How accurate is spirometry for diagnosing COPD?

A research article in this month’s issue of the journal Respiratory Medicine highlights the challenge practitioners face in accurately diagnosing COPD using the most reliable tool available today, spirometry. In fact, the Swedish researchers who conducted the study described in the article determined that only one third of COPD patients in their study population had prior spirometry results that were consistent with a COPD diagnosis. In other words, spirometry failed to detect COPD for nearly 70% of the study population. (Arne M, et al. How often is diagnosis of COPD confirmed with spirometry? Respiratory Medicine. 2010 April; 104(4): 550-556.)


This is somewhat troubling in that it means a significant portion of people in the study population likely experienced further lung function deterioration before they were diagnosed and prescribed treatment regimens for COPD. Some people might quibble with the study’s results as applicable to the U.S. since the study population was drawn from Sweden but we’ve seen enough “spirometry under-diagnosis” papers published in journals from across the globe to believe that the overall point raised by the study is valid even if the precise figures vary from country to country.

For a relatively brief (and hopefully not-too-technical) description of what a spirometry test involves and what results it produces, you can click here to be redirected to our Breathe Better for Life e-letter filing cabinet for an excerpt on spirometry from our Breathe Better for Life guide/CD.

What makes this study’s results noteworthy is it adds fuel to the fire in the long running debate within the medical community about how broadly to use spirometry to test people considered at risk for COPD (i.e. smokers, those who work in environments with heavy industrial air pollutants).

At one end of the pole, there is a group of physicians who believe that spirometry should be given early and often to people who fall into high risk categories so that doctors have a better chance to catch emerging COPD earlier and therefore prescribe treatment earlier in an effort to reduce the degree of lung function decline over time.

At the other end of the spectrum, there is another group of physicians who believe that over-prescribing spirometry tests is wasteful in that spirometry is unlikely to detect COPD in its early development and patients might be misdiagnosed with COPD based on poor spirometry results when they are otherwise asymptomatic (poor spirometry results may indicate lung conditions other than COPD).

For an excellent overview of the “damned if you, damned if you don’t” situation regarding spirometry as a diagnostic tool for COPD, there is an excellent paper authored by Dr. Neil MacIntyre, one of the leading pulmonary medicine researchers in the U.S., that was published last year in the journal Respiratory Care. You can view the full, free text of Dr. MacIntyre’s paper by clicking here.

From our perspective, the main takeaway for people who suffer from chronic shortness of breath is the following…if you are concerned that you might have emerging lung disease but your doctor says that your spirometry results don’t indicate COPD, ask to be tested again.

Alternatively, ask your doctor whether one or more of these other common lung function tests are appropriate for you - pulse oximeter readings, six minute walk test results, chest x-rays, CT scans, and/or arterial blood gas samplings. While none of these tests in and of themselves will confirm a COPD diagnosis, they may help your doctor identify or rule out COPD if your spirometry results are inconclusive. By the way, we published a previous post on pulse oximeters and how you can use one at home to keep tabs on your blood oxygen levels and gain some basic insight into the quality of your respiratory system. You can access that post by clicking here.