Early Detection of COPD: An Opportunistic Case Finding Study in Smokers and Ex-Smokers Visiting a Medical Centre

Abstract

Background: Different case finding approaches have been used to identify early COPD. The objective of this study was to assess the feasibility and the yield of opportunistic early COPD case finding in visitors to a large medical centre.

Patients and methods: From May 2014 to June 2017, we consecutively recruited adults aged ≥ 18 years visiting the Shaare Zedek Medical Center, in Jerusalem. Our 3-step intervention included: a) pre-screening for symptoms with the 5-item "Could it be COPD?" questionnaire (score= 0-5 pts); b) pre-BD spirometry; and c) referral to a caregiver. Airflow obstruction was defined by a FEV1/FVC < 0.7. Spirometry results were used as an incentive to promote smoking cessation and quit rates were verified by phone survey 3 months after the intervention.

Results: A total of 1001 subjects (956 smokers; 45 ex-smokers) were recruited. Mean (SD) age was 48.3 years (13.5). Airflow obstruction was detected in 180 (18%) subjects of whom 142 (78.9%) were unaware of it, including 27 subjects with severe (50% ≥ FEV1 ≤ 30% predicted) (n=25) or very severe (FEV1 < 30% predicted) (n=2) obstruction. Multiple logistic regression analysis found that age, BMI, cigarette smoking (p.y.) and a "Could it be COPD?" questionnaire score ≥ 3 points correctly classified 83.3% of cases of airflow obstruction. At follow-up, 54.5% of participants reported smoking as usual, 30.9% reduced smoking [mean (SD) = 10.1 ± 7.8 cigarettes/day], 7.4% increased smoking [mean (SD) = 9.2 ± 6.3 cigarettes/day] and 7.2% claimed smoking cessation. Among obstructed subjects, 38.7% had visited a physician because of COPD, while 20.7% were taking a new respiratory medication.

Conclusion: Early COPD case finding was feasible and effective in identifying undiagnosed airflow obstruction among visitors to a medical centre. Smoking cessation counselling based on spirometry promoted a small but clinically meaningful cessation rate.

Keywords: Could it be COPD?; airway obstruction; case finding; cigarette smoking; early COPD; hospital visitors; screening; spirometry.

Figure 1

Prevalence of airway obstruction in the participants stratified by age. Prevalence of airflow obstruction was relatively constant, around 7.5%, up to age 40 years, when it increased steadily to over 40% at age ≥ 71 years.

Figure 2

Prevalence of airflow obstruction in participants stratified by cigarette smoking. Prevalence of airflow obstruction remained below 10% for a cigarette consumption up to 10 p.y. From that point onwards it increased steadily to values beyond 30% for a cigarette consumption ≥ 40 p.y.

Figure 3

Prevalence of airflow obstruction in participants stratified by GOLD symptom score. Prevalence of airway obstruction increased linearly with an increase in GOLD symptom score, from 6.8% for subjects with a score of 1 pt to almost 40% for those with a score of 5 pts.

Figure 4

Logistic regression for airway obstruction according to age, BMI, cigarette smoking and GOLD score. ROC curve expressing the discrimination power of the logistic model presented in Table 3 including, as dependent variable, airway obstruction (FEV1/FVC < 0.7), and as independent variables, age, BMI, cigarette smoking (p.y.) and GOLD score ≥ 3. The curve is displaced to the upper left corner, indicating good discriminating power of the model (AUC=0.763).