Errors in Spirometry, Primary Care Contribute to COPD Misdiagnosis

Spirometry, primary care misdiagnosis, and patient-related factors may be primarily responsible for chronic obstructive pulmonary disease (COPD) misdiagnosis, according to a study published in Respiratory Medicine.¹

Stine Hangaard, MSc, from the Department of Health Science and Technology at Aalborg University in Denmark, spoke with Pulmonary Advisor about the important findings of the study. “The primary attributable cause of COPD misdiagnosis is spirometry. Spirometry may be seen as a simple test, but it is actually quite challenging to perform and interpret correctly.”

COPD is the most common chronic pulmonary disorder, and the fourth leading cause of death worldwide.⁴ Worldwide prevalence of COPD is increasing, and it is predicted to become the third leading cause of death by 2020.³

Accurate diagnosis of COPD is therefore critical. However, primary care physicians may have difficulty in classifying up to 20% of patients with obstructive pulmonary symptoms.⁵ For instance, differentiating between asthma and COPD can be difficult, but treatment and objectives differ between the 2 conditions,⁶ and misdiagnosis could lead to improper treatment and substandard outcomes.⁷

Spirometry may also lead to the misdiagnosis of COPD.¹ According to the Gold Initiative for Chronic Obstructive Lung Disease (GOLD),⁸ spirometry is required to confirm the diagnosis of COPD in patients with clinical symptoms or a history of risk factor exposure. A postbronchodilator forced expiratory volume in 1 second/forced vital capacity (FEV₁/FVC) ratio <0.70 confirms the diagnosis.⁸ However, this fixed value threshold of 0.70 has been criticized as leading to misdiagnosis.²

The American Thoracic Society and the European Respiratory Society have suggested that to limit misdiagnosis, the lower level of normal FEV₁/FVC for the age and sex of the patient be used instead of the fixed value threshold of 0.70.⁹

Because many factors may contribute to COPD misdiagnosis, the researchers broadly synthesized evidence from the literature on errors in the diagnostic process to determine what factors may be causing misdiagnosis.

Of 1865 potential papers, 73 were included in their review. The investigation found 5 potential causes of COPD misdiagnosis, including the threshold for defining COPD (36 papers), errors made in primary care (15 papers), errors linked to the spirometry test (13 papers), differential diagnoses (10 papers), and patient-related factors (8 papers).

The researchers discovered considerable debate over the spirometry threshold in the literature, most likely because of the lack of a gold standard to measure against the fixed value and lower level of normal. The fixed value threshold, despite being used consistently in clinical practice, has been found to overdiagnose older patients and underdiagnose younger patients. The lower level of normal has been recommended instead of the fixed value, but may lead to underdiagnosis of COPD.

Ms. Hangaard proposed, “One may argue that using spirometry to diagnose COPD is not ideal going forward. Perhaps we should let the challenges linked to spirometry pave the way for developing, using, and testing other objective tests for the diagnosis of COPD.”

The second leading potential cause of COPD misdiagnosis was errors made in primary care. Compared with specialists, general practitioners more frequently make mistakes in diagnosing COPD and frequently give a diagnosis or treatment for COPD with a negative spirometry test, both possibly leading to improper treatment. Also, general practitioners underdiagnose COPD, which could be the result of a lack of understanding of the condition.

Ms. Hangaard suggested that the Global initiative for chronic obstructive lung disease (GOLD), the American Thoracic Society (ATS), and the European Respiratory Society (ERS) may be helpful for primary care physicians in the diagnosis of COPD. The third leading potential cause of COPD misdiagnosis was spirometry errors. Factors that contributed included poor testing quality, technological errors, patient errors, and test administration and interpreting errors. In addition, the use of medications before the test and patients change in body habitus (lung capacity or height) may cause misdiagnosis. The researchers emphasized, “It seems relevant to provide better support for primary care in COPD diagnosis to improve the quality of the spirometry tests and thus limit misdiagnosis.”

The fourth leading potential cause of COPD misdiagnosis was differentiating COPD from other diseases including asthma, heart failure, ischemic heart disease, lung cancer, and acute coronary syndrome.

Last, patient-related factors contributed to COPD misdiagnosis. Women, obese and overweight patients, and some ethnic groups (having different lung capacities) tend to be misdiagnosed.

1. Hangaard S, Helle T, Nielsen C, et al. Causes of misdiagnosis of chronic obstructive pulmonary disease: A systematic scoping review. Respir Med. 2017;129:63-84.
2. Aggarwal AN, Gupta D, Agarwal R, et al. Comparison of the lower confidence limit to the fixed-percentage method for assessing airway obstruction in routine clinical practice. Respir Care. 2011;56(11):1778-1784.
3. GOLD. Global strategy for the diagnosis, management, and prevention of chronic obstructive pulmonary disease (updated 2014), 2014. http://goldcopd.org/gold-reports-2016/. Accessed August 18, 2017.
4. Corrao S, Brunori G, Lupo U, et al. Effectiveness and safety of concurrent beta-blockers and inhaled bronchodilators in COPD with cardiovascular comorbidities [published online August 9, 2017]. Eur Respir Rev. doi: 10.1183/16000617.0123-2016
5. Miravitlles M, Andreu I, Romero Y, et al. Difficulties in differential diagnosis of COPD and asthma in primary care. Br J Gen Pract. 2012;62(595):e68-e75.
6. Price DB, Yawn BP, Jones RC. Improving the differential diagnosis of chronic obstructive pulmonary disease in primary care. Mayo Clin Proc. 2010;85(12):1122-1129.
7. Tinkelman DG, Price DB, Nordyke RJ, et al. Misdiagnosis of COPD and asthma in primary care patients 40 years of age and over. J Asthma. 2006;43(1):75-80.
8. Vogelmeier CF, Criner GJ, Martinez FJ, et al. Global strategy for the diagnosis, management, and prevention of chronic obstructive lung disease 2017 report. GOLD executive summary. Am J Respir Crit Care Med. 2017;195(5):557-582.
9. European Respiratory Society. European Lung White Book, 2014. http://www.erswhitebook.org/chapters/chronic-obstructive-pulmonary-disease/. Accessed August 18, 2017.