Can Peak Flow (PEF) Aid in the Identification of Undiagnosed Clinically-Significant COPD?

Abstract

Purpose: This study examined the clinical validity of peak flow (PEF) as part of an approach (questionnaire + peak expiratory flow [PEF]) to help clinicians identify patients in need of diagnostic evaluation for clinically significant COPD (FEV1 < 60% predicted or at risk of exacerbation). Methods: Prospective, cross-sectional, multi-site case-control study. Subjects: >= 40 years recruited through US pulmonary and primary care clinics. Cases: Group 1: >= 1 exacerbation past 12 months; Group 2: FEV1 < 60% predicted, exacerbation free >= 12 months. Controls: Group 3: no COPD. Group 4: mild COPD, exacerbation free >= 12 months. Subjects completed a questionnaire booklet, PEF (3 maneuvers), and spirometry (if not on record). Results: N=346 (186 Cases, 160 Controls). Mean (SD) age=62.7 (10.1) years. 55% female. 86% white. 41% <0.0001); and differentiated GOLD (F=61.72, p<0.0001) and COPD Foundation categories (F=53.93, p<0.0001). It also distinguished Cases and Controls (202.2 [85.5] L/min & 363.6 [114.6] L/min; n=344; t=14.63, p<0.0001) and Groups (ANCOVA F=52.95, p<0.0001); Groups 1 or 2 versus 3 or 4, Tukey-Kramer adjustment, p<0.0001), but could not differentiate Groups 1 and 2. Conclusions: PEF exhibited evidence of validity as an indicator of airway obstruction, but could not differentiate exacerbators and non-exacerbators, supporting the use of additional assessment questions to identify patients who may have undiagnosed COPD with exacerbation risk. Clinical Implications: PEF can assist in the identification of patients in need of spirometric evaluation for COPD, but should not be used to identify patients at risk of exacerbation.