Prevalence and diagnosis of chronic obstructive pulmonary disease among smokers at risk. A comparative study of case-finding vs. screening strategies.

BACKGROUND

Early diagnosis of chronic obstructive pulmonary disease (COPD) remains the main intervention to prevent disease progression. However, conflicting results exist on the utility of two different diagnostic strategies that preclude freely recommending one strategy in favor of the other. Spirometry was used to determine the effectiveness of a symptom-based (case-finding) strategy vs. a screening strategy to detect COPD in smokers.

METHODS

The case-finding strategy was undertaken during the COPD Day campaign in smokers with respiratory symptoms who were willing to submit to lung function testing. Screening was carried out with smokers attending a smoking cessation program. A short standardized questionnaire on respiratory symptoms along with spirometry were carried out and analyzed for both strategies.

RESULTS

We evaluated 2781 smokers (mean pack/years 23.38): 1999 from the case-finding strategy and 782 from the smoking cessation program strategy (SCS). Prevalence of COPD according to the Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria was 10.1 and 13.3%, respectively (p < 0.01). With the exception of dyspnea (70.6% vs. 72.5%, p = 0.72), prevalence of symptoms such as cough (61.5 vs. 37, p < 0.001), phlegm (60.4 vs. 38.2, p < 0.001) and wheezing (56.7 vs.15.06, p < 0.001) was higher among smokers from the case-finding strategy. Multivariate logistic regression analysis showed that dyspnea [OR = 2.09 (95% CI 1.41-3.1)] was the only common predictor of COPD after jointly and separately analyzing case-finding and screening strategies.

CONCLUSIONS

For early diagnosis of COPD in a primary care setting, a screening strategy aimed at all smokers may be more useful than a case-finding strategy.