Office spirometry correlates with laboratory spirometry in patients with symptomatic asthma and COPD

ObjectivesSpirometry remains underutilized in the evaluation of obstructive lung disease. While office spirometry (OS) has been compared to formal laboratory-based spirometry (LS) in healthy subjects, the correlation has never been formally assessed in patients with symptomatic obstructive lung disease. The aim of this study was to investigate the correlation in this population. MethodsWe used a retrospective study design to analyze spirometry data from patients that underwent both OS and LS. Two flow sensing office (portable) spirometers were used and compared with laboratory-based (body plethymosgraph) spirometer. Accuracy and reliability were assessed using Bland Altman analysis. ResultsAmong 185 patients with symptomatic obstructive lung disease, 129 had undergone both OS and LS. Of these, 107 patients had both tests performed less than 90 days apart and were included in final analyses. Mean age was 54 years with mean FEV1 of 1.97 L (65% predicted). Ninety-two patients had airflow obstruction, as determined by a FEV1/FVC ratio of <70%. We found significant correlation in the values between OS and LS for both FEV1 and FVC (r=0.937 and 0.90, respectively, P<0.001). Eighty-seven percent of patients had a concordant spirometry in terms of airflow obstruction. Correlation was independent of the office spirometer (and hence the Flow-sensing mechanism) used. ConclusionsIn patients with known asthma and chronic obstructive pulmonary disease (COPD), OS is accurate and reliable when compared to formal laboratory-based spirometry. Routine use of OS should be encouraged to improve spirometry utilization and healthcare outcomes in patients with Asthma and COPD.