Docs Debate Home Spirometry

PHOENIX — Experts in lung diseases debated at the annual meeting of the American Academy of Allergy, Asthma & Immunology here whether at-home spirometry tests and devices, which are now available from multiple companies, should be elevated to prime-time use.

The tests are good enough to allow patients to monitor their lung function at home — reducing stress on doctors’ offices, especially in the time of COVID-19, argued Praveen Akuthota, MD, of the University of California San Diego.

But Loren Denlinger, MD, PhD, of the University of Wisconsin-Madison, wasn’t convinced, likening the devices to Cracker Jack toys with consequences.

Denlinger suggested that the devices on the market now are prone to error, have to be cleaned regularly, and are not as simple to use as people assume. “[The devices] are relying on the fact that people know how to take these things apart and then put them back together precisely, which could be a good thing, and then, it could be a disaster,” he said.

Denlinger said piston-based spirometry devices are often inaccurate, and although the new turbine-based devices are better, they still have a tendency to report inaccurate readings. In addition, he said, the devices have no filters — while office-based devices do — which means that particulate matter and even food particles can lodge in the devices and produce erratic and erroneous readings.

Such incorrect readings, Denlinger explained, can lead to a physician believing that a patient is having an asthma crisis, resulting in a prescription for a steroid burst to control what may be a non-existent exacerbation. In addition, he noted, steroid use can have unwanted, serious adverse events.

He pointed to studies that showed how comparisons between home-based readings and office-based readings indicated “there were plenty of cases in which the measurement accuracy would get failing grades according to standard criteria.”

Denlinger said that while he is worried about how well the devices will work and how well they are being maintained, a more important question is how these devices will fit into clinical practice, and if they really will influence years of clinical judgment. He said that in most cases, the added information from a home spirometry test is unlikely to change a physician’s clinical judgment.

On top of that, he noted, there are financial toxicities to be considered: device charges — most hover in the neighborhood of $200; subscription fees; training time for staff; over-reading and interpretation costs; and there is an unclear path for reimbursement. “All of this is unreimbursable right now,” Denlinger said.

In his counter argument, Akuthota said that a confluence of events makes 2022 the ideal time for home spirometry:

• Home-based spirometry is patient-centered: Home spirometry facilitates shared decision-making, and patients like to actively participate in their own care.

• Home-based spirometry is safe in the era of COVID-19: In contrast, use at office visits can lead to cross-contamination of medical devices, contamination in waiting rooms, testing rooms, and corridors, and may affect staff, providers, and other patients.

• Home-based spirometry is sufficiently accurate to make clinical decisions: “We perform spirometry to make diagnoses, to assess severity of respiratory disease, and to track lung function over time,” Akuthota said. He used the analogy that just as something as precise as an atomic clock is not needed to know it is lunchtime, with spirometry you don’t need the gold standard office spirometry device to provide enough information to make a diagnosis. “We don’t need a grade ‘A’ measurement in order to make an accurate clinical diagnosis,” and although it may be heretical, he said, “there is value in strict standards, but they have to be taken in context.”

Overall, Akuthota said, the devices are pretty good, they must meet national and international standards, and there are several that have been authorized by the FDA. He added that newer studies have shown close correlation with the home devices and office tests, and many of the devices come with video coaching.

Both Denlinger and Akuthota agreed, however, that allergists, pulmonologists, and other specialists should get behind a National Heart, Lung, and Blood Institute initiative — the PrecISE (Precision Interventions for Severe and/or Exacerbation-Prone Asthma) Network — which aims to identify unique therapies that work in biomarker-defined subgroups of patients with severe asthma as well as gain information about potential monitoring biomarkers for selected therapies.