New Developments in the Assessment of COPD: Early Diagnosis Is Key
Csikesz NG, Gartman EJ
Int J Chron Obstruct Pulmon Dis. 2014;9:277-286
Study Summary
Chronic obstructive pulmonary disease (COPD) is still widely present, underdiagnosed, and undertreated throughout the world. A recent review summarizes developments that can either be applied to current diagnostic and therapeutic practices or that very shortly will be applicable.
The authors present a short list of recent findings. The first finding is that about half of all patients who have COPD are unaware of their condition and undiagnosed. This results in significant delay in their diagnosis that will jeopardize their future health. Second, the rate of decline in lung function, which was previously thought to be accelerating with age, is probably greatest in the early to middle years of the condition -- a period when diagnosis and appropriate management might confer most benefit on its future course.
COPD mortality rates have been higher among women than men for about a decade. Self-perception of the disorder is also higher among women than men. Although smoking rates in the United States have been declining for decades, the public health burden of smoking remains largely unrecognized. COPD can occur in never smokers, alpha-1 antitrypsin deficiency being one such cause, but occupational and environmental factors may also contribute.
Early evidence of the decline in lung function with cigarette smoking suggested that the rate of decline accelerated with age and duration of smoking. However, more recent studies show that the most rapid rate of decline of forced expiratory volume in 1 second (FEV1) occurs in subjects with mild and moderate disease. Chest CT similarly shows a more rapid decline in lung structure at intermediate stages. These new findings stress the need for smoking cessation measures to be emphasized at earlier stages of the disorder.
Recent understanding of disease heterogeneity has been applied to treatment guidelines. Whereas lung function (eg, FEV1) has been found to correlate only weakly with disease progress, the severity of symptoms and the history of any acute exacerbations provide more precise depictions of patient status. This understanding has also been included in the most recent version of the GOLD guidelines for COPD.
New methods of lung function measurement are being sought; impulse oscillometry is one such method. Preliminary studies suggest that it will be more sensitive to early disease. However, it is not likely to replace traditional spirometry. Chest CT with high resolution is now able to quantify emphysema, air trapping, and airway wall thickening with considerable sensitivity, which may assist in the early detection of COPD.
Biomarkers of COPD, while showing some promise, are not yet considered reliable for routine use. Work continues on a search for genetic factors that predispose subjects to COPD. Apart from alpha-1 antitrypsin deficiency, no such factors have been clearly identified.
Among treatments, smoking cessation is by far the most important and effective modality. No bronchodilator or anti-inflammatory medications, or combinations thereof, have been shown to improve long-term outcomes in COPD. However, all of those agents and roflumilast have been shown to decrease the rate of acute exacerbations, which is desirable and may ultimately be shown to increase survival. Pulmonary rehabilitation has also now become an important component in patients with all degrees of COPD severity.