Todd L Allen

University of Pittsburgh, Pittsburgh, Pennsylvania, United States

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Publications (16)27.88 Total impact

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    ABSTRACT: BACKGROUND: Computed tomography (CT) pulmonary angiography use has increased dramatically, raising concerns for patient safety. Adherence to recommendations and guidelines may protect patients. We measured adherence to the recommendations of Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED II) investigators for evaluation of suspected pulmonary embolism and the rate of potential false-positive pulmonary embolism diagnoses when recommendations of PIOPED II investigators were not followed. METHODS: We used a structured record review to identify 3500 consecutive CT pulmonary angiograms performed to investigate suspected pulmonary embolism in 2 urban emergency departments, calculating the revised Geneva score (RGS) to classify patients as "pulmonary embolism unlikely" (RGS≤10) or "pulmonary embolism likely" (RGS>10). CT pulmonary angiograms were concordant with PIOPED II investigator recommendations if pulmonary embolism was likely or pulmonary embolism was unlikely and a highly sensitive D-dimer test result was positive. We independently reviewed 482 CT pulmonary angiograms to measure the rate of potential false-positive pulmonary embolism diagnoses. RESULTS: A total of 1592 of 3500 CT pulmonary angiograms (45.5%) followed the recommendations of PIOPED II investigators. The remaining 1908 CT pulmonary angiograms were performed on patients with an RGS≤10 without a D-dimer test (n=1588) or after a negative D-dimer test result (n=320). The overall rate of pulmonary embolism was 9.7%. Potential false-positive diagnoses of pulmonary embolism occurred in 2 of 3 patients with an RGS≤10 and a negative D-dimer test result. CONCLUSIONS: Nonadherence to recommendations for CT pulmonary angiography is common and exposes patients to increased risks, including potential false-positive diagnoses of pulmonary embolism.
    The American journal of medicine 11/2012; · 5.30 Impact Factor
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    ABSTRACT: PURPOSE CT pulmonary angiography (CTPA) is frequently used for diagnosis of suspected pulmonary embolism (PE). The rate of false positive and false negative studies increases when the pretest probability for PE is discordant with the results of this test. We measured rates of inaccurate diagnosis of suspected PE for CTPA as interpreted by general vs. chest radiologists and stratified the results by pretest probability. METHOD AND MATERIALS This retrospective study was conducted in the Emergency Departments at Intermountain Medical Center and LDS Hospital in Salt Lake City, Utah. All CTPAs from July 1, 2009 to April 30, 2010 were identified through a query of the Intermountain Enterprise Data Warehouse. Studies originally interpreted by the general radiology group were blindly re-interpreted by one of three fellowship-trained chest radiologists. The chest radiologists’ interpretations were used as the standard to measure the rates of false-positive and false-negative diagnosis. Kappa coefficients for agreement amongst the chest radiologists were calculated by overlapping 20% of the sample. Pretest probability was calculated for each patient using a Revised Geneva Score (RGS). The patients were stratified based on pretest probability and the rates of inaccurate diagnoses were reported for each group. RESULTS 241 consecutive positive studies and 241 randomly selected negative studies were distributed to the study radiologists and 99 studies overlapped with two study radiologists. Thirteen/298 studies (4.4%) were false-positive and 7/283 studies (2.5%) were false-negative. The chest radiologists’ Kappa coefficients were 1.0, 0.94, and 0.94. The pretest probabilities of the study sample by RGS were low probability 25%, intermediate probability 64%, and high probability 11%. False positive rates for low, intermediate, and high probability were 3.1%, 5.3%, and 0%. False negative rates for the same groups were 6.0%, 2.2%, and 0% respectively. CONCLUSION CTPA carries risk for inaccurate diagnosis. Our results showed that this risk of inaccuracy varied according to the pre-test probability for PE. CLINICAL RELEVANCE/APPLICATION The rates of inaccurate diagnosis of pulmonary embolism with CT pulmonary angiography vary with pre-test probability for disease. A pre-test probability assessment is recommended prior to imaging.
    Radiological Society of North America 2011 Scientific Assembly and Annual Meeting; 12/2011
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    ABSTRACT: We apply a previously described tool to forecast emergency department (ED) crowding at multiple institutions and assess its generalizability for predicting the near-future waiting count, occupancy level, and boarding count. The ForecastED tool was validated with historical data from 5 institutions external to the development site. A sliding-window design separated the data for parameter estimation and forecast validation. Observations were sampled at consecutive 10-minute intervals during 12 months (n=52,560) at 4 sites and 10 months (n=44,064) at the fifth. Three outcome measures-the waiting count, occupancy level, and boarding count-were forecast 2, 4, 6, and 8 hours beyond each observation, and forecasts were compared with observed data at corresponding times. The reliability and calibration were measured following previously described methods. After linear calibration, the forecasting accuracy was measured with the median absolute error. The tool was successfully used for 5 different sites. Its forecasts were more reliable, better calibrated, and more accurate at 2 hours than at 8 hours. The reliability and calibration of the tool were similar between the original development site and external sites; the boarding count was an exception, which was less reliable at 4 of 5 sites. Some variability in accuracy existed among institutions; when forecasting 4 hours into the future, the median absolute error of the waiting count ranged between 0.6 and 3.1 patients, the median absolute error of the occupancy level ranged between 9.0% and 14.5% of beds, and the median absolute error of the boarding count ranged between 0.9 and 2.8 patients. The ForecastED tool generated potentially useful forecasts of input and throughput measures of ED crowding at 5 external sites, without modifying the underlying assumptions. Noting the limitation that this was not a real-time validation, ongoing research will focus on integrating the tool with ED information systems.
    Annals of emergency medicine 09/2009; 54(4):514-522.e19. · 4.23 Impact Factor
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    ABSTRACT: Objectives. To determine whether the skill performance and psychomotor agility, as measured by the endotracheal intubation success rate, of air ambulance medical personnel would be affected by the potential fatigue incurred when increasing the length of their shifts from 12 to 24 hours. Methods. This was a retrospective review of all flight and intubation records from a large air medical transport system from 1997, when 24-hour shifts were in place, and six months (March–August) of 1996, during which 12-hour shifts were scheduled. Records of all intubation efforts during both periods, including multiple attempts per patient, and outcomes of all attempts, were recorded. Results of successes and failures were tabulated for both ultimate intubation outcome per patient and all attempts per patient for each calendar day and for the 12 hours between 19:00 and 07:00 when fatigue might play a role. Results from the two study periods were compared using Fisher's exact test. Results. During the six months of 1996, 190 of 199 (95.5%) patients were ultimately successfully intubated. These patients required 237 attempts (80.1% successful). During 1997, 362 of 376 (96.3%) patients were successfully intubated, and required 438 attempts (82.6% successful). There was no statistically significant difference in the number of ultimately successful intubations (p = 0.66) or total intubation attempts (p = 0.37) between 1996 and 1997. Analysis of intubations between 19:00 and 07:00 revealed 81 of 84 (96.4%) patients successfully intubated in 1996, with 81 of 103 (78.6%) attempts successful. During 1997, 173 of 180 (96.1%) patients were ultimately successfully intubated, with 173 of 212 (81.6%) attempts successful. Again, there was no significant difference in the number of successful intubations (p = 0.99) or intubation attempts (p = 0.55) between 1996 and 1997. Conclusion. Psychomotor agility of air ambulance medical personnel, as measured by the success rate of endotracheal intubation, was not affected by the potential additional fatigue incurred as a result of increasing shift length from 12 to 24 hours.
    07/2009; 5(4):340-343.
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    ABSTRACT: The goals of this investigation were to study the temporal relationships between the demands for key resources in the emergency department (ED) and the inpatient hospital, and to develop multivariate forecasting models. Hourly data were collected from three diverse hospitals for the year 2006. Descriptive analysis and model fitting were carried out using graphical and multivariate time series methods. Multivariate models were compared to a univariate benchmark model in terms of their ability to provide out-of-sample forecasts of ED census and the demands for diagnostic resources. Descriptive analyses revealed little temporal interaction between the demand for inpatient resources and the demand for ED resources at the facilities considered. Multivariate models provided more accurate forecasts of ED census and of the demands for diagnostic resources. Our results suggest that multivariate time series models can be used to reliably forecast ED patient census; however, forecasts of the demands for diagnostic resources were not sufficiently reliable to be useful in the clinical setting.
    Journal of Biomedical Informatics 06/2008; 42(1):123-39. · 2.13 Impact Factor
  • Annals of Emergency Medicine - ANN EMERG MED. 01/2008; 52(4).
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    JAAPA: official journal of the American Academy of Physician Assistants 08/2007; 20(7):27-8.
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    ABSTRACT: Intermountain Healthcare (Salt Lake City), in conjunction with emergency department (ED) staff at LDS Hospital, designed an integrated patient tracking system (PTS) and a specialized data repository (ED Data Mart) that was part of an overall enterprisewide data warehouse. After two years of internal beta testing the PTS and its associated data captures, an analysis of various ED operations by time of day was undertaken. Real-time data, concurrent with individual ED patient encounters from July 1, 2004 through June 30, 2005 were included in a retrospective analysis. A number of patterns were revealed that provide a starting point for understanding ED processes and flow. In particular, ED census, acuity, operations, and throughput vary with the time of day. For example, patients seen during low-census times, in the middle of the night, appear to have a higher acuity. Radiology and laboratory utilization were highly correlated with ED arrivals, and the higher the acuity, the greater the utilization. Although it is unclear whether or not these patterns will be applicable to other hospitals in and out of the cohort of tertiary care hospitals, ED cycle data can help all facilities anticipate the resources needed and the services required for efficient patient flow. For example, the fact that scheduling of most service departments falls off after 5:00 P.M., just when the ED is most in need of those services, illustrates a fundamental mismatch between service capacity and demand.
    Joint Commission journal on quality and patient safety / Joint Commission Resources 06/2007; 33(5):247-55.
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    ABSTRACT: Emergency department (ED) overcrowding has become a frequent topic of investigation. Despite a significant body of research, there is no standard definition or measurement of ED crowding. Four quantitative scales for ED crowding have been proposed in the literature: the Real-time Emergency Analysis of Demand Indicators (READI), the Emergency Department Work Index (EDWIN), the National Emergency Department Overcrowding Study (NEDOCS) scale, and the Emergency Department Crowding Scale (EDCS). These four scales have yet to be independently evaluated and compared. The goals of this study were to formally compare four existing quantitative ED crowding scales by measuring their ability to detect instances of perceived ED crowding and to determine whether any of these scales provide a generalizable solution for measuring ED crowding. Data were collected at two-hour intervals over 135 consecutive sampling instances. Physician and nurse agreement was assessed using weighted kappa statistics. The crowding scales were compared via correlation statistics and their ability to predict perceived instances of ED crowding. Sensitivity, specificity, and positive predictive values were calculated at site-specific cut points and at the recommended thresholds. All four of the crowding scales were significantly correlated, but their predictive abilities varied widely. NEDOCS had the highest area under the receiver operating characteristic curve (AROC) (0.92), while EDCS had the lowest (0.64). The recommended thresholds for the crowding scales were rarely exceeded; therefore, the scales were adjusted to site-specific cut points. At a site-specific cut point of 37.19, NEDOCS had the highest sensitivity (0.81), specificity (0.87), and positive predictive value (0.62). At the study site, the suggested thresholds of the published crowding scales did not agree with providers' perceptions of ED crowding. Even after adjusting the scales to site-specific thresholds, a relatively low prevalence of ED crowding resulted in unacceptably low positive predictive values for each scale. These results indicate that these crowding scales lack scalability and do not perform as designed in EDs where crowding is not the norm. However, two of the crowding scales, EDWIN and NEDOCS, and one of the READI subscales, bed ratio, yielded good predictive power (AROC >0.80) of perceived ED crowding, suggesting that they could be used effectively after a period of site-specific calibration at EDs where crowding is a frequent occurrence.
    Academic Emergency Medicine 11/2006; 13(11):1204-11. · 1.76 Impact Factor
  • Shari J Welch, Todd L Allen
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    ABSTRACT: To demonstrate how a comprehensive and internally driven Continuous Quality Improvement (CQI) program was designed and implemented in our Emergency Department (ED) in 1999. This program involved monthly data collection and analysis, data-driven process change, staff education in the core concepts of quality, and data reanalysis. Data components collected during the program included census data, physician profiling, and focused clinical audits. CQI measures collected at the beginning of the program and quarterly included: (1) CQI metric data (turnaround times [TAT] and rates of left against medical advice [AMA] or left without being seen [LWOBS]), (2) rates and nature of patient complaints, and (3) results of patient satisfaction surveys performed by an outside consulting firm contracted by hospital administration. During the 4 years since its implementation the program demonstrated improvement in all measured areas. Despite an increase in patient volume of 32% to nearly 37,000 visits/year, and only minimal staffing adjustments, the mean quarterly TAT decreased from 183 min to 165 min (9.8% decrease), the rate of complaints dropped by 56.1% (2.1 per 1000 patients to 0.92), and patients leaving AMA or LWOBS decreased 66.7% from 2.7% to 0.9%. Overall, 44.8% of ED patients rated their care as "excellent." In summary, we demonstrate how a comprehensive quality improvement program was structured and implemented at a tertiary care center and how such a program demonstrated improvement in specific CQI parameters.
    Journal of Emergency Medicine 05/2006; 30(3):269-76. · 1.33 Impact Factor
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    ABSTRACT: To examine the characteristics of pediatric patients (age =16 years) injured at winter resort scenes and transported by helicopter emergency medical services (HEMS) or ground EMS (GEMS) ambulance services to regional trauma centers. Between 1997 and 2001, a total of 119 patients (GEMS = 69; HEMS = 50) were identified from trauma registries and HEMS transport records. Demographic data, initial vital signs, hospital interventions, and discharge status of the two groups were examined. The distributions of gender, initial vital signs, Injury Severity Score (ISS; either = or > 15), intensive care unit (ICU) length of stay (LOS), total hospital LOS, and home discharge status were similar between the two groups (p = 0.05). Patients transported by HEMS were older (14 +/- 2 vs. 10 +/- 4, p < 0.001), less likely to be admitted to the hospital (73% vs. 98.5%; p < 0.001), and more likely to have multiple injuries [13 (27%) vs. 8 (11.6%), p = 0.032]. The GEMS patients had a higher rate of isolated extremity [33 (80.5%) vs. 8 (19.5%)] and thoracoabdominal [11 (73.3%) vs. 4 (26.7%)] injuries. The high orthopedic injury rate in the GEMS patients contributed to a higher rate of surgery in this group (45% vs. 24%, p = 0.028). Regardless of transport mode, patients requiring immediate interventions (intubation, chest tube placement, or blood product administration) had either a depressed level of consciousness (GCS = 12) on emergency department arrival or thoracoabdominal injuries. No deaths were recorded. Patients transported by HEMS and GEMS had similar hospital characteristics but different injury patterns. A prospective study examining the initial triage of pediatric patients injured at winter resorts would help to determine which subset of patients are best served by HEMS transport.
    Prehospital Emergency Care 01/2006; 10(1):35-40. · 1.86 Impact Factor
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    ABSTRACT: Venous thromboembolic (VTE) disease remains a significant cause of morbidity for trauma patients because many patients have injuries that may preclude effective VTE prevention and treatment. Retrievable vena cava filters may prove beneficial in this subset of trauma patients. Trauma patients at risk for VTE were identified and managed by institutional protocol. Patients who required a vena cava filter were managed with a device that could be retrieved or left in situ. A retrospective review of medical records was used to identify the use, indications, and complications associated with a retrievable filter. Fifty-three retrievable filters were placed in 51 patients. Two of these patients received a second filter, and 1 received a filter in the superior vena cava. Thirty-two filters were placed prophylactically, whereas 21 were placed for demonstrated venous thromboembolism (VTE). Retrieval was successful in 24 of 25 attempts. Twenty-nine filters became permanent: 10 for continued contraindications to anticoagulation without known VTE, 12 for known VTE and continued contraindications to anticoagulation, 1 for technical reasons, and 6 because of patient death. There were no complications of bleeding, device migration or thrombosis, infection, or pulmonary embolism. A retrievable vena cava filter appears safe and effective for the prevention of pulmonary embolism in the high-risk trauma patient who cannot receive anticoagulation.
    The American Journal of Surgery 07/2005; 189(6):656-61. · 2.52 Impact Factor
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    ABSTRACT: The aim of this study was to estimate the sensitivity, specificity, and positive predictive value (PPV) of computed tomography (CT) without oral contrast for diaphragm injuries (DIs) in blunt abdominal trauma. We prospectively enrolled 500 consecutive "trauma-one" patients who received CT imaging and interpretation (CT-Read1) of the abdomen within 45 minutes of their arrival from July 2000 to December 2001. All patients were imaged without oral contrast but with intravenous contrast. Computed tomographic images were reviewed within 24 hours of admission by research radiologists (CT-Read2) blinded to CT-Read1. True DIs were determined hierarchically by either laparotomy or autopsy. There were 9 patients with laparotomy or autopsy-proven blunt DIs; 8 of these injuries involved the left hemidiaphragm. The CT-Read1 correctly detected only 6 of 9 blunt DIs, thus missing 3 DIs. One of these involved the right hemidiaphragm, whereas the other 2 were left sided. There were no false-positive findings with CT-Read1 for blunt DI. The sensitivity and specificity of CT imaging with respect to DI were 66.7% (95% CI, 29.9%-92.5%) and 100% (95% CI, 99.2%-100%), respectively. The PPV for the test was 1.00 (95% CI, 0.65-1.00). Although the low number of blunt DIs in this study limits its general applicability, CT imaging of the diaphragm without oral contrast appears to perform within the range of reported imaging techniques using oral contrast. Still, CT scanning appears to have an unsatisfactorily low sensitivity to be reliably used in eliminating the diagnosis of blunt DI.
    American Journal of Emergency Medicine 06/2005; 23(3):253-8. · 1.70 Impact Factor
  • The Journal of trauma 02/2005; 58(1):175-80. · 2.35 Impact Factor
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    ABSTRACT: Computed tomographic (CT) scanning using intravenous and oral contrast material has traditionally been advocated for the evaluation of intra-abdominal injury, including blunt bowel and mesenteric injuries (BBMIs). The necessity of oral contrast in detecting these injuries has recently been called into question. The purpose of this study was to determine the sensitivity and specificity of CT scanning without oral contrast for BBMIs. We prospectively enrolled 500 consecutive blunt trauma patients who received CT imaging and interpretation (CT-Read1) of the abdomen from July 2000 to November 2001. All patients were imaged without oral contrast, but with intravenous contrast. CT images were reviewed within 24 hours of admission by a research radiologist (CT-Read2) blinded to CT-Read1. For study purposes, true BBMI was determined to be present if either laparotomy or autopsy identified bowel or mesenteric injury, or both CT-Read2 and the hospital discharge summary described bowel or mesenteric injury. Three-month telephone follow-up was also completed. CT-Read1 detected 19 of 20 bowel and mesenteric injuries. CT-Read1 missed one duodenal perforation. There were two patients with false-positive interpretations of CT-Read1 for bowel injury. The sensitivity and specificity of CT imaging for the detection of BBMIs were 95.0% and 99.6%, respectively. CT imaging of the abdomen without oral contrast for detection of BBMIs compares favorably with CT imaging using oral contrast.
    The Journal of trauma 03/2004; 56(2):314-22. · 2.35 Impact Factor
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    ABSTRACT: Adverse drug events (ADEs) are noxious and unintended results of drug therapy. ADEs have been shown to be a risk to hospitalized patients. The purpose of this study was to determine the rate and nature of ADEs in trauma patients and to characterize the population at risk. An electronic medical record, a hospital wide computerized surveillance program, and a clinical pharmacist prospectively investigated ADEs in 4,320 trauma patients from 1996 through 1999. The rate of ADEs in trauma patients (98/4320, 2.3%) was twice that of non-trauma hospital patients (1,111/96,218, 1.2%, p < 0.001). Traumatized females had ADEs 1.5 times more often than traumatized males (2.7% versus 1.8%, p = 0.052). The medication class most often associated with ADEs was analgesics with 54% involving morphine and 20% involving meperidine. The most common ADEs were nausea, vomiting, and itching. Only one ADE was directly attributed to a medical error. Trauma patients are at double the risk for ADEs. Analgesics are particularly associated with ADEs and use should be carefully monitored.
    The Journal of trauma 02/2003; 54(2):337-43. · 2.35 Impact Factor