Peak-flow or portable spirometry as a replacement for Spirometry in the diagnosis of COPD and Asthma

Introduction: The diagnosis of Asthma and COPD at Primary care level in India is limited by lack of access to spirometry. Aims and Objectives: To determine the correlation of Peak flow recording and lung volumes on a portable mini-spirometer with the lung volumes measured by spirometry in patients with COPD and Asthma. Methods: A hospital based cross-sectional study was done at 2 tertiary care hospitals among patients diagnosed as COPD or Asthma based on a pre-&post-bronchodilator spirometry. A trained health worker performed performed measurements using a peak flow meter (Breath-O-meter®) as well as a mini-spirometer (COPD6®). The FEV1 / FVC values by spirometry were correlated with the values of peak flow and with the FEV1/FEV6 measured by the mini-spirometer. The sensitivity and specificity of the mini-spirometer (FEV1/FEV6 <70%) and the peak-flow-meter (predicted PEFR <80%) in diagnosing airflow limitation was determined with the full spirometry (FEV1/FVC <70%) as a gold standard Results: 148 patients with obstructive airway disease were included. There was poor correlation for the PEFR with the FEV1/FVC on spirometry and for the FEV1/FEV6 or the FEV1 measured on a portable mini-spirometry with the FEV1/FVC or the FEV1 respectively on spirometry. A cut-off of <80% of predicted PERF to determine obstruction had a sensitivity of 88% and specificity of 49% (Gold standard-FEV1/FVC <70% on spirometry). A cut-off of 70% of FEV1/FEV6 on the mini-spirometry for determining obstruction had a sensitivity of 64% and specificity of 96% Conclusions: Our study findings suggest that PEFR may be a good screening tool, whereas the mini-spirometer may be used as a diagnostic test in resource limted settings