A troubling study was recently published in the International Journal of Chronic Obstructive Pulmonary Disease which highlighted that only 14% of the study subjects over the age of 40 could be confirmed with a diagnosis of COPD based on the criteria of the Global Initiative for Chronic Obstructive Lung Disease (GOLD).
The problem: 51% of the study subjects over 40 were diagnosed with COPD by the primary care physicians participating in the study and were prescribed some combination of bronchodilators or corticosteroids. That’s a pretty alarming difference and means a significant percentage of the study subjects may have received prescription medication that may not be appropriate for their reported respiratory symptoms.
The study, conducted in Spain, involved approximately 9,500 patients who had visited one of approximately 1,400 primary care physicians in Spain between May and November of 2008 complaining of respiratory symptoms and who were prescribed an inhaled therapy as a result of the visit. The research team conducting the study gathered the medical records related to the visits from each of the physicians and then looked at both the quantitative diagnostic test results reported by the doctors and the qualitative survey responses provided by the patients. (Izquierdo JL, et al. Misdiagnosis of patients receiving inhaled therapies in primary care. International Journal of Chronic Obstructive Pulmonary Disease. 2010:5 241–249)
The study team then compared the combination of the quantitative and qualitative test results with the internationally accepted criteria for establishing a diagnosis of COPD (the GOLD guidelines mentioned above) and the internationally accepted criteria for determining an asthma diagnosis (GINA – Global Initiative for Asthma). Overall, the primary care physicians diagnosed 43% of the total study population with COPD, 43% with asthma, and the remaining 14% with disease of unknown origin. When the researchers further parsed the data to look specifically at the study population over 40 years of age, they determined that the primary care physicians had diagnosed COPD in 51% of the over-40 group.
However, when the researchers applied the GOLD criteria to the over-40 study population, they found that only 14% had met all of the criteria necessary to confirm a diagnosis of COPD, not 51%! The paper’s authors noted, “These data suggest that there could be a significant percentage of patients with an incorrect or unclear diagnosis.”
In other words, many of the people diagnosed with COPD in this study might actually be suffering from a different respiratory condition (asthma, for example). It means that bronchodilators and steroids commonly prescribed for relieving temporary airway obstruction in COPD patients may not be appropriate for a large percentage of the people diagnosed with COPD in this study. As a result of the misdiagnosis, it is possible that the prescribed inhaled therapies may be masking the real respiratory condition, or may be preventing the patient from receiving an inhaled therapy that is more effective for the undiagnosed condition.
So what were the primary care physicians basing their diagnoses on? The study authors seem to indicate that the diagnoses were largely made based on the subjective judgment of the physicians involved - not based on the GOLD or GINA guidelines.
For example, in this study, of the 100% of patients prescribed an inhaled therapy as a result of a respiratory disease diagnosis determined by the participating primary care physicians, only about 50% received spirometry as part of their office visit.
Spirometry is a standard diagnostic test to determine the degree of airflow obstruction. A poor spirometry test result is not conclusive alone for diagnosing COPD but is widely considered a significant leading indicator and is one of the criteria elements of the GOLD guidelines. Spirometry is typically only administered if a physician suspects COPD based on other symptoms (there is a sizeable group of physicians opposed to providing blanket spirometry to all people who report respiratory symptoms – they view it as wasteful - so it is typically limited to those patients where COPD is suspected).
According to the research paper, of the 50% who took the spirometry test, approximately 45% of them received a functional confirmation of COPD – meaning that only 23% of the total study population had a spirometry test that indicated COPD – 100% x 50% x 45%).
So presuming the primary care physicians were accurate in their subjective judgments of other symptoms in deciding spirometry was appropriate for only 50% of the total study population, the maximum percentage of the total study population that should have received a COPD diagnosis was 23%. Yet, as state above, the primary care physicians diagnosed and treated 43% of the total study population for COPD.
Now, we suspect that some of you reading this article might conclude this must be a problem only in Spain but sadly this issue exists worldwide. We’ve written several previous articles about the misdiagnosis of COPD that you can find by visiting the archives of our blog site, www.breathebetterblog.blogspot.com, or if you are one of our e-letter subscribers, by visiting the website for your particular e-letter.
The studies we’ve highlighted in the past have dealt with under-diagnosis of COPD where this study seems to also reveal problems with over-diagnosis. Either way, there are some real problems confronting the medical profession and its ability to accurately diagnose COPD. The research team in this study seems to agree, “In conclusion, the majority of patients in our study who were receiving inhaled therapy in primary care did not have an accurate diagnosis according to current international guidelines for COPD or asthma…More initiatives for improving diagnosis accuracy in respiratory diseases must be implemented in primary care, and focusing on use of spirometry. Improving the differential diagnosis in primary care will improve the management of these common respiratory diseases and ultimately improve the health care of affected patients.”
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