CHEST and ATS advocate for Medicare physician fees to improve access to care

September 20, 2021

In response to the 2022 Physician Fee Schedule proposed by the Centers for Medicare and Medicaid Services (CMS), the Joint Clinical Practice Committee, comprised of leaders from the American College of Chest Physicians and the American Thoracic Society, formally submitted comments and suggested edits to the proposal. If adopted, the CHEST/ATS recommendations will sustain or improve the ability of our membership to provide care to beneficiaries.

Key positions include:

• Telehealth extension through 2023, with the addition of CPT codes for telephone evaluation and management services
• Strong opposition to proposed change in policy that would no longer allow E/M services to be billed on the same day as critical care by the same provider or providers in the same group, for instance, if a patient decompensates rapidly
• Appropriate reimbursement for the education and care delivered within each session over the course of pulmonary rehabilitation
• Expansion of pulmonary rehabilitation access for patients who had COVID-19 with prolonged symptoms
• Coverage of time spent on vaccine counseling to recognize the essential role of our membership in taking the time to have a dialogue with their patients to overcome vaccine hesitancy and end this public health crisis
• Extension of health equity data collection policies to the local and community level

Read the full response below.

This response is the result of advocacy efforts driven by CHEST on behalf of patients with lung disease and the clinicians who treat them. CHEST Advocacy is focused on strengthening the association’s voice for the best care for patients through legislative and regulatory actions. Members interested in participating in committee activities should contact advocacy@chestnet.org.

Response to Medicare Program; CY 2022 Payment Policies Under the Physician Fee Schedule and Other Changes to Part B Payment Policies

Dear Administrator Brooks-LaSure:

On behalf of our membership, the American Thoracic Society (ATS) and the American College of Chest Physicians (CHEST) appreciate the opportunity to submit our shared comments on the proposed Medicare Physician Fee Schedule for 2022. Our societies represent over 40,000 pulmonary, critical care, and sleep specialists dedicated to prevention, treatment, research, and cure of respiratory disease, critical care illness, and sleep-disordered breathing. Our members provide care to Medicare beneficiaries for a wide range of conditions including critical care illness, asthma, COPD, lung cancer, alpha-1 antitrypsin deficiency, pulmonary fibrosis, pulmonary hypertension, and other disorders of the lung, as well as sleep disorders. The proposed rule includes several policy changes and payment revisions that are of direct interest and impact to our members. We offer the following comments to help CMS craft the final 2022 Medicare Physician Fee Schedule rule.

Budget Neutrality

The ATS and CHEST share the concerns of the entire physician community facing the financial strains COVID-19 has placed on the physician practices. These financial strains are further exacerbated by the looming budget neutrality factor cuts expected to be implemented in 2022.

Recommendation: We strongly urge CMS and Congress to work collaboratively to address the budget neutrality issue. We further strongly urge CMS to use the full extent of its regulatory authority to prevent or at least, minimize the impacts of expected budget neutrality forced cuts in Medicare physician reimbursement.

Clinical Labor Pricing

ATS and CHEST support CMS’s proposal to use the US Bureau of Labor Statistics as the best source of data for clinical labor pricing.

Recommendation: We urge CMS to use the most recent year data is available to inform clinical labor pricing for physician payment costs. We urge CMS to consider quickly implementing the new labor pricing. ATS and CHEST further agree that the clinical labor rates should be updated to reflect more current estimates of per-hour wages. CMS should also continue to adopt standard assumptions for specific clinical labor tasks. Use of standardized tasks ensures that similar activities have similar cost estimates across services and simplifies the process of updating labor inputs. We also recommend that CMS provide more detail about the process for developing labor standards and the basis for their assumptions.

Extension of Policies Under the Public Health Emergency

The ATS and CHEST support the proposal to extend the telehealth policies that were instituted during the Public Health Emergency and urge CMS to consider granting an extension through 2023. We also recommend that the additional services added to the telehealth list during the COVID-19 PHE, particularly the CPT codes for telephone evaluation and management services (99441-99443), be included in the category of services that are proposed to remain on the telehealth list through 2023.

Definition of Critical Care

The agency is proposing to adopt the CPT prefatory language defining critical care as “the direct delivery by a physician(s) or another qualified healthcare professional of medical care for a critically ill/injured patient in which there is acute impairment of one or more vital organ systems, such that there is a probability of imminent or life-threatening deterioration of the patient’s condition.” Further, the proposed rule clarifies that critical care services can be reported by a physician or an appropriately qualified NPP per Medicare policy wording and based on CPT codebook language.

ATS and CHEST support these proposed definitions and clarifications that confirm current appropriate critical care use and believe they codify existing CPT language and previous CMS intent which are common critical care practices in the U.S.

Critical Care Bundled Services & Vascular Access Procedures

We note in the definition discussion, the proposed rule lists several services that are bundled with critical care services (CPT 99291, 99292) and hence cannot be billed separately. The proposed rule lists the following procedures:

Therefore, we are proposing that the following services would be bundled into critical care visits: Interpretation of cardiac output measurements (93561, 93562), chest X rays (71045, 71046), pulse oximetry (94760, 94761, 94762), blood gases, and collection and interpretation of physiologic data (for example, ECGs, blood pressures, hematologic data); gastric intubation (43752, 43753); temporary transcutaneous pacing (92953); ventilator management (94002– 94004, 94660, 94662); and vascular access procedures.

Recommendation: Not all vascular access procedures are bundled with critical care. We are concerned that the term “vascular access procedures” is too broad and might be misinterpreted to include all vascular access services. There are vascular access services that are separately billable and should remain so. In the final rule, we urge CMS to strike the phrase “vascular access procedures” and replace it with “and the following vascular access procedures 36000, 36410, 36415, 36591, 36600.” Listing these specific vascular access procedures is consistent with the CPT definition of critical care and will provide explicit clarity on which vascular access procedures are included in the critical care bundle and which vascular access procedures remain separately billable.

Critical Care Over Midnight

The proposed rule notes challenges with current policy that requires the critical care “clock” to reset at midnight, forcing providers to split contiguous critical care time provided in service of a patient over two calendar days. The ATS and CHEST support CMS’s intent to revise billing for continuous critical care that extends over midnight.

Recommendation: The ATS and CHEST recommend CMS consider changing the policy to allow the entire period of continuous critical care service, which extends over midnight, to be allowed to be attributed in its entirety to the calendar day the critical service was first initiated.

Critical Care Services Furnished Concurrently by Different Specialties

The ATS and CHEST appreciate that CMS has proposed to allow critical care services furnished as concurrent care to the same patient on the same day by more than one practitioner in more than one specialty, regardless of group affiliation, if the service meets the definition of critical care and is not duplicative of other services and assuming medically reasonable and necessary for diagnosis or treatment of the patient. Currently, CMS policy does not allow for concurrent billing.

Recommendation: The ATS and CHEST support CMS proposal to allow concurrent billing of critical care. We believe allowing for concurrent provision of critical care by providers of the same specialty and within the same provider group is medically appropriate.

Split/Shared Visits

CMS proposes to incorporate into regulation guidance on split (or shared) visits that was previously stated in the Medicare Claims Policy manual, with some refinements. We appreciate the recognition of team-based care in these revisions, but we are concerned that some elements of the proposed policy may conflict with current and future (CPT 2023) coding guidelines. We also note that some policies may need additional clarification. We recognize that coding is distinct from payment policies, but also strongly believe that maximizing consistency between coding guidance and payment policies will reduce administrative burden and that appropriate preparation for anticipated changes will minimize confusion for physicians. For example, CMS stated policy for the services described by revised office or other outpatient E/M codes in the Final Rule for 2020, even though those revisions would not be active until 2021. This provided an opportunity for additional public comment and enabled CPT to make additional revisions to its codes and guidance. We ask CMS to consider comments that improve alignment with CPT 2023 language in specific areas. In all cases, we do not believe the typical service or valuations will be affected. Specifically, CMS proposes to modify its previously existing policy for split (or shared) visits to:

• Allow billing for shared visits for new patients and initial visits;
• Limit shared visit billing to services performed in institutional settings where the concept of “incident to” does not apply;
• Allow shared visits to be billed for critical care and certain Skilled Nursing Facility/Nursing Facility E/M visits;
• Allow practitioners to bill for a prolonged E/M visit for a split (or shared) visit.

Recommendation: The ATS and CHEST supports these changes and urges CMS to finalize them as proposed. In addition, we seek clarification or offer feedback on the following:

• Multiple E/M services on the same date;
• “Incident to” services in the office/outpatient setting for new patients or new problems;
• Substantive portion of the split (or shared) service;
• Definition of “group”; and
• Use of a modifier to identify split (or shared) services

“Incident to” Services and Split (or Shared) Visits

CMS proposed to allow billing of split (or shared) services only in the institutional setting (defined as a hospital or skilled nursing facility) and to allow or reporting of such services furnished to new patients. CMS indicates that in the non-institutional setting services involving a physician and non-physician practitioner (NPP) would be billed as “incident to services”. The “incident-to” services policy is limited to established patients, and some have argued is further limited to established patients under a care plan (i.e., it may not be used for new problems).

Recommendation: CMS should consider allowing “incident-to” for new patients, but as only direct supervision is required for “incident-to”, it may be more appropriate to allow shared/split visits in the office setting. This may be a common occurrence and will facilitate greater access for the beneficiary who can more quickly be seen by the NPP working in a team practice with the physician who will also see the patient in person.

Modifier for Split (or Shared Services)

CMS proposed to create a modifier to describe split (or shared) visits and would require the modifier to be reported on Medicare claims for such visits. CMS also asked for comment on whether it needs to amend the regulations to explicitly state that Medicare does not pay for partial E/M visits.

Recommendation: ATS and CHEST oppose the creation of a modifier for split/shared services. Implementation of a new split/shared modifier would add administrative complexity and will be inconsistently used.

Critical Care Furnished Concurrently by Practitioners in the Same Specialty and Same Group (Follow-up Care)

The ATS and CHEST support CMS’s proposal to allow concurrent follow-up critical care. We generally support the proposed policy to address concurrent follow up care, but we raise a concern with a specific comment made in the proposed rule,

“Under our proposal, once the cumulative required critical care service time is met to report CPT code 99291, CPT code 99292 would not be reported by the practitioner or another practitioner in the same specialty and group unless an additional 30 minutes of critical care services are furnished to the same patient on the same day (114 total minutes).” (emphasis added)

Recommendation: We believe the “114 total minutes” statement is an error and the correct time should be 104 minutes. Initial critical care (CPT 99291) is 74 minutes and subsequent critical care (CPT 99292) encompasses the next 30 additional minutes of critical care, so the correct number should be 104 minutes. We are concerned that the wording in this comment thus proposes an increase in the overall time required by QHPs furnishing critical care services, not allowing for 99292 to be billed until >104 minutes of critical care have been delivered if two different providers are providing that service (for instance with a first QHP providing 60 minutes of critical care services, and a second QHP providing 35 minutes of critical care services). This fundamentally raises the bar for this time-based service, and the nature of critical care with highest acuity patients and dynamic clinical issues often requires care from multiple providers over a 24-hour period as CMS otherwise recognizes in this proposal.

Split/Shared Critical Care Services

CMS is proposing to revise current policy to “allow critical care services to be reported when furnished as split (or shared) services.” As part of the proposal, CMS is requiring that “total critical care time provided by a physician and NPP in the same group on a given calendar date to a patient would be summed, and the practitioner who furnishes the substantive portion of the cumulative critical care time would repot the critical care service(s).” CMS proposes to define the substantive portion as “more than half the cumulative total time in qualifying activities” based on the language of the CPT codebook for all the activities that go into critical care services.

Recommendation: The ATS and CHEST support CMS’s proposal to allow for split/shared billing of critical care services but have concerns with the definition of substantive portion used by CMS. While using >50% of time provided may be administratively simple, it does not account for the complex medical decision-making that drives critical care services. We further strongly recommend against CMS’s alternative proposal to require an individual physician or NPP directly perform the entirety of each critical care visit.

Critical Care Visits and Same-Day Emergency Department, Inpatient or Office/Outpatient Visits

For critical care, CMS is proposing that “no other E/M visit can be billed for the same patient on the same date as a critical care service when the services are furnished by the same practitioner, or by practitioners in the same specialty in the same group.” Under current policy, critical care and other E/M are both separately billable on the same day provided each service is supported by medical necessity.

Recommendation: The ATS and CHEST strongly oppose CMS’s proposal that “no other E/M visit can be billed for the same patient on the same date as a critical care service when the services are furnished by the same practitioner, or by practitioners in the same specialty in the same group.” Implementing such a policy would not reflect standard medical care and would penalize providers who care for very sick patients. While not a high frequency event, it is not uncommon for a patient with an underlying health condition to rapidly deteriorate and in the process may be legitimately be provided various levels of E/M services on the same day. For example, a patient with severe COPD who is suffering an exacerbation is seen in the doctor’s office, is sent to the emergency room department, and due to rapid deterioration of their condition is sent to the ICU. Each E/M service is appropriate, distinct, and should be separately billable.

The ATS and CHEST also have concerns with the alternative proposal to implement the equivalent of a multiple procedure rule for E/M services provided on the same day as a critical care service visit. We instead would urge CMS to rely on proper documentation of services to support the medical necessity and non-duplicative nature of a claim for CC on the same day as office E/M.

Critical Care Visits and Global Surgical Period

CMS is proposing to bundle critical care services with any procedure code that has a global surgical period. Under current policy, critical care services provided to patient’s post-surgery are separately billable, when the service is provided by a qualified health professional outside the surgical group performing the initial surgery and with documented medical necessity.

Under current policy, when medically necessary, physicians are able to provide, bill, and receive payment for critical care service provided to Medicare beneficiaries during a surgical global period provided the critical care service is medically necessary, delivered by a physician who is not in the surgical practice that performed the surgical global period service, is treating a condition unrelated to the surgical procedure, and is appropriately documented. Further, surgeons can bill for critical care provided during the surgical global period for burn, trauma, and immunosuppression patients.

Recommendation: The ATS and CHEST strongly recommend CMS retain the current policy that allows critical care to be provided to patients during the surgical global period provided the critical care service is medically necessary, addresses a critical care condition separate from the underlying surgery, is provided by a physician outside the surgical practice and is appropriately documented.

We strongly oppose any policy that would bundle critical care services in a global period. We note, such a proposed policy is a radical departure from current policy. Implementing the proposed policy would be bad medicine, deny physician payment for lifesaving medically necessary services, and would create extensive financial disruptions for intensive care units across the U.S. If CMS is proposing a more limited policy of eliminating separate billing of critical care by the surgeon during the global period for burn, trauma, and immunosuppression patients, ATS and CHEST would encourage CMS to provide a more thorough review of available Medicare data on the frequency of such services before moving forward with such policy.

The ATS and CHEST believe the current CMS policy allowing for separate billing during the global surgical period reflects appropriate medical practices and ensures the best care is provided to Medicare beneficiaries.

Critical Care Documentation Requirements

CMS is proposing to require total time of critical care services provided by each practitioner and essential documentation that services provided required critical care, and the role each QHP played when multiple providers are involved.

The ATS and CHEST support this proposal and believe such documentation is already common practice for the majority of critical care providers.

Pulmonary Rehabilitation 946X1, 946X2 - Practice Expense

CMS is proposing to refine the clinical labor time for activity CA011 Provide education/obtain consent from the RUC-recommended 15 minutes to 2 minutes for both CPT codes 946X1 and 946X2. CMS does not agree that it would be typical for these codes to require an additional 13 minutes for education and consent and is refining the time to the standard for this clinical labor task. The RUC acknowledges and we as the specialty societies performing these services that it is recommending more minutes than the standard; however, the additional time is justified given the extent of the education that is provided with these services. It is important to differentiate the traditional use of education, which is generally about the procedure or service. This education is different and goes beyond the standard education on the service, or in this case the exercise. Thus, if it does occur at every single encounter and each encounter, it is a different topic. As per society guidelines of the American Thoracic Society /European Respiratory Society Statement, Key Concepts and Advances in Pulmonary Rehabilitation, education is an integral component of pulmonary rehabilitation programs. There is education provided at each separate session following a curriculum outlined in the guidelines. As outlined by our specialties and agreed to by the AMA RUC we have listed 24 varying educational topics below in this letter and as was provided in the RUC summary of recommendation practice expense forms. We need to emphasize these are different at each session as they can and do occur multiple times a week.

It cannot be emphasized enough that education is as integral to the program as is the exercise portion, and therefore must be delivered in an asynchronous manner. For example, one day the education session may be devoted to education and use of respiratory medications and secretion clearance techniques and devices, and another day, the education session is devoted to breathing techniques and strategies on how to perform activities of daily living, and another day, the education session is devoted to smoking cessation strategies, and on another day, the education session is devoted to discussion about all the modes of oxygen delivery and their use. In summary, these are all separate educational discussions that are different at each session, occur with every session, and are not performed while the patient is exercising. CMS not accepting the time necessary for this important part of the service will significantly undervalue the service and could jeopardize the continued availability of these valuable services.

Educational Topics Concerning Self-Management
- Normal pulmonary anatomy and physiology
- Pathophysiology of chronic respiratory disease
- Communicating with the health care provider
- Interpretation of medical testing
- Breathing strategies
- Secretion clearance techniques
- Role and rationale for medications, including oxygen therapy
- Effective use of respiratory devices
- Benefits of exercise and physical activities
- Energy conservation during activities of daily living
- Healthy food intake
- Irritant avoidance/smoking cessation
- Early recognition and treatment of exacerbations
- Leisure activities
- Coping with chronic lung disease

Educational Topics Concerning Advance Care Planning
- Diagnosis and disease process
- Patient autonomy in medical decision-making
- Life-sustaining treatments
- Advance directives documents
- Surrogate decision-making
- Durable powers of attorney for health care
- Discussing advance care planning with health care professionals and family caregivers
- Process of dying
- Prevention of suffering

Recommendation: The ATS and CHEST recommend CMS adopt the AMA RUC approved practice expense time and inputs in their entirety for CPT 946X1 and 946X2.

Pulse Oximetry Monitoring and Pulmonary Rehabilitation codes (CPT 946X1 and 946X2)

CMS is asking for clarification regarding the utilization of pulse oximetry for pulmonary rehabilitation services. Pulse oximetry may be done intermittently as needed or continuously. The RUC agreed with this variation in practice and acknowledged the need for the 2 codes as accepted by the AMA CPT panel.

The 2 codes differ with the X1 being without pulse oximetry continuously monitored and the X2 with pulse oximetry continuously monitored. These were developed by our CPT team and approved by the AMA CPT panel consistent with the current pulmonary rehabilitation practices and parallel in structure to the cardiac rehabilitation codes. We recognize that typically, pulse oximetry in some form is utilized for this population of patients. Furthermore, pulse oximetry may be continuous or monitored intermittently according to each specific site or each specific patient’s disease status. This is the major distinction between the two codes and two services. It is important to have the two options of services as the practice expense is different for each. Patients may start out requiring continuous oximetry, but for those who consistently do not desaturate with exercise, they may transition to intermittent pulse oximetry. Other patients may newly require continuous pulse oximetry if their disease progresses, or they have an acute exacerbation of disease. So, while all patients would be expected to have oximetry monitored, the specifics of continuous vs. intermittent monitoring are not dictated by the guidelines, and practice does vary per site and patient as described. Recommendation: The ATS and CHEST recommend CMS adopt the AMA CPT approved codes and permit billing and Medicare reimbursement for both codes.

Expansion of Pulmonary Rehabilitation for Certain COVID-19 Beneficiaries

CMS is proposing to expand coverage of PR services to include beneficiaries who were hospitalized with a diagnosis of COVID-19 and continue to experience persistent symptoms, including respiratory dysfunction, for at least 4 weeks after hospital discharge.

Recommendation: We strongly support CMS’s proposed expansion of pulmonary rehabilitation coverage for patients with persistent COVID symptoms. Studies have confirmed the beneficial effect pulmonary rehabilitation offers patients with respiratory symptoms. A recent observational study compared the results of pulmonary rehabilitation of a larger group of severely impaired post-COVID-19 patients to individuals typically referred to PR. ^(Speilmann) Results demonstrated significant clinical and functional improvements in individuals who suffered from severe COVID-19 and underlines the importance of post-acute rehabilitation for COVID-19 recovery. Two recent studies of Medicare beneficiaries found significant differences in both the number of rehospitalizations (p<0.001) ^(Stefan) and risk of death (p<0.001) over 1 year between those beneficiaries who initiated PR within 90 days of hospitalization. ^(Lindenauer) While these findings did not include a COVID-19 population, the symptomatology is similar and would suggest that the exercise provided in PR is a promising therapy for long-COVID. ATS and CHEST urge CMS to expand pulmonary rehabilitation coverage to patients who were not hospitalized but are still experiencing long-COVID respiratory symptoms after a similar time frame beyond the initial illness. We believe there are many non-hospitalized patients with persistent long COVID respiratory symptoms that would also benefit from pulmonary rehabilitation.

Conforming changes among rehabilitation services

CMS is proposing to apply many of the definitions and policies developed for cardiac rehabilitation and intensive cardiac rehabilitation to pulmonary rehabilitation. CMS notes there are significant parallels between pulmonary rehabilitation and cardiac rehabilitation programs. The ATS and CHEST agree with the proposed definition changes.

Use of Modifier with Virtual Direct Supervision

CMS is seeking comment on the utility and appropriateness of creating a service level modifier used to report services provided with virtual direct supervision.

Recommendation: ATS and CHEST support the use of a service level modifier with direct supervision is being met via real time audio/video communications technology.

Vaccine Administration Services

CMS is requesting comments and information on a range of vaccination-related issues to develop policy that will improve vaccination rates for COVID-19 and other vaccines and develop more accurate payment rates for vaccine administration. CMS is specifically seeking input on:

• The different types of health care clinicians (and providers) who furnish vaccines and how those clinicians (and providers) changed since the start of the pandemic;
• How the costs of furnishing flu, pneumococcal, and hepatitis B vaccines compare to the costs of furnishing COVID-19 vaccines, and how costs may vary for different types of clinicians (and providers); and
• How the COVID-19 PHE may have impacted costs and whether clinicians (and providers) envision these costs to continue.

CMS also seeking comment on its proposal to create a $35 add-on payment for certain vulnerable beneficiaries when they receive a COVID-19 vaccine at home.

Recommendation: ATS and CHEST strongly support CMS’s efforts to improve vaccination rates and improve the vaccine administration policy. We recommend CMS adopt the recently created CPT code and associated RUC valuation for COVID-19 vaccinations.

Further, the ATS and CHEST strongly urge CMS to make payment available for time spent with a patient discussing how to reduce their COVID risk via vaccination. Specifically, we encourage CMS to make payment and coverage available for CPT code 99401 (Preventive medicine counseling and/or risk factor reduction intervention(s) provided to an individual (separate procedure); approximately 15 minutes), wRVU 0.48. Physicians continue to spend significant time counselling patients on the safety, effectiveness, and value of COVID vaccination. During the COVID pandemic, this counseling work is time-consuming, but an essential service physicians provide to our patients and the general public. CMS should recognize and reward physician vaccine counseling efforts by providing for appropriate coding, billing, and reimbursement for vaccine counseling.

ATS and CHEST further support a $35 add-on for vulnerable beneficiaries to receive a COVID-19 vaccine at home, which would include a private home, nursing home, assisted living facility, group home, or another congregate setting.

Health Equity Initiative

CMS proposes several policies to enhance data collection to support health equality efforts.

Recommendation: The ATS and CHEST appreciate the Administration’s commitment to improving health equity and support many of the data collection policies proposed by CMS. We strongly urge that the data collected by CMS on health equity be both publicly available and accessible to underserved communities to help target intervention at the local level. While national data provides useful information, local and community level data must be available to support effective interventions at the community level.

The ATS and CHEST appreciate the opportunity to submit comments on the proposed 2022 Medicare Physician Fee Schedule. We hope our comments will be carefully considered and will assist the agency in publishing a thoughtful final Medicare Physician Fee Schedule rule.

Sincerely,

Lynn Schnapp, MD, ATSF
President
American Thoracic Society

Steven Q. Simpson, MD, FCCP
President
American College of Chest Physicians

REFERENCES

1. Lindenauer PK, Stefan MS, Pekow PS, Mazor KM, Priya A, Spitzer KA, Lagu TC, Pack QR, Pinto-Plata VM, ZuWallack R. Association Between Initiation of Pulmonary Rehabilitation After Hospitalization for COPD and 1-Year Survival Among Medicare Beneficiaries. JAMA. 2020 May 12;323(18):1813-1823. doi: 10.1001/jama.2020.4437. PMID: 32396181; PMCID: PMC7218499.
2. Spielmanns M, Pekacka-Egli AM, Schoendorf S, Wolfram W, Hermann M. Effects of a Comprehensive Pulmonary Rehabilitation in Severe Post-COVID-19 Patients. International Journal of Environmental Research and Public Health 2021, 18, 2695. https://doi.org/10.3390/ijerph18052695. https://www.mdpi.com/journal/ijerph
3. Stefan MS, Pekow PS, Priya A, ZuWallack R, Spitzer KA, Lagu TC, Pack QR, Pinto-Plata VM, Mazor KM, Lindenauer PK. Association Between Initiation of Pulmonary Rehabilitation and Rehospitalizations in Patients Hospitalized with COPD. Am J Respir Crit Care Med. 2021 Jul 20. doi: 10.1164/rccm.202012-4389OC. Online ahead of print. PMID: 34283694.