The tip of the thromboembolism iceberg.
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Diagnostic Imaging↗
Biomedical subjects
J T Philbrick
Publications and source records attributed to J T Philbrick.
Inferior vena cava filters. Indications, safety, effectiveness.
BACKGROUND: Preventing pulmonary embolization by interrupting vena caval flow has been attempted since 1893. Inferior vena cava (IVC) filters have been available for 20 years, and currently there are five filters commercially available in the United States (Greenfield filter, Titanium Greenfield filter, Simon-Nitinol filter, Bird's Nest filter, and LGM or Vena Tech filter) and two other filters under development (Amplatz filter and Günther filter). Although these devices are widely used, their clinical utility and safety have not been completely evaluated. Controlled clinical trials to determine the clinical role for IVC filters have not been attempted, but numerous case series describing the outcomes of the seven current filters have been published. We have systematically reviewed these studies to clarify what is known about the indications, safety, and effectiveness of IVC filters. METHODS: Using the MEDLINE database, all English-language publications since 1970 that included follow-up clinical information after filter insertion were reviewed and eight methodologic guidelines were employed to assess the scientific quality of the clinical information. RESULTS: Twenty-four case series were reviewed: 16 concerned the Greenfield filter (1632 patients), and eight dealt with newer designs (925 patients). Commonly noted methodologic problems included failure to report the initial extent of thromboembolic disease, incomplete description of the patient assembly process, and incomplete and potentially biased outcome assessment. Recurrent clinical pulmonary embolism was rare after filter placement, and only eight deaths from pulmonary embolism were reported. Filter complications were common but rarely life threatening; four (0.16%) deaths from filter complications were noted among the reviewed studies. Thrombotic complications following filter placement included insertion-site deep vein thrombosis and IVC obstruction. These events were rare, but they occurred with all filter types. CONCLUSIONS: Inferior vena cava filters appear to be effective in preventing recurrent pulmonary embolism. Despite the large published experience with IVC filters, many questions remain about their indications, safety, and effectiveness. Anticoagulant therapy, if not contraindicated, should be used in conjunction with filters. While there is no ideal filter, some situations call for specific filters. Filter selection and insertion require experience, modern angiographic technique, and collaboration between clinicians caring for patients and the interventional radiologists or surgeons inserting the device.
Anticoagulants↗
Optimal management of suspected lower-extremity deep vein thrombosis. An evaluation with cost assessment of 24 management strategies.
Traditionally, patients suspected to have lower-extremity deep vein thrombosis have undergone venography, which is invasive, is expensive, and may cause deep vein thrombosis in healthy individuals. Recent studies have shown the safety and efficacy of alternative noninvasive approaches that employ impedance plethysmography or real-time ultrasonography. We compared these tests using decision analysis to model the consequences of 24 different management strategies for ambulatory patients suspected to have deep vein thrombosis. We also calculated the incremental cost per additional life saved for each strategy. Our analysis revealed that the optimal approach was to perform real-time ultrasonography followed by anticoagulation therapy if deep vein thrombosis is found. This approach was both effective and cost saving compared with no testing or treatment. Serial follow-up studies of patients whose initial study suggested no DVT saved additional lives, but at a cost of $390,000 per each additional life saved for patients with one follow-up study and $3.5 million per each additional life saved for patients with a second follow-up study. Venography should play a limited role in the contemporary evaluation of patients suspected to have deep vein thrombosis. Future research should focus on the determination of clinical predictors of patients who should undergo serial examinations.
Anticoagulants↗
Technetium-99m-RBC venography in the diagnosis of deep venous thrombosis of the lower extremity: a systematic review of the literature.
We systematically reviewed the six articles from the English-language medical literature, since 1979, which compared 99mTc-RBC venography with contrast venography for the diagnosis of deep venous thrombosis (DVT) of the lower extremity. The studies were generally small in size and poorly compliant with methodologic standards for diagnostic test research. There was considerable variation in both how the 99mTc-RBC venograms were performed and how they were interpreted. Sufficient clinical information on the patients was not provided. Although the overall sensitivities and specificities were high with a mean sensitivity of 0.89 and a mean specificity of 0.84, the small numbers of patients resulted in wide 95% confidence intervals. For distal disease, with only a total of 14 patients studied, the 95% confidence intervals were particularly broad. Although 99mTc-RBC venography is a promising technique, future studies with larger numbers of patients and closer adherence to methodologic standards are required.
Erythrocytes↗
Axillary and subclavian venous thrombosis. Prognosis and treatment.
To clarify the prognosis of axillary and subclavian deep venous thrombosis and to determine which clinical factors influence its sequelae, we systematically reviewed the English-language literature published on this subject since 1950. Seventy-one case reports and 17 case series describing a total of 329 patients met our inclusion criteria for detailed review. There were major deficiencies in the quality, as well as quantity, of the available clinical data: few patients were enrolled at axillary and subclavian deep venous thrombosis inception, and outcome assessments were susceptible to bias and based on insensitive diagnostic tests. Posttreatment symptoms were reported in 34% of cases, pulmonary embolism in 9.4% (one half documented by lung scan or angiography), and death in 1.2% (three of four deaths due to pulmonary emboli). These complications occurred regardless of etiologic category (spontaneous, catheter related, or miscellaneous). Thrombolytic agents and surgery, in addition to anticoagulation, were often used to treat axillary and subclavian deep venous thrombosis, but there were no controlled trials to support any one approach. Until such trials are performed, therapy should be based on the anticoagulation regimens proved to be effective for deep venous thrombosis of the lower extremity. In selected patients, thrombolytic therapy and surgery may have important roles.
Axillary Vein↗
Chronic fever and lymphadenopathy.
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Chronic Disease↗
Use of ambulatory electrocardiographic (Holter) monitoring.
PURPOSE: To evaluate the clinical efficacy of ambulatory electrocardiographic (ECG) monitoring and to develop guidelines for its use in clinical practice. DATA IDENTIFICATION: Studies reported since January 1978 were identified both through computer searches using Index Medicus and extensive manual searching of bibliographies of identified articles. STUDY SELECTION: Only studies that fulfilled methodologic criteria designed to limit bias were reviewed. DATA EXTRACTION: Information describing population and study results was assessed in four major categories (variability, diagnosis, prognosis, and therapy guidance) for both arrhythmia monitoring and ST-segment analysis. RESULTS OF DATA ANALYSIS: The day-to-day variability of arrhythmia and myocardial ischemia detected by ambulatory ECG monitoring may be considerable in an individual patient. Caution must therefore be used in interpreting serial tests. Ambulatory ECG monitoring with diary correlation permits documentation of cardiac arrhythmias causing symptoms, but the diagnostic yield is low unless symptoms are frequent. Such monitoring can provide information about prognosis in patients after acute myocardial infarction. The amount of prognostic information obtained is modest and is outweighed by other measures. There is insufficient information to make conclusions about such monitoring and prognosis in other conditions. Serial ambulatory ECG monitoring may be used to assess the effect of an antiarrhythmic drug in patients with frequent and reproducible ventricular ectopy. The effect of arrhythmia suppression on survival is uncertain. Because of its low sensitivity and specificity, analysis of ST-segment changes during ambulatory ECG monitoring is inaccurate in establishing or excluding the presence of coronary disease. Although anti-ischemic interventions reduce the frequency and duration of ST-segment changes on monitoring, there are no data on the utility of using reduction or elimination of the changes as the endpoint of therapy. CONCLUSIONS: Ambulatory ECG monitoring can provide diagnostic, prognostic, and therapeutic information in many situations, but similar information often may be better obtained in other ways.
Arrhythmias, Cardiac↗
Restoring balance to internal medicine training: the case for the teaching office practice.
Medical residents require an experience beyond the tertiary care hospital to understand many aspects of contemporary medical practice and to make informed career choices. To provide this balanced training, the University of Virginia has operated for 10 years an internal medicine teaching office practice to provide an outpatient experience similar to private practice. It allows residents to work closely with general internal medicine faculty and introduces them to the knowledge and skills necessary to establish and manage a successful practice. The curriculum of the 10 week rotation includes patient care in the office and by telephone, nursing home and home visits, tutorials and seminars on primary care and office management topics, and training in the use of microcomputers. A survey of 46 (92%) of the first 50 residents completing the rotation revealed that the content of the rotation was valuable, the rotation substantially influenced career choices, and the rotation helped provide a balanced view of internal medicine practice.
Curriculum↗
Plasma DNA. A simple, rapid test for aiding the diagnosis of pulmonary embolism.
Previously, we reported that the sensitivity of plasma DNA for patients with pulmonary emboli was 83 to 88 percent. To confirm these findings in a more comprehensive study, we collected plasma samples from 137 consecutive patients undergoing 148 ventilation-perfusion lung scans for pulmonary embolism. DNA was measured using a counter-immunoelectrophoresis technique that used high titer precipitating double-stranded DNA antibody from a patient with systemic lupus erythematosus. In addition to 17 patients (17 lung scans) excluded for not having plasma collected, 32 patients (37 lung scans) were excluded for having either a condition other than pulmonary embolism that could be associated with plasma DNA or for having nonacute symptoms. Eighteen of 22 patients with a diagnosis of pulmonary embolism (defined by either a high probability lung scan or abnormal pulmonary angiogram) had detectable plasma DNA. Only four of 27 patients without pulmonary embolism (defined by either a normal lung scan or normal pulmonary angiogram) had plasma DNA detected. Based on these results, plasma DNA had a sensitivity of 82 percent and a specificity of 85 percent for this condition. Plasma DNA is a promising test for pulmonary embolism and could help physicians interpret equivocal lung scan findings and thereby clarify difficult decisions such as the need for pulmonary angiography.
Counterimmunoelectrophoresis↗
Health perceptions of primary care patients and the influence on health care utilization.
This prospective study was conducted to determine the influence of primary care patients' health perceptions on their utilization of health care services. Patients' health perceptions were measured using the RAND Corporation's General Health Perceptions Questionnaire. Physicians provided scores of how they thought the patients perceived their health and of actual physical and emotional health. Utilization data (number of office visits, number of telephone calls to the physician, and ambulatory charges) were evaluated for a 12-month period after completion of the questionnaire. Of 208 patients, 62 (30%) patients with health perceptions scores less than 50 had greater degrees of anxiety (P less than .001), depression (P less than .001), health-related worry (P less than .001), and felt less able to resist illness (P less than .001) than patients with higher health perception scores. Analysis of covariance was used to control for differences in physical health among groups of patients with varying health perceptions. These analyses revealed that patients with low health perceptions made more office visits (P = .002), more telephone calls to the physician (P = .01), and had more office charges (P = .05) than patients with higher scores. Physicians accurately predicted the patients' health perceptions in 49% of the cases. In 37%, they thought patients would score their health perceptions higher than they did; in 14% they thought patients would score their health perceptions lower. Health perceptions are an important factor contributing to the use of health care by primary care patients, regardless of the patient's actual physical health. Persons with low health perceptions account for approximately 5% of office visits, a clinically important fraction, especially when compared to the 9% of office visits for hypertension, the most common disease treated in the medical office.
Adolescent↗
Real-time ultrasonography for the diagnosis of lower extremity deep venous thrombosis. The wave of the future?
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Forecasting↗
Do corticosteroids prevent postherpetic neuralgia? A review of the evidence.
A short course of corticosteroids is frequently used in herpes zoster to prevent postherpetic neuralgia. To clarify the evidence behind this routine practice, we reviewed the three randomized controlled trials on this subject. Although in all three similar dosages of corticosteroids (40 mg to 60 mg prednisone daily for 2 to 4 weeks) were used, deficiencies in reported clinical characteristics of study subjects, the potential for bias in the ascertainment of pain duration, and the inability to exclude type II error make it impossible to determine whether or not this practice is effective. More research on this subject is needed, with greater attention to good study methodology.
Adrenal Cortex Hormones↗
Calf deep venous thrombosis. A wolf in sheep's clothing?
To determine the natural history of calf deep venous thrombosis (C-DVT), an analytic review of the 20 relevant English-language papers published since 1942 was performed. Remarkably little methodologically sound research on this subject was found. However, available evidence suggests that C-DVT propagates to the thigh in up to 20% of cases and that propagation invariably occurs before embolization. No fatal emboli were reported in patients presenting with isolated C-DVT. Traditional anticoagulation treatment with heparin sodium and warfarin sodium of symptomatic patients with C-DVT appears to prevent extension, embolization, and early recurrence. There is no convincing evidence that C-DVT leads to chronic venous insufficiency or whether the risks of anticoagulation exceed the risks of no treatment. As an option to anticoagulation, physicians may choose to follow patients with C-DVT with serial impedance plethysmography, treating only if there is evidence of proximal extension.
Heparin↗
Single-dose antibiotic treatment for uncomplicated urinary tract infections. Less for less?
Because of the many differences among studies of single-dose antimicrobial therapy for uncomplicated urinary tract infection in women, we reviewed the 14 randomized controlled trials on this subject. Twelve concluded that single-dose therapy was as effective as conventional multiple-dose therapy. Although the studies were carefully conducted, none both reported and ascertained in a blinded manner the incidence of adverse drug reactions. Also, no study included enough patients to prevent type II error. To circumvent the problem of having too few patients in each study, we used a rational strategy for pooling the data from the reviewed studies. Single-dose amoxicillin (3 g) was significantly less effective than conventional multidose therapy (69% vs 84%), while single-dose sulfamethoxazole-trimethoprim (two or three double-strength tablets) was indistinguishable from multidose, although there still were too few patients to exclude type II error. More research on this subject is needed with greater attention to sample size and blinded ascertainment of adverse reactions.
Anti-Bacterial Agents↗
The limited spectrum of patients studied in exercise test research. Analyzing the tip of the iceberg.
To investigate reasons for the wide variation in formal studies of sensitivity and specificity indexes for the diagnostic efficacy of the graded exercise test for angiographically defined coronary disease, data were collected on 205 consecutive exercise tests at two hospital-based exercise laboratories. For calculations of sensitivity and specificity, stress test data are usually analyzed with many exclusions for ineligibility, with equivocal results omitted, and only in patients undergoing angiography. Consequently, only 3% of patients who received the tests in this survey would have been included in a typical formal study of diagnostic efficacy. In the same way that the visible tip of an iceberg misrepresents its extent and depth, the patients assembled in studies of diagnostic tests may be a highly selected group that misrepresents the intended population.
Coronary Angiography↗
Methodologic problems of exercise testing for coronary artery disease: groups, analysis and bias.
To determine why exercise testing remains controversial as a diagnostic test for coronary artery disease, a methodologic review was undertaken of 33 studies comprising 7,501 patients who had undergone both exercise tests and coronary angiography. Of seven methodologic standards for research design, only one received general compliance: the requirement for an adequate variety of anatomic lesions. Less than half of the studies complied with any of the remaining six standards: adequate identification of the groups selected for study; adequate analysis for relevant chest pain syndromes; avoidance of a limited challenge group; and avoidance of work-up bias, diagnostic review bias and test review bias. Only one study met as many as five standards. These methodologic problems may explain the wide range of sensitivity (35 to 88 percent) and specificity (41 to 100 percent) found for exercise testing, because the variations could not be attributed to the usual explanations: definition of anatomic abnormality, stress test technique or definition of an abnormal test. Determining the true value of exercise testing requires methodologic improvements in patient selection, data collection and data analysis.
Coronary Disease↗
Healthy patients who perceive poor health and their use of primary care services.
OBJECTIVE: To determine what proportion of patients who have poor health perceptions are physically healthy and to explore why some patients perceive a healthy state while others perceive illness. DESIGN: A prospective consecutive series of office patients completed the Rand Corporation's General Health Perceptions Questionnaire, and their physicians rated their physical health. Their use of health care services was determined for the following 12 months. SETTING: A rural teaching office practice. PATIENTS: Of 243 adult patients asked to complete the questionnaire, 32 were excluded, for dementia (8), illiteracy (4), illness (8), incomplete questionnaires (6), and other reasons (6). 208 patients (86%) formed the final study group. MEASUREMENTS AND MAIN RESULTS: 62 of 208 patients had poor health perception scores. 39 of the 62 were rated by physicians as physically healthy and were not statistically different in physical health ratings or numbers of prescribed medications from the 146 patients who had higher health perception scores. However, these 39 patients had significantly more health-related worry, acute pain, and depression than did the other 146 patients. They also made more office visits and telephone calls and had higher total primary care charges. CONCLUSIONS: This study suggests that 21% of adult primary care patients (39 of 208) have health perceptions lower than expected for their levels of physical health. These low health perceptions are correlated with increased emotional distress and higher utilization of health care resources. Strategies to identify these patients and interventions to improve their views of their health could reduce utilization.
Attitude to Health↗
A patient-based system for describing ambulatory medicine practices using diagnosis clusters.
OBJECTIVE: To develop a patient-based classification system to describe the clinical content of ambulatory medicine practices. DESIGN: A system of 100 diagnosis clusters was developed based on retrospective review of computerized problem lists of patients from a university practice, and then applied to the problem lists of patients in a community practice. Chart review of a 5% random sample (n = 184) of university practice patients who had problem lists was carried out to assess the accuracy of the computerized problem lists. SETTING: A university ambulatory medicine practice and a community ambulatory medicine practice. PATIENTS/PARTICIPANTS: For the same one-year period, all 4,490 patients seen in the university practice and all 1,294 patients seen two or more times in the community practice. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Of the 27,634 problems listed for university patients and the 5,648 problems listed for community patients, 22,629 (82%) and 4,924 (87%), respectively, were assigned to diagnosis clusters. For the university and community practices, the mean numbers of problems per patient were 6.1 (SD 5.4) and 4.4 (SD 3.7), and the mean numbers of diagnosis clusters per patient were 4.5 (SD 3.7) and 3.6 (SD 3.0), respectively. Among the ten most common diagnosis clusters in both practices were HYPERTENSION, SYMPTOM OR SIGN, OBESITY, and DIABETES. Only 18% (SD 3%) of patient problem lists in the university practice omitted one or more chronic, important medical problems (e.g., hypertension, dementia, COPD). CONCLUSIONS: This system of diagnosis clusters effectively and efficiently described the clinical content of two types of internal medicine practices, and has important applications in medical education, epidemiology, clinical and health services research, and public policy.
Ambulatory Care↗