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Biomedical subjects

W R Mower

Publications and source records attributed to W R Mower.

At least 19 recordsLinked to original sources
PubMed2001

Etiology of bloody diarrhea among patients presenting to United States emergency departments: prevalence of Escherichia coli O157:H7 and other enteropathogens.

Escherichia coli O157:H7 and other Shiga toxin-producing E. coli (STEC) infections have been associated with bloody diarrhea. The prevalence of enteropathogens among patients with bloody diarrhea was determined by a prospective study at 11 US emergency departments. Eligible patients had bloody stools, > or =3 loose stool samples per 24-h period, and an illness lasting <7 days. Among 873 patients with 877 episodes of bloody diarrhea, stool samples for culture were obtained in 549 episodes (62.6%). Stool cultures were more frequently ordered for patients with fever, >10 stools/day, and visibly bloody stools than for patients without these findings. Enteropathogens were identified in 168 episodes (30.6%): Shigella (15.3%), Campylobacter (6.2%), Salmonella (5.8%), STEC (2.6%), and other (1.6%). Enteropathogens were isolated during 12.5% of episodes that physicians thought were due to a noninfectious cause. The prevalence of STEC infection varied by site from 0% to 6.2%. Hospital admissions resulted from 195 episodes (23.4%). These data support recommendations that stool samples be cultured for patients with acute bloody diarrhea.

Adolescent↗
PubMed2001

Use of plain radiography to screen for cervical spine injuries.

STUDY OBJECTIVE: Standard radiographic screening may fail to reveal any evidence of injury in some patients with spinal injury. The purposes of this investigation were to document the efficacy of standard radiographic views and to categorize the frequencies and types of injuries missed on plain radiographic screening of the cervical spine. METHODS: All patients with blunt trauma selected for radiographic cervical spine imaging at 21 participating institutions underwent a standard 3-view series (cross-table lateral, anteroposterior, and odontoid views), as well as any other imaging deemed necessary by their physicians. Injuries detected with screening radiography were then compared with final injury status for each patient, as determined by review of all radiographic studies. RESULTS: The study enrolled 34,069 patients with blunt trauma, including 818 patients (2.40% of all patients; 95% confidence interval [CI] 2.40% to 2.40%) having a total of 1,496 distinct cervical spine injuries. Plain radiographs revealed 932 injuries in 498 patients (1.46% of all patients; 95% CI 1.46% to 1.46%) but missed 564 injuries in 320 patients (0.94% of all patients; 95% CI 0.94% to 0.94%). The majority of missed injuries (436 injuries in 237 patients [representing 0.80% of all patients]; 95% CI 0.80% to 0.80%) occurred in cases in which plain radiographs were interpreted as abnormal (but not diagnostic of injury) or inadequate. However, 23 patients (0.07% of all patients; 95% CI 0.05% to 0.09%) had 35 injuries (including 3 potentially unstable injuries) that were not visualized on adequate plain film imaging. These patients represent 2.81% (95% CI 1.89% to 3.63%) of all injured patients with blunt trauma undergoing radiographic evaluation. CONCLUSION: Standard 3-view imaging provides reliable screening for most patients with blunt trauma. However, on rare occasions, such imaging may fail to detect significant unstable injuries. In addition, it is difficult to obtain adequate plain radiographic imaging in a substantial minority of patients.

Adolescent↗
PubMed2001

Epidemiology of cervical spine injury victims.

STUDY OBJECTIVE: We sought to characterize demographics and injury patterns among patients undergoing emergency department cervical spine radiography for blunt traumatic injury. METHODS: All patients with blunt trauma undergoing cervical spine radiography at 21 centers were enrolled in this prospective, observational study. Patients' date of birth, age, sex, and ethnicity were noted before cervical spine radiography. RESULTS: Demographic factors associated with cervical spine injury, present in 818 of 33,922 patients, included the following: age of 65 years or older (relative risk [RR] 2.09; 95% confidence interval [CI] 1.77 to 2.59); "other" ethnicity (RR 1.79, 95% CI 1.46 to 2.19); male sex (RR 1.72, 95% CI 1.48 to 2.00); and white ethnicity (RR 1.50, 95% CI 1.31 to 1.72). Hispanic ethnicity (RR 0.64, 95% CI 0.51 to 0.79), female sex (RR 0.58, 95% CI 0.50 to 0.67), black ethnicity (RR 0.55, 95% CI 0.45 to 0.66), and age of less than 18 years (RR 0.39, 95% CI 0.27 to 0.55) were associated with reduced risk of cervical spine injury. CONCLUSION: Among patients undergoing ED cervical spine radiography, cervical spine injury is more common among the elderly, male subjects, and patients of white or "other" ethnicity. Because cervical spine injury occurs in patients in all demographic categories, however, this information cannot be used to select individual patients who should or should not undergo imaging.

Adolescent↗
PubMed2001

Distribution and patterns of blunt traumatic cervical spine injury.

STUDY OBJECTIVE: Previous studies of cervical spine injury involve individual institutions or special populations. There is currently little reliable information regarding natural cervical spine injury patterns after blunt trauma. This substudy of the National Emergency X-Radiography Utilization Study project was designed to accurately assess the prevalence, spectrum, and distribution of cervical spine injury after blunt trauma. METHODS: We prospectively enrolled all patients with blunt trauma undergoing cervical spine radiography at 21 diverse institutions. Injury status was determined by review of all radiographic studies obtained on each patient. For each individual injury, we recorded which specific films revealed the injury, the level and location of injury on each vertebra, and the age and sex of the patient. RESULTS: Of 34,069 enrolled patients with blunt trauma, 818 (2.4%) individuals had a total of 1,496 distinct cervical spine injuries to 1,285 different cervical spine structures. The second cervical vertebra was the most common level of injury (286 [24.0%] fractures, including 92 odontoid fractures), and 470 (39.3%) fractures occurred in the 2 lowest cervical vertebrae (C6 and C7). The vertebral body, injured in 235 patients, was the most frequent site of fracture. Nearly one third of all injuries (29.3%) were considered clinically insignificant. CONCLUSION: Cervical spine injuries occur in a small minority of patients with blunt trauma who undergo imaging. The atlantoaxial region is the most common site of injury, and the sixth and seventh vertebrae are involved in over one third of all injuries. Other spine levels are much more commonly involved than has previously been appreciated. A substantial minority of radiographically defined cervical spine injuries are of little clinical importance.

Adult↗
PubMed2001

Test performance of the individual NEXUS low-risk clinical screening criteria for cervical spine injury.

BACKGROUND: The National Emergency X-Radiography Utilization Study (NEXUS) recently validated the ability of a decision instrument to define a population with an extremely low risk of cervical spine injury (CSI) after blunt trauma. It is unclear whether each of the 5 individual criteria is necessary for the decision instrument to maintain its high sensitivity. METHODS: NEXUS was a prospective observational study at 21 emergency departments, which enrolled all patients with blunt trauma for whom cervical spine radiographs were ordered. In this substudy, we examined the NEXUS database to determine the contribution of each of the 5 individual low-risk clinical criteria to the overall sensitivity of the decision instrument. RESULTS: All but 8 of 818 patients with CSI, and all but 2 of 578 patients with significant CSI, were identified by using the decision instrument. A substantial number of patients with CSI (236/818 [29%]) and patients with significant CSI (175/578 [30%]) met only 1 of the 5 non--low-risk criteria, and each of the 5 criteria was the only indicator of non--low-risk status in at least 8 patients with CSI and at least 5 patients with significant CSI. CONCLUSION: Because each of the 5 low-risk criteria was the only marker of non--low-risk status in at least a few patients with significant CSI, modification of the overall NEXUS decision instrument by eliminating any one of the criteria would markedly reduce sensitivity and make the instrument unacceptable for clinical use.

Algorithms↗
PubMed2001

Use of flexion-extension radiographs of the cervical spine in blunt trauma.

STUDY OBJECTIVE: Flexion-extension (F/E) radiographs of the cervical spine are often used in patients with blunt trauma when the evaluating physician remains concerned about bony or ligamentous injuries despite negative or nondiagnostic standard radiographs. The use of this approach has never been addressed in a large prospective study. We sought to determine the clinical factors associated with ordering F/E views and the incidence of diagnostic F/E films in patients with a normal 3-view cervical spine series. METHODS: Patients with blunt trauma selected for radiographic cervical spine imaging at 21 participating institutions in the National Emergency X-Radiography Utilization Study project underwent standard 3-view (cross-table lateral, anteroposterior, and odontoid views) series, as well as any other imaging deemed necessary by their physicians. Injuries detected by means of screening radiography were then compared with final injury status for each patient, as determined by review of all radiographic studies. Patients who underwent F/E views were analyzed separately. RESULTS: Of 818 patients ultimately found to have cervical spine injury, 86 (10.5%) underwent F/E testing. Two patients sustained stable bony injuries detected only on F/E views. Four other patients had a subluxation detected only on F/E views, but all had other injuries apparent on routine cervical spine imaging. CONCLUSION: F/E imaging adds little to the acute evaluation of patients with blunt trauma. Other approaches, including magnetic resonance imaging, computed tomography, or delayed F/E, in the presence of specific clinical concerns would seem to provide a more reasonable approach to adjunctive imaging.

Cervical Vertebrae↗
PubMed2001

Simple geometric characteristics fail to reliably predict abdominal aortic aneurysm wall stresses.

PURPOSE: The treatment of patients with abdominal aortic aneurysms (AAAs) is typically based on the potential for rupture. Current rupture assessments are in turn based on statistics from aggregate populations and are incapable of providing precise risk estimates for individual AAAs. Significant benefit could be realized if rupture potential for individual AAAs could be reliably determined on the basis of simple geometric characteristics or the results of symmetric thin-shell analysis. This study seeks to determine whether it is possible to estimate wall stresses by use of these simple measures. METHODS: Linear finite element analysis was used to estimate the distribution of von Mises stresses in a series of homogeneous, isotropic, three-dimensional AAA models subject to static loading and assumed to have zero residual stresses. The magnitude of the peak stress was tabulated for each model along with the following characteristics: aneurysm volume; maximum diameter; maximum radius; maximal wall distention; aspect ratio (ratio of greatest anteroposterior diameter to transverse diameter); local radii of curvature (in both longitudinal and circumferential directions); and maximum symmetric thin-shell stress estimates (on the basis of the meridional contour). The relationship between peak stress and each of the characteristics was assessed by use of Spearman rank correlation coefficients, with values less than 0.95 interpreted as signifying unreliable associations. RESULTS: Peak stresses in the individual models ranged from 1.79 x 10(6) dyne/cm2 to 15.1 x 10(6) dyne/cm2. The circumferential and longitudinal radii of curvature were frequently able to predict the locations of high stress, but were unreliable in predicting the magnitude of peak stress. The aspect ratio showed the strongest correlation with peak wall stress (r = 0.88, 95% CI, 0.68-0.96), whereas the other characteristics showed even less correlation. Symmetric thin shell analysis accurately predicted stresses in axially symmetric models, but it was incapable of predicting either the location or magnitude of peak stress in asymmetric models. CONCLUSIONS: Simple geometric criteria and symmetric thin shell analyses are unreliable in predicting AAA stresses. Future attempts to estimate wall stress and assess risk of rupture for individual AAAs may require detailed three-dimensional modeling.

Aorta, Abdominal↗
PubMed2001

Distracting painful injuries associated with cervical spinal injuries in blunt trauma.

UNLABELLED: Distracting painful injuries (DPIs) may mask symptoms of spinal injury in blunt trauma victims and form an important element in a decision instrument used to identify individuals who require cervical spine radiography. OBJECTIVE: To identify the types and frequencies of injuries that actually act as DPIs among blunt trauma patients undergoing cervical spinal radiography. METHODS: This was a prospective observational study of consecutive blunt trauma victims presenting to an urban Level 1 regional trauma center between April 1, 1998, and September 30, 1998. Prior to cervical spinal radiography, treating physicians evaluated each patient to determine whether a DPI was present or absent and, if present, what type of injury was sustained. Injuries were categorized as fractures, soft-tissue injuries and lacerations, burns, visceral injuries, crush injuries, or other injuries. RESULTS: Data were collected for 778 patients, between 1 month and 98 years old, of whom 264 (34%) were considered to have DPIs. Physicians were unable to determine the DPI status in 47 (6%) additional cases. Fractures accounted for a majority of DPIs (154, or 58%), 42 (16%) were soft-tissue injuries or lacerations, and 86 (34%) were due to a variety of other entities, including visceral, crush, burn, or other miscellaneous injuries. Among the 37 (5%) patients with an acute cervical spinal injury, 20 (54%) had a DPI, including three (8%) who had DPI as the only indication for cervical radiography. CONCLUSIONS: A significant number of blunt trauma patients are believed by clinicians to have DPIs that can possibly mask the presence of cervical spinal injury. Fractures and trauma to soft tissues are the most common types of DPI.

Adult↗
PubMed2001

Epidemiology of thoracolumbar spine injury in blunt trauma.

OBJECTIVE: To evaluate the prevalence, distribution, and demographics of thoracolumbar (TL) spine injuries following blunt trauma. METHODS: Prospective, cross-sectional study of a consecutive sample of all blunt trauma patients presenting initially to the emergency department (ED) of a Level 1 trauma center and undergoing thoracic and/or lumbar spine radiography from August 1997 to November 1998. The age, sex, and mechanism of injury of each patient as well as location and type of spine injury were recorded for those patients with vertebral fractures, dislocations, or subluxations. RESULTS: Two thousand four hundred four blunt trauma patients were enrolled. Vertebral injuries were identified in 152 individuals (6.3%, 95% CI = 5.4% to 7.4%). Two hundred sixty distinct anatomic levels of injury were identified in these 152 individuals. Of these 260 injuries, 42 (16.2%) occurred at L1, 38 (14.6%) at L2, 29 (11.1%) at L3, and 27 (10.4%) at T12, making these the most commonly injured vertebrae. Injuries were most common (34 patients) in those aged 30-39 years and were least common (12 patients) in those under 18 years. Compression fractures (52%) were the most common injury in the thoracic spine, while transverse process fractures (48%) were the most common injuries in the lumbar spine. CONCLUSIONS: The prevalence of TL injuries in ED blunt trauma patients undergoing TL radiographs is 6.3%. The most commonly injured area of the TL spine is the thoracolumbar junction.

Adolescent↗
PubMed2001

A prospective multicenter study of cervical spine injury in children.

OBJECTIVE: Pediatric victims of blunt trauma have developmental and anatomic characteristics that can make it difficult to assess their risk of cervical spine injury (CSI). Previous reports, all retrospective in nature, have not identified any cases of CSI in either children or adults in the absence of neck pain, neurologic symptoms, distracting injury, or altered mental status. The objective of this study was to examine the incidence and spectrum of spine injury in patients who are younger than 18 years and to evaluate the efficacy of the National Emergency X-Radiography Utilization Study (NEXUS) decision instrument for obtaining cervical spine radiography in pediatric trauma victims. METHODS: We performed a prospective, multicenter study to evaluate pediatric blunt trauma victims. All patients who presented to participating emergency departments underwent clinical evaluation before radiographic imaging. The presence or absence of the following criteria was noted: midline cervical tenderness, altered level of alertness, evidence of intoxication, neurologic abnormality, and presence of painful distracting injury. Presence or absence of each individual criterion was documented for each patient before radiographic imaging, unless the patient was judged to be too unstable to complete the clinical evaluation before radiographs. The decision to radiograph a patient was entirely at the physician's discretion and not driven by the NEXUS questionnaire. The presence or absence of CSI was based on the final interpretation of all radiographic studies. Data on all patients who were younger than 18 years were sequestered from the main database for separate analysis. RESULTS: There were 3065 patients (9.0% of all NEXUS patients) who were younger than 18 years in this cohort, 30 of whom (0.98%) sustained a CSI. Included in the study were 88 children who were younger than 2, 817 who were between 2 and 8, and 2160 who were 8 to 17. Fractures of the lower cervical vertebrae (C5-C7) accounted for 45.9% of pediatric CSIs. No case of spinal cord injury without radiographic abnormality was reported in any child in this study, although 22 cases were reported in adults. Only 4 of the 30 injured children were younger than 9 years, and none was younger than 2 years. Tenderness and distracting injury were the 2 most common abnormalities noted in patients with and without CSI. The decision rule correctly identified all pediatric CSI victims (sensitivity: 100.0%; 95% confidence interval: 87.8%-100.0%) and correctly designated 603 patients as low risk for CSI (negative predictive value: 100.0%; 95% confidence interval: 99.4%-100.0%). CONCLUSIONS: The lower cervical spine is the most common site of CSI in children, and fractures are the most common type of injury. CSI is rare among patients aged 8 years or younger. The NEXUS decision instrument performed well in children, and its use could reduce pediatric cervical spine imaging by nearly 20%. However, the small number of infants and toddlers in the study suggests caution in applying the NEXUS criteria to this particular age group.

Adolescent↗
PubMed2000

Validity of a set of clinical criteria to rule out injury to the cervical spine in patients with blunt trauma. National Emergency X-Radiography Utilization Study Group.

BACKGROUND: Because clinicians fear missing occult cervical-spine injuries, they obtain cervical radiographs for nearly all patients who present with blunt trauma. Previous research suggests that a set of clinical criteria (decision instrument) can identify patients who have an extremely low probability of injury and who consequently have no need for imaging studies. METHODS: We conducted a prospective, observational study of such a decision instrument at 21 centers across the United States. The decision instrument required patients to meet five criteria in order to be classified as having a low probability of injury: no midline cervical tenderness, no focal neurologic deficit, normal alertness, no intoxication, and no painful, distracting injury. We examined the performance of the decision rule in 34,069 patients who underwent radiography of the cervical spine after blunt trauma. RESULTS: The decision instrument identified all but 8 of the 818 patients who had cervical-spine injury (sensitivity, 99.0 percent [95 percent confidence interval, 98.0 to 99.6 percent]). The negative predictive value was 99.8 percent (95 percent confidence interval, 99.6 to 100 percent), the specificity was 12.9 percent, and the positive predictive value was 2.7 percent. Only two of the patients classified as unlikely to have an injury according to the decision instrument met the preset definition of a clinically significant injury (sensitivity, 99.6 percent [95 percent confidence interval, 98.6 to 100 percent]; negative predictive value, 99.9 percent [95 percent confidence interval, 99.8 to 100 percent]; specificity, 12.9 percent; positive predictive value, 1.9 percent), and only one of these two patients received surgical treatment. According to the results of assessment with the decision instrument, radiographic imaging could have been avoided in the cases of 4309 (12.6 percent) of the 34,069 evaluated patients. CONCLUSIONS: A simple decision instrument based on clinical criteria can help physicians to identify reliably the patients who need radiography of the cervical spine after blunt trauma. Application of this instrument could reduce the use of imaging in such patients.

Cervical Vertebrae↗
PubMed1999

Evaluating bias and variability in diagnostic test reports.

Diagnostic testing is an important component of modern medical care. Unfortunately, many diagnostic tests are not rigorously evaluated before general application. Studies examining test characteristics often have methodologic flaws that impair their ability to provide reliable information on test performance. These flaws can introduce systematic nonrandom errors (biases) that distort measures of test accuracy. Other design errors can make it difficult to generalize the results of individual studies. These problems may enhance the apparent performance of poor tests while obscuring the performance of good tests, and they may result in the widespread use of tests with uncertain or limited efficacy. This article explores the ways in which studies of diagnostic test efficacy can be affected by bias and variability.

Bias↗
PubMed1998

EMERGEncy ID NET: an emergency department-based emerging infections sentinel network. The EMERGEncy ID NET Study Group.

Acute infectious disease presentations among many at-risk patient groups (eg, uninsured, homeless, and recent immigrants) are frequently seen in emergency departments. Therefore EDs may be useful sentinel sites for infectious disease surveillance. This article describes the background, development, and implementation of EMERGE ncy ID NET, an interdisciplinary, multicenter, ED-based network for research of emerging infectious diseases. EMERGE ncy ID NET was established in cooperation with the National Center for Infectious Diseases, Centers for Disease Control and Prevention (CDC) as part of the CDC's strategy to expand and complement existing disease detection and control activities. The network is based at 11 university-affiliated, urban hospital EDs with a combined annual patient visit census of more than 900,000. Data are collected during ED evaluation of patients with specific clinical syndromes, and are electronically stored, transferred, and analyzed at a central receiving site. Current projects include investigation of bloody diarrhea and the prevalence of Shiga toxin-producing Escherichia coli, animal exposures and rabies postexposure prophylaxis practices, seizures and prevalence of neurocysticercosis, nosocomial ED Mycobacterium tuberculosis transmission, and hospital isolation bed use for adults admitted for pneumonia or suspected tuberculosis. EMERGE ncy ID NET also was developed to be a mechanism for rapidly responding to new diseases or epidemics. Future plans include study of antimicrobial use, meningitis, and encephalitis, and consideration of other public health concerns such as injury and national and international network expansion.

Acute Disease↗
PubMed1998

Selective cervical spine radiography in blunt trauma: methodology of the National Emergency X-Radiography Utilization Study (NEXUS).

Fear of failure to identify cervical spine injury has led to extremely liberal use of radiography in patients with blunt trauma and remotely possible neck injury. A number of previous retrospective and small prospective studies have tried to address the question of whether any clinical criteria can identify patients, from among this group, at sufficiently low risk that cervical spine radiography is unnecessary. The National Emergency X-Radiography Utilization Study (NEXUS) is a very large, federally supported, multicenter, prospective study designed to define the sensitivity, for detecting significant cervical spine injury, of criteria previously shown to have high negative predictive value. Done at 23 different emergency departments across the United States and projected to enroll more than 20 times as many patients with cervical spine injury than any previous study, NEXUS should be able to answer definitively questions about the validity and reliability of clinical criteria used as a preliminary screen for cervical spine injury.

Cervical Vertebrae↗
PubMed1998

Interrater reliability of cervical spine injury criteria in patients with blunt trauma.

STUDY OBJECTIVE: To determine the interrater reliability of previously defined risk criteria for cervical spine injury. METHODS: Two emergency physicians independently evaluated patients with blunt trauma to determine whether they exhibited any of four risk criteria: (1) altered neurologic function; (2) evidence of intoxication; (3) spinous process or posterior midline cervical tenderness; or (4) distracting painful injury. Each criterion was explicitly described on study data forms. Physician concordance was measured, and the kappa statistic was calculated, for the combined risk criteria (based on the presence of any individual criterion), and for each individual criterion. RESULTS: There were 122 patients evaluated. Physicians agreed on overall classifications for 107 patients (87.7%; kappa, .73; confidence interval [CI], .61 to .86). Agreement for individual criteria were as follows: (1) altered neurologic function--102 patients (83.6%; kappa, .58; CI, .41 to .74); (2) intoxication--118 patients (96.7%; kappa, .86; CI, .72 to .99); (3) posterior midline tenderness--109 patients (89.3%; kappa, .77; CI .65 to .89); (4) distracting injury--112 patients (91.8%; kappa.77; CI, .64 to .91). CONCLUSION: The combined cervical spine injury criteria have substantial interrater reliability. Individual criteria are slightly less reliable.

Adolescent↗