Kathryn A. Volz

Prevalence of Bicycle Helmet Use by Users of Public Bikeshare Programs

STUDY OBJECTIVE Public bikeshare programs are becoming increasingly common in the United States and around the world. These programs make bicycles accessible for hourly rental to the general public. We seek to describe the prevalence of helmet use among adult users of bikeshare programs and users of personal bicycles in 2 cities with recently introduced bikeshare programs (Boston, MA, and Washington, DC). METHODS We performed a prospective observational study of adult bicyclists in Boston, MA, and Washington, DC. Trained observers collected data during various times of the day and days of the week. Observers recorded the sex of the bicycle operator, type of bicycle, and helmet use. All bicycles that passed a single stationary location in any direction for a period of between 30 and 90 minutes were recorded. RESULTS There were 43 observation periods in 2 cities at 36 locations; 3,073 bicyclists were observed. There were 562 (18.3%; 95% confidence interval [CI] 16.4% to 20.3%) bicyclists riding shared bicycles. Overall, 54.5% of riders were unhelmeted (95% CI 52.7% to 56.3%), although helmet use varied significantly with sex, day of use, and type of bicycle. Bikeshare users were unhelmeted at a higher rate compared with users of personal bicycles (80.8% versus 48.6%; 95% CI 77.3% to 83.8% versus 46.7% to 50.6%). Logistic regression, controlling for type of bicycle, sex, day of week, and city, demonstrated that bikeshare users had higher odds of riding unhelmeted (odds ratio [OR] 4.4; 95% CI 3.5 to 5.5). Men had higher odds of riding unhelmeted (OR 1.6; 95% CI 1.4 to 1.9), as did weekend riders (OR 1.3; 95% CI 1.1 to 1.6). CONCLUSION Use of bicycle helmets by users of public bikeshare programs is low. As these programs become more popular and prevalent, efforts to increase helmet use among users should increase.

Creatine kinase-MB does not add additional benefit to a negative troponin in the evaluation of chest pain☆

OBJECTIVE The aim of this study was to determine whether current troponin assay alone can be used for initial screening for acute myocardial infarction (AMI) and whether creatine kinase-MB (CK-MB) can safely be eliminated from this evaluation in the emergency department (ED). METHODS A retrospective cohort study of patients who had cardiac troponin T (Roche, Basel, Switzerland) and CK-MB ordered at an urban academic level 1 trauma center with more than 55,000 annual visits. Patients with troponin testing in the ED were identified over a period of 12 months, and corresponding CK-MB indexes were examined identifying patients with negative troponins (<0.01) and positive CK-MB indexes (>6.0). In these patients, further cardiac markers, hospital course, and 30-day mortality were then evaluated. A 99% confidence interval around point estimate was used in data analysis. RESULTS During the study period, there were 11,092 separate ED patient encounters where a patient had at least one troponin resulted. Most (97.9%) of the samples had an associated CK-MB ordered. There were 7545 initial negative troponins representing 68% of all initial samples. Seven of these had an associated positive MB index. When subsequent troponins were evaluated, an additional 4910 negative troponins were identified, with 4 patients having a positive MB. None of these 11 patients were judged to have ruled in for AMI by the treating physicians. The rate of true-positive CK-MB index with negative troponin was 0% (99% confidence interval, 0-0.04%). CONCLUSION Our results suggest that CK-MB is not necessary in the initial screening for AMI and may safely be omitted in patients with negative troponins.

Should creatine kinase-MB index be eliminated in patients with indeterminate troponins in the ED?

OBJECTIVES The objective of this study is to determine whether creatine kinase-MB (CK-MB) index (CK-MBi) is useful in the evaluation of acute myocardial infarction (AMI) in patients with indeterminate troponin (Tn) in the emergency department (ED). METHODS A retrospective cohort study was conducted of patients at an urban academic ED with over 55 000 annual visits who underwent Tn T (Roche, Indianapolis, IN) and CK-MB testing. One year of ED patients who had Tn testing were identified, and their corresponding CK-MBi was examined to find patients with indeterminate Tn (0.01-0.09) and positive CK-MBi (>6.0). Subsequent cardiac enzymes and hospital course were reviewed to identify patients diagnosed with AMI. A 95% confidence interval around point estimates were used in data analysis. RESULTS Over 1 year, 11 718 initial Tn were identified. Indeterminate Tn was seen in 2512 cases. Of these, 28 had positive CK-MBi. Of the 28, 5 were judged by treating physicians to be having AMI and underwent cardiac catheterization. Of the 5 patients, 4 had subsequent positive Tns on serial enzyme testing. One of the patients thought to be having AMI had no coronary artery disease on catheterization. The rate of true positive CK-MBi with indeterminate Tn was 0.16% (95% confidence interval, 0.04%-0.41%). CONCLUSION Initial results identify rare cases of AMI where CK-MBi is positive in the setting of indeterminate Tn. However, most patients with indeterminate Tn and positive CK-MBi were not judged to be having AMI. In most cases, CK-MBi is not positive with indeterminate Tn and when positive more commonly confuses the picture. This suggests CK-MBi could be eliminated in patients with indeterminate Tns.

Waiting for Triage: Unmeasured Time in Patient Flow

Introduction The Centers for Medicare and Medicaid Services (CMS) requires reporting of multiple time-sensitive metrics. Most facilities use triage time as the time of arrival. Little is known about how long patients wait prior to triage. As reimbursement to the hospital may be tied to these metrics, it is essential to accurately record the time of arrival. Our objective was to quantify the time spent waiting to be triaged for patients arriving to the emergency department (ED). Methods We conducted this study in an urban, academic, tertiary care center with approximately 54,000 annual ED visits. All patients arriving to the ED from November 1, 2012, to October 1, 2013, were enrolled. If patients didn’t go directly to a bed or triage, an observer greeted patients as they entered the ED and recorded the time of arrival. The triage time was recorded as normal. We calculated the difference between the arrival time and triage time. Results There were 50,576 patient visits during the study period. Of these, 7,795 (15.4%) patients did not go directly to a bed or triage. For patients who waited for triage, median time from arrival to triage was 11 minutes (IQR 5–19, range 1–105). When stratified by the number of new patients who arrived in the ED in the previous hour, the percentage of greeted patients who waited more than 10 minutes for triage was: 0–5 new patients − 12.4%; 6–10 new patients − 48.8%; 11–15 new patients − 64.4%; 16+ new patients − 68%. Conclusion Patients often waited more than 10 minutes to be triaged. As the number of patients registered in the previous hour increased, the percentage of patients who waited more than 10 minutes for triage increased significantly. During times of peak volume, 8.5% of all patients arriving to the ED waited more than 10 minutes for triage. This wait is not accounted for in the normal reporting of ED throughput times and metrics.

Effect of Two Different FDA-approved D-dimer Assays on Resource Utilization in the Emergency Department

BACKGROUND The D-dimer assay has been shown to be an appropriate test to rule out pulmonary embolism (PE) in low-risk patients in the emergency department (ED). Multiple assays now are approved to measure D-dimer levels. Studies have shown a newer assay, Tina-quant, to have similar diagnostic accuracy to the VIDAS assay. OBJECTIVES The objective was to determine effects of transitioning from the VIDAS assay to the Tina-quant D-dimer assay on the need for computed tomography angiogram (CTA) and ED length of stay (LOS) in patients being evaluated for PE in the ED. METHODS A retrospective cohort study was conducted of patients who had D-dimer levels ordered at an urban, academic, Level I trauma center with over 55,000 annual ED visits. The results of D-dimer levels in the ED were recorded over a period of 6 months prior to and 6 months after the transition to the new D-dimer assay. The numbers of positive and negative D-dimers and need for subsequent CTAs were recorded for comparison. LOS was also recorded to determine time saved. Medians were calculated and compared using Wilcoxon rank sum. RESULTS During the initial period, 875 D-dimers were ordered, with a positive rate of 41.5%. During the period after the introduction of the Tina-quant assay, 859 tests were ordered, with 25.5% having positive results. An absolute decrease of 16% in the number of necessary CTAs (p < 0.003) was seen after the transition to the Tina-quant assay. LOS data showed a mean LOS of 481 minutes in the ED for patients who underwent testing with the Tina-quant assay compared to 526 minutes with the VIDAS assay, saving an average of 45 minutes per patient (p < 0.003). The positive rate on performed imaging studies for D-dimer of > 500 rose from 13 of 308 (4.2%) to 17 of 187 (9.1%). CONCLUSIONS Switching D-dimer assays reduced both LOS and number of imaging studies in our patient population.

A 67-year-old man with anterior neck swelling.

Dr. Carlo Rosen: The patient was a 67-year-old manwho just got off an airplane from Florida complaining ofanterior neck swelling that developed either late the nightprior or early that morning. He was concerned enough inFlorida that he wanted to come to Boston, where all hisdoctors were, so he obtained a flight to Boston with hiswife. He said over the past few hours, the swelling hadgotten worse, and that he had developed a little bit of ahoarse voice. Initially he got put into one of our resusci-tation rooms, and a quick history revealed that he was oncoumadin for atrial fibrillation. He also denied fevers,denied any history of anything like this happening in thepast, denied rash or any pain or discomfort anywhere else,and was able to give a full history by himself. Other pastmedical history was significant for a previous carotid stentand asthma. He did say he had allergies to shellfish,associated with a rash, and took no other medications butthe coumadin. Are there any questions?Dr. Richard Wolfe: How many hours passed from theonset of his symptoms to the point he presented?Dr. C. Rosen: He was vague about the exact timing. Heprobably had symptoms the night before starting with theswelling, and the voice change happened over the past fewhours.Dr. Wolfe: You saw him roughly at what time?Dr. C. Rosen: Probably early afternoon. He took a taxifrom the airport to the Emergency Department (ED).Dr. C. Rosen: Tomethereweretwoworrisomepartsto the history. One was the swelling which had gone onfor probably 18 h. The second, and more concerning,was the voice change, which hesaidhadoccurredover2–3 h.Dr. Wolfe: I am not clear why he was taking coumadin.There was absolutely no history of any trauma, correct?Dr. C. Rosen: There was no history of trauma. He wason coumadin for atrial fibrillation, and said he had beentaking his usual dose. On physical examination the vitalswere: temperature of 36.5 C (97.7 F,) pulse 117 beats perminute, blood pressure 156/88 torr., respirations 25 breathsper minute, and oxygen saturation 99% on room air. Helooked very comfortable. The only alarming thing aboutthe examination was he had a slightly hoarse voice. I thinkwe picked up the voice changes more than he himself or hiswife did. He clearly had anterior submandibular neckswelling from the whole anterior mid to upper part of theneck. He had some tongue elevation and some sublingualecchymosis; it was not woody, but it was definitely feelingfull. The rest of the examination was normal. He wastotally appropriate and wide awake and not in a whole lotof distress.