DEPARTMENT OF HEALTH &. HUMAN SERVICES 	 OHlce of Inspector General 

Washington, D.C. 20201 

DEC 29 2009 

TO: 	 Charlene Frizzera 

Acting Administrator 

Centers for Medicare & Medicaid Services 

FROM: Stuart Wright 

Deputy Inspector General 

for Evaluation and Inspections 

SUBJECT: 	 Memorandum Report: Vulnerabilities in Medicare Payments for Pressure 

Reducing Support Surfaces. OEI-02-07-00421 

This memorandum report provides infolmation on vulnerabilities in Medicare payments for 

pressure reducing support surfaces (support surfaces), It specifically focuses on Medicare 

payments for claims that have GA and GZ modifiers. Suppliers use these modifiers to indicate 

that they expect Medicare to deny the claim as not reasonable and necessary, Suppliers may also 

use these modifiers to indicate that they provided an upgraded item to the beneficiary. An 

upgrade is a durable medical equipment (DME) item that contains a component, such as an 

equipment feature, that is in excess of the beneficiary's medical needs. 

Staff at the Centers fOl' Medicare & Medicaid Services (eMS) asked the Office of Inspector 

,General (010) to provide information on these claims following a report issued by 010 on 

support surfaces. I 'In that evaluation, 010 found that 86 percent of claims for gl'OUp 2 support 

surfaces did not meet Medicare coverage criteria in the first half of 2007, which amounted to an 

estimated $33 million in inappropriate payments. In response to that report. eMS staff were 

concerned .that suppliers were inconectly using GA and GZ modifiers on suppo11 surface claims 

and that Medicare was inappropriately paying for these items. 

Based on an analysis of 2007 data, we found that Medicare paid for 72 percent of all support 

surface claims with OA or OZ modifiers. Medicare potentially inappropriately paid $4.4 million 

for these claims. We also found that suppliers submitted only foUl' claims for upgrades for 

support surfaces in 2007, indicating that they may not be using the appropriate modifiers when 

providing upgrades. Further, for a number of other claims, Medicare inappropriately paid for 

more than one support surface for the same beneficiary on the same service date. In several 

1 OIG. Inappropriate Medicare Payments for Pressure Reducing Buppo/·t Bul'iaces, OEI-02-07-00420, August 2009. 

OEI-02-07-00421 Vublerabilities in Medicare Payments for Pressure Reducing Support Surfaces 
Page 2 – Charlene Frizzera 

other instances, Medicare paid for a higher priced support surface, as opposed to a lower priced 

support surface. 

BACKGROUND 

Pressure Reducing Support Surfaces 

Support surfaces are used for the care or prevention of pressure ulcers. A pressure ulcer, also 

known as a bedsore or decubitus ulcer, is an area of skin that breaks down when a person stays in 

one position for too long without shifting his or her weight. Pressure ulcers commonly occur 

among the elderly and among individuals with spinal cord injuries. Medicare pays for most 

support surfaces as rental items under its Part B DME benefit. In 2007, Medicare payments for 

all support surfaces totaled $137 million, $118 million of which was for rentals. 

CMS categorizes support surfaces into three groups based on the complexity of their features. 

The three support surface groups have varying characteristics and include the following: 

 Group 1 support surfaces are generally designed to be placed on top of standard hospital or 

home mattresses and include pressure pads and mattress overlays (foam, air, water, or gel). 

These support surfaces may be rented or purchased. 

 Group 2 support surfaces, which can be special mattresses used alone or placed directly over 

a bedframe, include powered air flotation beds, powered pressure reducing air mattresses, 

and nonpowered advanced pressure reducing mattresses. These support surfaces may only 

be rented and are more expensive than Group 1 support surfaces. 

 Group 3 support surfaces are complete bed systems, known as air-fluidized beds, which 

simulate the movement of fluid by circulating filtered air through silicone-coated ceramic 

beads. These support surfaces may only be rented and are the most expensive of the groups. 

Modifiers for Services Not Reasonable and Necessary 

GA or GZ modifiers can be used to bill for certain Part B items or services, including support 

surfaces, that are expected to be denied by Medicare as not reasonable and necessary.2 For DME 

items, examples of when suppliers can use these modifiers include the following:3

(1) The item was not ordered by a provider who is qualified to prescribe the item. 

(2) The item does not meet medical necessity criteria or frequency guidelines. 

(3) The item is the same as or similar to covered items that the beneficiary is already using. 

2 CMS added the GZ modifier and issued instructions to suppliers on how to use both the GZ and GA modifiers, effective 

January 1, 2002. CMS Program Memorandum, CR 1820, Transmittal B-02-020, Coding for Non-Covered Services and 

Services Not Reasonable and Necessary, March 27, 2002. 

3 See, e.g., Noridian Administrative Services LLC, “Proper Use of GY, GA, and GZ Modifiers,” Happenings, August 2007. 

Available online at https://www.noridianmedicare.com/dme/news/bulletins/happenings/issue6_aug07.pdf. Accessed on August 

10, 2009. 

OEI-02-07-00421 Vulnerabilities in Medicare Payments for Pressure Reducing Support Surfaces 
Page 3 – Charlene Frizzera 

(4) The safety or effectiveness of the item in the home setting has not been established. 

(5) The item is experimental or investigational. 

Suppliers use the GA modifier when they have a signed Advance Beneficiary Notice of 

Noncoverage (ABN) on file.4 The purpose of the ABN is to inform a Medicare beneficiary, 

before he or she receives specified items or services, that Medicare certainly or probably will not 

pay for the item or service on that particular occasion.5 A beneficiary may sign the ABN and 

indicate on the form that he or she accepts liability for the item or service and may need to pay 

out-of-pocket or through other insurance if Medicare denies payment.6 In contrast, suppliers use 

the GZ modifier when they expect that the claim will be denied as not reasonable and necessary, 

but do not have an ABN on file.7 In these cases, if Medicare denies the claim as not reasonable 

and necessary, the beneficiary cannot be held liable for the cost of the item. 

Upgrades 

An upgrade is a DME item that contains a component, such as an equipment feature, that is in 

excess of the beneficiary’s medical needs.8

 The supplier may choose to provide an upgrade to 

the beneficiary free of charge, perhaps for the supplier’s own convenience. The supplier may 

also charge the beneficiary for an upgrade, perhaps because the upgrade was requested by the 

beneficiary. In the case of support surfaces, a Group 1 support surface can be upgraded to a 

Group 2 or Group 3 support surface, or a Group 2 support surface can be upgraded to a 

Group 3 support surface. 

When a supplier provides an upgraded DME item, it must use certain modifiers on the claim to 

indicate that such an upgrade occurred. If the supplier is providing the upgrade free of charge, 

the supplier submits a claim for the item that the beneficiary qualifies for and adds a GL modifier 

to the claim.9 If the supplier wants to obtain payment for the upgrade, the supplier submits two 

line items on the claim: the first line item is for the upgraded item and the second line item is for 

the item that the beneficiary actually qualifies for. The supplier adds a GA or GZ modifier to the 

4 CMS Program Memorandum, CR 1820, Transmittal B-02-020, Coding for Non-Covered Services and Services Not 

Reasonable and Necessary, March 27, 2002. In 2007, the ABN was known simply as the Advance Beneficiary Notice. See 

Form No. CMS-R-131-G, June 2002. 

5 CMS, Medicare Claims Processing Manual, Pub. No. 100-04, “Ch. 30 - Financial Liability Protections,” §40.3 (October 1, 

2003). The Financial Liability Protection provisions of the Social Security Act protect beneficiaries and healthcare providers

under certain circumstances from unexpected liability for charges associated with claims that Medicare does not pay. See 

CMS, Medicare Claims Processing Manual, Pub. No. 100-04, “Ch. 30 - Financial Liability Protections,” §10 (October 1, 2003). 

6 The beneficiary could also indicate on the ABN that he or she chooses not to receive the item or service. See Form 

No. CMS-R-131-G that was in effect in 2007. In addition, CMS revised the ABN in March 2008 to provide an additional 

option to indicate that a beneficiary would pay for the item or service and the supplier would not bill Medicare. See Form 

No. CMS-R-131. 

7 CMS Program Memorandum, CR 1820, Transmittal B-02-020, Coding for Non-Covered Services and Services Not 

Reasonable and Necessary, March 27, 2002. 

8 CMS, Medicare Claims Processing Manual, Pub. No. 100-04, “Ch. 20 - Durable Medical Equipment, Prosthetics, Orthotics, 

and Supplies,” § 120 (as of Rev. 1142; effective April 1, 2007). 

9 Ibid. 

OEI-02-07-00421 Vulnerabilities in Medicare Payments for Pressure Reducing Support Surfaces 
Page 4 – Charlene Frizzera 

first line item to indicate that it expects the claim for the upgrade to be denied as not reasonable 

and necessary. The supplier adds a GK modifier to the second line item to indicate that the item 

is associated with the GA or GZ modifier and is reasonable and necessary.10 When an upgrade is 

not medically necessary, Medicare should deny the first line item and allow the second line 

item.11

Claims Processing and Program Safeguard Activities 

CMS contracts with four Durable Medical Equipment Medicare Administrative Contractors

(DME MAC) that are responsible for processing and paying all DME claims. CMS may provide 

instruction to DME MACs to process certain claims for review or denial. Currently, there is no 

claims processing instruction to DME MACs for how to process claims with either a GA or a GZ 

modifier.12, 13

METHODOLOGY 

This analysis focuses on all Part B claims for Group 1, 2, and 3 support surfaces with a date of 

service in 2007. We obtained the universe of support surface claims from CMS’s National 

Claims History file. Multiple line items may be billed within a single claim. For the purposes of 

this report, we refer to a line item as a claim. In total, there were 197,145 denied claims and 

504,848 allowed claims. 

For the first part of our analysis, we determined the proportion of all claims that had a GA or GZ 

modifier that Medicare denied and the proportion of these claims that Medicare allowed. We 

then calculated the total amount Medicare potentially inappropriately paid for these claims. For 

the second part of our analysis, we determined the number of sets of claims in which Medicare 

paid for two or more support surfaces for the same beneficiary on the same service date.14 We 

excluded claims that had a GA or GZ modifier from this analysis to keep this part of the analysis 

10 Suppliers must give an ABN to a beneficiary prior to furnishing an item or service when they expect Medicare to reduce the 

level of payment because part of the item or service is not reasonable and necessary. See CMS, Medicare Claims Processing 

Manual, Pub. No. 100-04, “Ch. 30- Financial Liability Protections,” § 50.7.5 (as of Rev. 1; effective October 1, 2003).

11 CMS, Medicare Claims Processing Manual, Pub. No. 100-04, “Ch. 20 - Durable Medical Equipment, Prosthetics, Orthotics, 

and Supplies,” § 120 (as of Rev. 1142; effective April 1, 2007). 

12 The only claims processing instructions provided to DME MACs for Part B claims with GA or GZ modifiers is to treat a 

claim as unprocessable if the supplier added both a GA and GZ modifier to the same claim line item. See CMS, Medicare 

Claims Processing Manual, Pub. No. 100-04, “Ch. 23 - Fee Schedule Administration and Coding Requirements,” §§ 20.9.1.1 

(as of Rev. 1; effective October 1, 2003). 

13 CMS recently provided additional instructions to contractors on the use of modifiers associated with ABNs for Part A 

claims submitted by institutional providers. Beginning in April 2010, Part A claims with a GA modifier will be automatically 

denied as a beneficiary liability. In addition, Medicare created a new GX modifier for providers to indicate that they 

voluntarily provided an ABN to the beneficiary for a service or item that is not covered under the Medicare statute. Part A 

claims with a GX modifier will be automatically denied as a beneficiary liability. See CMS, Pub 100-04 Medicare Claims 

Processing, CR 6563, Transmittal 1840, Billing for Services Related to Voluntary Uses of Advanced Beneficiary Notices of 

Noncoverage, October 29, 2009. 

14 There is one situation in which a supplier could potentially order two different replacement parts for a Group 1 support 

surface at the same time. We did not include these sets of claims in our analysis. 

OEI-02-07-00421 Vulnerabilities in Medicare Payments for Pressure Reducing Support Surfaces 
Page 5 – Charlene Frizzera 

distinct from the first. For these sets of claims, we considered the amount that Medicare paid for 

the lower priced support surface to be appropriate and any higher priced support surfaces to be 

inappropriate. Finally, we identified additional sets of claims in which Medicare paid for a 

higher priced support surface and denied a lower priced support surface for the same beneficiary 

on the same service date. If these were for upgrades, Medicare should have only paid for the 

lower priced support surface, as opposed to the higher priced support surface. To identify these 

claims, we matched the allowed and denied claims by beneficiary and service date. For each set 

of claims, we calculated the difference between the higher priced support surface and the lower 

priced support surface as the amount that Medicare potentially inappropriately paid for these 

claims. 

For these analyses, we took a conservative approach by only including claims that had the same 

service date because there could be legitimate reasons for a beneficiary to rent two support 

surfaces on different dates during a month. For example, a beneficiary may rent one support 

surface, have an unexpected hospital stay, and return home needing a different support surface in 

the same month. 

We also determined whether the claims in our analysis were associated with the same supplier 

based on the supplier’s business name. We obtained each supplier’s business name from the 

National Supplier Clearinghouse. Using the supplier’s business name allowed us to combine all 

of a supplier’s branch locations.15

In addition, we looked at the frequency of GA and GZ modifiers in a sample of support surface 

claims that we reviewed for medical necessity in a previous evaluation.16 We analyzed these 

data to determine the number of claims with GA or GZ modifiers that did not meet Medicare 

coverage criteria. 

This study was conducted in accordance with the “Quality Standards for Inspections” approved 

by the Council of the Inspectors General on Integrity and Efficiency. 

RESULTS 

In 2007, Medicare Paid for 72 Percent of Support Surface Claims With GA or GZ 

Modifiers, Amounting to $4.4 Million in Potentially Inappropriate Payments in 2007 

Suppliers use the GA and GZ modifiers when they expect that Medicare will deny the claim as 

not reasonable and necessary. In 2007, suppliers submitted a total of 21,145 support surface 

claims with GA or GZ modifiers. Of these claims, Medicare denied only 28 percent 

(5,893 claims) and paid the remaining 72 percent (15,252 claims). Medicare potentially 

inappropriately paid $4.4 million for these claims in 2007. 

15 We did not analyze the data by suppliers’ National Provider Identifiers because suppliers were not required to use these 

identifiers until May 2007. 

16 OIG, Inappropriate Medicare Payments for Pressure Reducing Support Surfaces, OEI-02-07-00420, August 2009. 

OEI-02-07-00421 Vulnerabilities in Medicare Payments for Pressure Reducing Support Surfaces 
Page 6 – Charlene Frizzera 

The 15,252 paid claims represented 3 percent of all paid support surface claims in 2007. Almost 

all of these claims had a GA modifier (15,211 claims), whereas 41 claims had a GZ modifier. 

See Table 1. These claims were from all four DME MAC regions. However, 11 percent of these 

claims were submitted by a single supplier. 

Table 1: Claims with GA or GZ modifiers 

Number of claims 

Potential inappropriate 

payments 

Claims with GA modifiers 15,211 $4,355,780 

Claims with GZ modifiers 41 $30,031 

 Total 15,252 $4,385,811 

Source: OIG analysis of pressure reducing support surface claims, 2009. 

In addition, in our sample of support surface claims that we reviewed for medical necessity, we 

found that 13 claims in our sample of 387 had a GA modifier.17 Of these, 11 did not meet 

Medicare coverage criteria. Specifically, five were medically unnecessary, four were completely 

undocumented, and two were insufficiently documented to determine medical necessity. The 

remaining two claims met Medicare coverage criteria. 

Suppliers Submitted Few Claims With Modifiers Indicating That They Provided Upgrades 

Suppliers can use GA and GZ modifiers with a GK modifier on an associated claim to indicate 

that they provided an upgrade to the beneficiary. In 2007, suppliers submitted only four claims 

with GA or GZ modifiers that had a second claim with a GK modifier. Medicare paid all four of 

these claims appropriately by reimbursing only the second claim. Since this was relatively 

uncommon, it could mean that some of the claims with GA or GZ modifiers were, in fact, for 

upgrades in which supplier did not include a GK modifier on an associated claim. 

For a Number of Other Claims, Medicare Inappropriately Paid for More Than One 

Support Surface for the Same Beneficiary on the Same Service Date 

Medicare should pay for only one support surface for the same beneficiary on the same service 

date. For 145 sets of claims, Medicare paid for two support surfaces within the same group for 

the same beneficiary on the same service date. For another four sets of claims, Medicare paid for 

three support surfaces for the same beneficiary on the same service date. As shown in Table 2, 

most of these sets of claims were for Group 1 support surfaces. In total, these sets of claims 

amounted to $39,380 in inappropriate payments. 

17 None of the claims in this sample had a GZ modifier. 

OEI-02-07-00421 Vulnerabilities in Medicare Payments for Pressure Reducing Support Surfaces 
Page 7 – Charlene Frizzera 

Table 2: Sets of claims for two or more support surfaces within the same 

group for the same beneficiary 

Sets of claims Inappropriate payments 

Sets of claims for two or more 

Group 1 support surfaces 106 $7,587 

Sets of claims for two or more 

Group 2 support surfaces 42 $29,027 

Sets of claims for two or more 

Group 3 support surfaces 1 $2,766 

 Total 149 $39,380 

Source: OIG analysis of pressure reducing support surface claims, 2009. 

In addition, for 31 sets of claims, Medicare paid for both a Group 1 and a Group 2 support 

surface for the same beneficiary on the same service date. See Table 3. For three other sets of 

claims, Medicare paid for both a Group 2 and a Group 3 support surface. Medicare should not 

have paid for two support surfaces for the same beneficiary on the same service date. If these 

claims were for upgrades, Medicare should have only paid for the lower priced support surface, 

unless the higher priced surface was found to be medically necessary. In total, these sets of 

claims amounted to $29,405 in inappropriate payments in 2007. 

Table 3: Sets of claims for two different groups of support surfaces 

for the same beneficiary 

Sets of claims Inappropriate payments 

Sets of claims for Group 1 and 

Group 2 support surfaces 31 $20,551 

Sets of claims for Group 2 and 

Group 3 support surfaces 3 $8,854 

 Total 34 $29,405 

Source: OIG analysis of pressure reducing support surface claims, 2009. 

In Several Other Instances, Medicare Paid for a Higher Priced Support Surface, as 

Opposed to a Lower Priced Support Surface 

For another 91 sets of claims, Medicare paid the claim for a higher priced support surface and 

denied one or more claims for a lower priced support surface that was for the same beneficiary 

on the same service date. As shown in Table 4, for 64 sets of claims, Medicare paid for a 

Group 2 support surface and denied one or more claims for a Group 1 support surface. For 

27 sets of claims, Medicare paid for a Group 3 support surface and denied one or more claims for 

a Group 2 support surface. Two suppliers submitted these 27 sets of claims. 

If these were for upgrades, Medicare should have only paid for the lower priced support surface, 

as opposed to the higher priced support surface, unless the higher priced surface was found to be 

OEI-02-07-00421 Vulnerabilities in Medicare Payments for Pressure Reducing Support Surfaces 
Page 8 – Charlene Frizzera 

medically necessary. These sets of claims amounted to an additional $73,022 in potentially 

inappropriate payments in 2007. 

Table 4: Sets of claims in which Medicare paid for a higher priced 

support surface, as opposed to a lower priced support surface 

Sets of claims 

Potential inappropriate 

payments 

Group 2 was paid, Group 1 was 

denied 64 $25,997 

Group 3 was paid, Group 2 was 

denied 27 $47,025 

 Total 91 $73,022 

Source: OIG analysis of pressure reducing support surface claims, 2009. 

CONCLUSION

We found that in 2007, Medicare paid for 72 percent of all support surface claims with GA or 

GZ modifiers. Suppliers use these modifiers when they expect that Medicare will deny the claim 

as not reasonable and necessary. Medicare potentially inappropriately paid $4.4 million for these 

claims. In addition, suppliers submitted only four claims for upgrades in 2007, indicating that 

they may not be using the appropriate modifiers when providing upgrades. 

Further, for a number of other claims, Medicare inappropriately paid for more than one support 

surface for the same beneficiary on the same service date. Some of these claims were for support 

surfaces within the same group, whereas others were for support surfaces in two different groups. 

In total, these claims amounted to $68,785 in inappropriate payments in 2007. In several other 

instances, Medicare paid for a higher priced support surface, as opposed to a lower priced 

support surface. These claims amounted to an additional $73,022 in potentially inappropriate 

payments. 

Taken together, these results indicate that DME MACs may not have appropriate safeguards in 

place to pay for Part B claims with GA or GZ modifiers. They also show that the DME MACs 

do not have controls in place to flag claims for multiple support surfaces for the same beneficiary 

on the same service date. Further, the results demonstrate that suppliers may need further 

instructions on the appropriate use of these modifiers when they provide upgraded items to 

beneficiaries. 

It is important to note that these modifiers can be used for other DME items, such as 

wheelchairs, hospitals beds, and prosthetics and for Part B services. In response, we plan to 

conduct additional work on these modifiers for other items and services. We will also refer the 

suppliers associated with the claims in the current analysis to CMS in a separate memorandum. 

OEI-02-07-00421 Vulnerabilities in Medicare Payments for Pressure Reducing Support Surfaces 
Page 9 – Charlene Frizzera 

OEI-02-07-00421 Vulnerabilities in Medicare Payments for Pressure Reducing Support Surfaces 

This report is being issued directly in final form because it contains no recommendations. If you 

have comments or questions about this report, please provide them within 60 days. Please refer 

to report number OEI-02-07-00421 in all correspondence.