Department of Health and Human 
 Servces 

OFFICE OF


INSPECTOR GENERAL


ZERO CROSSERS


( JiL Richard P. Kusserow 

INSPECTOR GENERA 

,f3a AUGUST 1991
OFFCE OF INSPECfORGENRA


The mission of the Offce of Inspector General (OIG), as mandated by Public Law 95-452 

as amended, is to protect the integrty of the Department of Health and Human Servce 

(HHS) programs as well as the health and welf!ire of beneficiaries served by those programs.

Th statutory mission is carried out through a natiOfwi e network of audits, investigations 

, and inspetions conducted by three OIG operating 'components: the Offce of Audit 

Servce, the Office of Investigations, amI the Offce of Evaluation and Inpections. The 

DIG also inform the Secretary of HHS of program and management problems and 

recmmends courses to correct them. 

OFFCE OF AUDIT SERVICE 

The DIG's Offce of Audit Servces (OAS) provides all auditing servce for HHS, either by 

conducting audits with its own audit resurce or by overseeing audit work done by others. 

Audits examine the performance of HHS programs and/or itS grantees and contractors in 

carrng out their respective responsibilities and are intended to provide independent 

asesments of HHS programs and operations in order to reduce waste, abuse, and 

mimanagement and to promote economy and effciency throughout the Department. 

OFFICE OF INTIGATIONS 

The DIG's Offce of Investigations (01) conducts criminal, civil, and administrative 

investigations of allegations of wrongdoing in HHS programs or to HHS beneficiaries and of 

unjust enrchment by providers. The investigative effort of 01 lead to crinal convictions 

admintrative sanctions, or civil money penalties. The 01 also oversee State Medicaid fraud 

control units which investigate and prosecute fraud and patient abuse in the Medicaid 

program. 

OFFCE OF EVALUATION AN INSPECTONS 

The DIG's Office of Evaluation and Inpections (DEI) conducts short-term management and 

progrm evaluations (called inspections) that focus on isues of Concern to the Department 

the Congress, and the public. The' findings and recommendations contained in these 

inpetion report generate rapid, accurate, and up-to-ate information on the effciency, 

wlnerabilty, and effectiveness of departmental programs. 

The report was prepared by the Philadelphia Regional office under the direction of 

Joy Quil, Regional Inspector General and Robert Vito, Deputy Regional Inpector General. 

Project Staff: 

Robert A Katz, Project Leader 

Cythia R. Hansford


W. Mark Krushat (Headquarters)


Wayne Powell (Headquarters)

Department of Health and Human Services


OFFICE OF


INSPECTOR GENERA


ZERO CROSSERS


Richard P. Kusserow 

INSPECfOR GENERAL 

'.t 

Ciao OEI-03-91­
EXECUTIVE SUMMAR 


PUROSE 

This report quantifies Medicare reimbursement for in-office diagnostic tests of arteries and veins conducted with ultrasonic detecting devices using a "zero-crossing technique. 

BACKGROUN 

In a previous report (Low-Cost U1trasound Equipment, OEI-03-88-01401), we reviewed the appropriateness of Medicare reimbursement for diagnostic tests conducted with unsophisticated, ultrasonic devices. We encountered two basic tyes of devices-- Pocket Dopplers and Zero Crossers. 

Pocket Dopplers are the least sophisticated tye of ultrasound equipment. Small 

hand-held devices, they are tyically nondirectional and their only output is audio. 

A variety of devices exist at a technological step above Pocket Dopplers. These 

devices--which we term Zero Crossers--document test results via a recordable 

waveform, similar to an electrocardiograph (EKG) record. Typically, these devices 

are bidirectional, constructed in a table-top configuration, and cost between $3000 

and $7000.


METHODOLOGY 

This report is based on a random sample consisting of 480 services from 8 Medicare 

carriers. The selected carriers represent more than half of in-office allowances for 

ultrasonic vascular tests nationally. We limited the selected servces to in-office 

diagnostic vascular tests conducted during 1988. 

FININGS 

Seventeen Percent of Servces Were Conducted Wih Zero Crossers 

Fifty- three servces in our ample--represeI)ting 17 percent of the responses--were 

conducted with Zero Crossers. We calculate that Zero Crossers were used to 

conduct 62 079 servces in 1988. 
Medicare Allowed Between $8 and $12 Million for Servces Conducted With Zero


Crossers in 1988


We estimate that Medicare allowed about $8 milion for servces conducted with 

Zero Crossers. If non-respondents and respondents had the same usage rate, an additional $4 milion could have been allowed for Zero Crossers in 1988. 

Many Tests Done Wtth Zero Crosers May Be Inaccuate 

A review of scientific literature revealed a number of studies highlighting deficiencies

in the accuracy of equipment using zero-crossing technology. 

Reimburement for Zero Crossers and More Sophisticated Eqipment are Simil 

Zero Crossers were reimbursed about the same as devices producing sophisticated and clinically detailed imaging. The Medicare allowance for Zero Crossers was 

approximately $125 (weighted average) while the average allowance for state-of-theart equipment was about $135. 

CONCLUSION 

Our "Low-Cost Ultrasound Equipment" report recommends that HCF A advocate 

revisions in procedure codes and reimbursement rates to reflect the different levels 

of sophistication and quality of diagnostic information provided in such tests. 

\Ve continue to support this recommendation. If HCF A adopts it, potential savings from the 5-year period beginning 1992 range from about $25 million to $124 millon 

depending on the reimbursement level. 
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

TABLE OF CONTENTS


EXUT SUMY


INODUCTON . . . . . . . . . . . I


FIINGS ................................................... 5


CONCLUSION . . . . . . . . . . . . . 7


APPENIX . . . . . . . . . . . . . A­
INTRODUCTION


PUROSE 

This report quantifies Medicare reimbursement for in-office diagnostic tests of arteries and veins conducted with ultrasonic detecting devices using a "zero-crossing technique. 

BACKGROUN 

Diagnosticians use sensitive instruments operating on ultrasound principles to detect arterial and vascular diseases. These devices emit high frequency soundwaves into 

the tissues. Depending on the sophistication of the device used, reflected ultrasound signals may be detected by one of four techniques--audio only, strip-chart recording 

using a "zero crossing" technique, spectral analysis, or imaging. In general, audioonly devices are considered the least accurate and refined of the various methods.


Imaging devices produce superior diagnostic output.


Diagnostic ultrasound tests are usually conducted using "mid-level" equipment. This equipment costs from $15 000 to $60 000 and offers a wide range of sophisticated options, such as remote control, selectable frequency ranges, and video spectrum analysis of blood flow measurements. The ensuing diagnostic output provides a level 

of quality which meets the needs of most clinicians. 

More expensive (so-called "state-of-the-art ) equipment offers two-dimensional 

displays, computerized analysis, and color-flow imaging. Devices equipped with 

color-flow imaging produce video pictures of blood flow velocities in combinations of 

red, blue, and green. Changes in the intensity of color and blood flow velocity can indicate an irregularity, such as a blockage. 

Nationally, Medicare allowances for four major procedure codes used in diagnostic ultrasound tests of arteries and veins surpassed $88 million for in-office servces in 

1989, an increase of more than 31 percent over 1988. These tests increased almost 

25 percent for the corresponding period.


In a previous report (Low,.Cost Ultrasound Equipment, OEI-03-88-01401), we reviewed the appropriateness of Medicare reimbursements for diagnostic tests conducted with inexpensive. relatively unsophisticated ultrasonic devices. We 

encountered two basic types of devices--Pocket Dopplers and Zero Crossers. 
Pocket Dopplers and Zero Crossers 

Pocket Dopplers are the least sophisticated type of ultrasound equipment. A handheld device, the typical Pocket Doppler transmits a continuous or pulsed beam of 

ultrasound at moving blood cells. Typically, the Pocket Doppler is non directional 

(i. , it is incapable of determining the direction of blood flow) and produces audio 

signals only. Such tests can be conducted in less than five minutes. These devices 

are marketed as diagnostic ultrasound equipment and generally cost under $1000. 

We reported the impact of Pocket Doppler usage in a Management Advisory 

Report, entitled "Pocket Dopplers" (OEI-03-91-00461). Our findings on Zero Crossers are addressed in this report. 

A variety of devices exist at a technological step above Pocket Dopplers. These 

devices--which we term Zero Crossers--document test results via a recordable 

waveform. This process converts the mean frequency of the doppler signal into a 

proportional display via a frequency-to-voltage (zero crossing) strip-chart tracing, 

similar to an electrocardiograph (EKG) recording. Typically, these devices are 

bidirectional (capable of determining blood flow direction), constructed in a tabletop configuration, and cost between $3000 and $7000. 

Test result evidence is the most obvious clinical difference between Pocket Dopplers 

and Zero Crossers. (Pocket Dopplers do not produce objective test evidence while 

Zero Crossers provide tangible evidence.) More sophisticated equipment provides 

detailed documentation using spectral analysis or high-resolution images. 

A device using zero-crossing technology records the average speed of all the cars on 

a highway, while spectral analysis registers the individual speed of each car, according to an analogy offered by one expert. In effect, a Zero Crosser provides a single 

frequency display of the soundwave whereas spectral analysis records multiple 

quantitative frequencies. State-of-the-art equipment tyically produces test results in 

a video hard-copy image.


Approximately 15 manufacturers produce and market Pocket Dopplers and Zero 

Crossers. Industry sources estimate that at least 100 000 units are in active use in 

the medical community. About 20 000 new units were sold in 1990. 
Prevous Inspection Finings 

Our previous study highlighted a number of issues and concerns. Briefly, we found: 

A variety of ultrasound equipment exists ranging from Pocket Dopplers to 

state-of-the art equipment costing more than $300 000. 

Medicare procedure codes fail to distinguish between test tyes or results. 

The Health Care Financing Administration Procedure Coding System (HCPCS) does not differentiate between the extent of a test or the nature 

test results. Further, the same rate of reimbursement applies to a test without regard to its extensiveness or the quality of the data produced. 

There are strong incentives for excessive use. Since Medicare 

reimbursements do not consider the quality of equipment used and the 

quality of test results, excessive payments can be claimed for a relatively simple screening test based on a comparatively modest investment. 

The Health Care Financing Administration (HCF A) is vulnerable to 

inappropriate bilings. Medicare carriers lack sufficient safeguards to detect bilings based on inferior test results. 

A precedent exists to deny payments for Pocket Doppler tests. In a previous 

decision, HCF A ruled that a portable hand-held x-ray instrument "should be 

reimbursed as part of the physician s professional service, and no additional 

charge should be allowed. 

We recommended that HCFA prohibit payment for Pocket Doppler tests and 

advocate revisions in procedure codes and reimbursement rates to reflect the 

different levels of sophistication and quality of diagnostic information provided in 

ultrasound tests. 

METIODOLOGY 

This report is based on a 2-stage random sample consisting of 480 servces from 8 

Medicare carriers. During the first stage of sampling, 8 Medicare carriers were 

randomly selected, with the probability of selection proportionate to total amounts 

reimbursed under Medicare in 1988. The selected carriers represent more than half 

of in-office allowances for ultrasonic vascular tests nationally. The carriers were 

Florida Blue Shield; Michigan Blue Shield; Empire Blue Shield (New York); California Blue Shield; Arkansas Blue Shield, as the carrier for Louisiana; Blue 

Shield of Indiana; Transamerica Occidental of California; and the Railroad 

Retirement Board.

At the second stage of sampling, we selected 60 servces per carrier from 1988 Part 

B Medicare Annual Data (BMA) bilings. We limited the selected services to inoffice diagnostic vascular tests conducted during 1988. The services consist of four of 

the most commonly used HCPCS codes by practitioners of these tests: 93910 

(noninvasive studies of lower extremity arteries); 93950 (noninvasive studies of lower 

extremity veins); 93860 (noninvasive studies of carotid arteries); and 93890 

(noninvasive studies of upper extremity arteries). 

After the carriers supplied us with pertinent claims data, we wrote to the 

practitioners requesting detailed information on the tyes of equipment used conduct the tests. In particular, we were interested in five features--configuration 

(pocket, portable, pen, tabletop); power source; blood flow direction; price; and 

documentation capabilty. We also requested copies of any charts, graphs, or 

printouts produced during the tests. 

We reviewed the responses against scientific publications, manufacturers' catalogs and related technical materials to determine if low-cost devices had been used to 

conduct the tests. We consulted with a Registered Vascular Technologist (RVT) 

who reviewed test results and assisted us in making determinations. 
FINDINGS


Seventeen Percent of Servces Were Conducted With Zero Crossers 

Sixty-five percent of the providers in our sample (314 of 480) responded to our 

requests. Based on our analysis, we determined that 53 services in our sample-­

representing 17 percent of the responses--were conducted with Zero Crossers. 

Applying the 17 percent usage rate and the 65 percent response rate, we calculate 

Zero Crossers were used to conduct 62 079 services in 1988. If non-respondents 

usage rates were the same as for respondents, servces conducted by Zero Crossers 

could increase by 33 427 in 1988, bringing total 1988 servces to 95 506. 

In our "Pocket Doppler" report, we found that Pocket Dopplers accounted for 7 

percent of ultrasound tests in 1988. Taken together, tests done by Pocket Dopplers and Zero Crossers represent nearly one-quarter of all in-office ultrasound tests 

conducted in 1988. 

Medicae Alowed Between $8 and $12 Mion for Servces Conducted With Zero 

Crossers in 1988. Alowances for 5 Years Could be $124 Mion 

Allowances for sample servces conducted with Zero Crossers ranged from a low of 

$15 to a high of $324 with an overall weighted average of $125. Based on our 

projections, we estimate that Medicare allowed approximately $8 millon for these 

services. If we assume that non-respondents and respondents had the same usage 

rate, an additional $4 milion could have been allowed for Zero Crossers in 1988. 

\Ve estimate that Medicare will allow approximately $124 milion for services 

conducted with Zero Crossers for the 5-year period beginning in 1992. To estimate 

Medicare allowances, we applied the 65 percent response rate and the 17 percent 

Zero Crosser usage rate to the 700 700 allowed services for the 4 codes in 1989. 

Non-respondents were not included in our calculations even though there is no 

reason to suspect the usage rate for non-respondents differs from respondents. 

assumed an annual 20 percent increase in the number of servces (the actual annual 

increase from 1987 to 1989 was between 25 and 30 percent). We used the 1988 

average allowed amount of $125 per service for all 5 years. We omitted possible reimbursement increases because of recent legislative changes designed to minimize 

ITcreases. 

Many Tests Done With Zero Crossers May Be Inaccurate 

Deficiencies in the accuracy of equipment using zero-crossing applications have been 

recognized for many years. 1988 study of 157 patients concluded: 
... . , 

, 

the errors...of zero-crossing techniques have been recognized for 10 to 15 

years...The inability of the zero-crossing tracing to provide complete and 

accurate information in 50 percent of the cases severely limits its 

usefulness. ' 'I 

A 1977 study on multiple arterial readings concluded: 

recordings made by zero-crossing detectors cannot be used for quantitative 

analysis. Moreover, errors are common enough that even qualitative 

interpretation of the recordings may be questionable in many cases. 

Additional pertinent references are. cited in the Appendix. 

Our consultant who examined a sample of test results confirmed that Zero Crossers 

often produce questionable results compared with more sophisticated equipment. 

Reimburements for Zero Crossers and More Sophiticated Equipment are Simar 

The 53 devices we determined to be Zero Crossers were reimbursed about the same 

as devices producing sophisticated and clinically detailed imaging. Overall, the 

weighted Medicare average allowance for Zero Crossers was approximately $125 

while the average allowance for services conducted with more sophisticated 

equipment was $135. 

In theIr efforts to market Zero Crossers, manufacturers do not neglect the potential

compensation which their products provide. As an example, one of the brochures 

we encountered contained this advice: 

In addition to its diagnostic value, low cost and simplicity of operation


the annotated charts provide invaluable documentation in this age of


medical-legal liability. (Name of device) tests are MEDICARE approved 

and reimbursable by third party insurers under several CPT codes. Average 

reimbursement exceeds $150. 

1 Cynthia Kupper Burnham, RVT, Nancy Dewhirst, RVT, and Steven J. 

Burnham, MD Doppler Spectral Waveforms For Recording Peripheral Arterial 

Signals: The Preferred Method The Joumal of Vascular Technology, April, 1989. 

2 K. Wayne Johnston, MD, Bruno C. Maruzzo, MASc, and Richard S. C. 

Cobb aId, ARCS, MSc, PhD Inaccuracies Of A Zero-Crossing Detector For 

Recording Doppler Signals Surgcal Forum, 1977. 
CONCLUSION


Our report on Low-Cost Ultrasound Equipment recommends that HCF A advocate 

revisions in procedure codes and reimbursement rates to reflect the different levels 

of sophistication and quality of diagnostic information provided in such tests. (We 

understand HCF A has encouraged procedure code revisions in vascular tests during 

recent contacts with the American Medical Association s editorial board. 

We estimate the following potential savings on Zero Crosser servces if HCF A 

adopted our recommendation. The chart depicts various payment options ranging 

from non-coverage to $100 for I-year and 5-year periods. 

ZERO CROSSERS


REIMBURSEMENT YEAR SAVINGS YEAR SAVINGS 

$16. MILLION $124. 5 MILLION 

$20 $14. MILLION $104. 5 MILLION 

$40 $11.4 MILLION $84. MILLION 

S60 $8. 7 MILLION $64. MILLION 

$80 $6, 0 MILLION $44. MILLION 

$100 $3. 3 MILLION $24. 9 MILLION 
, 

, , , , , 

APPENDIX


REFERENCES 

Barnes, Robert W. Noninvasive Diagnostic Techniques In Peripheral Vascular 

Disease American Heart Joumal February, 1979. 

Flax, S. , Webster, J. , and Updike, S. Noise And Functional Limitations Of 

The Doppler Blood Flowmeter " Department of Electrical Engineering, Department 

of Medicine, University of Wisconsin, Madison, Wisconsin. 

Johnston, K. Wayne, Maruzzo, Bruno c., and Cobbold, Richard S. Errors And 

Artifacts Of Doppler Flowmeters And Their Solution " Read Before The 25th 

Meeting Of The International Cardiovascular Society, Rochester, New York, June 16 

1977. 

Nix, M. Lee, and Barnes, Robert W. Noninvasive Peripheral Vascular Laboratory 

Diagnostic Techniques " University of Arkansas For Medical Sciences, Little Rock 

Arkansas, 1985. 

Reneman, Robert S., Clarke, Howard F., Simmons, Norman, and Spencer, Merrill P. 

In Vivo Comparison Of Electromagnetic And Doppler Flowmeters: With Special 

Attention To The Processing Of The Analogue Doppler Flow Signal Cardiovascular 

Research, 1973. 

Reneman, Robert S., and Hoeks, Arnold P. Doppler Ultrasound In The 

Diagnosis Of Cerebrovascular Disease Research Studies Press, 1982. 

Reneman, Robert S., and Spencer, Merril P. Difficulties In Processing Of An 

Analogue Doppler Flow Signal; With Special Reference To Zero-Crossing Meters 

And Quantification " Janssen Research Foundation, Beerse, Belgium, and Institute of 

Environmental Medicine and Physiology, Seattle, Washington.