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Biomedical subjects

J F Polak

Publications and source records attributed to J F Polak.

At least 55 records · Page 3Linked to original sources
PubMed1999

Frequency of pulmonary embolism in patients with low-probability lung scan and negative lower extremity venous ultrasound.

STUDY OBJECTIVES: To define the prevalence of pulmonary embolism (PE) in patients who are undergoing pulmonary arteriography because of a high clinical suspicion for PE but who have had a low-probability lung scan and a negative lower extremity venous ultrasound examination. DESIGN: A retrospective review of the medical records of 365 consecutive patients who underwent pulmonary arteriograms for suspected PE was undertaken. RESULTS: Of the 365 pulmonary arteriograms, 62 were performed in patients with suspected PEs despite a low-probability lung scan and a negative lower extremity venous ultrasound examination. In the latter group, five patients (8%; 95% confidence interval, 2.7% to 18%) had PEs revealed on the arteriogram. CONCLUSIONS: In patients whose presentation provokes a high clinical suspicion for PE despite having had a low-probability lung scan, a negative lower extremity venous ultrasound examination is insufficient to preclude proceeding to pulmonary angiography.

Adult↗
PubMed1998

Risk factors for 5-year mortality in older adults: the Cardiovascular Health Study.

CONTEXT: Multiple factors contribute to mortality in older adults, but the extent to which subclinical disease and other factors contribute independently to mortality risk is not known. OBJECTIVE: To determine the disease, functional, and personal characteristics that jointly predict mortality in community-dwelling men and women aged 65 years or older. DESIGN: Prospective population-based cohort study with 5 years of follow-up and a validation cohort of African Americans with 4.25-year follow-up. SETTING: Four US communities. PARTICIPANTS: A total of 5201 and 685 men and women aged 65 years or older in the original and African American cohorts, respectively. MAIN OUTCOME MEASURES: Five-year mortality. RESULTS: In the main cohort, 646 deaths (12%) occurred within 5 years. Using Cox proportional hazards models, 20 characteristics (of 78 assessed) were each significantly (P<.05) and independently associated with mortality: increasing age, male sex, income less than $50000 per year, low weight, lack of moderate or vigorous exercise, smoking for more than 50 pack-years, high brachial (>169 mm Hg) and low tibial (< or = 127 mm Hg) systolic blood pressure, diuretic use by those without hypertension or congestive heart failure, elevated fasting glucose level (>7.2 mmol/L [130 mg/dL]), low albumin level (< or = 37 g/L), elevated creatinine level (> or = 106 micromol/L [1.2 mg/dL]), low forced vital capacity (< or = 2.06 mL), aortic stenosis (moderate or severe) and abnormal left ventricular ejection fraction (by echocardiography), major electrocardiographic abnormality, stenosis of internal carotid artery (by ultrasound), congestive heart failure, difficulty in any instrumental activity of daily living, and low cognitive function by Digit Symbol Substitution test score. Neither high-density lipoprotein cholesterol nor low-density lipoprotein cholesterol was associated with mortality. After adjustment for other factors, the association between age and mortality diminished, but the reduction in mortality with female sex persisted. Finally, the risk of mortality was validated in the second cohort; quintiles of risk ranged from 2% to 39% and 0% to 26% for the 2 cohorts. CONCLUSIONS: Objective measures of subclinical disease and disease severity were independent and joint predictors of 5-year mortality in older adults, along with male sex, relative poverty, physical activity, smoking, indicators of frailty, and disability. Except for history of congestive heart failure, objective, quantitative measures of disease were better predictors of mortality than was clinical history of disease.

Black or African American↗
PubMed1998

Pulmonary embolism: comparison of cut-film and digital pulmonary angiography.

PURPOSE: To compare "cut-film" (film hard-copy) angiography (CFA) with digital pulmonary angiography in the detection of pulmonary embolism (PE). MATERIALS AND METHODS: Thirty-six adult patients (39 lungs) underwent selective digital pulmonary angiography for suspected PE. Imaging was repeated in one selected projection by using cut film. The standard was consensus interpretation of both CFA and digital angiographic images and clinical course. Three vascular radiologists subsequently reviewed the digital and cut-film images in a blinded fashion and ranked the likelihood of the presence of PE on a five-point scale. The two modalities were compared by means of receiver operating characteristic (ROC) analysis. Image quality (i.e., sharpness, opacification of subsegmental vessels, and exposure) was judged on a three-point scale. The highest-order pulmonary artery branch seen on each study was recorded. RESULTS: ROC curve analyses for all three operators showed similar diagnostic performance for digital pulmonary angiography and CFA, with one operator showing better performance with digital subtraction angiography than with CFA (P = .04). Compared with the final diagnosis, single-plane digital pulmonary angiography had higher sensitivity for the detection of PE than had CFA. The specificity was 100% for both modalities. The mean score in patients with findings positive for PE was higher in the digital pulmonary angiography group than in the CFA group (P < .005). There was no difference in the mean score in patients who did not have a PE. There also was no difference in the smallest detectable subsegmental branch (P = .87) or in the average estimate of image quality. CONCLUSION: Selective digital pulmonary angiography and CFA offer similar diagnostic performance and image quality. Digital pulmonary angiography is a reasonable alternative to CFA in the diagnosis of PE.

Adult↗
PubMed1998

Hypoechoic plaque at US of the carotid artery: an independent risk factor for incident stroke in adults aged 65 years or older. Cardiovascular Health Study.

PURPOSE: To investigate the association between incident (first) stroke and the echogenicity of internal carotid arterial plaque at ultrasonography (US). MATERIALS AND METHODS: A cohort of 4, 886 individuals who, at baseline, were 65 years of age or older and without symptoms of cerebrovascular disease was followed up for an average of 3.3 years. Baseline clinical findings were from color Doppler and duplex US studies of the carotid arteries and a record of traditional risk factors: age, sex, presence of diabetes mellitus, pack-years of cigarette smoking, presence of hypertension, elevated systolic and diastolic blood pressure, elevated low-density lipoprotein cholesterol level. RESULTS: Incident strokes, excluding hemorrhagic strokes and strokes of cardiac origin, were seen in 104 individuals (2.1%) at risk. Age- and sex-adjusted odds ratios for incident stroke were significant for hypoechoic plaque (odds ratio, 2.53; 95% CI, 1,42,4.53). After controlling for risk factors in a Cox proportional hazards model, the relative risk (RR) of incident stroke was 1.72 (p = .015) for hypoechoic plaque and 2.32 (P = .004) for internal carotid arterial narrowing of at least 50%. In addition, hypoechoic plaque (RR, 2.78; CI, 1.36,5.69) and 50%-100% stenosis (RR, 3.08; CI, 1.28, 7.41) were associated with ipsilateral, nonfatal stroke. CONCLUSION: In asymptomatic adults aged 65 years or older, that risk of incident stroke was associated with two US features: hypoechoic internal carotid arterial plaque and an estimated internal carotid arterial stenosis of 50%-100%.

Aged↗
PubMed1998

Asymptomatic internal carotid artery stenosis defined by ultrasound and the risk of subsequent stroke in the elderly. The Cardiovascular Health Study.

BACKGROUND AND PURPOSE: We sought in this study to relate carotid ultrasound findings in asymptomatic older adults to the 5-year risk of various cerebrovascular outcomes used in the Asymptomatic Carotid Atherosclerosis Study (ACAS). METHODS: The Cardiovascular Health Study (CHS) is a longitudinal study of people 65 years and older. Analyses of internal carotid artery stenosis defined by multiple different cutoffs of peak systolic velocity, rather than one particular cutoff, were performed in the 5441 participants who underwent carotid ultrasound and lacked a history of transient ischemic attack or stroke. The 5-year risks of 7 cerebrovascular disease outcomes used in ACAS were estimated for each cutoff. RESULTS: Associations with the 5-year risk of outcomes were substantially elevated only at cutoffs with high peak systolic velocities. In this population, the number of people with such high velocities was small. For example, with a cutoff of approximately 2.5 m/s, suggesting a stenosis of >70%, the 5-year risk of an ipsilateral fatal or nonfatal stroke was 5%, and only 0.5% of the group had velocities at least this high. CONCLUSIONS: In a group of older adults likely to participate in a screening program, as evidenced by willingness to participate in CHS, high peak systolic velocities consistent with high-grade carotid stenosis were uncommon and risk of subsequent cerebrovascular disease outcomes was relatively low. These findings do not suggest that similar populations of older adults would benefit from a program using ultrasound to screen for asymptomatic carotid stenosis.

Aged↗
PubMed1998

Non-invasive assessment of brachial artery endothelial vasomotor function: the effect of cuff position on level of discomfort and vasomotor responses.

Non-invasive assessment of brachial artery flow-mediated dilation using cuff occlusion of the arm above or below the elbow to stimulate flow is emerging as a highly useful technique to examine endothelial vasomotor function in human subjects. In anticipation of a large-scale investigation, an important issue is the acceptability of the technique to participants. The purpose of this study was to determine the level of discomfort associated with the technique and compare it to the commonly used procedure of venipuncture. Flow-mediated dilation was determined using cuff occlusion of the arm above the elbow and a blood sample was obtained by standard venipuncture from 54 subjects. The level of discomfort for each procedure was assessed and compared using a visual analogue scale and was found to be extremely low. When the occlusion cuff was positioned above the elbow, the discomfort was slightly more severe (1.9+/-1.9 cm) than venipuncture (1.0+/-1.3 cm, p = 0.003). In 27 subjects, the effect of cuff position (above or below the elbow) was compared: the below the elbow position was associated with a reduction in the percentage increase in flow (570+/-280% versus 900+/-560%, p = 0.005), flow-mediated dilation (6.8+/-3.8% versus 9.8+/-5.7%, p = 0.008) and discomfort (1.6+/-0.8 versus 3.7+/-2.2 cm, p = 0.008). When the cuff was located below the elbow, the level of discomfort was equivalent to that associated with venipuncture. Thus, non-invasive assessment of flow-mediated brachial artery dilation is well tolerated and appears to be suitable for a large-scale study of endothelial function.

Adult↗
PubMed1998

Peripherally inserted central venous catheters: factors affecting patient satisfaction.

OBJECTIVE: We studied factors that affect satisfaction of patients who have undergone placement of peripherally inserted central venous catheters (PICCs) by interventional radiologists and patients' willingness to undergo placement of future PICCs. SUBJECTS AND METHODS: This longitudinal prospective consecutive cohort study included 85 patients referred for PICC placement. A record was made of catheter type, time taken for placement, patient age, and possible complications. Follow-up was obtained by telephone interview to determine the effect of site of placement in the arm, residence time of catheter, additional complications, and interference with activities of daily living on patient willingness to undergo future PICC placement at the same site. Logistic regression analysis was used to determine factors statistically predictive of patient willingness to undergo placement of future PICCs. RESULTS: Patients having PICCs placed above the elbow were more often satisfied (55 of 61 respondents) with catheter location than patients having placements at the elbow (three of 17 respondents). Patient willingness to undergo future PICC placement was strongly related to catheter location (p < .0001) and interference with activities of daily living (p < .0001). Catheter type, residence time, time taken for the placement, age, and complications were not associated with patient willingness to undergo future PICC placement. CONCLUSION: PICC placement above the elbow is more acceptable to patients than placement at the elbow. PICC placement above the elbow and patients' perception of less interference by the PICC with activities of daily living are positively related to patient willingness to undergo future PICC placement.

Activities of Daily Living↗
PubMed1998

Correlation of diagnostic imaging and subsequent autopsy findings in patients with pulmonary embolism.

OBJECTIVE: We determined the frequency of correct antemortem diagnosis in patients who underwent lung scintigraphy for suspected pulmonary embolism and for whom the pulmonary embolism was proven at autopsy. MATERIALS AND METHODS: We performed a longitudinal follow-up study of 1210 consecutive patients who underwent scintigraphic imaging for suspected pulmonary embolism. Patients for whom pulmonary embolism was proven at autopsy within 30 days of lung scintigraphy were studied. Diagnostic testing and risk factors were compared in patients with and without an antemortem diagnosis of pulmonary embolism. RESULTS: The antemortem diagnosis was made in four of eight patients with autopsy-proven pulmonary embolism, yielding a sensitivity of 0.5 (95% confidence interval, 0.16-0.84). The diagnosis was made by high-probability lung scintigraphy in two patients, by pulmonary arteriography in one patient, and by lower extremity venous sonography in another patient. The imaging investigation for suspected pulmonary embolism included only lung scintigraphy in four patients in whom the antemortem diagnosis was incorrect: two with low-probability scintigraphy and two with intermediate-probability scintigraphy. Risk factors were similar for patients with and without pulmonary embolism. CONCLUSION: In this cohort study of patients suspected of having pulmonary embolism, the antemortem diagnosis was not made in 50% of patients in whom pulmonary embolism was later proven at autopsy. Underuse of diagnostic testing may have been to blame. We therefore believe that further study is needed to help identify patients with suspected pulmonary embolism who may benefit from additional diagnostic testing after low- or intermediate-probability lung scintigraphy.

Adolescent↗
PubMed1998

Dual-isotope single-photon emission computerized tomography scanning in patients with glioblastoma multiforme: association with patient survival and histopathological characteristics of tumor after high-dose radiotherapy.

OBJECT: The study was conducted to determine the association between dual-isotope single-photon emission computerized tomography (SPECT) scanning and histopathological findings of tumor recurrence and survival in patients treated with high-dose radiotherapy for glioblastoma multiforme. METHODS: Studies in which SPECT with 201Tl and 99mTc-hexamethypropyleneamine oxime (HMPAO) were used were performed 1 day before reoperation in 47 patients with glioblastoma multiforme who had previously been treated by surgery and high-dose radiotherapy. Maximum uptake of 201Tl in the lesion was expressed as a ratio to that in the contralateral scalp, and uptake of 99mTc-HMPAO was expressed as a ratio to that in the cerebellar cortex. Patients were stratified into groups based on the maximum radioisotope uptake values in their tumor beds. The significance of differences in patient gender, histological characteristics of tissue at reoperation, and SPECT uptake group with respect to 1-year survival was elucidated by using the chi-square statistic. Comparisons of patient ages and time to tumor recurrence as functions of 1-year survival were made using the t-test. Survival data at 1 year were presented according to the Kaplan-Meier method, and the significance of potential differences was evaluated using the log-rank method. The effects of different variables (tumor type, time to recurrence, and SPECT grouping) on long-term survival were evaluated using Cox proportional models that controlled for age and gender. All patients in Group I (201Tl ratio < 2 and 99mTc-HMPAO ratio < 0.5) showed radiation changes in their biopsy specimens: they had an 83.3% 1-year survival rate. Group II patients (201Tl ratio < 2 and 99mTc-HMPAO ratio of > or = 0.5 or 201Tl ratio between 2 and 3.5 regardless of 99mTc-HMPAO ratio) had predominantly infiltrating tumor (66.6%); they had a 29.2% 1-year survival rate. Almost all of the patients in Group III (201Tl ratio > 3.5 and 99mTc-HMPAO ratio > or = 0.5) had solid tumor (88.2%) and they had a 6.7% 1-year survival rate. Histological data were associated with 1-year survival (p < 0.01): however, SPECT grouping was more closely associated with 1-year survival (p < 0.001) and was the only variable significantly associated with long-term survival (p < 0.005). CONCLUSIONS: Dual-isotope SPECT data correlate with histopathological findings made at reoperation and with survival in patients with malignant gliomas after surgical and high-dose radiation therapy.

Adolescent↗
PubMed1997

New indices to classify location, severity and progression of calcific lesions in the abdominal aorta: a 25-year follow-up study.

The purpose of the present study was to assess the location, severity and progression of radiopaque lumbar aortic calcifications and to evaluate the utility of summary scores of lumbar calcification in a population-based cohort. Lateral lumbar films, obtained in 617 Framingham heart study participants, were analysed for the presence of abdominal aortic wall calcification in the region corresponding to the first through fourth lumbar vertebrae. The severity of the anterior and posterior aortic calcification were graded individually on a 0-3 scale for each lumbar segment and the results were summarized to develop four different composite scores: (1) affected segments score (range 0-4); (2) anterior and posterior affected score (range 0-8); and (3) antero-posterior severity score (range 0-24). The prevalence of aortic calcification was 37% in men and 27% in women at baseline and 86% in both genders at the follow-up exam 25 years later. During the follow-up interval, the mean of the affected segments score increased from 0.7 in men (0.5 in women) to 2.7 (2.8 in women), the mean of the anterior and posterior affected score from 1.2 (0.8 in women) (P = 0.012 for difference between genders) and the mean of the antero-posterior severity score increased from 1.5 (1.3 in women) to 9.3 (10.3 in women). The antero-posterior severity score offered a slight advantage over other composite scores and had the highest inter-rater intra-class correlations. In summary, lumbar aortic calcification can be graded and composite summary scores are reproducible. This technique appears to provide a simple, low cost assessment of subclinical vascular disease.

Aged↗
PubMed1997

Duplex ultrasound criteria for the identification of carotid stenosis should be laboratory specific.

BACKGROUND AND PURPOSE: Published criteria for the determination of carotid stenosis have been widely applied by vascular laboratories. We compared two vascular laboratories and their duplex ultrasound (DU) machines in terms of their overall diagnostic performance and the optimal criteria to identify patients who have a 70% to 99% stenosis of the internal carotid artery. METHODS: Measurements of stenosis by DU and angiography were compared for 123 carotid arteries (60 arteries, laboratory A; 63 arteries, laboratory B). Receiver operating characteristic (ROC) curves were created, and the areas under the ROC curves and the optimal criteria for determining a 70% to 99% stenosis were compared. Multiple regression analysis was used to measure the effect of laboratory on the relationship between angiographic stenosis and DU velocity parameters. RESULTS: Areas under the ROC curves were similar for both laboratories (0.89 to 0.90, laboratory A; 0.90 to 0.92, laboratory B). However, the optimal criterion for the identification of a 70% to 99% carotid stenosis was different for each laboratory. For most velocity parameters, based on regression analyses, the predicted percent angiographic stenosis for laboratory A was significantly greater than that for laboratory B. In addition, performance differed between the laboratories when established criteria from the literature were applied. CONCLUSIONS: Two vascular laboratories with similar diagnostic accuracy by ROC analysis have markedly different "optimal" DU criteria. For a given angiographic stenosis, velocities in one laboratory were consistently greater than those in the other laboratory. Laboratory-specific criteria rather than published criteria should be used to identify patients with internal carotid artery stenoses.

Aged↗
PubMed1997

Noninvasive assessment of endothelium-dependent flow-mediated dilation of the brachial artery.

Coronary atherosclerosis is characterized by an early loss of endothelium-dependent vasodilation. However, the methods of assessing coronary endothelial function are invasive and difficult to repeat over time. Recently, a noninvasive ultrasound method has been widely used to measure flow-mediated dilation in the brachial artery as a surrogate test for endothelial function. We seek to further validate this method of measuring vascular function. The brachial artery diameters and blood flow of 20 normal volunteers (10 males and 10 females) were measured using high resolution (7.5 MHz) ultrasound and strain gauge plethysmography. Flow-mediated endothelium-dependent vasodilation was measured in the brachial artery during reactive hyperemia after 5 minutes of cuff occlusion in the upper arm. The brachial artery diameter increased maximally by 9.7 +/- 4.3% from baseline at 1 min after cuff release and blood flow increased by 1002 +/- 376%. Five min of cuff occlusion was sufficient to achieve 97 +/- 6% of maximal brachial artery dilation and degree of dilation was not different whether the cuff was inflated proximally or distally to the image site. The intraobserver variability in measuring brachial diameters was 2.9% and the variability of the hyperemic response was 1.4%. In young, healthy men and women, the baseline brachial artery diameter was the only factor that was predictive of the flow-mediated vasodilation response. The brachial noninvasive technique has been further validated by the determination of flow-mediated dilation. This method of assessing endothelial function may help to determine the importance of vasodilator dysfunction as a risk factor in the development of atherosclerosis.

Adult↗
PubMed1997

Treatment of patients with suspected pulmonary embolism and intermediate-probability lung scans: is diagnostic imaging underused?

OBJECTIVE: We compared patient treatment with imaging strategy in patients with clinically suspected pulmonary embolism (PE) and intermediate-probability lung scans (IPLS). MATERIALS AND METHODS: We retrospectively reviewed the medical records of 214 consecutive patients with clinically suspected PE with IPLS. RESULTS: Treatment (full anticoagulation, filter placement, or both) was given in 66 (31%) of 214 patients. Only 37% of patients were treated on the basis of definitive diagnostic imaging results. Most patients (134 [63%] of 214) were treated without an imaging diagnosis: 30 (14%) of 214 patients were treated for acute PE on clinical grounds, and the diagnosis of PE was not excluded in 104 (49%) of 214 patients. CONCLUSION: Most patients with IPLS are treated without a definitive imaging diagnosis. This lack of diagnosis may result in the overtreatment of patients who do not have acute PE or, more importantly, in the undertreatment of patients who do have acute PE. Further studies are necessary to evaluate the impact of the current management strategies on patient outcome.

Anticoagulants↗
PubMed1996

Association of fibrinogen and coagulation factors VII and VIII with cardiovascular risk factors in the elderly: the Cardiovascular Health Study. Cardiovascular Health Study Investigators.

The cross-sectional correlates of three hemostatic factors--fibrinogen, factor VII, and factor VIII--were examined in the Cardiovascular Health Study, a population-based cohort study of 5,201 subjects over age 65 years. Subjects were recruited in 1989-1990 in Forsyth County, North Carolina; Sacramento County, California; Washington County, Maryland; and Pittsburgh, Pennsylvania. In multivariate linear regression models, cardiac risk factors significantly associated with fibrinogen were current smoking, race, lipids, and white blood count. In women, alcohol use, obesity, physical activity, and insulin level were also significant, while in men hypertension was correlated. The significant correlates of factor VII were lipids and white blood count in men and estrogen use, alcohol use, race, lipids, insulin level, white blood count, and obesity in women. The independent correlates of factor VIII were insulin, glucose, and race in both sexes; low density lipoprotein cholesterol, white blood count, and diuretic use in men; and alcohol use in women. In multivariate models, factors known to be modifiable risk factors for cardiovascular disease accounted for more of the population variance of these hemostatic factors in women than in men, especially for factor VII. The hemostatic factors may mediate some effects of risk factors on disease, and this should be considered in longitudinal studies.

Age Distribution↗
PubMed1996

Carotid artery measures are strongly associated with left ventricular mass in older adults (a report from the Cardiovascular Health Study).

Associations of carotid artery diameter and intimal-medial thickness by ultrasound with echocardiographic left ventricular (LV) structure were examined in 3,409 participants in the Cardiovascular Health Study, a population-based study of risk factors for coronary heart disease and stroke in men and women aged > or = 65 years. At baseline, sector-guided M-mode echocardiography and B-mode ultrasound were used to evaluate the left ventricle and carotid arteries, respectively. Common carotid artery diameter and intimal-medial thickness were significantly related to LV mass in correlational analysis (r=0.40 and 0.20, respectively, p<0.01), and each was independently associated with LV mass after adjustment for age, gender, weight, systolic and diastolic blood pressure, antihypertensive medication use, prior coronary heart disease, electrocardiographic abnormalities, high-density lipoprotein, and factor VII. We speculate that changes in the arterial wall affect impedance to LV ejection leading to increases in LV mass. Further follow-up of this cohort is in progress and will help to determine whether such carotid artery measures could, by exacerbating LV hypertrophy, constitute another important risk factor for adverse cardiovascular outcomes.

Aged↗
PubMed1996

Bolus recombinant urokinase versus heparin in deep venous thrombosis: a randomized controlled trial.

Bolus urokinase (Abbokinase ) is effective for initial treatment of deep venous thrombosis but is associated with a high rate of rigors. This randomized controlled trial was undertaken among patients with deep venous thrombosis to evaluate the efficacy and safety of a novel thrombolytic agent, recombinant urokinase (rUK), administered as three bolus infusions of 1 million U over a 24-hour period versus heparin alone. Of 361 patients with DVT screened, 17 (5%) were enrolled. Recent surgery was the most common reason for exclusion (n = 113, 31%). Images of the patients were obtained at baseline, 24 to 48 hours after randomization, and before hospital discharge. Two patients in each treatment group had minor clot progression. One patient in the heparin group had no change; all other patients showed mild (< 50%; n = 5 in each group) or moderate (> 50%; n = 1 in each group) improvement. No bleeding complications or rigors developed in patients randomized to rUK. Mean bleeding times among patients given rUK were not significantly different from mean values of patients given heparin at any of the measured time points available for comparison (331 vs 387 seconds at baseline and 381 vs 416 seconds at 24 hours). However, mean fibrinogen levels declined with successive urokinase boluses and were significantly lower than levels in patients treated with heparin at 24 (233 mg/dl vs 466 mg/dl, p = 0.01) and 48 hours (270 mg/dl vs 474 mg/dl, p = 0.02). Although bolus rUK had a favorable safety profile, rUK was no more effective than heparin in achieving clot lysis at the doses used in this trial.

Adult↗
PubMed1996

Summary receiver operating characteristic curves as a technique for meta-analysis of the diagnostic performance of duplex ultrasonography in peripheral arterial disease.

RATIONALE AND OBJECTIVES: We summarized and compared the diagnostic performance of duplex and color-guided duplex ultrasonography in the evaluation of peripheral arterial disease. We present our research as an example of the use of summary receiver operating characteristic (ROC) curves in a meta-analysis of diagnostic test data. METHODS: A search of the English-language medical literature published between 1984 and 1994 retrieved 48 reports, 14 of which met the inclusion criteria. The analysis was limited to the aortoiliac and femoropopliteal segments because only two studies reported results of infrapopliteal arteries. Diagnostic performance of duplex and color-guided duplex, defined as the ability to detect a stenosis of 50-99% or an occlusion, was compared using summary ROC curve methodology. This method takes into account heterogeneity across studies attributable to differences in the threshold values used. RESULTS: The summary ROC curves demonstrated a high level of diagnostic performance for both types of duplex imaging, with color-guided duplex scanning being superior (p = .022). For example, at a false-positive rate of .05 (specificity = .95), the analysis predicted a true-positive rate (sensitivity) of .83 for duplex alone and .93 for color guided duplex. Differences in the case mix of the study population and study design did not affect the results. Furthermore, sensitivity analysis did not reveal a strong effect of any single study on the results. CONCLUSION: For aortoiliac and femoropopliteal arteries, the addition of color flow imaging to duplex scanning improves diagnostic performance in evaluating peripheral arterial disease.

Humans↗