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Biomedical subjects

M G Hunink

Publications and source records attributed to M G Hunink.

At least 55 records · Page 3Linked to original sources
PubMed1994

Hospital costs of revascularization procedures for femoropopliteal arterial disease.

PURPOSE: On the basis of analyses performed 8 to 10 years ago, hospital costs for percutaneous transluminal angioplasty were believed to be no more than one third those of bypass. Given increasing awareness of cost as an important component in management decisions, updated information is needed. METHODS: From 1985 to 1991, clinical and hospital cost data were collected prospectively for 255 admissions for femoropopliteal bypass and 82 for femoropopliteal angioplasty. Mean hospital costs and length of stay per admission were calculated for subgroups of patients defined by procedure and indication, and multiple regression analysis was performed. RESULTS: For all admissions the mean hospital cost for angioplasty was $16,341 and for bypass it was $17,076 (nonsignificant difference). Excluding admissions associated with additional procedures, angioplasty cost on average $8019 and bypass $13,439, a significant difference (p = 0.0001). Stratification by indication demonstrated a significant difference for patients with disabling claudication (p = 0.0001), but the difference was of borderline significance for patients with critical ischemia (p = 0.08). An increasing trend in costs for angioplasty of $1270/yr was demonstrated during the study period, whereas the costs for bypass decreased by $370/yr. CONCLUSION: In contrast to what has been reported previously, the ratios of hospital costs of angioplasty to bypass were 53% for patients with disabling claudication and 75% for those with critical ischemia.

Aged↗
PubMed1993

Detection and quantification of carotid artery stenosis: efficacy of various Doppler velocity parameters.

OBJECTIVE: The purpose of this study was to evaluate and compare the accuracies of the different Doppler velocity parameters used to grade stenoses of the carotid artery. MATERIALS AND METHODS: Seven velocity parameters determined with Doppler spectra were compared with angiographic findings in 138 carotid bifurcations: the peak systolic and peak end-diastolic velocities in the internal and common carotid arteries, the ratios of peak systolic and peak end-diastolic velocities between the internal and common carotid arteries, and the ratio of peak systolic velocity in the internal carotid artery to peak end-diastolic velocity in the common carotid artery. A receiver-operating-characteristic (ROC) analysis was performed, with and without correction for the bias introduced by preferentially selecting patients for angiography, if the Doppler results indicated a lesion. Multiple regression analysis was performed to predict the percent stenosis and to predict the probability of a 70% or greater stenosis. RESULTS: Of the Doppler parameters, the peak systolic velocity in the internal carotid artery and its ratio to the peak end-diastolic velocity in the common carotid artery were the most accurate and had equivalent test performance (ROC area = 0.94; after correction for verification bias, ROC area = 0.78). In multiple regression analysis, the peak systolic velocity in the internal carotid artery was the most significant parameter, although its ratio to the peak end-diastolic velocity in the common carotid artery had incremental value in detecting a 70% or greater stenosis, and the peak systolic velocity in the common carotid artery provided additional information for quantifying the stenosis. CONCLUSION: The peak systolic velocity in the internal carotid artery is the best single velocity parameter for quantifying a stenosis and for detecting a 70% or greater stenosis.

Bias↗
PubMed1993

Risks and benefits of femoropopliteal percutaneous balloon angioplasty.

PURPOSE: The purpose of this study was to evaluate the efficacy of angioplasty in the treatment of femoropopliteal arterial disease. METHODS: From 1980 to 1991, 126 angioplasty procedures were performed in 131 limbs of 106 patients with 175 femoropopliteal lesions (26 common femoral, 118 superficial femoral, and 31 popliteal). Critical ischemia was present in 55 limbs (42%), and claudication was present in 76 (58%). Angioplasty was performed for a single lesion in 87 limbs (66%) and for multiple lesions in 44 (34%). In 13 limbs (10%) the most severe lesion was an occlusion; in 118 (90%) all lesions were stenoses. Distal runoff was good (2 or 3 vessels patent) in 72 limbs (55%) and poor (0 or 1 vessel patent) in 59 (45%). RESULTS: Death within 30 days occurred in 0.8%, nonfatal systemic morbidity in 7.1%, and local morbidity in 1.6% of procedures. Multivariate analysis revealed that indication and age were predictive of increased morbidity and mortality rates. Immediate success was achieved in 95% of limbs treated. Mean follow-up time was 2.0 years. The overall 5-year cumulative primary patency rate was 45% (+/- 5%). In a proportional hazards model indication and lesion type were predictive (p < 0.01) of long-term failure, with relative risks of 2.0 (1.2 to 3.3) and 2.7 (1.3 to 5.6), respectively. The 5-year primary patency rate after angioplasty for stenoses and claudication was 55% (+/- 7%), for stenoses and critical ischemia it was 29% (+/- 11%), and for occlusions it was 36% (+/- 14%). CONCLUSION: These results suggest that femoropopliteal angioplasty is a low-risk procedure with acceptable long-term results in patients with claudication and stenoses.

Angioplasty, Balloon↗
PubMed1992

Prospective double-blinded comparison of MR imaging and aortography in the preoperative evaluation of abdominal aortic aneurysms.

The authors conducted a prospective double-blind study comparing spin-echo axial and coronal magnetic resonance (MR) imaging with aortography in the preoperative evaluation of 20 patients with abdominal aortic aneurysms. Receiver-operating-characteristic (ROC) analysis was used to evaluate the performance of MR imaging versus aortography in assessing arterial stenotic disease. Both modalities were equivalent in demonstrating the upper extent of the abdominal aortic aneurysms with respect to the renal and visceral arteries. MR imaging was superior in demonstrating aneurysmal iliac arteries and intraluminal thrombus. Although aberrant venous anatomy, associated pathologic changes, and other concomitant lesions were demonstrated with MR imaging, it performed poorly in assessing arterial stenoses and occlusions. Thus, the authors caution against the routine substitution of spin-echo MR imaging for aortography in the evaluation of abdominal aortic aneurysms. Conventional angiography should continue to be performed in patients with suspected mesenteric ischemia, significant hypertension, and symptomatic iliofemoral atherosclerosis, at least until robust MR angiographic techniques have proved themselves under similar rigorous clinical evaluation.

Aged↗
PubMed1990

CT and MR assessment of tumors of the nose and paranasal sinuses, the nasopharynx and the parapharyngeal space using ROC methodology.

Neoplastic disease of the nose and paranasal sinuses, the nasopharynx and the parapharyngeal space requires thorough assessment of location and extension in order to plan appropriate treatment. This study evaluates computer tomography and magnetic resonance imaging in the workup of malignant and non-malignant tumors of the nose and paranasal sinuses, the nasopharynx and the parapharyngeal space in 76 patients. An attempt is made to characterize histopathology on magnetic resonance images by analyzing the signal intensities on T1- and T2-weighted images relative to muscle and brain tissue. The test performance of computer tomography and magnetic resonance imaging in the assessment of tumor extension are compared with receiver operating characteristic methodology. Although no definitive conclusions can be made as to the histopathology on the basis of the signal intensities on magnetic resonance imaging, some tumors show characteristic images. Receiver operating characteristic analysis of the performance of computer tomography and magnetic resonance imaging in the assessment of extension of neoplastic disease of the nose and paranasal sinuses, the nasopharynx and the parapharyngeal space, demonstrates no statistically significant difference in overall test performance. However, in evaluating regions involving predominantly soft tissue structures and comparatively large bony structures magnetic resonance imaging is superior to computer tomography, whereas in evaluating regions involving thin bony structures, computer tomography performs better than magnetic resonance imaging.

Adenocarcinoma↗
PubMed1988

Dacryocystography after paranasal sinus surgery.

The influence of nasolacrimal duct dissection and irradiation of the lacrimal system on lacrimal drainage were assessed. Findings at dacryocystography, in correlation with the results of dye tests and symptoms, are presented. Lacrimal drainage obstruction was demonstrated in one of 10 patients after paranasal sinus surgery not followed by irradiation and in four of 10 patients in which surgery was followed by irradiation.

Adolescent↗
PubMedDate not supplied

Cost-effectiveness of vitamin therapy to lower plasma homocysteine levels for the prevention of coronary heart disease: effect of grain fortification and beyond.

CONTEXT: A high homocysteine level has been identified as an independent modifiable risk factor for coronary heart disease (CHD) events and death. Since January 1998, the US Food and Drug Administration has required that all enriched grain products contain 140 microg of folic acid per 100 g, a level considered to decrease homocysteine levels. OBJECTIVES: To examine the potential effect of grain fortification with folic acid on CHD events and to estimate the cost-effectiveness of additional vitamin supplementation (folic acid and cyanocobalamin) for CHD prevention. DESIGN AND SETTING: Cost-effectiveness analysis using the Coronary Heart Disease Policy Model, a validated, state-transition model of CHD events in adults aged 35 through 84 years. Data from the third National Health and Nutrition Examination Survey (NHANES III) were used to estimate age- and sex-specific differences in homocysteine levels. INTERVENTION: Hypothetical comparison between a diet that includes enriched grain products projected to increase folic acid intake by 100 microg/d with the same diet without folic acid fortification; and a comparison between vitamin therapy that consists of 1 mg of folic acid and 0.5 mg of cyanocobalamin and the diet that includes grains fortified with folic acid. MAIN OUTCOME MEASURES: Incidence of myocardial infarction and death from CHD, quality-adjusted life-years (QALYs) saved, and medical costs. RESULTS: Grain fortification with folic acid was predicted to decrease CHD events by 8% in women and 13% in men, with comparable reductions in CHD mortality. The model projected that, compared with grain fortification alone, treating all patients with known CHD with folic acid and cyanocobalamin over a 10-year period would result in 310 000 fewer deaths and lower costs. Over the same 10-year period, providing vitamin supplementation in addition to grain fortification to all men aged 45 years or older without known CHD was projected to save more than 300 000 QALYs, to save more than US $2 billion, and to be the preferred strategy. For women without CHD, the preferred vitamin supplementation strategy would be to treat all women older than 55 years, a strategy projected to save more than 140 000 QALYs over 10 years. CONCLUSIONS: Folic acid and cyanocobalamin supplementation may be cost-effective among many population subgroups and could have a major epidemiologic benefit for primary and secondary prevention of CHD if ongoing clinical trials confirm that homocysteine-lowering therapy decreases CHD event rates.

Adult↗
PubMedDate not supplied

Use of a collagen hemostatic closure device to achieve hemostasis after arterial puncture: a cost-effectiveness analysis.

PURPOSE: To evaluate whether a collagen hemostatic closure device is a safe, cost-effective alternative to manual compression for achieving hemostasis at arterial puncture sites. MATERIALS AND METHODS: A cost-effectiveness analysis, based on a meta-analysis of published data, was performed from the perspective of the health-care system. The gain in effectiveness was expressed as the decrease in rate of puncture-site complications that required treatment. Costs associated with achieving hemostasis and treating complications were included. RESULTS: Use of a collagen closure device decreased the number of puncture-site complications from 31:1,000 to 16:1,000. The average cost of using the device was $177 per patient compared with $42 per patient for manual compression. The incremental cost of averting one complication exceeded $9,000. CONCLUSION: Use of a collagen closure device to achieve hemostasis after an arterial puncture may reduce the complication rate, but the additional cost per complication averted is very high.

Aneurysm, False↗
PubMedDate not supplied

Representing both first- and second-order uncertainties by Monte Carlo simulation for groups of patients.

Actual implementation of probabilistic sensitivity analysis may lead to misleading or improper conclusions when it is applied to groups of patients rather than individual patients. The practice of combining first- and second-order simulations when modeling the outcome for a group of more than one patient yields an erroneous marginal distribution whenever the parameter values are randomly sampled for each patient while the results are presented as simulated means for the group of patients. This practice results in underrepresenting the second-order uncertainty. It may also distort the shape (especially the symmetry or extent of the tails) in the simulated distribution. As a result, it may lead to premature or incorrect conclusions of superiority. It may also result in inappropriate estimates of the value of further research to inform parameter values.

Confidence Intervals↗
PubMedDate not supplied

In search of tools to aid logical thinking and communicating about medical decision making.

To have real-time impact on medical decision making, decision analysts need a wide variety of tools to aid logical thinking and communication. Decision models provide a formal framework to integrate evidence and values, but they are commonly perceived as complex and difficult to understand by those unfamiliar with the methods, especially in the context of clinical decision making. The theory of constraints, introduced by Eliyahu Goldratt in the business world, provides a set of tools for logical thinking and communication that could potentially be useful in medical decision making. The author used the concept of a conflict resolution diagram to analyze the decision to perform carotid endarterectomy prior to coronary artery bypass grafting in a patient with both symptomatic coronary and asymptomatic carotid artery disease. The method enabled clinicians to visualize and analyze the issues, identify and discuss the underlying assumptions, search for the best available evidence, and use the evidence to make a well-founded decision. The method also facilitated communication among those involved in the care of the patient. Techniques from fields other than decision analysis can potentially expand the repertoire of tools available to support medical decision making and to facilitate communication in decision consults.

Carotid Stenosis↗
PubMedDate not supplied

Testing for fetal pulmonary maturity: ROC analysis involving covariates, verification bias, and combination testing.

The lecithin/sphingomyelin ratio (L/S) and the measured value of saturated phosphatidylcholine (SPC), amniotic fluid determinations obtained to assess fetal pulmonary maturity, were evaluated with receiver operating characteristic (ROC) curve analysis. The effects of covariates on the ROC curves were analyzed with a regression methodology that took into account all the available data when constructing an ROC curve for each subgroup. To correct for verification bias the authors used a logistic regression analysis to model the probability of verification, thereby permitting correction for verification bias of a fully stratified data set in spite of small cell frequencies. They examined combination testing with prediction rules using prospective logistic modeling, including as variables test results and clinical features. The L/S was found to be significantly better than SPC for assessing fetal pulmonary maturity. For older gestational age the L/S and SPC performed better than for younger gestational age. Contamination of the specimen degraded the ROC curves. Correcting for verification bias did not influence the ROC curves significantly but changed the cutoff value of the test variable for any particular operating point. Prediction rules to evaluate combination testing showed that obtaining the SPC level in addition to the L/S ratio added no significant information compared with the L/S only. Including gestational age in the prediction rule of either test improved the prediction.

Bias↗
PubMedDate not supplied

Meta-analysis of failure-time data with adjustment for covariates.

The objective of this study was to present and illustrate a technique for combining failure-time data from various sources, adjusting for differences in case-mix among studies. Based on the proportional-hazards model and the actuarial life-table approach, the method used assumes that the variation across studies is in part due to heterogeneity of the case-mix and adjusts for the case-mix before pooling results. As an example, the technique is applied to life-table data from six selected papers reporting patency of affected arteries following femoropopliteal angioplasty. Published 4- and 5-year patency results ranged from 25% to 58%, with a pooled five-year cumulative patency rate (without adjustment for case-mix) of 45% (+/- 2%). The populations in these studies, however, differed markedly in the prevalence of factors with prognostic value: type of lesion and distal runoff vessels. After adjustment for these differences in case-mix, the pooled five-year patency rates ranged from 60% (+/- 2%) for patients with stenotic lesions and good runoff to 24% (+/- 9%) for those with occlusion and poor runoff. The authors conclude that pooling studies without considering the effect of case-mix yields an average result with inappropriately narrow confidence intervals that does not reflect the variability across subgroups. The presented technique provides a method for combining failure-time data, adjusting for case-mix.

Analysis of Variance↗
PubMedDate not supplied

Patency results of percutaneous and surgical revascularization for femoropopliteal arterial disease.

To estimate the patency results of percutaneous transluminal angioplasty and bypass surgery in the treatment of femoropopliteal arterial disease, a Medlars search of the English-language medical literature was performed. Inclusion required that studies 1) report original data, 2) report patency with a life table or Kaplan-Meier analysis with the number at risk or standard errors, 3) define patency as hemodynamic improvement, 4) report the distribution of covariates, and 5) not duplicate other published material. Using a method based on the proportional-hazards model and the actuarial life-table approach, the results were adjusted for differences in case-mix of the study populations and patency was predicted for subgroups at various levels of risk for failure. The unadjusted pooled life tables yielded five-year patencies of 45% (+/- 2%) for angioplasty, 73% (+/- 2%) for bypass surgery using a vein graft, and 49% (+/- 3%) for bypass surgery using a polytetrafluoroethylene graft. Adjusted five-year primary patencies after angioplasty varied from 12% to 68%, the best results being for patients with claudication and stenotic lesions. Adjusted five-year primary patencies after surgery varied from 33% to 80%, the best results being for saphenous vein bypass performed for claudication. The authors conclude that pooling life-table data without adjustment for covariates can be misleading. Indication, lesion type, vein graft availability, and site of the distal graft anastomosis need to be considered in predicting patency results of revascularization for femoropopliteal arterial disease.

Angioplasty, Balloon↗
PubMedDate not supplied

The relationship between descriptive and valuational quality-of-life measures in patients with intermittent claudication.

The study objective was to assess the relationship between descriptive and valuational quality-of-life measures in patients with intermittent claudication. In telephone interviews, 68 patients completed a questionnaire consisting of a descriptive health status measure (RAND 36-Item Health Survey 1.0), and several valuational measures (standard gamble, time tradeoff, rating scale, and McMaster health utility index). All measures demonstrated reduced quality of life in the patients. Scores on the RAND-36 dimensions correlated moderately well with the rating scale and McMaster health utility index (R = 0.37-0.67) but less well with the standard gamble and the time tradeoff (R = 0.10-0.46). Multiple regression analysis demonstrated that 28% of the variance in the time-tradeoff values and 14% of the variance of the standard-gamble utilities could be explained by the best combination of RAND dimensions. These results suggest that answers to descriptive health-status questions cannot reliably predict standard-gamble utilities or time-tradeoff values.

Adult↗