Transplant Talk: All About Spirometry

What is spirometry? 

• Spirometry is a test that measures lung function 
• It is used in both disease diagnosis and monitoring of disease progression
• Spirometry is relevant for a number of respiratory diseases: asthma, COPD, pulmonary fibrosis, cystic fibrosis, etc. 

Spirometry in a clinic: 

Traditionally, a spirometry test is performed in a healthcare clinic. During the test, patients are instructed to breathe into a tube connected to a spirometer. A patient is usually asked to perform a series of blows, and the clinician takes the best attempt and analyzes the results.

Key spirometry results 

• FVC (forced vital capacity) – the volume of the entire blow,  typically measured in Liters
  •  A low FVC value may be indicative of restrictive lung disease (i.e. IPF), as  patients are unable to inhale fully 
• FEV1 (forced expiratory volume, 1 second)—the volume of  the first second of the blow, also measured in Liters ○ A low FEV1 value relative to FVC (FEV1/FVC) may be indicative of  obstructive lung disease (i.e. COPD or asthma), characterized by difficulty exhaling

Home spirometry—the early days 

• Home spirometry has been in use since at least 1990—32 years! 
• Early devices were quite different from the digital versions that are now available ○ Data was displayed directly on the device 
• Most devices did not store the data 
• None of the devices shared data with the clinical team automatically 
• Patients were relied on to keep a paper diary 
• FVC was not recorded on many early home spirometers

Digitization of home spirometry and  implementation in remote patient monitoring 

• There are now a number of Bluetooth or cellular-enabled home spirometers on the  market which send data to your smartphone and/or clinicians  
• Not all digital home spirometers have the same level of clinical validation 
• Connected apps vary widely by features, function, and reliability

Spirometry is a key indicator of patient health post-lung transplantation 

• Spirometry is commonly used post-lung transplant for follow-up care 
• Typically, spirometry is done in a clinic (PFT Lab) every 3 months after a baseline is  established during the first several months following the transplant 
• Declines in key spirometry values, particularly FEV1 (but also FVC), may indicate  complications: 
• Rejection 
• Bronchiolitis obliterans syndrome (BOS) 
• Infection 

COVID-19 spike in digital health 

The COVID-19 pandemic was a major catalyst for digital health adoption.
Some statistics based on an EY survey of 2000 patients and 300 physicians: 

• In April 2020, 43.5% of Medicare primary care visits were telemedicine, compared to 0.1% in February 2020.
• Use of telephone and video at physician practices increased from 20% (before pandemic) to 80% (during pandemic). 
• 81% of physicians surveyed planned to accelerate the introduction of new digital technologies.

Digital health (including remote patient monitoring  [RPM]) will remain “sticky” moving forward: 

• 2021 use of telehealth declined from its COVID-19 peak in 2020 but has leveled off at much higher levels than pre-pandemic.
• CMS made major changes to telehealth and remote patient monitoring.
• Reimbursement changes in the last few years have allowed for increased adoption. 
• A 2021 survey from MSI international found that 80% of consumers are in favor of using RPM.

Key reasons are: 

• convenience 
• efficiency 
• control over personal health 
• peace of mind 

Remote patient monitoring (RPM) including home spirometry in lung transplant care. 

RPM may be used as part of a follow-up care plan after a lung transplant.

Patients are supplied with medical devices (spirometers, pulse oximeters, weighing scales, etc.) and a connected mobile application to send physiological data to their clinical team in between routine care appointments. 

In addition to physiological data, patient-reported outcome data (i.e., surveys about quality of life, breathlessness, etc.) can be quite useful in capturing a more complete picture of patient well-being.

Care teams may review this data regularly for any alarming changes, or use it as a reference point during telehealth visits.

Benefits of remote monitoring versus routine care 

1. Quicker identification of changes in physiologic values (i.e., FEV1) may indicate infection or rejection, and allow patients and clinicians to intervene appropriately to prevent or reduce the impact of these acute events.
2. Long-term monitoring of spirometry and other data allow patients and their care teams to communicate more frequently and effectively, adjusting care plans accordingly. 
3. Patients and clinicians have better peace of mind, knowing that both are actively participating in the care process even in between appointments. 
4. Fewer or less frequent in-person follow-up appointments may be needed, allowing patients the comfort and convenience of making fewer trips, and freeing up capacity for health systems.

What are the costs and who pays for it? 

• Home spirometers can vary widely in cost, but most handheld devices will likely be in the $100 to 200 range. ○ Some of these devices are available direct-to-consumer and may  interface with downloadable apps. 
• Remote patient monitoring programs are typically paid for by healthcare systems. 
• There are reimbursement codes available for RPM that the center would bill patients’ insurance for each month.

Home spirometry has not come without challenges and controversy.

One of the earlier publications in home spirometry (2001) concluded that: 

“Even under ideal conditions, home spirometry provides an incomplete (and therefore potentially biased) picture of long term changes in pulmonary function.” 

Sources: https://pubmed.ncbi.nlm.nih.gov/11182009/ 

More recently in 2019, a study assessing the efficacy and safety of pirfenidone in ILD patients was unable to draw any statistical conclusions due to variability in home spirometry data. 

This was largely due to the lack of statistical controls for removing outlier values, but nevertheless, many questioned the accuracy of home spirometry. 

Sources: https://pubmed.ncbi.nlm.nih.gov/31578169/

How can we ensure high-quality home spirometry? 

• The technology is improving, along with understanding about how/when/what to use home spirometry for.
• Clinicians can analyze flow-volume curves to assess blow quality. 
• Home spirometry platforms can employ algorithms to assess quality in real time, or to coach patients through the process.
• Coaching can be done via video consultation with a clinician when technique is under question. 
• One to two week “learning curve” for new home spirometry users.
• Keep in mind the difference between “research quality” spirometry and the level of accuracy that is needed to track changes over time in a clinical or patient-led application.
• Outlier values will occur and need to be accounted for (i.e., a patient might cough during a blow).

Sample IPF patient home vs clinic FVC, consented to share

Other possible cons of home spirometry or RPM 

• Access to technology or internet may be limited.
• Some patients may find it burdensome to track data, or it may increase anxiety or stress 
• RPM and digital medicine in general cannot replace all face-to-face visits.
• All insurance providers may not cover RPM.

How can patients find the right home spirometer and platform for them? 

• First, ask your care team if they have a remote monitoring  program or if they recommend a particular device and platform.
• Ask patient advocacy groups for recommendations.
• Check for clinical studies validating the device and platform.
  • These can often be found on company websites, or use a site like  clinicaltrials.gov to check for publications. 
• Read about the pros and cons of different devices/platforms on company websites.

○ For example, do I plan to keep a log of other data (i.e., weight, symptoms)? Do I want a way to track my medications? What’s the cost of the device?

Conclusions 

• Spirometry is a key tool for long-term follow up of lung transplant recipients.
• Home spirometry is becoming an increasingly reliable method of making spirometry more accessible and convenient.
• Remote monitoring technologies allow for home  spirometry data to be shared easily with care teams, allowing for quicker identification of adverse events and peace of mind for all.
• There is still work to do to ensure home spirometry accessibility, reliability, and affordability.

Sources: 

https://www.ey.com/en_ch/health/how-covid-19-has-triggered-a-sprint-toward-smarter-health-care

https://www.atsjournals.org/doi/10.1164/rccm.201505-0932ED

https://lungtransplantfoundation.org/wp-content/uploads/2022/03/bronchiolitis-obliterans-syndrome.pdf

https://www.mayoclinic.org/tests-procedures/spirometry/about/pac-20385201

https://www.chp.edu/our-services/pulmonology/patient-procedures/spirometry-testing