COPD under-diagnosed among heart disease patients

About a year ago, I was discussing the woeful levels of patient access to pulmonary rehabilitation with one of the chief pulmonology scientists at the National Institutes of Health. During our conversation, the scientist indicated that diagnosing and treating lung disease/COPD is becoming more complicated because of the growing prevalence of lung disease among people who have other significant health conditions – most notably heart disease, hypertension or diabetes.

It seems that among these diseases/conditions, lung disease is the one that is often under-diagnosed by doctors. In a way, one can understand how this happens. The diagnostic tests to assess heart disease, hypertension and diabetes are relatively easy to administer and interpret by most practitioners (generalists and specialists alike) while the primary test for determining a person's lung function, spirometry, is not. In addition, the shortness of breath symptoms that typically are warning signs of emerging lung disease can be associated with symptoms of heart disease, hypertension and diabetes.

A recent study published in Chest underscores this point. A group of Spanish researchers hypothesized that COPD was under-diagnosed among patients with cardiovascular disease and coronary artery disease. For the study, the research team sought out people who had been previously diagnosed with these two heart conditions but who had not been assessed for lung disease. They then administered spirometry tests to these patients to determine whether there was notable airflow limitation in the study population. (Soriano JB, et al. High Prevalence of Undiagnosed Airflow Limitation in Patients With Cardiovascular Disease. Chest. 2010 Feb; 137 (2):333-40)

In a spirometry test, a patient blows air into a spirometer (a device that measures the volume of air expired in either 1 second or 6 seconds). The output of the test is a statistic called either FEV1 or FEV6 (the amount of air expired in either 1 or 6 seconds). While this sounds easy to interpret, it is not. The output of the test is actually a graphic depicting the curve of the expired air. It takes a skilled practitioner to look at the results and determine whether the FEV1 or FEV6 values reveal emerging lung disease.

What the researchers found was astonishing. Over 20% of those diagnosed with cardiovascular disease had airflow limitation consistent with COPD diagnosis. The spirometry tests in the patient group with coronary artery disease showed 33% with COPD-like levels of airflow limitation. The researchers concluded that in order to catch and treat lung disease more aggressively, physicians should administer spirometry tests for all patients who have been diagnosed with heart disease. Sounds like a worthy recommendation.

These findings are somewhat consistent with a different study published in Thorax in 2008. In this study, the researchers desired to understand what co-morbidities existed among COPD patients undergoing pulmonary rehabilitation (meaning what other chronic diseases where present among these COPD patients). (Chrisafulli E. Role of co-morbidities in a cohort of patients with COPD undergoing pulmonary rehabilitation. Thorax. 2008 Jun; 63(6):487-92)

Overall, over 50% of the study patients had at least one co-morbidity with the most prevalent co-morbidities being hypertension (27%), heart disease (20%), and diabetes (10%). The study researchers, echoing the sentiments shared by the NIH scientist I spoke with last year about the increasing complexity of treating lung disease, said, "Complex chronic co-morbidities may significantly affect the clinical severity of COPD being present in up to 56% of patients with COPD compared with non-COPD subjects of the same age."

The takeaway - if you have heart disease, hypertension or diabetes and you suffer from chronic shortness of breath, ask your doctor for a referral to a pulmonologist to conduct a spirometry test. It's a quick and easy test to take (not so much to interpret) but it may help you spot lung disease earlier in its development when you have a better chance of slowing or halting the progression of disease through applying the practices and principles of pulmonary rehabilitation and otherwise treating short-term symptoms with medication.