Detecting patients at a high risk of developing chronic obstructive pulmonary disease in general practice: cross sectional case finding study

Abstract

Objectives: To investigate the effectiveness of case finding of patients at risk of developing chronic obstructive pulmonary disease, whether the method is suitable for use in general practice, how patients should be selected, and the time required.

Design: Cross sectional study.

Setting: Two semirural general practices in the Netherlands.

Participants: 651 smokers aged 35 to 70 years.

Main outcome measures: Short standardised questionnaire on bronchial symptoms for current smokers, lung function with a spirometer, and the quality of the spirometric curve.

Results: Of the 201 smokers not taking drugs for a pulmonary condition, 169 produced an acceptable curve (fulfilling American Thoracic Society criteria). Of these, 30 (18%, 95% confidence interval 12% to 24%) had a forced expiratory volume in one second (FEV(1)) <80% of predicted. When smokers were preselected on the basis of chronic cough, the proportion with an FEV(1) <80% of predicted increased to 27% (17 of 64; 12% to 38%). Chronic cough was a better predictor of airflow obstruction than other symptoms, such as wheeze and dyspnoea. The presence of two symptoms was a slightly better predictor than cough only (odds ratio 3.02 (1.37 to 6.64) v 2.50 (1.14 to 5.52)). Age was also a good predictor of obstruction; smokers over 60 with cough had a 48% chance of having an obstruction. The mean time needed for spirometry was four minutes. Detecting one smoker with an FEV(1) <80% of predicted cost 5 pound sterling to 10 pound sterling.

Conclusions: Trained practice assistants could check all patients who smoke for chronic obstructive pulmonary disease at little cost to the practice. Cough and age are the most important predictors of the disease. By testing one smoker a day, an average practice could identify one patient at risk a week.

Figure 1

Percentage of smokers with forced expiratory volume in one second <80% of predicted by age group

Figure 2

Chance of having bronchial obstruction with increasing age in smokers with or without cough. Bars are 95% confidence intervals