Monitoring peak expiratory flow could predict COPD exacerbations: A prospective observational study

Exacerbation of chronic obstructive pulmonary disease (ECOPD) is an important event during the course of the disease. It causes a more rapid decline in lung function, which is associated with hospitalization and the risk of death. Therefore, it is essential to discover approaches to early detection and prevention of ECOPD. Peak expiratory flow (PEF) can be safely used instead of spirometry which can assess the severity of COPD as a standard tool. We hypothesized that monitoring PEF could possibly be used to predict the ECOPD.To verify this hypothesis, daily morning PEF was monitored for 6 months in 53 patients with moderate to severe COPD (mean FEV1 31.53%predicted) who were enrolled in Ningbo, China.A total of 69 exacerbations of COPD (63 of gradual onset, six of sudden onset) were recorded in this study. Thirty cases (43.5%) of gradual onset exacerbations needed to be hospitalized, and the mean PEF significantly decreased (vs baseline) during the 5 days that preceded those exacerbations (from 161.9 ± 39.4 L/min to 137.9 ± 36.1 L/min, P < 0.05, statistical power = 0.92). However, this was not the case with non-hospitalized exacerbations (from 175.4 ± 42.5 L/min to 161.5 ± 39.3 L/min, P = 0.172, statistical power = 0.63). The ROC analysis demonstrated that 24 h before hospitalized exacerbation, the optimal cutoff value of ΔPEF for its prediction was 28 L/min (17% from baseline), with a sensitivity and specificity of 76.7% and 72.7%, respectively (area under the curve [AUC] = 0.84, P < 0.05, statistical power = 0.78). While 48 h before hospitalized exacerbation, the optimal cutoff value of ΔPEF for its prediction was 14 L/min (9% from baseline), with a sensitivity and specificity of 86.7% and 66.7%, respectively (AUC = 0.863, P < 0.05, statistical power = 0.87).As a rapid, inexpensive method, PEF could be used for the prediction and early detection of hospitalized exacerbation of COPD. This may provide opportunity for early intervention of ECOPD.