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This short paper analysed data from the third National Health and Nutrition Survey (NHANES III). A total of 3874 subjects aged 50–90 years were included and their percentage predicted forced expiratory volume in 1 second (FEV1), FEV1/FVC ratio, peak flow rate (PEF), smoking history, and respiratory symptoms were analysed using specialised statistical techniques (see www.cdc.gov/nchs/data/nhanes/nhanes3/cdrom/nchs/manuals/nh3guide.pdf for further details). 265 subjects with COPD (7.8% prevalence; 54% male; mean age 65 years) were identified, of whom 235 had a PEF of less than 80% predicted. The adjusted sensitivity for detecting all subjects with COPD was 91%, and for moderate to severe COPD (FEV1 ⩽59% predicted) it was 100%. The specificity of an abnormal PEF was 82%, although 62% of the false positive cases were smokers and 47% had airflow obstruction on spirometry, but less than that required to make a diagnosis of COPD.
The authors suggest that using PEF as a screening method for COPD in primary care could save money for interventions such as smoking cessation strategies instead of using resources for the provision of spirometric tests. Other studies have previously shown that exacerbations of COPD are associated with a significant fall in PEF, so it is reasonable to state that PEF measurements may prove to be a more valuable tool in the diagnosis and/or monitoring of COPD than was previously recognised.