse cardiovascular events (MACE) consisted of cardiac death, myocardial infarction, or coronary revascularization at 30-days. Fisher's exact tests were used to compare NSTEMI ruled out and MACE rates between patient age intervals. Negative likelihood ratios (NLR) with 95% confidence interval (CI) were calculated for 30-day MACE.

Results

Overall 1430 participants were enrolled with 15.7% (224/1430) young, 57.4% (821/1430) middle-aged, and 26.9% (385/1430) being older. The ESC 0/1 hour hs-cTnT algorithm NSTEMI rule-out rates were 79.9% (179/224), 62.1% (510/821) and 35.6% (137/385) respectively for these age groups (p&lt;0.0001). The overall 30-day MACE rate was 14.2% (203/1430) with interval age rates of 7.1% (16/224) in younger, 13.1% (108/821) middle aged and 20.5% (79/385) older patients. Amongst NSTEMI ruled-out patients MACE occurred in 1.1% (2/179) of younger, 3.3% (17/510) middle aged and 2.9% (4/137) older individuals (p=0.320). NLR for 30-day MACE was 0.15 (95% CI 0.04, −0.54) in younger, 0.23 (95% CI 0.15–0.35) middle aged and 0.12 (95% CI 0.04–0.31) for older patients.

Conclusions

With increasing age ED patients were less often rapidly ruled out for NSTEMI during their initial cardiac evaluations. The STOP-CP US study demonstrated that older age interval alone was not an independent variable that increased the risk for 30-day MACE in patients ruled out for NSTEMI using the ESC 0/1 hour hs-cTnT algorithm. Our report suggests that cardiac risk stratification scores using age as an independent variable for predicting 30-day MACE in these patients require reevaluation.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): Roche, Basel, Switzerland

Patients with known coronary artery disease who are ruled out for acute myocardial infarction using a high sensitivity troponin T 0/1-hour algorithm have increased 30-day major adverse cardiac events

Background

The European Society of Cardiology (ESC) 0/1-hour high sensitivity troponin (hs-cTn) algorithm is widely used in the evaluation of patients presenting to the Emergency Department (ED) with symptoms suspicious for non ST-segment elevation myocardial infarction (NSTEMI). There is limited data available for the use of this algorithm comparing NSTEMI rule-out rates and 30-day adverse outcomes in patients with and without known coronary artery disease (CA), defined as prior myocardial infarction [MI], coronary revascularization, or ≥70% coronary stenosis.

Purpose

The objective of this secondary analysis of the STOP-CP (High Sensitivity Cardiac Troponin T to Optimize Chest Pain Risk Stratification) United States (US) multicenter study was to compare the ESC 0/1-hour algorithm for rapid NSTEMI rule-out and 30-day adverse outcomes in patients with and without known CAD.

Methods

Patients (≥21 years old) presenting to the (ED) with symptoms suggestive of NSTEMI were enrolled (1/25/2017–9/6/2018) at 8 US medical centers. The ESC hs-cTnT 0/1-hour hs-cTnT algorithm was used to stratify patients into rule-out, observe, and rule-in zones. Algorithm performance for 30-day adverse outcomes was analyzed in patients with or without known CAD. Major adverse cardiovascular events (MACE) consisted of cardiac death, MI, or coronary revascularization. Fisher's exact tests were used to compare NSTEMI rule-out and 30-day MACE rates in patients with and without known CAD. Negative likelihood ratios (NLR) with a 95% confidence interval (CI) were calculated for 30-day MACE.

Results

Overall 1430 patients were enrolled. Of these 31.4% (449/1430) had known CAD while 14.2% (203 /1430) experienced 30-day MACE. Using the ESC 0/1-hour hs-cTnT algorithm 39.6% (178/449) of patients with known CAD were placed in the rule-out zone compared to 66.1% (648/981) without CAD (p&lt;0.0001). Of patients with known CAD 23.2% (104/449) had 30-day MACE compared to 10.1% (99/981) of those without known CAD (p&lt;0.0001). Additionally, amongst those patients placed in the rule-out zone, 30-day MACE occurred in 7.9% (14/178) of individuals with known CAD and 1.4% (9/648) of those without known CAD (p&lt;0.0001). NLR for 30-day MACE was 0.28 (95% CI 0.17–0.47) in patients with known CAD and 0.13 (95% CI 0.07–0.23) in those without CAD.

Conclusions

In the multicenter US STOP-CP study patients with known CAD were less often rapidly ruled out for NSTEMI and had higher 30-day MACE rates than those without known CAD. Patients with known CAD who were rapidly ruled out for NSTEMI had a higher 30-day MACE rate compared to those without known CAD. Our analysis suggests that patients with known CAD require further cardiac reevaluations whether they are ruled out for NSTEMI by the ESC 0/1 hour hs-cTnT algorithm or not.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): Roche, Basel, Switzerland

Age differences in the safety and effectiveness of the HEART Pathway accelerated diagnostic protocol for acute chest pain

BACKGROUND

The HEART Pathway is a validated protocol for risk stratifying emergency department (ED) patients with possible acute coronary syndrome (ACS). Its performance in different age groups is unknown. The objective of this study is to evaluate its safety and effectiveness among older adults.

METHODS

A pre-planned subgroup analysis of the HEART Pathway implementation study was conducted. This prospective interrupted time series accrued adult ED patients with possible ACS who were without ST-elevation across three US sites from 11/2013-01/2016. After implementation, providers prospectively used the HEART Pathway to stratify patients as low-risk or non-low-risk. Patients were classified as older adults (≥65 years), middle-aged (46-64 years), and young (21-45 years). Primary safety and effectiveness outcomes were 30-day death or MI and hospitalization at 30 days, determined from health records, insurance claims, and death index data. Fisher's exact test compared low-risk proportions between groups. Sensitivity for 30-day death or MI and adjusted odds ratios (aORs) for hospitalization and objective cardiac testing were calculated.

RESULTS

The HEART Pathway implementation study accrued 8474 patients, of which 26.9% (2281/8474) were older adults, 45.5% (3862/8474) middle-aged, and 27.5% (2331/8474) were young. The HEART Pathway identified 7.4% (97/1303) of older adults, 32.0% (683/2131) of middle-aged, and 51.4% (681/1326) of young patients as low-risk (p < 0.001). The HEART Pathway was 98.8% (95% CI 97.1-100) sensitive for 30-day death or MI among older adults. Following implementation, the rate of 30-day hospitalization was similar among older adults (aOR 1.25, 95% CI 1.00-1.55) and cardiac testing increased (aOR 1.25, 95% CI 1.04-1.51).

CONCLUSION

The HEART Pathway identified fewer older adults as low-risk and did not decrease hospitalizations in this age group.

Major adverse cardiac event rates in moderate-risk patients: Does prior coronary disease matter?

BACKGROUND

Despite negative troponins and nonischemic electrocardiograms (ECGs), patients at moderate risk for acute coronary syndrome (ACS) are frequently admitted. The objective of this study was to describe the major adverse cardiac event (MACE) rate in moderate-risk patients and how it differs based on history of coronary artery disease (CAD).

METHODS

A secondary analysis of the HEART Pathway implementation study was conducted. This prospective interrupted time-series study accrued adults with possible ACS from three sites (November 2013-January 2016). This analysis excluded low-risk patients determined by emergency providers' HEART Pathway assessments. Non-low-risk patients were further classified as high risk, based on elevated troponin measures or ischemic ECG findings or as moderate risk, based on HEAR score ≥ 4, negative troponin measures, and a nonischemic ECG. Moderate-risk patients were then stratified by the presence or absence of prior CAD (MI, revascularization, or ≥70% coronary stenosis). MACE (death, myocardial infarction, or revascularization) at 30 days was determined from health records, insurance claims, and death index data. MACE rates were compared among groups using a chi-square test and likelihood ratios (LRs) were calculated.

RESULTS

Among 4,550 patients with HEART Pathway assessments, 24.8% (1,130/4,550) were high risk and 37.7% (1715/4550) were moderate risk. MACE at 30 days occurred in 3.1% (53/1,715; 95% confidence interval [CI] = 2.3% to 4.0%) of moderate-risk patients. Among moderate-risk patients, MACE occurred in 7.1% (36/508, 95% CI = 5.1% to 9.8%) of patients with known CAD versus 1.4% (17/1,207, 95% CI = 0.9% to 2.3%) in patients without known prior CAD (p < 0.0001). The negative LR for 30-day MACE among moderate-risk patients without prior CAD was 0.08 (95% CI = 0.05 to 0.12).

CONCLUSION

MACE rates at 30 days were low among moderate-risk patients but were significantly higher among those with prior CAD.

The influence of patient size on the overall uncertainty in radiographic dose audit

The aim of this work was to investigate the effect of patient and cohort size on the overall uncertainty associated with dose audit using radiography of the abdomen as the exemplar. Water equivalent diameterDwwas used as the surrogate for patient size and its distribution (σ(Dw)) was used to quantify the effect of sample size. The more precise the kerma area product calibration, the more patients are required in the cohort to have the same impact on the overall uncertainty. Patient sample sizes of 300-400 will result in expanded uncertainties approaching the theoretical limit of double the measurement uncertainty when audits are performed with instruments having measurement uncertainties equal to ±7%, ±10% or ±12.5%. By way of example, for a field instrument with a measurement uncertainty of ±10%, a minimum sample size of 350 is required to achieve a total expanded uncertainty of ±21%. In the case of instruments with associated measurement uncertainty of ±3.5%, patient sample sizes of 300-400 will result in expanded uncertainties of approximately ±10%. From review of the literature and comparison with the results obtained here, it is conjectured that for radiographic dose audits of all parts of the trunk the contribution to overall uncertainty due to patient and sample size could be predicted using an indicative value forσ(Dw) of 3.4 where local data is not available.

A Modified Delphi Study for Development of a Pediatric Curriculum for Emergency Medicine Residents

OBJECTIVES

Emergency medicine (EM) trainees are expected to learn to provide acute care for patients of all ages. The American Council for Graduate Medical Education provides some guidance on topics related to caring for pediatric patients; however, education about pediatric topics varies across residency programs. The goal of this project was to develop a consensus curriculum for teaching pediatric emergency care.

METHODS

We recruited 13 physicians from six academic health centers to participate in a three-round electronic modified Delphi project. Participants were selected on the basis of expertise with both EM resident education and pediatric emergency care. The first modified Delphi survey asked participants to generate the core knowledge, skills, and experiences needed to prepare EM residents to effectively treat children in an acute care setting. The qualitative data from the first round was reformulated into a second-round questionnaire. During the second round, participants used rating scales to prioritize the curriculum content proposed during the first round. In round 3, participants were asked to make a determination about each curriculum topic using a three-point scale labeled required, optional, or not needed.

RESULTS

The first modified Delphi round yielded 400 knowledge topics, 206 clinical skills, and 44 specific types of experience residents need to prepare for acute pediatric patient care. These were narrowed to 153 topics, 84 skills, and 28 experiences through elimination of redundancy and two rounds of prioritization. The final lists contain topics classified by highly recommended, partially recommended, and not recommended. The partially recommended category is intended to help programs tailor their curriculum to the unique needs of their learners as well as account for variability between 3- and 4-year programs and the amount of time programs allocate to pediatric education.

CONCLUSION

The modified Delphi process yielded the broad outline of a consensus core pediatric emergency care curriculum.

Combined Versus Detailed Evaluation Components in Medical Student Global Rating Indexes

Introduction

To determine if there is any correlation between any of the 10 individual components of a global rating index on an emergency medicine (EM) student clerkship evaluation form. If there is correlation, to determine if a weighted average of highly correlated components loses predictive value for the final clerkship grade.

Methods

This study reviewed medical student evaluations collected over two years of a required fourth-year rotation in EM. Evaluation cards, comprised of a detailed 10-part evaluation, were completed after each shift. We used a correlation matrix between evaluation category average scores, using Spearman’s rho, to determine if there was any correlation of the grades between any of the 10 items on the evaluation form.

Results

A total of 233 students completed the rotation over the two-year period of the study. There were strong correlations (>0.80) between assessment components of medical knowledge, history taking, physical exam, and differential diagnosis. There were also strong correlations between assessment components of team rapport, patient rapport, and motivation. When these highly correlated were combined to produce a four-component model, linear regression demonstrated similar predictive power in terms of final clerkship grade (R²=0.71, CI₉₅=0.65–0.77 and R²=0.69, CI₉₅=0.63–0.76 for the full and reduced models respectively).

Conclusion

This study revealed that several components of the evaluation card had a high degree of correlation. Combining the correlated items, a reduced model containing four items (clinical skills, interpersonal skills, procedural skills, and documentation) was as predictive of the student’s clinical grade as the full 10-item evaluation. Clerkship directors should be aware of the performance of their individual global rating scales when assessing medical student performance, especially if attempting to measure greater than four components.

Preclinical development of AMG 139, a human antibody specifically targeting IL-23

BACKGROUND AND PURPOSE

AMG 139 is a human anti-IL-23 antibody currently in a phase II trial for treating Crohn's disease. To support its clinical development in humans, in vitro assays and in vivo studies were conducted in cynomolgus monkeys to determine the pharmacology, preclinical characteristics and safety of this monoclonal antibody.

EXPERIMENTAL APPROACH

The in vitro pharmacology, pharmacokinetics (PK), pharmacodynamics and toxicology of AMG 139, after single or weekly i.v. or s.c. administration for up to 26 weeks, were evaluated in cynomolgus monkeys.

KEY RESULTS

AMG 139 bound with high affinity to both human and cynomolgus monkey IL-23 and specifically neutralized the biological activity of IL-23 without binding or blocking IL-12. After a single dose, linear PK with s.c. bioavailability of 81% and mean half-life of 8.4-13 days were observed. After weekly s.c. dosing for 3 or 6 months, AMG 139 exposure increased approximately dose-proportionally from 30 to 300 mg·kg(-1) and mean accumulation between the first and last dose ranged from 2- to 3.5-fold. Peripheral blood immunophenotyping, T-cell-dependent antigen responses and bone formation markers were not different between AMG 139 and vehicle treatment. No adverse clinical signs, effects on body weight, vital signs, ophthalmic parameters, clinical pathology, ECG, organ weights or histopathology were observed in the monkeys with the highest dose of AMG 139 tested (300 mg·kg(-1) s.c. or i.v.).

CONCLUSIONS AND IMPLICATIONS

The in vitro pharmacology, PK, immunogenicity and safety characteristics of AMG 139 in cynomolgus monkeys support its continued clinical development for the treatment of various inflammatory diseases.

Vitamin D deficiency in children with fractures

OBJECTIVE

This study aimed to determine whether healthy children with fractures resulting from minor accidental trauma have a higher prevalence of vitamin D deficiency than that of healthy children without fractures.

METHODS

This was a prospective case-control study of ambulatory children younger than 18 years with and without fractures in a pediatric emergency department. Evaluation included serum 25-hydroxyvitamin D (25(OH)D) level, complete metabolic panel, and phosphorus level. Vitamin D deficiency was defined as a 25(OH)D level of less than 20 ng/mL and insufficiency less than 30 ng/mL but 20 ng/mL or greater. A level of 30 ng/mL or greater was considered sufficient. Fisher exact test was used to test for association between 25(OH)D level and fracture status. Logistic regression was used to examine the relationship between 25(OH)D levels and the odds of fracture, conditioned on season, age, race, body weight percentile, history of fracture, multivitamin use, and estimated daily milk intake.

RESULTS

The sample included 100 case and 100 control patients. There was no statistical difference in median 25(OH)D levels between fracture and control groups (26.7 vs 25.45 ng/mL, P = 0.84). There was no difference in the proportion of patients with sufficient 25(OH)D levels or in the distribution of sufficient, insufficient, and deficient. After adjusting for male sex and season of enrollment, vitamin D sufficiency was not a significant predictor of fracture status in a multiple variable logistic model (odds ratio, 0.94; 95% confidence interval, 0.51-1.77; Wald P = 0.859).

CONCLUSIONS

We found no relationship between vitamin D deficiency and fracture risk in our study population.

An unusual case of cerebral venous sinus thrombosis in a pediatric patient

BACKGROUND

Cerebral venous sinus thrombosis (CVST) is a rare, but potentially devastating illness. It is important for emergency physicians to be aware of the classic and most common risk factors leading to this illness, including genetic and acquired prothrombotic states, infection, inflammatory conditions, and certain drugs.

OBJECTIVES

The objectives of this article are to discuss a case of CVST and describe the signs and symptoms of CVST as well as the radiologic modalities used to diagnose this disease. Finally, we will discuss the causes and risk factors that lead to this potentially devastating diagnosis.

CASE REPORT

An 11-year-old girl was found unconscious and without pulses in an apparent drug overdose. Emergency Medical Services responders and Emergency Department personnel resuscitated the patient to a return of spontaneous circulation. The patient was intubated and admitted to the intensive care unit. As part of an altered mental status work-up, a magnetic resonance imaging scan of the head was performed and showed a cerebral venous sinus thrombosis. This was thought to be due to the drug overdose and the low-flow state that occurred during loss of circulation. After anticoagulation therapy and antibiotic treatment for sinusitis, the patient had a full recovery.

CONCLUSION

Rapid diagnosis of CVST was essential to the appropriate care of this patient. Being aware of signs, symptoms, and risk factors leading to CVST will assist the emergency physician in making this diagnosis.

Lemierre syndrome

Lemierre syndrome is a disease that presents with oropharyngeal infection, sepsis, internal jugular vein thrombosis, and septic emboli with the Gram-negative organism Fusobacterium necrophorum cultured as the etiologic agent. Clindamycin, metronidazole and ampicillin-sulbactam are effective antibiotic treatments, although the length of treatment has not been firmly established. The syndrome is seen less frequently in the current age of antibiotics. It is important, however, that physicians be aware of the syndrome as initiation of prompt antibiotic therapy, including anaerobic coverage, is essential for avoiding morbidity and mortality. We describe a case of Lemierre syndrome.

Multistate equilibrium unfolding of Escherichia coli dihydrofolate reductase: thermodynamic and spectroscopic description of the native, intermediate, and unfolded ensembles

The thermodynamic and spectroscopic properties of a cysteine-free variant of Escherichia coli dihydrofolate reductase (AS-DHFR) were investigated using the combined effects of urea and temperature as denaturing agents. Circular dichroism (CD), absorption, and fluorescence spectra were recorded during temperature-induced unfolding at different urea concentrations and during urea-induced unfolding at different temperatures. The first three vectors obtained by singular-value decomposition of each set of unfolding spectra were incorporated into a global analysis of a unique thermodynamic model. Although individual unfolding profiles can be described as a two-state process, a simultaneous fit of 99 vectors requires a three-state model as the minimal scheme to describe the unfolding reaction along both perturbation axes. The model, which involves native (N), intermediate (I), and unfolded (U) states, predicts a maximum apparent stability, DeltaG degrees (NU), of 6 kcal mol(-)(1) at 15 degrees C, an apparent m(NU) value of 2 kcal mol(-)(1) M(-)(1), and an apparent heat capacity change, DeltaC(p)()(-NU), of 2.5 kcal mol(-)(1) K(-)(1). The intermediate species has a maximum stability of approximately 2 kcal mol(-)(1) and a compactness closer to that of the native than to that of the unfolded state. The population of the intermediate is maximal ( approximately 70%) around 50 degrees C and falls below the limits of detection of > or =2 M urea or at temperatures of <35 or >65 degrees C. The fluorescence properties of the equilibrium intermediate resemble those of a transient intermediate detected during refolding from the urea-denatured state, suggesting that a tryptophan-containing hydrophobic cluster in the adenosine-binding domain plays a key role in both the equilibrium and kinetic reactions. The CD spectroscopic properties of the native state reveal the presence of two principal isoforms that differ in ligand binding affinities and in the packing of the adenosine-binding domain. The relative populations of these species change slightly with temperature and do not depend on the urea concentration, implying that the two native isoforms are well-structured and compact. Global analysis of data from multiple spectroscopic probes and several methods of unfolding is a powerful tool for revealing structural and thermodynamic properties of partially and fully folded forms of DHFR.

An essential intermediate in the folding of dihydrofolate reductase

The folding of Escherichia coli dihydrofolate reductase was examined at pH 7.8 and 15 degrees C by using stopped-flow fluorescence and absorbance spectroscopies. The formation of a highly fluorescent intermediate occurs with relaxation times ranging between 142 and 343 msec, whereas stopped-flow absorbance spectroscopy using methotrexate binding assays shows a distinct lag phase during these time frames for the native state. The lag in absorbance kinetics and the lack of fast-track folding events indicate that the formation of this ensemble of intermediates is an obligatory step in the folding reaction.

Localized, stereochemically sensitive hydrophobic packing in an early folding intermediate of dihydrofolate reductase from Escherichia coli

Mutational analysis was performed to probe the development of hydrophobic clusters during the early events in the folding of dihydrofolate reductase. Replacements were made in several hydrophobic subdomains to examine the roles of hydrophobicity and stereochemistry in the formation of kinetic intermediates. Amide protons in two of these clusters, including residues I91, I94, and I155, have been shown to be protected against solvent exchange within 13 ms of folding. Additional hydrophobic clusters were probed by substitutions at residues I2, I61, and L112; these residues are not protected from exchange until later in the folding reaction. Valine and leucine replacements at positions I91, I94, and I155 significantly diminish the formation of the burst phase kinetic intermediate, relative to the wild-type protein. In contrast, I2 and I61 are insensitive to these substitutions in the first 5 ms of the folding reaction, as is the replacement of L112 with either isoleucine or valine. These results demonstrate that the tightly packed core of dihydrofolate reductase is acquired in a non-uniform fashion, beginning in the submillisecond time frame. The progressive development of specific side-chain packing in localized hydrophobic clusters may be a common theme for complex protein folding reactions.

A comparison of the antibacterial action of five udder washes

Five commercially available udder washes were tested for antibacterial action. Four contained iodine and one chlorhexidine. Each product was used exclusively for 10 days and its bactericidal action compared with that of water. Bactericidal activity was demonstrated in all five washes but the chlorine based product performed better than the iodine washes. However, the results suggested that the skin of cows' teats can be cleansed with water as effectively as with an added product.