Cost effectiveness of diagnosis of deep vein thrombosis in symptomatic patients.

BACKGROUND: The most widely used noninvasive test for deep vein thrombosis is Doppler ultrasonographic imaging of the lower extremities. The best evaluated of the noninvasive approaches are ascending contrast venography, impedance plethysmography, Doppler ultrasonography with B-mode imaging. Economic evaluation is aimed at helping decision makers to reach their goal of maximizing the health of the population served, subject to the available resources. METHODS: The data that provided the basis for this cost effectiveness analysis were derived from a prospective study of approximately 500 patients referred to a regional thromboembolism program with a first episode of clinically suspected deep vein thrombosis. The application of cost effectiveness analysis to the diagnosis of deep vein thrombosis is readily accomplished using cost minimization. This cost effectiveness technique makes it possible to rank the diagnostic approaches from "worst" to "best", with the best approach defined as that which accomplishes the desired health effect at minimum cost. Effectiveness (health benefit) may be defined in this context as the number or proportion of patients with deep vein thrombosis correctly identified by objective testing or, the number or proportion in whom treatment was correctly withheld. RESULTS: Clinical diagnosis is cost ineffective; $1,590,784 Canadian, $2,624,220 US. Outpatient diagnosis using noninvasive testing was the most cost effective. Serial Doppler ultrasonography is more costly ($618,265 Canadian, $1,326,180 US) than serial impedance plethysmography ($527,165 Canadian, $1,052,880 US). Combined Doppler ultrasonography and serial impedance plethysmography offers a less costly strategy ($551,065 Canadian, $1,124,580 US) than serial ultrasonography alone. DISCUSSION: Objective testing is mandatory. Outpatient testing is preferred, avoiding unnecessary hospital admissions. Noninvasive testing is the most cost effective. The most widely used test, serial Doppler ultrasonography, is less cost effective than serial impedance plethysmography. The combined approach of initial Doppler ultrasonography followed by serial impedance plethysmography combines the advantage of an initial ultrasound image with less costly serial impedance plethysmography.

A practical, cost-effective, noninvasive system for cardiac output and hemodynamic analysis.

Impedance cardiography is a relatively inexpensive, noninvasive technique for measuring cardiac output on the basis of resistive changes in the thorax to electrical current flow. In conjunction with blood pressure monitoring and physiologic maneuvers, the technique may be used to monitor thoracic and total body fluid volume and express a variety of contractility indexes as well as relative and absolute measurements of stroke volume. We have tested hemodynamics in our laboratory by using a cost-effective, powerful microcomputer-based portable noninvasive technique, which makes possible the ensemble averaging of impedance cardiographic waveforms. In conjunction with physiologic maneuvers, the technique has been implemented at our institution and has provided helpful information in our experience in evaluating volume overload, hypertension, hypotension, shock, and heart failure. It is hoped that this noninvasive, relatively cost-effective approach will be more widely appreciated in the future, given the economic realities of medicine today.

Suspected deep vein thrombosis. Management by impedance plethysmography.

Controversy exists as to whether patients suspected of having deep vein thrombosis (DVT) can be studied safely without venography, with its attendant expense, inconvenience, and potential risk. We used impedance plethysmography (IPG) in 1,464 consecutive patients suspected of having DVT, with 96% of these patients with normal IPGs, there were no fatal pulmonary emboli (PE). The incidence of nonfatal PE was 1%. In 284 outpatients suspected of having DVT, but discharged without treatment because of normal IPGs, only one patient returned with subsequent symptoms of DVT (0.4%). Noninvasive testing with IPG is a safe and highly cost-effective alternative to venography for routine management of patients suspected of DVT.

Cost effectiveness of clinical diagnosis, venography, and noninvasive testing in patients with symptomatic deep-vein thrombosis.

Until the past decade, physicians were content to base therapeutic decisions on the clinical diagnosis of deep-vein thrombosis. Subsequently, numerous studies demonstrated that clinical diagnosis of this condition is nonspecific. Although many now use objective methods to diagnose venous thrombosis, their relative cost and effectiveness have not been adequately studied. We performed a cost-effectiveness analysis of 516 patients with clinically suspected venous thrombosis who were evaluated by clinical diagnosis, venography, and the less invasive combination of impedance plethysmography and leg scanning. We used this analysis to rank these alternative approaches in terms of both cost and effectiveness. The results indicate that clinical diagnosis is cost ineffective. Venography is cost effective--more so when applied as an outpatient investigation. Impedance plethysmography plus leg scanning is a practical, less invasive alternative to outpatient venography. The cost of inpatient diagnosis is likely to remain the major cost; thus, emphasis should be placed on outpatient diagnostic procedures.

Therapeutic and economic implications of emergency department evaluation for venous thrombosis.

Records of 160 emergency department patients with lower extremity complaints were reviewed to determine the economic and therapeutic impact of noninvasive venous impedance testing. Venograms obtained in 86 extremities were used to determine diagnostic accuracy. The incidence of pulmonary thromboembolic events, postphlebitic syndrome and complications of anticoagulation was ascertained. Outflow impedance testing correctly identified all patients with deep venous thrombosis and overall diagnostic accuracy was 95% (41/43 patients). In 123 patients (33 positive results, 90 negative) therapeutic decisions were based solely on impedance test results. Examination required 20 to 30 minutres at a cost of $35. Follow-up ranging from 4 to 60 weeks failed to reveal documented thromboembolic complications or recurrence of lower extremity symptoms. In 37 patients (six positive results, 31 negative) impedance test results were ignored and inpatient workup, including invasive venography, was undertaken. Hospital charges for these patients averaged $1,500. In addition to its ease of performance and high degree of accuracy, comparison with inpatient evaluation documents its cost effectiveness. Impedance testing for emergency department evaluation of suspected deep vein thrombosis appears appropriate.

Measurement of cardiac output in man with a U.S. $150 plethysmograph

It has been found possible to adapt a simple battery-operated plethysmograph costing U.S.$150 for the measurement of cardiac output. Although the method is certainly less convenient and possibly less accurate than the computerized impedance cardiographs(costing $23 000) now often used in the United States, it provides a useful measurement of changes in cardiac output over a period of time. In developing countries, it can be recommended for the repeated assessment or monitoring of patients during surgery, in Critical Care Units and in the evaluation of patients during circulatory stress tests (AU)