May 31st 2016

Current and former smokers may not show all the signs of chronic obstructive pulmonary disease, but they may still have respiratory problems and use a variety of medications without any evidence basis.

Current and former smokers may not show all the signs of chronic obstructive pulmonary disease (COPD), but they may still have respiratory problems and use a variety of medications without any evidence basis.

Patients meet criteria for a COPD diagnosis if they have a ratio of forced expiratory volume in 1 second (FEV1) to forced vital capacity (FVC) of <0.70 after bronchodilator use.

Retail clinicians need more guidance on how to treat patients who don’t have COPD (meaning, they have FEV1 and FCV values in the normal range), yet have exacerbations, limited activity, and airway disease.

A new study published inThe New England Journal of Medicineexamined around 2700 current or former smokers and patients who had never smoked. The study participants’ respiratory symptoms were measured through a COPD assessment test (CAT).

In addition, the researchers examined whether the smokers who had not only preserved pulmonary function as assessed by spirometry, but also COPD symptoms, had a higher risk of respiratory exacerbations than asymptomatic smokers.

They found that half of the current or former smokers with preserved pulmonary function had respiratory symptoms, and the symptomatic smokers had more respiratory exacerbations than the control group or the asymptomatic smokers.

The smokers who showed symptoms also demonstrated greater limitations with activities. For example, they were more likely to have a shorter 6-minute walk distance.

In addition, the symptomatic smokers had lower FEV1, reduced FVC and inspiratory capacity, and more airway wall thickening without emphysema. This was true regardless of the study participants’ history of asthma.

“Although adults with a new diagnosis of COPD can occasionally receive an incorrect diagnosis of asthma, we assessed the effect of asthma by performing sensitivity analyses that controlled for and then excluded persons on the basis of a previous diagnosis of asthma (diagnosed during childhood or ever),” the researchers noted.

Since obesity can also affect spirometry findings, the researchers excluded extremely obese patients from the study and also controlled for body mass index.

When they looked into current smoking and its ability to cause “cough and sputum without apparent airway obstruction,” it still didn’t explain the higher exacerbation rates.

“Nonetheless, despite our efforts, it remains possible that other coexisting conditions, such as undiagnosed cardiovascular and metabolic abnormalities, could contribute to symptoms and some respiratory ‘exacerbations’ in these persons, as they do in persons with COPD,” the researchers noted.

Around 42% of the symptomatic smokers used bronchodilators, and 23% used inhaled glucocorticoids.

The researchers stated that their findings were concerning, considering the lack of guidance.

“Many of these patients are already being treated with respiratory medications despite a lack of data from clinical trials,” the researchers stated. “This finding suggests that the current use of spirometry to define who should receive a diagnosis of COPD may not adequately cover the breadth of symptomatic smoking-related lung disease.”

The researchers suggested that perhaps the clinical definition of COPD may need to be changed, or a new entity to describe these patients should be considered.

They also called for more research to find out if maintenance therapy with bronchodilators or inhaled glucocorticoids could help lower the rate of exacerbations in this patient population. In addition, they posited that the CAT could serve as a useful tool to identify smokers at high risk for exacerbations.

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