How Useful Is Spirometry?


Vol. 19 •Issue 5 • Page 25
How Useful Is Spirometry?

Opinions Diverge on Its Ability to Diagnose, Treat COPD

It happens from time to time, even in professional basketball.

Instead of jamming the ball home for two, the dunker misjudges his leap, doesn’t reach quite the height he needs and rams the ball into the rim instead of straight down the gullet of the net. It caroms out, leaving fans groaning and one NBA player red-faced.

Pulmonology’s clinical elite recently had their own version of a slam-dunk gone awry. Call it the spiraling fortunes of spirometry.

So persuaded are most pulmonologists of the value of measuring expiratory lung volume and FEV1, especially in middle-aged and older adults who smoke, that they want the spirometer enshrined in the primary care physician’s office as a routine testing tool, alongside the blood pressure cuff and the reflex hammer.

To add legitimacy to their campaign, members of the American Thoracic Society’s Spirometry Task Force sought out an unbiased and credible panel of experts to undertake a comprehensive literature review and assess spirometry’s value to diagnose and manage COPD, the world’s fourth leading cause of mortality.

They chose for the job the Agency for Healthcare Research and Quality (AHRQ), an office within the U.S. Department of Health and Human Services highly regarded for its evidence-based reviews.

Instead of the anticipated slam-dunk, though, AHRQ experts in their August 2005 report gave spirometry a somewhat mixed review—more positive than negative, to be sure—but less than the glowing endorsement advocates expected.

Among those most disappointed was Thomas Petty, MD, who for 25 years has fought to include spirometry in the practice of family medicine. Petty called the AHRQ’s perceptions of spirometry’s shortcomings “deplorable.”

“I’m concerned about it because the AHRQ has clout, and they’re setting back progress immensely,” he told ADVANCE. “I’m not sure they know what they’re talking about. Spirometry is key to the diagnosis of so many conditions. It’s based on fundamental principles. They’re just dead wrong.”

Spirometry’s Shortcomings

Most significantly, the AHRQ report said spirometry comes up short in these ways:

• Symptoms are a better predictor of future lung impairment than spirometry,

• Patients diagnosed with COPD through spirometry are no more likely to quit smoking than those without the diagnosis, and

• Different spirometry results among patients and over time “do not provide useful guidance to physicians in prescribing the best therapy for their patients.”1

Concerning spirometry’s ability to diagnose COPD, the report states that spirometry in the primary care setting “is likely to label a relatively large proportion of individuals as diseased with airflow obstruction who do not have respiratory symptoms or whose symptoms are unlikely to affect their health status.

“Conversely,” it continues, “spirometry is normal in a relatively large percentage of adults who report respiratory symptoms including dyspnea, the respiratory symptom having the greatest impact on quality of life.”

That second assertion “has no validity,” Petty countered. As for the first part, “it’s well-known that spirometric-diagnosed symptoms herald the onset of later disease,” he said. “The NIH’s Lung Health Study showed that if you had airflow obstruction, you had rapid onset of disease if you continue to smoke. It’s also well shown that symptoms are not predictive of airflow obstruction.”

A “huge” body of evidence demonstrates that spirometry is a tool that “correlates with all-cause mortality: heart attacks, stroke, COPD,” Petty continued. “It should be the first test insurers underwrite.”

Spirometry and Primary Care

At the heart of this emerging rift is whether or not spirometry should become a routine test in the primary care setting.

In 2000, a consensus statement appeared in Chest, the journal of the American College of Chest Physicians, that recommended the widespread use of office spirometry by primary care providers for patients 45 years or older who smoke.2

Spirometry “easily” detects COPD in its pre-clinical phase, the consensus statement contended, continuing: “we recommend the development, validation, and implementation of a new type of spirometry–office spirometry–for this purpose in the primary care setting.”

Such widespread use is not warranted by the evidence, said Timothy Wilt, MD, MPH, lead author of the AHRQ review.

“The evidence does not support use of spirometry in primary care settings for all adults with persistent respiratory symptoms (including cough, sputum production, wheeze) or having a history of exposure to pulmonary risk factors regardless of symptom status (e.g. tobacco smoke) for case-finding, improving smoking cessation rates, monitoring the clinical course of COPD or adjusting COPD interventions,” noted Wilt, professor of medicine at the University of Minnesota School of Medicine, in an e-mail to ADVANCE.

Routine spirometric testing in primary care settings “is likely to result in considerable testing and treatment costs, resource utilization and health care personnel time,” he noted. “It might reduce the number of individuals being labeled as having COPD or receiving disease-specific treatment in the absence of severe to very severe airflow obstruction. However, it is likely to label a large number of individuals (many not reporting bothersome respiratory symptoms or having non-disabling symptoms) as diseased who would not benefit from testing or treatment.

“Therefore,” he concluded, “evidence indicates that spirometry should not yet be considered a ‘standard test’ in a primary care providers’ office.”

Spirometry’s Costs

As it always does—and must—money figures into the debate.

Simple office spirometers cost less than $2,000 including printer, Petty said. Reimbursement is about $30-$35. “It’s possible to get an elaborate pulmonary function test done that is totally unnecessary for the diagnosis of CODP,” he said. “All that’s needed is volume and flow.”

Wilt put the cost of a single primary care-based spirometric evaluation between $10 and $40 but added: “This does not include confirmatory evaluations via diagnostic spirometry, bronchodilator testing and/or follow-up office-based tests and treatment of individuals, many whom might not have bothersome respiratory symptoms and/or airflow obstruction severe enough whereby treatment has been demonstrated to be beneficial.”

Those costs don’t seem justified when weighed against the results, Wilt continued.

“If primary care spirometry were conducted according to some current recommendations, 66 percent of a clinic population similar to population-based respondents would undergo spirometric testing, 1.3 percent would be treatment candidates and 0.07 percent would have prevention of an exacerbation during six months to several years,” he asserted.

“If symptomatic adults with FEV1 < 80 percent are assumed to benefit, then 5.3 percent would be treatment candidates and 0.3 percent would have an exacerbation prevented.”

Spirometry and Steroids

Another bone of contention is spirometry’s value in guiding corticosteroid therapy in those already diagnosed with COPD.

According to Wilt et al., spirometry (in combination with clinical examination) helps to determine when to initiate therapy, that is, to determine at what threshold of airflow obstruction initiating therapy is likely to improve clinical outcomes.

However, “the evidence does not support” using spirometry “to monitor disease status among patients already receiving treatment,” Wilt explained.

His report puts it this way: “Monitoring with spirometry to guide additional therapyÉdoes not appear to be beneficial.”

Petty will have none of that line of reasoning. “I don’t know what the basis of that is,” he said. “How can you treat diabetes without measuring blood sugar? How can you tell if a corticosteroid is working unless you have objective evidence that it’s working?”

Petty said spirometry might come into wider use for liability reasons if nothing else. “I know of several lawsuits involving failure to use spirometry, including one case this year in which a board-certified pulmonlogist failed to do spirometry in a patient who was using corticosteroids,” he said.

That patient went on to develop bilateral asceptic necrosis of the femoral heads following an unrelated inflammatory renal disease. The sockets of his hip bones, in essence, rotted away. The patient’s attorney argued that since no spirometric tests had ever been done, the pulmonologist’s care was substandard. The pulmonologist had only performed peak flow measurements showing improvements in airflow in response to corticosteroid therapy.

“The patient sued and won a huge settlement,” Petty said. “I don’t think (the threat of lawsuits) is going to go away.”

Spirometry and Smoking

Petty also had plenty to say about the AHRQ’s contention that spirometric testing as a motivational tool to improve smoking cessation rates is “unlikely” to provide more than a small benefit.

“I think there are very positive indicators for a reduction in smoking,” he said. “One Italian study showed no difference, but other studies do show a difference. In an article I wrote early this year (2005) in the International Journal of COPD, I cited three articles that show a powerful association between first spirometric abnormality and quitting smoking. They’re missing a lot of evidence. There are hugely powerful studies on spirometric abnormalities and smoking.”

All in all, the AHRQ report prompted the ATS Spirometry Task Force, led by Homer Bushey, MD, to publish an editorial in the ATS’s American Journal of Respiratory and Critical Care Medicine that calls the report “hard to accept” albeit “an unimpeachable review of the evidence.” AHRQ, the editorial states, “identifies deficiencies in the tools and treatments now available (for diagnosis and management of COPD) and identifies gaps in knowledge that must be filled by research.”

Petty, meanwhile, isn’t so conciliatory. “I think it’s time for us to counterattack these guys,” he said. “No matter what you say, you’re not up-to-date with reality without solid study in peer-reviewed journals. How can you treat a disease without diagnosing it? And we are under-diagnosing COPD.

“I feel strongly about this,” he concluded. “For 25 years I’ve waged this campaign. I’ve never been known for quitting.”

References:

1. Wilt T, Niewoehner D, Kim C, et al. Use of spirometry for case finding, diagnosis and management of chronic obstructive pulmonary disease (COPD). AHRQ Publication No. 05-EO17-1. Aug. 2005.

2. Ferguson G, Enright P, Buist S., et al. Office spirometry for lung health assessment in adults: a consensus statement from the National Lung Health Education Program. Chest. (2000;117:1146-1161).

3. Petty T. Benefits of and barriers to the widespread use of spirometry. Current Opinion in Pulmonary Medicine. (2005;11, 2: 115-120).

You can reach Michael Gibbons at mgibbons@merion.com.

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