Purpose: The present study reports on the biochemical validation of the self-reported smoking status of patients with chronic obstructive pulmonary disease (COPD). The objective is to establish the proportion of overestimation of self-reported success rates.
Methods: A cross-sectional smoking-status validation study including 60 patients with COPD who reported that they had stopped smoking. In the analysis of urine samples, a cut-off point of 50 ng/mL of cotinine was used.
Results: At the time of biochemical validation, 55 patients reported that they had quit smoking while five patients resumed smoking. Smoking status was biochemically confirmed for 43 patients (78%) and 12 patients (22%) were classified as smokers. The sensitivity of the self- report of smoking was 29% and the specificity was 100%.
Conclusion: Many primary care patients with COPD do not provide valid information on their smoking status, which hamper adequate therapeutic interventions. Integration of biochemical validation in daily care could overcome this problem, but may harm the doctor-patient relationship.
Keywords: biochemical validation; chronic obstructive pulmonary disease; general practice; outcome measurement; smoking cessation.