Comparison between objective measures of smoking and self-reported smoking status in patients with asthma or COPD: are our patients telling us the truth?

Abstract

OBJECTIVE: Smoking prevalence is frequently estimated on the basis of self-reported smoking status. That can lead to an underestimation of smoking rates. The aim of this study was to evaluate the difference between self-reported smoking status and that determined through the use of objective measures of smoking at a pulmonary outpatient clinic. METHODS: This was a cross-sectional study involving 144 individuals: 51 asthma patients, 53 COPD patients, 20 current smokers, and 20 never-smokers. Smoking status was determined on the basis of self-reports obtained in interviews, as well as through tests of exhaled carbon monoxide (eCO) and urinary cotinine. RESULTS: All of the asthma patients and COPD patients declared they were not current smokers. In the COPD and asthma patients, the median urinary cotinine concentration was 167 ng/mL (range, 2-5,348 ng/mL) and 47 ng/mL (range, 5-2,735 ng/mL), respectively (p < 0.0001), whereas the median eCO level was 8 ppm (range, 0-31 ppm) and 5 ppm (range, 2-45 ppm), respectively (p < 0.05). In 40 (38%) of the patients with asthma or COPD (n = 104), there was disagreement between the self-reported smoking status and that determined on the basis of the urinary cotinine concentration, a concentration > 200 ng/mL being considered indicative of current smoking. In 48 (46%) of those 104 patients, the self-reported non-smoking status was refuted by an eCO level > 6 ppm, which is also considered indicative of current smoking. In 30 (29%) of the patients with asthma or COPD, the urinary cotinine concentration and the eCO level both belied the patient claims of not being current smokers. CONCLUSIONS: Our findings suggest that high proportions of smoking pulmonary patients with lung disease falsely declare themselves to be nonsmokers. The accurate classification of smoking status is pivotal to the treatment of lung diseases. Objective measures of smoking could be helpful in improving clinical management and counseling.

Can severe asthmatic patients achieve asthma control? A systematic approach in patients with difficult to control asthma followed in a specialized clinic

“…Patients classified as GINA steps 4 and 5 followed at our asthma clinic for at least 4 years, with free access to anti-inflammatory therapies, educational programs and proper evaluation of factors associated with non-control composed our population [27–31]. Given the lack of control add on therapy would be the next natural step to be implemented in everyday practice.…”

The Effect of Different Case Definitions of Current Smoking on the Discovery of Smoking-Related Blood Gene Expression Signatures in Chronic Obstructive Pulmonary Disease

“…However, self-report is subject to reporting bias and has been shown to underestimate smoking prevalence and intensity. 8,9 Objective biochemical measures for smoking status include exhaled carbon monoxide (eCO) and cotinine levels in serum, urine or saliva. Measuring eCO is attractive because it is relatively inexpensive, noninvasive and the measurements are well-standardized and can accurately identify recent smokers.…”

Measurement of exhaled breath carbon monoxide in clinical practice

“…in (Foulds et al., ; Jarvis, Tunstall‐Pedoe, Feyerabend, Vesey, & Saloojee, ). However, recent literature has recommended the cutpoint much lower at eBCO < 7 ppm (Stelmach et al., ) and <5 ppm (Cropsey et al., ). This controversy over the correct eBCO cutpoint to be used to confirm abstinence from combustible tobacco use (Cropsey et al., ; Javors et al., ) makes it difficult for the healthcare provider to know which number to use when validating smoking status.…”