Comparison between presence of respiratory symptoms and peak expiratory flow (PEF) values <80% predicted as screening tools for obstructive airways diseases (OAD)

Abstract

When screening large populations for OADs, it is not known whether respiratory symptoms or PEF is a better predictor.

Aim: To compare predictive values of presence of respiratory symptoms vs PEF values < 80% predicted for detecting OADs.

Methods: 7154 employees from 24 bus depots and 7 cities and towns of Andhra Pradesh State in India were administered a respiratory health questionnaire and performed peak flow metry using an EU scale Peak Flow Meter (Breathometer, Cipla Ltd. India). Subjects with presence of at least one respiratory symptom and/or PEF values <80% predicted underwent Spirometry according to ATS/ERS standards. OAD was defined as FEV1/FVC <70%, small airways obstruction (SAO) as FEF25-75%<65% of predicted.

Results: Of the 3348 subjects who performed spirometry, 1433 had PEF <80% predicted (Group A), 746 had at least one respiratory symptom but PEF >80% predicted (Group B) and 1169 had both PEF <80% predicted and presence of at least one respiratory symptom (Group C). The prevalence of OAD was 8.9%, 4.1% and 10.5% in Groups A, B and C respectively while the prevalence of SAO was 49%, 27.5% and 46.6% respectively. Use of PEF <80% predicted was a significantly better predictor of OAD (Δ 4.8%; p=0.01) and SAO (Δ 21.5%; p<0.0001) than the presence of respiratory symptoms.

Conclusion: PEF values <80% predicted is a better predictor of OAD and SAO than presence of respiratory symptoms. We recommend use of PFM as a screening tool for OAD in large epidemiological studies.