Supervised Exercise Therapy for Symptomatic Peripheral Artery Disease: A REVIEW OF CURRENT EXPERIENCE AND PRACTICE-BASED RECOMMENDATIONS : Journal of Cardiopulmonary Rehabilitation and Prevention

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Scientific Reviews

Supervised Exercise Therapy for Symptomatic Peripheral Artery Disease

A REVIEW OF CURRENT EXPERIENCE AND PRACTICE-BASED RECOMMENDATIONS

Ehrman, Jonathan K. PhD; Gardner, Andrew W. PhD; Salisbury, Dereck PhD; Lui, Karen BSN, RN; Treat-Jacobson, Diane PhD, RN

Author Information
Journal of Cardiopulmonary Rehabilitation and Prevention 43(1):p 15-21, January 2023. | DOI: 10.1097/HCR.0000000000000723

KEY PERSPECTIVES

  • This article summarizes contemporary key items necessary to understand when developing and implementing a supervised exercise therapy (SET) program for those with symptomatic peripheral artery disease.
  • Clinical exercise program staff should familiarize themselves with all aspects of SET, which include patient recruitment and selection, SET implementation and progression, and insurance and billing information.

It is well established by numerous randomized controlled trials that regular structured exercise therapy improves the walking performance of those with symptomatic peripheral artery disease (PAD).1 Furthermore, evidence is accumulating that performing supervised exercise therapy (SET) following revascularization for claudication will more likely lead to maximal functional benefits versus revascularization or SET alone.2,3 In May 2017, the Centers for Medicare & Medicaid Services (CMS) in the United States approved coverage of SET for beneficiaries with intermittent claudication. Supervised exercise therapy is considered the gold standard for improvement in walking performance and is a class IA recommendation in the current ACC/AHA Guideline for the treatment of PAD.4 The CMS Decision Memo allows for SET to be implemented in either a clinical/physician office or in a hospital outpatient setting (ie, cardiac rehabilitation [CR] environment).5

Currently, little is known about the implementation of SET in the United States. Dua et al6 gathered information by survey regarding availability, awareness, and utilization of SET in the United States. Of the 900 vascular surgeons, medicine physicians, and cardiologists who were sent the survey (8 questions), 135 (15%) responded. Of these, 54% stated that they did not have a program at their hospital facility and 5% did not know whether a program existed. Those with a program available were overwhelmingly in the CR setting (81%). When asked about referring a patient to a SET program, 98% stated that they would refer a patient; however, only 49% stated that they had referred. Seventy-four percent of respondents were aware of CMS coverage for SET, but only 39% of these stated that they had referred. These data demonstrate that both referral to and access of programs are barriers. This article provides practical information about the implementation of SET, focusing on aerobic exercise training, in those with symptomatic PAD, along with information about billing practices and utilization.

AEROBIC EXERCISE MODES AND PRESCRIPTION FOR SET

Peripheral artery disease is caused by atherosclerotic lesions and obstructions in the arteries of the lower extremities, which reduces blood flow to the leg musculature and causes a mismatch between oxygen supply and metabolic demands of the muscle during exercise.7 In mild PAD, this mismatch does not result in symptoms, but as PAD becomes more severe, patients experience leg pain during walking, called “claudication,” which leads to a sedentary lifestyle.8 Exercise sessions during SET cause the mismatch between oxygen supply and muscle metabolic demands to occur, resulting in claudication, which eventually forces patients to stop walking and rest. During the rest period, ischemia in the leg musculature dissipates and pain resolves, which enables a subsequent walking bout to be initiated free of pain. Intermittent walking done chronically causes vascular and muscular adaptations in the legs that lead to improvements in walking distances typically observed with SET.9,10 These adaptations are not well understood, but numerous mechanisms have been proposed to explain the improvement in walking distances.11 Potential mechanisms include improved endothelium-dependent vasodilation,12 increased capillary density of the gastrocnemius muscle,13 improved skeletal muscle metabolism,14 reduced levels of inflammatory biomarkers,15 improved walking economy,16 and improved aerobic capacity.11 Improved walking distances may enable patients with PAD to walk more during each day at moderate intensity, which is associated with better vascular function,17 and which may increase the likelihood of meeting physical activity time-intensity guidelines recommended for adults.18 To better ensure that a program of SET improves walking distances, several key factors need to be considered related to the mode of exercise and the exercise prescription.

The goal of SET for patients with PAD is to improve walking performance. Most studies have demonstrated the efficacy of intermittent treadmill walking exercise in patients with PAD.19 The traditional exercise prescription includes intermittent treadmill walking and is reviewed in Figure 1. Table 1 provides the pain/discomfort scale. This training pattern should be continued throughout the 12 wk/36 sessions of a SET program.

F1
Figure 1.:
Progressive treadmill walking training program example for supervised exercise therapy (SET) in those with symptomatic peripheral artery disease. Each arrow provides information about decisions to be made for individual patient participating in SET. This figure is available in color online (www.jcrpjournal.com).
Table 1 - Pain/Discomfort Scale for Exercise Traininga
0: No pain
1: Initial pain/discomfort, very mild
2: Mild pain/discomfort
3: Moderate pain/discomfort
4: Severe pain/discomfort
aCareful use of the pain/discomfort scale is important. All patients should be anchored to what “no pain” and “severe pain” feel like. This will improve the likelihood that a patient can recognize when he or she is at the “mild” or “moderate” pain/discomfort levels. Some guidelines refer to level 3 as moderately severe pain/discomfort.

Although the typical mode of exercise during the SET program is treadmill exercise, alternative modes of exercise may be utilized.4,8 These can include aerobic arm exercise20–22 and total body recumbent stepping,23 which are effective in improving walking performance in these patients. These alternative modes may be particularly appropriate for patients who are not able to safely walk on a treadmill, those who do not progress appropriately, and those with more severe disease who can perform only treadmill walking for short periods of time, which limits the exercise duration required to gain benefit.

It is recommended that the initial exercise prescription begin with intermittent treadmill walking and then switch to another mode if needed for safety, or if the patient does not progress after performing several sessions of treadmill exercise. Examples are provided in case format later in this article. If patients who perform these alternative modes of exercise experience ischemic leg symptoms (ie, pain/discomfort of claudication), progression would mirror that of treadmill exercise. If no pain/discomfort is experienced, progression of the exercise prescription would be based on rating of perceived exertion and target heart rate.10

For the first SET session, the exercise professional should have specific objectives as described previously.10 Namely, the most appropriate exercise training modality for each patient should be determined, followed by selecting an appropriate exercise intensity to perform, and educating the patient about the planned progression of the SET sessions in terms of increases in duration and intensity of exercise. The SET sessions should be performed according to the appropriate individualized exercise prescription for each patient regarding the intensity, session duration, frequency, claudication intensity, work-to-rest ratio, and the planned progression of the program as shown in the Table 2. Also refer to Figure 1 and Table 1 for information on progression and the pain/discomfort scale.

Table 2 - Exercise Prescription for Training Patients With Peripheral Artery Disease With Claudicationa
Variable Recommendation
Ideal modality Supervised treadmill walking
Intensity 40-60% maximal workload based on baseline treadmill test
Session duration Begin with 30-50 min intermittent exercise with the goal of accumulating 30-50 min of total walking exercise
Maximum claudication intensity Mild to moderate pain/discomfort (see )
Work-to-rest ratio Ideally walking duration should be between 5-10 min. If mild/moderate pain/discomfort occurs earlier than 5 min, then intensity should be reduced. If later than 10 min, then intensity should be increased. Walking bouts are followed by rest until pain/discomfort has dissipated (often in 2-5 min)
Frequency 3 times/wk supervised; supplemented with home walking
Program duration ≥12 wk and 36 sessions; consider more sessions as indicated by individual patient
Progression Every 1-2 wk or greater: increase duration of training session to achieve 50 min (see Figure 1)
Maintenance Lifelong maintenance ≥2 times/wk, but preferably 6-7 times/wk
aAdapted from Treat-Jacobson et al.10

EXERCISE TRAINING LOCATION: CLINIC VERSUS COMMUNITY SETTINGS

RATIONALE FOR CONSIDERING COMBINING SET AND HOME-BASED EXERCISE SESSIONS

During the initial SET program, a total of 36 exercise sessions are covered during a 12-wk period by CMS and most commercial insurers.10 Following this initial training program, an additional 36 SET sessions can be requested if the patient continues to have lower extremity ischemic symptoms. The CMS coverage policy does not specify a time frame for completion of these additional 36 sessions, which yield a total of 72 lifetime exercise sessions. However, interpretation is at the discretion of the Medicare Administrative Contractor of each state. These exercise sessions need to be completed in a supervised setting, such as a hospital outpatient setting. They cannot be completed at home. However, home exercise training may be advantageous for some patients as either an adjunct to, or in place of, SET in a hospital or clinic setting.

In addition, although a SET program is highly efficacious to improve walking ability, overall functional status, and health-related quality of life,9>36-72 exercise sessions are needed for continued lifetime ambulatory and health benefits, as well as to lower risks of all-cause mortality, cardiovascular mortality, and cardiovascular events.24–26 For these reasons, it is important to implement home-based exercise sessions on a long-term basis both during and once the allotment of SET sessions is completed.

PRACTICAL ASPECTS FOR COMBINING SET AND HOME-BASED EXERCISE SESSIONS

During the initial 12-wk program, three SET sessions and more should be performed each week, with a goal of two additional home-based exercise sessions and more included in the weekly exercise prescription to provide an adequate volume of weekly exercise. Given that these exercise sessions will be performed at a moderate intensity or above, the combination of the SET and home-based sessions will enable patients to meet the 2018 aerobic Physical Activity Guidelines for Americans by performing 150-300 min/wk of moderate-intensity aerobic activity.27

In addition, another advantage of combining SET sessions with home-based exercise is that patients learn to incorporate exercise into their lifestyle. This aspect becomes increasingly important if patients transition from the 12-wk/36 visit program to an additional 36 SET sessions afterward. As an example, one approach to this phase might be completing one SET session/wk for 36 wk, supplemented with four home-based exercise sessions/wk. The SET sessions could be interspersed >1 wk apart to lengthen the total time of utilizing all the additional 36 SET sessions, if desired. In this manner, a similar weekly volume of exercise can be completed during the long-term phase compared with the initial 12-wk phase of the program, and supervised SET sessions can occur continuously for ≥48 sessions/wk.

It is important that home-based exercise sessions match SET sessions as closely as possible.28 Fortunately, with the availability of many physical activity–monitoring devices for patients to wear during each home-based exercise session, the ability to confirm adherence to completing exercise sessions as well as to quantify the duration and intensity of the exercise sessions is possible. The exercise prescription for each home-based exercise session should be similar to the SET program, specifically regarding intensity, session duration, claudication intensity to reach during exercise, the work-to-rest ratio, and finally modifications made to achieve the appropriate progression throughout the program.

Because a Medicare-insured patient is limited to 72 SET sessions during their lifetime, consideration for each individual patient should be made regarding whether to use all those sessions at once, or to save them if the patient requires SET in the future. One avenue of thought is to use them all at the initial referral so that patients can maximize their improvement and potentially learn to exercise long-term. In addition, there is no guarantee that a patient will ever be able to use remaining sessions in the future because of financial or health situations. Another avenue of thought is to save the sessions. An example would be to discharge patients from SET once they have demonstrated sufficient improvement (to be defined by the patients) and are able to independently exercise. Another example might be to transfer to a maintenance program (eg, phase 3) to save SET sessions. This latter suggestion, in most cases, would be a less expensive out-of-pocket cost for the patient (eg, SET session copay ∼$11.50 vs typical maintenance program cost of $50–60/mo).

EXAMPLES OF THE PAD PATIENT IN “REAL-LIFE” SET

The clinical exercise professional is regularly presented with several challenges over the course of a SET program. Often, the first and most challenging aspects are establishing the proper initial exercise prescription and the overall evaluation of the initial SET sessions. The exercise goals of the first two SET sessions are to (1) establish the primary exercise modality to be used during the SET program, and (2) determine the proper intensity where mild to moderate pain/discomfort (2-3/4) (Table 1) develops within 5-10 min of exercise for modalities that induce pain/discomfort.20,29 In addition, it is important for the clinical exercise professional to be watchful for the following: prolonged rest intervals during interval exercise and a lack of improvement in walking performance. Awareness of these and other exercise-related factors is important for a successful SET program. The following real-life cases provide examples.

EXAMPLE 1: APPROPRIATE USE OF MULTIMODAL AEROBIC EXERCISE

Following the first two SET sessions, it is essential for the clinical exercise professional to review the exercise logs to determine the primary exercise modality in subsequent SET sessions. To accomplish this, attention should be focused on absolute exercise intensity (metabolic equivalent task [METs]), durations of exercise and rest bouts, and total exercise time. For instance, if an individual performs treadmill exercise and has a pattern of low intensity (ie, <2.5 METs) and short walking bouts (<5 min), it is important to prescribe multimodal aerobic exercise instead of treadmill exercise alone.29 Supplemental Digital Content 1, available at: https://links.lww.com/JCRP/A412, illustrates this point. In the first SET session, the patient had short walking bouts, a low absolute exercise intensity, and a short total walking time. In the second session, following a second short- and light-intensity walking bout, the exercise modality was switched to total body recumbent stepping, which resulted in exercise bout durations approximately 5- to 10-fold longer than treadmill walking at a similar MET level. This patient performed multimodal aerobic exercise for the remaining SET sessions. This approach can also be useful to maximize the dose of exercise accumulated over the course of the SET program.23,29

EXAMPLE 2: ESTABLISHING THE CORRECT INTENSITY FOR EXERCISE MODALITIES THAT INDUCE CLAUDICATION

Determining the intensity that produces mild to moderate (2-3/4 rating; see Table 1) pain/discomfort during walking (or other exercise) within 5-10 min requires both a review of the exercise history of the patient and a trial-and-error approach.29 Supplemental Digital Content 2, available at: https://links.lww.com/JCRP/A412, illustrates trial-and-error approach to establish the appropriate exercise intensity that induces pain/discomfort. In this example, workloads for both patients 1 and 2 were inappropriately adjusted throughout the session. Exercise intensity should have been decreased for walking bouts 2 and 3 for patient 1 and increased for patient 2. Patient 3 depicts an appropriate trial and error to inducing mild to moderate pain/discomfort within 5-10 min of walking. In this trial-and-error approach, the initial comfortable walking speed chosen by the patient (1.8 mph) induced mild to moderate pain/discomfort in <5 min. Since there is no specific guidance for adjusting the intensity to target 5- to 10-min walking bouts, the clinical exercise professional decided to reduce the intensity by roughly 20% (0.4 mph) in that the next walking bout was performed at 1.4 mph. This change resulted in a walking time >10 min in the second walking bout. Therefore, for the third walking bout, the clinical exercise professional decided to use the average speed of walking first and second walking bouts (1.6 mph) in the third walking bout. This approach yielded a walking bout that produced moderate pain/discomfort within 5-10 min of walking and was used as their baseline exercise prescription.

EXAMPLE 3: PROLONGED REST PERIODS

Careful consideration of the length of rest intervals, particularly in the initial several SET sessions, can help achieve a maximal dose of exercise. The typical amount of time for pain/discomfort to dissipate following exercise to mild to moderate pain ranges between 2 and 5 min and may depend on patient perception of pain, disease severity, pain severity during exercise, and method of rest (eg, sitting vs standing). In Supplemental Digital Content 3, available at: https://links.lww.com/JCRP/A412, the rest intervals were 8-9 min throughout the SET sessions. During SET, this patient performed three walking bouts/session. If rest intervals were reduced to 5 min, the total session time would shorten by approximately 9-12 min. This time savings would allow one more walking bout/session to occur, thereby increasing the total exercise dose. At the lowest MET level of walking during SET for this patient (ie, session 1 = 2.8 METs), one additional 9-min walking bout could be performed each session, which accumulates to an additional 907 MET-min of exercise over 36 sessions. In this example, the patient may not have been paying close attention to pain dissipation, and staff monitoring may be successful in shortening the rest intervals.

EXAMPLE 4: “I DON'T THINK MY WALKING IS GETTING BETTER” VERSUS “THE TRUE NON-RESPONDER”

It is not unusual for patients to become frustrated with progress during SET, particularly during interval exercise. Patients may focus on the lack of increase in bout (interval) duration and may not recognize that progression in exercise intensity is designed to keep bout durations within 5-10 min. In this event, the clinical exercise professional should listen to the patient concerns and utilize the exercise logs to demonstrate potential changes in exercise intensity that the patient may have not considered. Alternatively, repeating the exercise prescription of the first SET session is an excellent practical method to demonstrate improvement in walking bout duration. This is demonstrated in Supplemental Digital Content 4, available at: https://links.lww.com/JCRP/A412 (depicts exercise logs accumulated for several selected sessions) where Patient A walked for 8:15 min during the first walking bout of their first SET session (2.0 mph and 1%). By session 12, Patient A still had walking bouts 6-8 min in duration but had progressed to 2.0 mph and 4%. Despite the change in METs over the first 12 sessions evident upon review of the training logs, Patient A voiced there was no improvement in walking performance. In response the clinical exercise professional repeated session 1 intensity (2.0 mph and 1%) at the beginning of the 13th session to compare for potential walking improvements. At this intensity Patient A walked for 12:30 min before moderate claudication was experienced which represented a 4:15 min improvement and made clear to the patient that there was improvementhttps://links.lww.com/JCRP/A412.

An example of lack of improvement is depicted for patient B where a review of the exercise logs showed no change in total exercise time and intensity (METs). As for patient A, the first walking bout of session 1 was repeated at the beginning of the 13th session. However, in the case of patient B, there was only a 22-sec improvement in walking time to mild to moderate pain when repeating the session 1 exercise prescription. As a result, the exercise prescription of patient B was switched from a treadmill only modality to multimodal aerobic exercise including both treadmill and total body recumbent stepping. This is a suggested practice in those showing little improvement during walking.10

MISINTERPRETATION OF THE EXERCISE PRESCRIPTION FOR INTERVAL TRAINING MODALITIES

Finally, it is important for the clinical exercise professional to closely review the duration of exercise bouts recorded in patient exercise logs, particularly in patients allowed to independently determine when to stop walking, and intensity progression. When performing exercise that induces pain, it is a common misinterpretation by the patient to exercise for a specific bout duration and not into mild to moderate pain. Since the goal in this type of exercise is to induce mild to moderate pain/discomfort within 5-10 min, look for exercise logs that are continuously displaying bout durations of 5 or 10 min.

PAYMENT AND REIMBURSEMENT

Although most insurance carriers now consider SET for those with symptomatic PAD to be a reimbursable service, there are questions, issues, and concerns relative to coverage determinations, out-of-pocket expenses, and potential for low adherence and nonparticipation. This section reviews the general reimbursement rules and provides other payment information.

As stated, CMS reimburses for SET services for Medicare beneficiaries with symptomatic PAD. Well-established evidence for the benefit of SET with this population led to the CMS coverage policy in 2017.5 Through this policy, SET is recommended as the initial treatment for patients with claudication, and Medicare beneficiaries are eligible to participate in SET if claudication is present. Notably, there are no ankle-brachial index (ABI), disease burden, or other qualifying criteria required for eligibility. Patients who have had a recent surgical intervention, such as a stent, continue to be eligible for SET if symptoms of claudication are still present.

The Medicare regulation is the National Coverage Determination (NCD) 20.35 (5-25-2017), Supervised Exercise Therapy for Symptomatic Peripheral Artery Disease. Within this document, the following expectations are outlined for the physician referral of an eligible patient to a SET program:

  • The patient must have a face-to-face visit with the physician to obtain a referral to SET.
  • The patient must receive information at the office visit regarding PAD risk factor reduction and cardiovascular disease; this may include education, counseling, behavioral interventions, and outcome assessments.

The NCD also outlines requirements specifically for the SET program, which have been provided elsewhere in this document.

Although SET can be provided in a CR program setting, by the same staff, and concurrent with a CR session, it is important to recognize that SET is a separate service from CR. Each program (CR and SET) has a distinct coverage provision. For example, CR requires a monthly individualized treatment plan (ITP) with exercise, educational, and assessment components. Supervised exercise therapy does not require this. As noted previously, education/counseling for PAD is the responsibility of the referring physician. Although both CR and SET services may be delivered concurrently and in the same space with the same qualified staff, it would not be clinically logical for a patient to receive CR and SET at the same time. Clinical need should determine which treatment takes precedence. It would be clinically appropriate for a patient with qualifying diagnoses for both CR and for SET to enroll in and complete one program (typically CR) and then follow with SET if CR training did not resolve claudication and symptoms continue to justify a course of SET.

Another stipulation in the SET NCD that merits clarification is that Medicare Administrative Contractors have the discretion to cover SET beyond 36 sessions over 12 wk and may cover up to an additional 36 sessions with a new referral order, but not exceeding 72 sessions, over an extended period. Keep the points in Table 3 in mind when interpreting coverage by Medicare.

Table 3 - Considerations for Interpreting Insurance Coveragea
  • CMS limits SET to a maximum of 72 sessions in the “Medicare lifetime” of a beneficiary.

  • CMS uses the HIPAA Eligibility Transaction System (HETS) software to track Medicare services that are capped. SET for PAD and pulmonary rehabilitation are two examples of such services.

  • HETS initially displays 72 SET sessions on provider query screens for all Medicare beneficiaries. Hospital billing departments have access to this information.

  • As sessions are used, HETS displays the remaining number of SET sessions left. There can be a 1- to 2-mo lag in the accuracy of the HETS sessions count.

  • When 72 SET sessions have been delivered, any further claims to FFS Medicare will be denied, with or without a qualifying diagnosis for SET.

  • Medicare Advantage Organizations (MAOs) process and pay their own claims. It is plan-specific whether the KX modifier rule is followed and whether the total number of sessions in the “Medicare lifetime” of a beneficiary is limited.

  • It is suggested to ask each patient whether he or she has had SET sessions previously for his or her PAD. If they respond “yes,” it is recommended to investigate how many sessions are remaining using HETS. A hospital or clinic billing office should be able to determine this information.

  • It is at the MAC discretion, retroactively, whether more sessions will be reimbursed beyond the “up-to-36 session” course or beyond the 12-wk time frame (ie, extra 36 visits over 24 or 36 wk).

    • A second referral is required for these additional sessions.5

    • The inclusion of a KX modifier on the claim is attestation by the provider of the services that documentation is on file verifying that further treatment beyond the 36 sessions and/or over 12 wk meets the requirements of the medical policy.30

    • Retroactive claims that are denied by the MAC are the financial responsibility of

      • the beneficiary if an ABN was signed, or

      • the institution if an ABN was not obtained.

  • Various commercial insurances will have their own coverage conditions.

  • For commercial payors, consider performing a “coverage determination” before enrolling a patient in SET.

Abbreviations: ABN, advanced beneficiary notice; CMS, Centers for Medicare & Medicaid; FFS, fee-for-service; HIPAA, Health Insurance Portability and Accountability Act; MAC, Medicare Administrative Contractors; PAD, peripheral artery disease; SET, supervised exercise therapy.
aEach bullet provides information to consider when assessing individual patient insurance coverage for SET and when making determinations to extend visits beyond the initial 36.

There is one procedure code (CPT 93668) available for SET services, which may be used one time/d.31 There is no requirement or restriction on the number of d/wk SET may be provided to a Medicare beneficiary. An inclusive list of eligible International Classification of Diseases, Tenth Revision (ICD-10) codes can be found in published Medicare regulations for SET.31

A major barrier to adherence to a SET program is Medicare and Medicare Advantage plan copayments. These patient costs are incurred per session and are in the range of $11 to $12. For beneficiaries with a lower socioeconomic status, and others, it is a deterrent to completion. Research indicates a higher prevalence of PAD in this subset of patients, possibly due to an increased prevalence of cardiovascular risk factors and poor access to health care.32

REFERRAL PROCESSES AND PROGRAM BEST PRACTICES

Divakaran et al33 published a paper assessing SET PAD referral and participation since CMS coverage approval. They assessed Medicare data from June 1, 2017, through December 31, 2018, representing the initial 18 mo of coverage. In that period, there were 129 699 individuals identified with a claudication diagnosis based on ICD-10 coding. Of these, only 1735 (1.3%) enrolled in a SET program and had ≥1 billable session. And of these, the median sessions performed was 16 (IQR: 6, 28), and only 89 (5.1% of those enrolled) completed the full allotment of 36 sessions. Those who enrolled (vs not enrolled) were slightly older (74 ± 8 vs 73 ± 9 yr; P = .02), more likely to be White (87% vs 84%), less likely to be Black (9% vs 11%) and female (39% vs 43%), and less likely to be dually enrolled in Medicaid (13% vs 22%). Most enrollees were from the Midwest (48%) and Northeast (16%) regions of the United States. These data suggest that age, race, sex, and socioeconomic status may play a role in enrollment to SET. A possible limitation of this early data is a low availability of programs providing SET. Although this remains a barrier to participation, there has been an increase in locations offering SET across the United States.

Using CMS data for 2020, 30 945 claims were submitted to CMS for SET through November 23, 2020.34 Using the median number of sessions performed (ie, 16) this suggests that more than 1900 patients attended ≥1 session of SET. Applying this to the 18-mo period for the data reported in the previous paragraph, this suggests that about 3250 patients would have been referred over 18 mo. This is an increase of 88% enrolled in SET compared with the initial 18 mo following CMS coverage approval. For comparison, for CR (CPT 93797, 93798, GO422) the number of CMS claims were 3.5 million over the same period, representing nearly 146 000 patients.

Although the article by Divakaran et al did not report on SET program referral rates, it is likely that this rate is low.33 Referral rates have been a focus in the CR patient community, and the implementation of automatic referrals via electronic medical record when a patient is in the hospital recovering from an event or procedure has pushed this rate to well more than 95% in many of the eligible patient categories. Unlike those eligible for CR, most often those with symptomatic PAD who are eligible for revascularization but not at risk of an acute limb event are not hospitalized. Thus, an automatic referral process at discharge will not produce the same effect at improving the referral rate as in the CR population. Thus, it is very important for SET practitioners to consistently educate and communicate with those treating physicians (and their staff) who regularly see these patients in their clinics as they will be the best resource for referrals. Although it is recognized that various practitioners and staff in an office may provide assessment and education, the referral order must come from a physician.

Although CMS lists several deliverables that must be provided during SET (eg, 30- to 60-min sessions of therapeutic exercise training; delivered by qualified auxiliary personnel trained in exercise therapy for PAD; under the direct supervision of a physician or advanced practice practitioner) that align with CR, they are silent on several other items that are considered best practices for CR. These would seem to reasonably apply to patients performing SET in the CR setting and include an adequate patient-to-staff ratio and the use of an individualized treatment plan to target behavior change and risk factor reduction. Important areas of focus for the individualized treatment plan would be exercise, smoking cessation, and diabetes management with the latter two being the most important risk factors in these patients relative to disease progression. Also note that CMS allows advanced practice practitioners to provide the required direct supervision for SET services, different than the current requirement for CR, which changes in 2024 to allow advanced practice practitioners the same ability. Regarding the patient-to-staff ratio, it is likely in many instances that this ratio is lower than the 4:1 or 5:1 often considered the norm in CR, although this can vary on the basis of patient factors (age, frailty, ambulatory independence, etc). Because of the specific intermittent exercise training typically performed, there is often a need for a 1:1 staffing ratio, particularly during the initial several SET sessions. This is because patients need to learn the atypical exercise, rest, and intensity progression process used in most SET programs. Once a patient adequately learns and can apply this process, he or she likely will not require as much staff attention. However, some patients may never reach this level of independence.

SUMMARY

Improvement in walking performance is a universally accepted benefit of SET for those with claudication. Supervised exercise therapy has been an insurance-reimbursed therapy since mid-2017 in the United States. Although referral rates are unknown, but likely low, participation rate of eligible patients is assuredly low. Barriers include poor accessibility to locations offering SET, transportation, and cost (eg, copay). These issues were similar in the past in CR and have, to some degree, been overcome, although CR participation is still low. Education of CR programs currently not offering SET and physicians who see eligible patients but do not refer are two areas in which strategies may be focused to help overcome barriers to participation in SET. Ongoing research is a must as there is a paucity of SET-related presentations at national vascular surgery, vascular medicine, and cardiology meetings. Finally, a national PAD awareness campaign by the American Heart Association was released on May 25, 2022 (https://professional.heart.org/-/media/PHD-Files-2/Science-News/p/PAD-National-Action-Plan.pdf), and focuses on patients, providers, insurance companies, and programs that may provide SET services. The overall goal of these activities is to enhance PAD awareness and treatment access.

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Keywords:

cardiac rehabilitation; exercise training; intermittent claudication

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