Wound Size Matters: Analysis of the New Restrictive Skin Substitute LCD Policy

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This month, the Medicare Administrative Contractors (MACs) Novitas, First Coast, and CGS published a new Local Coverage Determination (LCD) for CTPs or cellular, acellular, matrix-like products (CAMPs). While there are many changes in the LCD that are beneficial to patients, the reduction of the number of skin substitute applications from 10 to 4 over a twelve-week treatment period has been universally perceived amongst wound care specialists, researchers and patient advocate groups as a decision that will unfavorably impact patient outcomes while concurrently increasing overall healthcare expenditures.
 
Most stakeholders seem to agree that changes in practice habits and product pricing related to the current utilization of CAMPs is necessary, but a broader data analysis may be needed to determine if the current 4-application limit in the soon to be released LCD is actually appropriate across all sites of service (hospital outpatient departments [HOPD], private clinics, and the post-acute care setting), for different wound sizes and takes into account the varying wound types and comorbidities of our immunocompromised patients. It stands to reason that wound size matters as on average larger wounds will likely require more applications than smaller wounds in order to heal.

Loading Dose Effect

Our data suggests that there is often less change in the wound size during the first few applications as CAMPs help to transition the wound bed from the inflammatory phase to the proliferative phase of healing (Figure 1). Two to three weeks after the initial few rounds of CAMP applications, wound closure often starts to accelerate more rapidly as the wound bed milieu has been optimized for healing. With the limit set at 4 applications, many wounds will not get out of the inflammatory phase and the benefit will be wasted, just like osteomyelitis will assuredly return to square one if only 2 weeks of IV antibiotics were allowed instead of the standard of 6 weeks, or cancer will recur in patients underdosed with chemotherapy using arbitrarily lowered weight calculations on heavier patients. 

New Clinical Data

Our 10,000-patient private wound practice submitted retrospective data to CMS this month which included a review of 289 wounds that healed while receiving CAMPs. Our data showed that only 19% of wounds healed after just 4 applications. Twenty-four percent of wounds in Caucasian patients healed after 4 applications, while only 11% of wounds in African American patients healed after 4 applications. Conversely, 73% of wounds in African American patients required 7 or more applications to heal. The initial average wound size for African Americans was 50% larger than for Caucasians.
 
This trend suggests a direct correlation between the increasing size of wounds and the increased number of CAMP applications necessary to heal them, as well as the ramifications for our most at-risk patients. It also supports the concept of a loading dose effect within the first 4 applications for all races.

LCD Evidence: One Retrospective Study

The retrospective study by Armstrong et al, “Observed Impact of Skin Substitutes in Lower Extremity Diabetic Ulcers: Lessons From The Medicare Database (2015-2018)” was the key study cited by the MAC’s to restrict the number of grafts to 4 applications.¹ Like most research on skin substitutes, an important aspect of the study is that it only included the HOPD setting. One should take into consideration that as a result of limitations created by the bundled payment structure in the HOPD setting, larger sized wounds tend to present more often in the private office or post-acute setting where they can be treated on a per square cm basis. This clinical trend was a limitation in the “Observed Impact” study since the analysis captured mostly small and medium sized wounds.
 
The majority of the studies investigating the use of CAMPs cited by LCD commenters examined only smaller wounds (less than 25 sq cm). Even then, these studies found that the average applications required to heal small wounds was higher than 4. It is confusing why the mean of 3.7 applications was used to determine that applying 4 CAMPs is adequate without taking into account the standard deviation of 3.6. Adding the standard deviation back in to the calculus would have brought the number of applications required to heal up to at least 7.

Wound Size Matters

The LCD assumes a one-size-fits-all approach that doesn't take into consideration that wounds come in multiple sizes, etiologies, and are associated with multiple comorbidities. For instance, the average wound size for our private practice is 32 sq cm. But up to this point, the wound specialist community has not created a universally accepted scale for wound size categorization. What is the definition of a Small, Medium, Large, or Extra-Large wound? For the Medicare Claims Data study, a very broad definition of sizes was used (Chart 1).
 
Because it was an HOPD-only study, less than 0.5% of the wounds included “Large” sizes (>100 sq cm). This definitively shows that larger wounds are not being treated with CAMPs in HOPDs, but instead are being treated in the private office and post-acute settings. Furthermore, the “Medium” category included a huge range (21-100 sq cm), which is four times bigger than the “Small” category (20 sq cm or less). Because we have not defined more incremental parameters for wound sizes, we have not adequately studied how different wound sizes may require different protocols.

Wound Sizing Scale

To meet this basic need of categorizing wounds by size, my large group practice has created a new Wound Sizing Scale (Table 1).

Below are examples of these wound sizes, and how many average CAMP applications our practice data suggests would be required to heal each size (click green text to view photos).

Small 0–25 cm: 4 sq cm DFU (avg 7 apps to heal)

Medium >25–50 cm: 30 sq cm plantar heel DFU (avg 8 apps to heal)

Large >50–75 cm: 72 sq cm dorsal VLU (avg 9 apps to heal)

X-Large >75–100 cm: 96 sq cm DFU (avg 10 apps to heal)

XX-Large wound >100 cm: 250 sq cm diabetic VLU (avg 10 apps to heal)

By design, the Wound Sizing Scale corresponds to existing CPT skin substitute application codes. Based on data from our 26 wound clinics, we have found that a reasonable number of skin substitute applications necessary to treat most wounds is as follows (Table 2).

The purpose of these CPT code pairings is to allow for research studies using easily obtainable claims data based on the application codes used. The sliding scale takes into account that larger wounds will likely require more applications.
 
Since there are no existing studies that examine the number of applications required to heal wounds depending on size, the Wound Sizing Scale can be used to conduct retrospective studies on established databases to determine a more accurate application limit. But until then, the MACs’ decision to establish a one-size-fits-all application limit seems arbitrary and intended to reduce utilization without taking into account individual patient needs.
 
Additionally, the result is a policy that will discriminate against patients with larger wounds. In our large practice wounds in African American patients are 54% larger than wounds in Caucasian patients, making this new policy devastating for our most at-risk patient population especially with respect to lower extremity amputations.

Temporary Solution: Medically Unnecessary Edits (MUE)

By incorporating the Wound Sizing Scale with its size-based application limits, the MACs could consider assigning a Medically Unnecessary Edit (MUE) to the 15000 series CPT application codes as illustrated above. The MACs would still save millions of dollars and curb overutilization while avoiding discrimination against our most at-risk patients. But if such sophistication is not possible within the software system just yet, then a temporary compromise of a limit of 7 CAMP applications for all wound sizes would at least lessen the unintended discriminatory effect of the current policy. It would also allow time to do comprehensive research to determine the appropriate average number of CAMP applications required to heal wounds by type and size instead of just theorizing.

In Conclusion

With so many unanswered questions remaining, an immediate compromise on the number of applications to allow 7 is warranted both from an ethical and medical perspective. Arbitrary restriction of applications is clearly not based on an accurate interpretation of the available literature. Sixty-six out of 67 commenters echoed this position in the Response to Comments article posted by the MACs.² Basing the application restriction on data from only one wound type (DFU) and only one site of service (HOPD) has insufficient evidentiary basis to extend it to all other types of wounds/sizes or sites of service. The discussion should not be revolving around the arbitrary lowering of application numbers, especially if the wounds are making progress while undergoing CAMP treatment. Instead, we should be discussing how to lower the pricing structure of CAMPs as a whole to create a more sustainable system.
 
A more robust conversation with the MACs is in order so that a concise and logical framework can be put into place. Future LCDs should take wound size into account and include the input of wound experts, researchers, and patient advocate groups on the front end. We should allow for a thorough and honest review of the literature and define a gold standard for CAMP application numbers that will empower clinicians to achieve optimal patient outcomes without discriminating against our most at-risk patients.

Shaun Carpenter, MD, CWSP, WMS, is the Chief Medical Officer of MedCentris Wound Healing Institutes throughout rural Louisiana and Mississippi.

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Reference
 
1. Armstrong DG, Tettelbach WH, Chang TJ, et al. Observed impact of skin substitutes in lower extremity diabetic ulcers: lessons from the Medicare Database (2015-2018). J Wound Care. 2021 Jul 1;30(Sup7):S5-S16. doi: 10.12968/jowc.2021.30.Sup7.S5. PMID: 34256590.

2. Centers for Medicare and Medicaid Services. Response to Comments: Skin Substitute Grafts/Cellular and or Tissue-Based Products for the Treatment of Diabetic Foot Ulcers and Venous Leg Ulcers.