Monitoring Peak Expiratory Flow Could Predict COPD Exacerbations

Background: 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.Method:This observational,prospective study was conducted between November 1,2017 and May 1,2018 in China.Patients were recruited from the affiliated hospital of Ningbo University and Ningbo No.9 Hospital.The daily(8am)PEF of the enrolled patients was continuously monitored for 6 months and data were recorded.Statistical methods: Data were analyzed using the SPSS(version 23)software.Based on the normality of data distribution,all quantitative variables were presented as mean and standard deviation(SD),or medians and interquartile range(IQR);whereas qualitative data were presented as percentages.The analyses were performed by Mann–Whitney U test or Student's t-test,and Pearson's chi-squared test or Fisher's test.A P value of <0.05 was regarded as statistically significant.The discriminating power of the change in PEF to predict hospitalized exacerbation was analyzed by receiver operating characteristic(ROC)curves.Result: 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).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).The ROC analysis demonstrated that 24 h before hospitalized exacerbation,the optimal cutoff value of ?PEF 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).While 48 h before hospitalized exacerbation,the optimal cutoff value of ?PEF 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).Conclusions: 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.Abbreviations: ROC=receiver operating characteristic;?PEF=change in PEF relative to baseline.