Mild chronic obstructive pulmonary disease: Why spirometry is not sufficient

INTRODUCTION: Chronic obstructive pulmonary disease (COPD) - an inflammatory disease of the airways, alveoli and lung microvasculature - is a leading cause of death worldwide. Smokers with milder airway obstruction constitute the majority of patients with this disease. Many studies have shown increased morbidity, activity-related dyspnea, exercise intolerance and mortality in such patients, compared with age-matched healthy populations. Clinical evaluation of symptomatic smokers with ostensibly mild airway obstruction poses a challenge in clinical practice as spirometry can obscure extensive heterogeneous pathophysiological impairment. Areas covered: A detailed review of the evidence for complex biological, physiological and radiological abnormalities in smokers who barely fit arbitrary spirometric criteria for COPD diagnosis. A brief discussion of the debate about current diagnostic spirometric criteria for COPD that can lead to diagnostic confusion and, in-some-instances, to inappropriate management. Finally, we provide a review of the clinical implications of these structural and functional abnormalities and try to build a solid rationale for earlier detection and effective, timely management. Expert commentary: The prevalence of mild COPD among smokers is high, yet under-diagnosis remains a major problem and there is lack of evidence-based management recommendations for this sub-population. Further tests beyond spirometry are useful in uncovering patho-physiological derangements that are clinically relevant