BackgroundThe diagnosis of chronic obstructive pulmonary disease (COPD) is usually made based on history and physical exam alone. Symptoms of dyspnea, cough, and wheeze are nonspecific and attributable to a variety of diseases. Confirmatory testing to verify the airflow obstruction is available but rarely used, which may result in substantial misdiagnoses of COPD. The aim of this study is to evaluate the use of confirmatory testing and assess the accuracy of the diagnosis.MethodsFrom January 2011 through December 2013, 6,018 patients with COPD as a principal or leading diagnosis were admitted at a community teaching hospital. Of those, only 504 (8.4%) patients had spirometry performed during hospitalization. The studies were reviewed by two board-certified pulmonologists to verify presence of persistent airflow obstruction. Charts of these patients were then examined to determine if the spirometry results had changed the diagnosis or the treatment plan for these patients.ResultsSpirometry confirmed the diagnosis of COPD in 270 patients (69.2%) treated as COPD during their hospitalization. Restrictive lung disease was found to be present in 104 patients (26.6%) and normal in 16 patients (4.2%). Factors predictive of airflow obstruction included smoking status and higher pack-year history. Negative predictive factors included higher body mass index (BMI) and other medical comorbidities. These patients were significantly more likely to be misdiagnosed and mistreated as COPD.ConclusionUp to a third of patients diagnosed and treated as COPD in the hospital may be inaccurately diagnosed as COPD based on confirmatory spirometry testing. Factors contributing to the inaccuracy of diagnosis include less smoking history, high BMI, and associated comorbidities.

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