Abstract
BACKGROUND—In general practice airway obstruction and the bronchodilator response are usually assessed using peak expiratory flow (PEF) measurements. A study was carried out in patients presenting with persistent cough to investigate to what extent PEF measurements are reliable when compared with tests using forced expiratory volume in one second (FEV1) as the measure of response. METHODS—Data (questionnaire, physical examination, spirometry, PEF) were collected from 240 patients aged 18-75 years, not previously diagnosed with asthma or chronic obstructive pulmonary disease (COPD), who consulted their general practitioner with cough of at least two weeks duration. The relationship between low PEF (PEF < PEFpred − 1.64RSD) and low FEV1 (FEV1 < FEV1pred − 1.64RSD) was tested. A positive bronchodilator response after inhaling 400 µg salbutamol was defined as an increase in FEV1 of ⩾9% predicted and was compared with an absolute increase in PEF with cut off values of 40, 60, and 80 l/min and ΔPEF % baseline with cut off values of 10%, 15%, and 20%. RESULTS—Forty eight patients (20%) had low FEV1, 86 (35.8%) had low PEF, and 32 (13.3%) had a positive bronchodilator response. Low PEF had a positive predictive value (PPV) for low FEV1 of 46.5% and a negative predictive value (NPV) of 95%. ΔPEF of ⩾10%, ⩾15%, or ⩾20% baseline had PPVs of 36%, 52%, and 67%, respectively, and ΔPEF of ⩾40, ⩾60, and ⩾80 l/min in absolute terms had PPVs of 39%, 45%, and 57%, respectively, for ΔFEV1⩾9% predicted; NPVs were high (88-93%). CONCLUSIONS—Although PEF measurements can reliably exclude airway obstruction and bronchodilator response, they are not suitable for use in the assessment of the bronchodilator response in the diagnostic work up of primary care patients with persistent cough. The clinical value of PEF measurements in the diagnosis of reversible obstructive airway disease should therefore be re-evaluated.
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- Brand P. L., Quanjer P. H., Postma D. S., Kerstjens H. A., Koëter G. H., Dekhuijzen P. N., Sluiter H. J. Interpretation of bronchodilator response in patients with obstructive airways disease. The Dutch Chronic Non-Specific Lung Disease (CNSLD) Study Group. Thorax. 1992 Jun;47(6):429–436. doi: 10.1136/thx.47.6.429. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Cross D., Nelson H. S. The role of the peak flow meter in the diagnosis and management of asthma. J Allergy Clin Immunol. 1991 Jan;87(1 Pt 1):120–128. doi: 10.1016/0091-6749(91)90223-b. [DOI] [PubMed] [Google Scholar]
- Dales R. E., Spitzer W. O., Tousignant P., Schechter M., Suissa S. Clinical interpretation of airway response to a bronchodilator. Epidemiologic considerations. Am Rev Respir Dis. 1988 Aug;138(2):317–320. doi: 10.1164/ajrccm/138.2.317. [DOI] [PubMed] [Google Scholar]
- Dekker F. W., Schrier A. C., Sterk P. J., Dijkman J. H. Validity of peak expiratory flow measurement in assessing reversibility of airflow obstruction. Thorax. 1992 Mar;47(3):162–166. doi: 10.1136/thx.47.3.162. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Godschalk I., Brackel H. J., Peters J. C., Bogaard J. M. Assessment of accuracy and applicability of a portable electronic diary card spirometer for asthma treatment. Respir Med. 1996 Nov;90(10):619–622. doi: 10.1016/s0954-6111(96)90020-7. [DOI] [PubMed] [Google Scholar]
- Jones K., Lane D., Holgate S. T., Price J. Asthma: a diagnostic and therapeutic challenge. Fam Pract. 1991 Mar;8(1):97–99. doi: 10.1093/fampra/8.1.97. [DOI] [PubMed] [Google Scholar]
- Kelly C. A., Gibson G. J. Relation between FEV1 and peak expiratory flow in patients with chronic airflow obstruction. Thorax. 1988 Apr;43(4):335–336. doi: 10.1136/thx.43.4.335. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Nicklaus T. M., Burgin W. W., Jr, Taylor J. R. Spirometric tests to diagnose suspected asthma. Am Rev Respir Dis. 1969 Aug;100(2):153–159. doi: 10.1164/arrd.1969.100.2.153. [DOI] [PubMed] [Google Scholar]
- Quanjer P. H., Tammeling G. J., Cotes J. E., Pedersen O. F., Peslin R., Yernault J. C. Lung volumes and forced ventilatory flows. Report Working Party Standardization of Lung Function Tests, European Community for Steel and Coal. Official Statement of the European Respiratory Society. Eur Respir J Suppl. 1993 Mar;16:5–40. [PubMed] [Google Scholar]
- Sears M. R. The definition and diagnosis of asthma. Allergy. 1993;48(17 Suppl):12–23. doi: 10.1111/j.1398-9995.1993.tb04692.x. [DOI] [PubMed] [Google Scholar]
- Thiadens H. A., De Bock G. H., Dekker F. W., Huysman J. A., Van Houwelingen J. C., Springer M. P., Postma D. S. Value of measuring diurnal peak flow variability in the recognition of asthma: a study in general practice. Eur Respir J. 1998 Oct;12(4):842–847. doi: 10.1183/09031936.98.12040842. [DOI] [PubMed] [Google Scholar]
- Thiadens H. A., de Bock G. H., Dekker F. W., Huysman J. A., van Houwelingen J. C., Springer M. P., Postma D. S. Identifying asthma and chronic obstructive pulmonary disease in patients with persistent cough presenting to general practitioners: descriptive study. BMJ. 1998 Apr 25;316(7140):1286–1290. doi: 10.1136/bmj.316.7140.1286. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Tweeddale P. M., Merchant S., Leslie M., Alexander F., McHardy G. J. Short term variability in FEV1: relation to pretest activity, level of FEV1, and smoking habits. Thorax. 1984 Dec;39(12):928–932. doi: 10.1136/thx.39.12.928. [DOI] [PMC free article] [PubMed] [Google Scholar]