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University of Vermont College of Medicine, Burlington, VT
Correspondence to: David A. Kaminsky, MD, FCCP, Pulmonary Disease-Critical Care, University of Vermont, Given C-317, Burlington, VT 05405; e-mail: dkaminsk{at}zoo.uvm.edu
To the Editor:
As pulmonologists interested in detecting early airways disease and helping our patients stop smoking, we are enthusiastic about the publication of the consensus statement on office spirometry by the National Lung Health Education Program in 2000.1 However, the pulmonary community has yet to see convincing evidence that screening of smokers at high risk of COPD will enhance smoking cessation.2 The recent publication by Gorecka and colleagues (June 2003)3 is pertinent to this issue, but we have concerns about the interpretation of this study.
These authors prospectively assessed the effects of voluntary participation in a spirometry screening and smoking intervention program in smokers. Those smokers who had moderate and severe airflow limitation on spirometric screening were more likely to have quit smoking when contacted 1 year later, compared to those with mild or no airflow limitation. The authors concluded that "the diagnosis of airflow limitation motivated smokers to attempt to quit smoking." However, there is no direct evidence that the spirometric results, per se, influenced the smokers. Rather, low lung function was a predictor of success in smoking cessation, and simply may have served as a marker of those smokers with more severe symptoms, as the authors do acknowledge.
In addition, the title of the study is misleading because it implies that the diagnosis of airflow limitation of any degree increased the smoking cessation rate, when in fact the cessation rates of the two groups (normal lung function and airflow limitation) were not statistically different. Only the subgroup of individuals with moderate and severe airflow limitation had increased smoking cessation rates. Furthermore, this study did not test the hypothesis that spirometry would enhance smoking cessation because there was no control group that did not receive spirometric testing or, at least, did not have their spirometric findings used in the smoking cessation intervention.
There are good reasons to perform screening spirometry in middle-aged persons with a smoking history,1 and we applaud Gorecka and colleagues3 from Poland on their work in population screening. However, we still need well-designed trials to determine whether and how we should use screening spirometry specifically for the purpose of encouraging smoking cessation. Unfortunately, prior randomized controlled trials of other types of biofeedback (eg, genetic testing) have not improved cessation rates.45
References
Institute of Tuberculosis and Lung Diseases, Warsaw, Poland
Correspondence to: Dorota Górecka, MD, FCCP, Professor of Medicine, Institute of Tuberculosis and Lung Diseases, Plocka 26, 01-138 Warsaw, Poland; e-mail: d.gorecka{at}igichp.edu.pl
To the Editor:
We appreciate the comments of Dr. Kaminsky and Dr. Marcy regarding our study (June 2003).1 We agree that our study has limitations: it was not a randomized, controlled trial. But our goal was not to assess the value of spirometric testing in making people stop smoking. We rather wanted to see if the diagnosis of airflow limitation (AL) made at the time of spirometric screening of middle-aged smokers for COPD, when combined with a doctor’s stop-smoking advice, influenced the cessation rate.
We offered every smoker advice to stop smoking while explaining the results of the spirometric test. In our study, the overall difference in the smoking cessation rate between those with abnormal lung function and those with normal lung function (NLF) was very small (1.7%). However, there were significant differences in cessation rates of smokers with moderate/severe disease (16.5%) as compared to those with mild disease (6.4%, p < 0.001) and smokers with NLF (8.4%, p < 0.05). In another Polish study,2 the differences between cessation rates in smokers with AL (15%) and those with NLF (4.5%) were more pronounced.
It seems that our study was underpowered to show statistically significant differences in smoking cessation. To show a significant difference of 5% between groups of smokers with AL and NLF with p = 0.05 and ß = 0.2, the number of smokers in each group should be 603.
We suggested in the "Discussion" section that the fact that more smokers with moderate/severe disease as compared to those with mild disease quit smoking might result from more symptoms observed in more advanced disease. We have now looked into our database for more details: 66% of smokers with AL vs 68% of smokers with NLF produced sputum (not significant), and 71% vs 60%, respectively, complained of cough (p < 0.05). There was also an increasing trend in the phlegm production in more severe disease, but we have not found significant differences in symptoms after stratifying the patients with AL according to disease severity.
Our results (10.1% of patients with COPD and 8.4% of those with NLF who remained nonsmoking after 12 months) compare favorably with the results of the Italian study3 (6.5% of smokers offered spirometric testing and counseling quit as compared to 4.5% of control subjects offered minimal intervention), and the Norwegian study4 in male subjects with low lung function resulting in a 5.6% quit rate at 12 months after sending a personalized letter explaining the results of spirometric testing with advice to stop smoking, as compared to 3.5% in control subjects (p < 0.01) who were not informed about their lung function.
We have also found, after additional random telephone screening of smokers who did not attend the follow-up visit, that only smokers with airflow limitation quit smoking (an additional four patients who stopped smoking). Also, smokers with the diagnosis of AL were more successful in reducing the number of cigarettes smoked (five fewer cigarettes per day, p < 0.05), as compared to smokers without AL (two fewer cigarettes per day, not significant). We believe therefore that the diagnosis of AL motivated smokers to try to quit.
Every effort should be made to make people stop smoking. This is especially true for smokers at risk and with early diagnosis of COPD. This issue is now being discussed, in trying to assess the role of spirometric testing in motivating smokers to quit.5678
We agree with Dr. Kaminsky and Dr. Marcy that larger studies are needed, including a control group of smokers given stop-smoking advice without spirometry, to assess the cost-effectiveness of spirometry as part of a smoking cessation program. But as Krahn and Chapman7 have quoted, "even modest quit rates attributable to screening spirometry may result in highly favorable cost effectiveness ratios."
References
This article has been cited by other articles:
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  R. E. Dales, K. L. Vandemheen, J. Clinch, and S. D. Aaron Spirometry in the Primary Care Setting: Influence on Clinical Diagnosis and Management of Airflow Obstruction Chest, October 1, 2005; 128(4): 2443 - 2447. [Abstract] [Full Text] [PDF]
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