Many diagnostic guidelines use black or white parameters – either patients meet the criteria and have the disease, or they don’t. While guidelines like this can be useful for developing clear definitions, in practice many patients fall within a gray area. The current diagnosis of Chronic Obstructive Pulmonary Disease (COPD), for example, relies on spirometry results that show airflow limitation (i.e. a ratio of FEV1/FVC<0.70). Some smokers who do not meet this criterion, however, have reported symptoms suggestive of COPD and are potentially even being treated for COPD.
To better define this potential patient population, Woodruff et al report the results of an observational study, SPIROMICS, in this week’s NEJM. The authors enrolled over 2,000 ever-smokers (current and former smokers) and never-smokers (non-smoking controls) into the study. They then subdivided the ever-smokers into those with FEV1/FVC≥0.70 (i.e. with a diagnosis of COPD) or those without a diagnosis of COPD based on spirometry parameters. Using the COPD Assessment Test (CAT), they found that 50% of ever-smokers with preserved spirometry had symptoms of COPD, which was a bit less than the prevalence in ever-smokers with COPD (65%, p<0.001), but greater than the prevalence of symptoms in never-smokers (16%, p<0.001). Further, they followed these patients over time and found that ever-smokers with preserved spirometry had higher rates of exacerbations, reduced exercise tolerance, and higher rates of airway wall thickening on chest imaging in comparison to asymptomatic ever-smokers and never-smoking controls.
These data are an initial foray into defining a new population of patients who do not meet the criteria for COPD diagnosis, but who nonetheless suffer from symptoms suggestive of COPD due to their smoking history. Now that this population has been provisionally identified, Leonardi Fabbri, MD posits, in an accompanying editorial, that more work must be done to define treatments for this group. This means running more clinical trials to find treatments that can help these patients that fall in the gray area.
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Rachel is a fifth-year MD/PhD student at Harvard Medical School. She is originally from Okemos, MI, and graduated from Stanford University in 2011. For her PhD research, she is studying the regulation of cell growth in response to nutrients.