Peak expiratory flow as a screening tool to detect airflow obstruction in a primary health care setting

Peak expiratory flow (PEF) measurement is less expensive and requires fewer skills than spirometry testing. It is thus expected to be a reasonable substitute for spirometry in airflow obstruction screening when spirometry is unavailable.

To evaluate the validation of PEF measurement in the detection of airflow obstruction using newly established regression equations.

The PEFs of 553 'normal' participants aged 40-85 years were measured using mechanical devices. Based on these data, regression equations were generated to predict normal PEF values. Data were then collected from 3379 subjects. The specificity and sensitivity of the different predicted PEF cut-off points for detecting airflow obstruction were evaluated by spirometry, based on previously generated regression equations.

Using newly established reference values for PEF, PEF had higher sensitivity and specificity than the questionnaire in detection of airflow obstruction. That PEF < 80% of predicted was more effective in the detection of airflow obstruction was confirmed by the lower limit of normal of forced expiratory volume in 1 second/forced vital capacity, Global Initiative for Chronic Obstructive Lung Disease (GOLD), and GOLD plus symptom, with a sensitivity of 78.7%, 76.8%, 85.3% and a specificity of 81.9%, 83.8%, 81.4%, respectively.

Mechanical PEF may be a reasonable method of screening for airflow obstruction in settings where spirometry is unavailable.