Underdiagnosis and misclassification of COPD in Sweden

Abstract

Introduction: The prevalence of COPD seems to have leveled or decreased in some high income countries. Worldwide, population studies using spirometry have found substantial underdiagnosis of COPD. Aim: To investigate underdiagnosis and misclassification of COPD in Sweden. Methods: A randomly selected sample (n=1839; age 21-78 years; women 52.6%) was derived from two large scale population studies in Sweden, the West Sweden Asthma Study (WSAS) and the Obstructive Lung Disease in Northern Sweden (OLIN) Studies. Examinations including spirometry and structured interviews were conducted 2009-2012. COPD was defined following GOLD 2017: post-bronchodilator FEV1/FVC Results: Of those with COPD (GOLD) identified at the clinical examinations, 24% had, prior to the study, been diagnosed with COPD, emphysema, or chronic bronchitis (COPD-cluster), while 46% had been diagnosed with the COPD-cluster, asthma, or used medicines for airway disease (any OAD). The corresponding figures for those fulfilling the criteria of COPD GOLD grade ≥2 were 39% (COPD-cluster) and 62% (any OAD). Among the subjects who, prior to the study, had been diagnosed with COPD, 78% fulfilled the criteria of COPD, but among those who had been diagnosed as having any of the diseases in the COPD-cluster, 31% fulfilled the criteria of COPD. Conclusion: The proportion of underdiagnosis of COPD is still large in Sweden. Some misclassification of COPD was also found. The results reflect underuse of spirometry in primary care.