The Costs of 
Hyperbaric Oxygen Therapy
Prepared for: The Hyperbaric Oxygen Therapy Association, Inc.
Prepared by:Kevin A. Coleman
The Lewin Group
December 31, 1998

executive summary

The Lewin Group has conducted an analysis of the costs and proposed outpatient payment of hyperbaric oxygen therapy (HBOT) for the Hyperbaric Oxygen Therapy Association (HBOTA), Inc. This study consisted of three parts:

·        Reviewing of the treatment of HBOT under Health Care Financing Administration?s (HCFA) proposed outpatient prospective system (OPPS);

·        Conducting a cost survey of HBOT provided in hospital outpatient departments; and

·        Applying cost survey data to HCFA HBOT claims data to calculate HBOT costs.

The results of this analysis suggest that the OPPS? proposed reimbursement amount for HBOT, $134, is less than half the median costs of providing this service. An analysis of this study?s cost survey data determined that median HBOT costs were $273 to $292. Applying key elements from the cost survey data to HCFA HBOT claims data calculated median costs of $374 and mean costs of $277 for HBOT. Each part of the study?s analysis is described below.

First, the treatment of HBOT under the Health Care Financing Administration?s (HCFA?s) proposed outpatient prospective payment system (OPPS) rule published in the September 8, 1998 Federal Register was reviewed. It is one of the few procedures that has its own ambulatory patient classification (APC), and HBOT is not subject to any multiple procedure discounting. Other features of the proposed OPPS are more problematic for HBOT. For example, the proposed OPPS payment amount for HBOT ($134) is less than the beneficiary copayment amount ($142). This is the only APC where beneficiary copayments exceed the HCFA payment amount, and suggests that HCFA used very low cost to charge ratios when converting HBOT charges to costs. This would reduce both its estimates of HBOT costs, and in turn, its payment for HBOT under its OPPS.

The second part of the study was to conduct a cost survey of HBOT departments. A total of 46 departments responded to the cost survey. The results of the cost survey included the following:

·        HBOT departments bill differently – some departments bill for each 90 minute HBOT session, others bill for an initial 60 minute session followed by 30 minute sessions, while others bill for shorter sessions (15 or 30 minutes);

·        CCRs appear to be much higher than those used by HCFA – the median CCR calculated for cost survey respondents was 51 percent compared to  a median of 24 to 25 percent for the HBOT CCRS HCFA used; and

·        Costs per HBOT session are much higher than HCFA?s proposed OPPS payments – median costs per HBOT session were $273 to $292, and 80 percent of respondents had costs per HBOT session that exceeded HCFA?s proposed payment amount ($134).

The last part of the study was to analyze the claims data file HCFA used to develop its proposed OPPS. Claims with HBOT were extracted from this file. There were a total of 15,505 claims for 254 hospitals. Next, these HBOT claims data were then matched to the cost survey data; 31 hospitals representing 2,917 HBOT claims could be matched. The matched hospitals were then compared to all 254 hospitals that provided HBOT services in hospital outpatient departments. While the 31 hospitals tended to provide more HBOT sessions to more patients and their costs and charges were slightly higher, this set of hospitals appeared to be broadly representative of all hospitals providing HBOT to Medicare beneficiaries in hospital outpatient settings.

Two key elements from the cost survey were then applied to the HBOT claims data for the 31 matched hospitals. First, information on how each hospital billed for HBOT was used to convert their units of service as reported in the HCFA claims data to a common standard unit (a 90 minute HBOT session). This adjustment on average reduced total HBOT units by 21 percent. Second, the CCRs calculated from cost survey cost and charge data were applied to HBOT charges on the HCFA claims data to calculate HBOT costs. Using the cost survey CCRs increased HBOT costs by an average of 71 percent. The units of service adjustment and cost survey CCRs combined to increase median HBOT costs for the 31 matched hospitals from $139 to $374.

As a last step, hospitals responding to the cost survey were contacted and asked to supply copies of Worksheet C, Part II, from the Medicare Cost Reports for FY96 and FY97. This part of the Medicare cost report is where hospitals report their CCR calculations. Eleven hospitals supplied this information. A review of this cost report data indicated that CCRs as reported in the Medicare cost report for these two fiscal years were on average higher than the CCRs calculated from cost survey data. This review provides further evidence that the CCRs HCFA used to determine HBOT costs might have been too low. Using lower CCRs would lead HCFA to underestimate HBOT costs and thus set HBOT reimbursement amounts at too low a level.

II.      introduction

In the September 8, 1998 Federal Register, the Health Care Financing Administration (HCFA) presented its proposed hospital outpatient prospective payment system (OPPS) based on ambulatory patient classifications (APCs). The OPPS maps CPT-4 codes into APCs to determine payment for each outpatient visit; a single outpatient visit may include multiple APCs. One of the APCs is 969: Hyperbaric Oxygen. APC 969 includes a single CPT-4 code, 99183 (Physician Attendance and Supervision of Hyperbaric Oxygen Therapy, per Session). On page 47830 of the September 8, 1998 Federal Register, the proposed national payment amount for APC 969 is $134.27, and the proposed beneficiary copayment amount is $141.70.

A new professional association, the Hyperbaric Oxygen Therapy Association, Inc. (HBOTA), contacted The Lewin Group to express its concerns regarding the proposed treatment of hyperbaric oxygen therapy (HBOT) under HCFA?s OPPS. In particular, HBOTA believed the proposed payment amount for APC 969 was too low and would not cover the costs of providing this service to Medicare beneficiaries in most hospital outpatient settings. In addition, a question was also raised about the beneficiary copayment amount for APC 969. This is the only APC that has a beneficiary copayment that exceeds its proposed reimbursement amount. HBOTA was concerned that there could be problems either with the hyperbaric oxygen data HCFA used and/or with the analysis HCFA conducted using these data.

For these reasons, HBOTA contracted with The Lewin Group to conduct a study of the costs of providing HBOT. This project consisted of three tasks. First, the proposed rule?s treatment of 99183 was reviewed.

Second, a cost survey was prepared and then sent to hospital-based hyperbaric oxygen therapy departments. The results of this survey were then analyzed to determine how different departments bill for HBOT and their costs of providing these services.

Third, a data file for HBOT was extracted from the 1996 claims file HCFA used to develop its OPPS. These data were then compared for hospitals that completed the cost survey and for all hospitals that provided HBOT in 1996. This analysis suggested that the cost survey hospitals were broadly representative of all hospitals providing HBOT. Next, several key data elements from the cost survey were then applied to the HCFA claims data to re-estimate HBOT costs. The results of this analysis suggest that the proposed reimbursement for APC 969 is considerably below the costs of providing these services.

III.    review of the proposed rule

HCFA has placed HBOT (CPT-4 code 99183) in its own APC (969). This is unusual, because most APCs consist of groups of different CPT-4 codes. Payment for HBOT thus is not directly affected by the costs of other CPT-4 codes. In addition, APC 969 has a status indicator of ?S.? This means that payment for APC 969 is never subject to multiple procedure discounting.[1]

Other aspects of the proposed OPPS have troubling implications for HBOT. As mentioned above, APC 969 is the only APC that has a beneficiary copayment ($141.70) that exceeds the proposed payment amount ($134.27). This suggests that HCFA may be using cost to charge ratios (CCR) for HBOT that are very low relative to other outpatient CCRs. While the actual computations are more complex, in rough terms, payment amounts for each APC are based on that APC?s median costs per procedure. HCFA used department-level cost to charge ratios to convert charges to costs on a line item basis on each claim. If charges per HBOT service are over $700 and the proposed payment is $134, this implies that the CCR HCFA used to convert costs to charges for HBOT must have been in the neighborhood of 19 to 20 percent. These CCRs appear to be quite low, particularly for services as capital intensive as HBOT.[2] Typically, outpatient department CCRs range between 50 and 70 percent.

One other issue was the use of ?singleton? claims data in setting APC relative payment weights. Under the OPPS, payment is for the most part based on a relative payment weight and a conversion factor.[3] Each APC?s relative payment weight is equal to the median cost per service for that APC divided by the median cost for a reference APC (a mid-level clinic visit). Relative payment weights are then multiplied by a single conversion factor to translate relative weights into payments.

HCFA faced a problem when calculating its relative payment weights. In addition to medical procedures, most claims include supplies and other ancillary services that are packaged with procedures when payments are being made. On procedures with more than one significant procedure, it is not clear which ancillary charges should be packaged with which significant procedure. HCFA?s solution was to use only ?singleton claims? – claims with only one significant procedure, in its relative weight calculations.

This choice meant that relative weights were frequently based on comparatively few claims. The 1996 claims file HCFA used to create its hospital OPPS included 98 million claims. Of this total, 15 million claims were eliminated because they were for non-covered services. Of the resulting 83 million claims, 46 million were multiple procedure claims and 37 million were singleton claims. Of the 37 million singleton claims, a further 11 million claims were eliminated because these claims were for services reimbursed separately under the laboratory fee schedule. Thus, only 26 million claims were used to calculate relative weights. While this is a large number of claims overall, in practice for specific APCs relatively few claims were available for analysis.

For hyperbaric oxygen, we determined that there were 15,505 claims that included the 99183 CPT-4 code. Of this total, 4,754 were singleton claims.[4] There are two problems using singleton claims to represent HBOT costs. First, very few patients receive only HBOT during an outpatient visit. Most patients are receiving HBOT for wound therapy. During their visit, their dressings are cleaned and changed, often their wounds are debrided or treated in some other fashion. This means that most typical HBOT occurs during multiple procedure visits. Thus, singleton claims may not be representative of an ?average? HBOT visit. Second, most HBOT patients receive a large number of HBOT sessions. The 15,505 claims represented 100,077 units of HBOT service, or more than six units per claim. Very often, departments bill on a weekly or monthly basis, and these ?series? bills are especially likely to include other significant procedures (e.g., debridements, skin repairs, etc.). Singleton claims therefore represent a disproportionately low number of the total number of HBOT units of service and may not be representative of ?typical? HBOT. 

IV.   cost survey analysis

The potential data problems HCFA faced suggested that this study should collect data directly from hospital-based HBOT programs. In this section, the cost survey instrument and how it was fielded are discussed first. Next, the findings from the survey are then described.

A.     Developing and Fielding the Cost Survey

A copy of the cost survey used in this study is included in Appendix A. As the survey was developed, several key issues were raised by HBOTA board members. First, it became apparent that HBOT departments billed for their services in different ways. Some departments billed for their services separately, while others billed as part of a larger department (e.g., respiratory therapy or anesthesiology). In addition, departments defined a HBOT ?procedure? in very different ways. For example, while many departments defined a procedure as a 90 minute session (under pressure), others used shorter periods, or defined two periods – an initial 60 minute period followed by a 30 minute period. The survey clearly needed to ask questions regarding how departments bill for their services to make ?apples to apples? comparisons. Second, the survey needed to be kept simple, to allow enough time to collect and analyze the data during the proposed rule?s comment period and to improve the response rate. Finally, the data collected by the survey needed to remain strictly confidential.

The resulting survey collected the following information:

·        Contact name and address – these data were collected until to keep track of who responded to the survey (to encourage non-respondents to complete their response) and to identify a ?point person? at each institution if survey responses needed clarification or to request additional information;

·        Medicare provider number and wage index – the provider number allowed these data to be linked to the HCFA claims data (described below), and to convert cost and charge data to national amounts;

·        Reporting period – most departments provided data from FY97 or FY98. The reporting period information was then used to convert cost and charge data into 1998 dollars (as of October 1, 1998);

·        Whether HBOT  is reported as separate cost center;

·        How HBOT is billed and when 99183 coding started – each department responded how it bills for HBOT (by procedure, by different time increments, etc.). One reason for billing differences across departments was the introduction of the 99183 code. Traditionally, departments billed two HBOT codes – 99180 (initial period) and 99182 (each subsequent period). While these codes did not define initial and subsequent periods, many departments billed for the first hour of HBOT under 99180 and for each additional period (15 or 30 minutes) under 99182. The 99183 code replaced the 99180 and 99182 codes starting in 1994, but hospitals were allowed a two year ?grace period? to make this change. There is some evidence that 99180 and 99182 may have been used as local codes during or after 1996;[5]

·        Charge per HBOT service;

·        Size and Medicare share – departments were asked to report their number of patients and number of HBOT procedures provided, and indicate what share of these services were provided to Medicare patients;

·        Facility costs by category – the cost survey asked each department for its costs in the following categories: (1) plant; (2) equipment; (3) supplies; (4) contract labor; (5) direct labor; (6) payments to service providers running their program on a contract basis; (7) bad debt and charity care; and (8) other.

·        Facility charges (Medicare and non-Medicare); and

·        Case mix – departments were also asked to provide the number of services and charges by CPT for other non-HBOT services they provided. These data were not used in this analysis.

There was insufficient time during the comment period to field the cost survey to a random sample of departments that provide HBOT.[6] To allow as many departments as possible to respond to the survey, the HBOTA worked through the Undersea Hyperbaric Medical Society (UHMS), a professional organization for physician specialists in hyperbaric medicine. The UHMS contacted its 3,000 physician members and forwarded them copies of the survey, requesting that the physicians then provide the survey to the hospital-based HBOT departments where they treat patients. In addition, HBOTA board members also used the contacts with HBOT departments to encourage more hospitals to participate in the survey. With this approach, nearly all hospital outpatient departments providing HBOT had the opportunity of responding to the cost survey.

B.    Survey Results

To encourage participation in the survey, respondents were guaranteed complete confidentiality. Respondents either mailed, faxed, or emailed their survey responses directly to The Lewin Group. The data were then entered into an electronic database that The Lewin Group had sole access to during this study. The current plan is to destroy these data sometime after the study has been completed. To further maintain confidentiality, information from the survey is presented using only summary statistics – e.g., means, medians, and ranges. No individual data are reported.

A total of 46 departments responded to some or all portions of the cost survey. Of these respondents, 31 could be matched to HCFA claims data using Medicare provider numbers. Below, responses to each survey question are presented.

The responses for all respondents are then compared to respondents who could be identified later in the HCFA claims database (?In HCFA?). As we will see below, the responses for all respondents are quite similar to the responses for the In-HCFA respondents. There is no reason to suppose that the In-HCFA subsample does not fairly represent all respondents to the cost survey.

1.      Where Are Respondents Located?

There is broad geographic representation among the 46 survey respondents (Table One). Respondents represent seven of the nine Census Division regions. The geographic distribution of cost survey respondents is also compared to the distribution of hospitals providing HBOT to Medicare beneficiaries in outpatient settings (tabulated from the 1996 Medicare claims HCFA used to develop its OPPS). The distribution of departments across Census Division Regions is quite similar. Relative to the HCFA data, respondents to the cost survey were more likely to be located in the South Atlantic and West South Central Regions, and less likely to be located in the New England, Mountain, East South Central Regions. It does not appear that the large number of Texas respondents to the cost survey had any effect on the cost survey?s qualitative findings.[7]

Table One

Percentage of HBOT Departments in Each Census Division Region: Cost Survey and 1996 HCFA Outpatient Claims Data Sets

 

Census Division Region	Cost Survey Respondents	1996 HCFA Outpatient Claims Data
New England	0.0%	2.0%
Mid Atlantic	8.7%	8.7%
South Atlantic	21.7%	17.3%
East North Central	10.9%	12.6%
East South Central	4.3%	8.7%
West North Central	8.7%	6.3%
West South Central	34.8%	28.3%
Mountain	0.0%	5.5%
Pacific	10.9%	10.6%

2.      How Do HBOT Departments Report Their Costs and Bill for Their Services?

HBOT departments vary considerably in the way they report their costs and in how they bill for their services. Forty-one of the 46 respondents indicated how they report their costs. Most HBOT departments (32 of 41) report their costs separately. The other nine departments report their costs either as part of the anesthesia (two) or respiratory therapy (seven) departments. This variation should be accounted for when converting charges to costs, as HCFA did in calculating costs and relative payment weights for APC 969.

There is even more variation in how departments bill for their services. The 41 departments that responded to this question reported nine different ways of billing for HBOT, including:

·        Per procedure (18);[8]

·        Initial 60 minute increments, followed by 30 minute additional increments (10);

·        60 minute increments (4);

·        30 minute increments (2);

·        15 minute increments (3);

·        Each minute (1);

·        By procedure and then in 15 increments (1); and

·        60, 90, or 120 minute increments (2).

This variation in how departments bill for HBOT makes it difficult to compare the costs of providing services across departments. In particular, HCFA had no way of knowing from the claims data alone how each department defined an HBOT session. This has important implications for the way HCFA calculated APC 969?s relative payment weight. Departments that bill in shorter sessions probably dominated the median cost calculations, because they would be reporting more claims and more units per claim for the same amount of HBOT service. This would have the effect of decreasing APC 969?s median costs and thus its relative payment weight.

3.      How Large Are HBOT Departments?

Table Two

HBOT Department Size and Medicare Share Statistics

 

Statistic	All Respondents (n = 46)	In-HCFA Respondents (n=31)
Number of Procedures
Responses to Question	39	26
Median	1,760	2,295
Mean	2,279	2,667
Number of Patients
Responses to Question	33	24
Median	122	135
Mean	152	151
Medicare Share
Responses to Question	35	24
Median	52.0%	52.4%

4.      Charges per Service

The cost survey asked respondents to provide their list price (charge) for a 90 minute HBOT session. While most departments did provide this information, others provided charges for 60 minute or 60 and 30 minute sessions. Still other departments provided charges for both routine and emergency sessions.[10] These data were converted into charges for 90 minute sessions, and when more than one charge was provided, the lower charge for a routine session was used.

The charge data were then converted into national dollar amounts as of October, 1998. First, the wage indices published in the proposed rule were applied to 60 percent of the charge amount. Next,  the wage adjusted charge data were inflated by 3.6 percent per year from the midpoint of the reporting period until October, 1998. Of the 44 departments submitting cost and charge data (two respondents provided answers to other survey questions), 15 provided data from FY98, 17 from calendar year (CY) 97, 10 from FY97, and two from CY96. These data thus tended to be more recent than the 1996 claims data used by HCFA to develop its OPPS.

Table Three presents mean and median charge statistics for all respondents and for In-HCFA respondents. Median charges per service for each group were virtually identical ($608 versus $609), although mean charges for all respondents were higher ($774 versus $638). These higher mean charges per service, however, were due to a single institution with extremely high charges per service. If that institution is not included in the mean calculation, the mean charge per service would fall to $661 for all respondents.

Table Three

Median and Median Charges per 90 Minute HBOT Session

 

Statistic	All Respondents (n = 46)	In-HCFA Respondents (n= 31)
Responses to Question	42	27
Median	$608	$609
Mean	$774	$638

5.      Cost to Charge Ratios

The primary purpose for collecting department level total costs and total charges was to calculate cost to charge ratios (CCRs). The CCRs could then be applied to the charges per 90 minute HBOT session data to estimate the cost per session.

Several calculations were conducted to derive CCRs. First, any bad debt and charity costs were excluded when calculating CCRs. Next, capital costs (plant and equipment) were reduced by 10 percent and operating costs (all other costs) by 5.8 percent. The resulting reduced costs were then divided by total charges (Medicare and non-Medicare) to determine each department?s CCR.

Some departments did not report plant and equipment costs separately. For departments that did report plant and equipment costs, the 10 percent reduction in capital costs and 5.8 percent reduction in operating costs yielded an average reduction in total costs (weighted by cost) of 7.2 percent. This 7.2 percent reduction was applied to departments that did not report plant and equipment costs before calculating their CCRs.

Table Four presents median CCRs for the all respondents and for In-HCFA respondents. The median CCRs were 51.3 percent for all respondents and 54.4 percent for the In-HCFA sample. This is one major apparent departure between the cost survey data and the data HCFA used to develop its OPPS and thus calculate costs and payments for APC 969. The CCRs for cost survey respondents appear to be considerably higher than the CCRs HCFA appears to have used in estimating HBOT costs. This issue will be discussed in more detail in the next section.

Table Four

Cost to Charge Ratios (CCRs)

 

Statistic	All Respondents (n = 46)	In-HCFA Respondents (n = 31)
Responses to Question	37	23
Median	51.3%	54.4%

6.      HBOT Costs

The next step was to apply the CCRs to the charge per session amounts for each department. This provides estimates of costs per HBOT session for each responding department. The charge data used here were adjusted for wages and inflation as previously described.

The resulting cost per HBOT session statistics are reported in Table Five. Two sets of calculations were conducted. First, median and mean costs per session were calculated for those departments that provided both department cost and charge data and a charge per HBOT session. Second, for those departments reporting only HBOT charges per session, the median CCR for all respondents (51.3 percent) was used to convert charges into costs.

Table Five

Median Costs per 90 Minute HBOT Session

 

Statistic	All Respondents (n = 46)	In-HCFA Respondents (n = 31)
Departments Reporting HBOT Charges per Session and Department Cost and Charge Data
Responses	35	21
Median	$273	$302
Number of Departments with Costs Greater than HCFA?s Proposed Payment ($134)	28	17
Departments Reporting Only HBOT Charges per Sessions
Responses	39	25
Median	$292	$282
Number of Departments with Costs Greater than HCFA?s Proposed Payment ($134)	32	21

Median costs ranged from $273 to $302, more than twice the $134 proposed payment amount under HCFA?s OPPS. In addition, most HBOT departments report their costs per  session to be above HCFA?s proposed payment. For departments reporting both CCRs and charges, 28 of 35 (80 percent) report their costs as above the proposed payment rate.

V.     Applying cost survey data to hcfa data

The last task in this analysis was to bridge across from the cost survey data collected in the cost survey with the data HCFA used to develop its OPPS. This task in turn consists of three parts. First, the HCFA data are compared for: (1) all hospitals in the HCFA data set that report providing HBOT (the ?All HCFA? sample); (2) the hospitals in the HCFA data set that also responded to the HBOT cost survey (the ?In-HCFA? sample); and (3) hospitals that provide HBOT but are not in the cost survey (?Other?). This comparison is designed to assess how representative respondents to the cost survey are of all providers of HBOT.

Second, several data elements are extracted from the cost survey data set and then applied to the HCFA data. In particular, data on how hospitals bill are used to adjust the  HCFA units of service field, and the CCRs from the cost survey (calculated from department cost and charge data) are then applied to HCFA charge data for HBOT.

Finally, as is discussed below, the CCRs HCFA used to calculate HBOT costs are much lower than the CCRs calculated using cost survey data. Several survey respondents were contacted and asked to provide data from their filed Medicare cost reports. These cost report data are then used to calculate CCRs for these HBOT departments, and those CCRs are then compared to the CCRs HCFA used in developing HBOT costs and payments under its OPPS.

A.     Comparing HCFA Data for Cost Survey Respondents and All HBOT Providers

For the past several years, The Lewin Group and ORION Consulting have worked together to replicate the data base HCFA used to develop its OPPS. This process started with the same 1996 hospital outpatient department claims file with 98 million records. From this file, we applied the edits HCFA used to eliminate claims for non-covered services. The remaining 83 million claims were then grouped into APCs, and APC payments were then calculated by using HCFA?s proposed relative payment weights, conversion factor, multiple procedure discounting rules, and wage index adjustments.

In addition, costs and current payments were also calculated at the CPT procedure level. HCFA provided us with its file of department-level ratios of cost to charges (CCRs), and these were applied to charge data at the line item level to calculate costs. We also used HCFA?s proposed packaging rules to package ancillaries and other services with significant procedures. Finally, we simulated current payments by applying HCFA?s current payment methodologies at the claims level. For some codes, this included calculating the lesser of charges, costs, and blended Ambulatory Surgical Center (ASC) payments, where the blend formulas were adjusted for formula driven overpayment (FDO) corrections mandated in the 1997 Balanced Budget Act (BBA).

Our current payment simulations, however, depend critically on department-level CCRs provided to us by HCFA. If there is some problem with these CCRs, this will affect our payment calculations. For example, if the CCR used in our payment simulations is too low, this would lower our estimate of the cost for a service, which could reduce our simulated payment amount.

 

From  the 83 million claims, we have extracted all claims that include at least one 99183 CPT code. There are 15,505 claims with 99183 at 254 hospitals. Our claims-level data base included the following information for the 99183 line on these claims:

·        Total costs (including packaged costs);

·        Total charges (including packaged costs);

·        The CCR;

·        Units of service;

·        Current payment; and

·        Proposed APC payments.

As indicated above, 31 hospitals could be matched from the cost survey to the HCFA HBOT claims data. These 31 hospitals represented 2,917 of the 15,505 claims (18.8 percent) and 19,233 of the 100,077 units (19.2 percent).

1.      Units of Service

There is tremendous variation in the units of service reported for HBOT for the All HCFA, In-HCFA, and Other hospital samples (Table Six). For unit of service ranges (one, two to five, six to 10, etc.), Table Six displays the percentage of claims for each hospital sample represented by that unit of service range. In addition, it also presents the percentage of total units of service for each units of service range. For example, for All HCFA hospitals, 22 percent of all claims and 28 percent of all units have a units of service between six and 10. Units of service vary from one to 50, and a large percentage of both claims and total units of service are represented by units of service of 11 or more.

Two factors probably account for this variation. First, many departments probably bill by the week or even month, and some patients would receive a large number of HBOT sessions during that period. Second, the cost survey indicated that a large number of departments bill in short time increments (as low as 15 to 30 minutes). A single HBOT session of 90 minutes thus may represent three or even six units of service for some hospitals.

The distribution of claims and total units by units of service ranges is similar across all three hospital groups. The primary difference between the In-HCFA hospitals and the other two groups of hospitals is that the In-HCFA hospitals have more claims and total units with either one unit of service or 11 or more units of service.

Table Six

The Distribution of HBOT Claims and Total Units of Service by Units of Service: 1996 HCFA Hospital Outpatient Data

 

Units of Service Range	All  HCFA Hospitals (n = 254)		In-HCFA Hospitals (n = 31)		Other Hospitals (n = 223)
	Percentage of Claims	Percentage of Total Units	Percentage of Claims	Percentage of Total Units	Percentage of Claims	Percentage of Total Units
One	30.9%	4.8%	37.2%	5.6%	29.5%	4.6%
Two to Five	28.6%	13.8%	29.7%	13.3%	28.2%	13.9%
Six to 10	22.1%	28.2%	10.1%	12.1%	25.0%	26.2%
11 to 20	11.8%	27.8%	14.6%	33.5%	11.1%	26.4%
21 to 50	6.6%	30.2%	8.4%	35.5%	6.2%	28.9%

                                                                                   

The wide disparity in units of service across different departments has important implications for the reimbursement of HBOT within HCFA?s proposed OPPS. If some of the difference in units of service is due to differences in how long a HBOT ?session? is at each hospital, it is impossible to make an ?apples to apples? comparison of the costs per unit across hospitals. In addition, statistics including median costs per unit for HBOT are also distorted, because units are not consistently defined. Hospitals that report shorter HBOT sessions will likely have lower costs per unit and thus will reduce any median cost per unit across all hospitals.

2.      Department Size

The units of service and number of claims were also used to compare department size for the three hospital groups (Table Seven). The In-HCFA hospitals had larger departments with more total units of service and more HBOT claims. The number of claims per unit, however, were much more similar across the All Hospital, In-HCFA, and Other hospital groups.

Table Seven

Total Units, Claims, and Units per Claim: HCFA Data

 

Statistic	All HCFA Hospitals	In-HCFA Hospitals	Other Hospitals
Total Units
Median	160	620	363