Abstract
Background. Smoking cessation is the most important therapeutic intervention in patients with chronic obstructive pulmonary diseases (COPD) and the health benefits are immediate and substantial. Major efforts have been made to develop methods with high smoking cessation rates. Objectives. To study whether a combination of spirometry and brief smoking cessation advice to smokers with COPD, annually for three years, increased their smoking cessation rate in comparison with groups of smokers with normal lung function. Method. Prospective, randomized study in primary care. Smoking cessation rates were compared between smokers with COPD followed-up yearly over a period of three years and smokers with normal lung function followed-up yearly for three years or followed-up only once after three years. Results. The point-prevalence abstinence rate and prolonged abstinence rate at 6 and 12 months increased yearly and in smokers with COPD at year 3 was 29%, 28%, and 25%, respectively. The abstinence rates were significantly higher in smokers with COPD than in smokers with normal lung function. Smoking cessation rates among smokers with normal lung function did not increase with increasing number of follow-ups. Conclusion. Smokers diagnosed with COPD stopped smoking significantly more often than those with normal lung function.
Chronic obstructive pulmonary disease (COPD) is one of the major leading causes of morbidity and mortality worldwide Citation[1], Citation[2]. Smoking cigarettes is the major risk factor for development of COPD Citation[3] and also constitutes a risk factor for other serious illnesses such as cardiovascular diseases, stroke, and several malignant diseases Citation[4].
Smoking cessation is the most important therapeutic intervention in patients at all stages of COPD since it is the only intervention that has been shown to slow down the disease progression and lead to improvement of respiratory symptoms Citation[5–8]. Furthermore, smoking cessation is associated with a reduction in the risk of developing stroke, coronary heart disease, several types of cancer, and increased life expectancy Citation[9–12]. To sum up, the health benefits of smoking cessation are immediate and substantial. Major efforts have been made to develop and test methods for smoking cessation with the aim of finding methods with high smoking cessation rates.
Smoking cigarettes is the major risk factor for development of COPD and smoking cessation is the most important therapeutic intervention in patients at all stages of COPD.
A multiple-intervention approach, including annual spirometry, brief smoking cessation advice by a nurse, and a subsequent letter from the physician, showed high smoking cessation rates for smokers with mild COPD.
Increased number of follow-ups did not increase the smoking cessation rates among smokers with normal lung function.
In a previous study, we offered a free spirometry test to detect COPD in an early stage in smokers aged 40–55 years Citation[13]. COPD was defined as FEV1/FVC ratio (FEV%) <88% of predicted for males and <89% for females according to ERS criteria Citation[1]. In that study we identified 371 smokers with normal lung function and 141 smokers with COPD. In connection with the spirometry, all participants received brief smoking cessation advice, and written information on the relation between smoking and COPD and the deleterious effects of smoking on health Citation[13].
In this study, our aim was to study whether annual spirometry, brief smoking cessation advice by a nurse, and a personal letter from the physician regarding lung function increased the smoking cessation rate in smokers with COPD compared with smokers with normal lung function. In addition, we wanted to study whether smoking cessation in smokers with normal lung function was affected by different time intervals.
Material and methods
Population
The study was performed in primary care centres in the city of Motala, Sweden. Six primary healthcare centres and their respective asthma/COPD nurses participated. In a screening study, 371 smokers with normal lung function and 141 smokers with COPD were identified according to ERS criteria Citation[1], Citation[13]. Accordingly, COPD was defined as FEV1/FVC ratio (FEV%) <88% of predicted for males and <89% for females, and the obstruction was classified as mild if FEV1% predicted was ≥70, moderate if FEV1% predicted was 50–69, and severe if FEV1% predicted was <50% Citation[1].
In this follow-up study, 22 of 141 smokers with COPD were excluded as they lived more than 60 km from the centre and were presumed to have high dropout rates. In addition 45 of 371 smokers with normal lung function were excluded as they had entered another study. These 45 smokers were allocated to enter that study since their spirometry values were in agreement with a definition of pre-COPD (FEV% predicted 98–93 for males, 90–93 for females, or FEF50≤60%). So, in this study, 119 of the smokers with COPD and 326 of the smokers who had normal lung function were invited to participate (see ).
Figure 1. Trial design showing excluded and annual follow-up rates. Twelve of the smokers with normal lung function (NLF) (group B) and 13 of the smokers with COPD did not wish to be followed up at all. A number of smokers dropped out because of moving to another city or had died. *Smokers not present at this particular visit.
The 326 smokers with normal lung function were randomized into two groups. In group A, subjects with an uneven day of birth (n = 165) were invited for new spirometry after 3 years and in group B, subjects with an even day of birth (n = 161) were annually invited for new spirometry during 3 years. The purpose of this randomization of healthy smokers was to evaluate whether their smoking cessation rate was influenced by a different number of follow-ups. These spirometries were performed by the nurses at the primary health centres who had performed the primary spirometry in our first study Citation[13].
All 119 smokers with COPD (group C), 50% (n = 73) of the smokers in group A, and 51% (n = 84) of the smokers in group B were followed-up at the main centre. The remaining spirometries were performed by the nurses at the primary health centres who had performed the primary spirometry in our first study Citation[13].
Smoking cessation advice
All participants received brief smoking cessation advice after the spirometry had been performed by the study nurse, consisting of 5–8 minutes’ discussion about the smoker's smoking habits. Brief smoking cessation advice is defined as smoking advice given for less than 10 minutes. If the participants had stopped smoking the nurse encouraged them to remain non-smokers. If they still were smokers at the control, the nurses encouraged them to stop smoking, and gave them advice and information about nicotine replacement therapy and bupropion. Nicotine replacement therapy is sold over the counter and if they wanted to try bupropion the prescription was sent by mail. An identical procedure was used each year.
The results from all spirometries performed by the nurses, and the questionnaires, were sent to the prime investigator (GS) for evaluation and comparison with the previously performed spirometry. A few weeks after spirometry all participants received a letter with the result of the spirometry, information on any changes, and also a brief standardized information document concerning the advantages of smoking cessation regardless of whether they still were smokers or not.
Questionnaire
In connection with the spirometry, smoking status was assessed with a questionnaire. The questions asked whether they had stopped smoking or not. Those who had stopped smoking were asked to specify the duration of the non-smoking period and if they had used any nicotine replacement therapies, bupropion, or snuff.
Assessment of lung function
The spirometry was performed and interpreted according to the guidelines of the American Thoracic Society Citation[14]. The participants performed at least three dynamic spirometry tests at their visit to the asthma/COPD nurses.
Smoking cessation measurements
Outcome measures used were according to the recommendations of the Society for Research on Nicotine and Tobacco (SRNT) Citation[15]. The primary outcome variables were the annual point-prevalence abstinence rate and the prolonged-prevalence abstinence rate. The number of smokers who were abstinent ≥30 days immediately prior to the annual visit was used to calculate the point prevalence abstinence. Smokers who were abstinent for 6 and 12 months, respectively, prior to the annual visit were used to calculate the prevalence of prolonged abstinence. Participants who did not attend a given visit were assumed to be smokers at that visit. The data on point prevalence abstinence and prolonged abstinence rates were based on the questionnaire answers given by the participants at each annual visit. In addition the mean number of smoking-free months for each group was calculated.
Pack-years was defined as number of cigarettes per day/20×n years of smoking.
Statistics
Data were analysed using Minitab 14. Calculations of point prevalence abstinence and prolonged abstinence were performed according to an intention to treat principle, i.e. smokers who did not attend a given visit were assumed to be smokers at that visit. Chi-square was used analysing point prevalence and prolonged prevalence abstinence and a z-test regarding comparisons of proportions. A mood median test was used to analyse mean number of smoking-free months.
Ethics
The study was approved by the Ethics Committee, University Hospital, Linköping, Sweden.
Results
Of the 445 subjects included, 35 were excluded, of whom 25 did not want to participate (). In total, 410 smokers were included for follow-up. Baseline characteristics in all three groups at entry into the study are given in . Smokers with COPD had more pack-years, 32 pack-years, in comparison with those with normal lung function, 24 pack-years (p < 0.001). They also smoked more, on average 19 cigarettes per day, in comparison with 16 among those with normal lung function.
Table I. Baseline characteristics showing gender, mean age, number of pack-years, cigarettes/day, and lung function by study group.
In group A, at the only follow-up at year 3, 144 of 165 (93%) participated. In group B, 145 of 161 (90%) participated in at least one of the yearly follow-ups and 120 (84%) participated at all 3 follow-ups (see ). In group C, the COPD group, 101 of 119 (85%) were examined more than once and 70 (59%) participated at all 3 follow-ups.
The point prevalence abstinence, smokers who were abstinent ≥30 days immediately prior to the annual visit, and also the prolonged prevalence abstinence at 6 and 12 months were higher in group C compared with group B at each annual visit (). At year 3, the point prevalence abstinence was significantly higher (p = 0.001, chi-square) among those with COPD compared with those in group B with normal lung function. There was no difference between participants in group A and B regarding smoking cessation at year 3 (p = 0.75, chi-square).
Table II. Data on subjects who stopped smoking at the annual visit by study group.
At year 3, the prolonged prevalence abstinence rate at 6 and 12 months was significantly higher in group C than in group B (p < 0.001, z = 3.92, and p < 0.001, z = 3.96, respectively). There was no significant difference in prolonged prevalence abstinence at 6 or 12 months comparing group A and B at year 3. The mean number of smoking-free months for the participants who had stopped smoking at the last annual visit was higher in group C than in group B but the difference was not significant (p = 0.097) (see ).
Subjects in group C who stopped smoking used more nicotine replacement therapy and snuff than group B (z = 3.6, p < 0.001) and group A (z = 3.7, p < 0.001) but there was no difference when comparing groups A and B (). For the duration of the study, 29% (n = 34) of patients in group C used nicotine replacement therapy and 23% (n = 27) used snuff.
Table III. The use of nicotine replacement therapy (NRT), bupropion and snuff in subjects who had stopped smoking (point-prevalence abstinence) and subjects who were still smokers and present at the last annual visit.
Discussion
In this study, intervention was performed by annual spirometry, brief smoking cessation advice by the nurse, and a personal letter from the physician regarding lung function during the three years. The point prevalence abstinence after 3 years was significantly higher in smokers with diagnosed COPD than in smokers with normal lung function (29% and 14%, respectively). The prolonged prevalence abstinence rate after 3 years was significantly higher in smokers with COPD than in those with normal lung function. This study also showed that a higher number of follow-ups did not increase the smoking cessation rates among smokers with normal lung function.
Strengths and limitations
Our study may have some possible limitations. The participants were recruited from our previous screening study, and may therefore be more motivated to stop smoking than the general patient because they had actively chosen to participate in the study. In the previous study, all smokers with abnormal spirometry had to perform a second spirometry at the main centre Citation[13]. Therefore, all smokers with COPD were followed up there, as well as approximately 50% of those with normal lung function. The remaining smokers were followed up at the same centres by nurses who had performed the first spirometry. It may be questioned whether the higher smoking cessation rates among smokers with COPD were influenced by this allocation of all subjects with COPD to one nurse. However, this is unlikely, as all nurses have had the same education, instructions, and at least 5 years’ experience.
Of eligible participants from our previous study, 22 participants with COPD were excluded due to a long distance to the study centre and 45 with normal lung function due to inclusion in another study. These 45 all had spirometry values in the vicinity of mild COPD and were selected for further diagnostic evaluation of their lung function. In total, 67 of 512 (13%) were excluded before randomization, which should not influence the results.
The results in our study may be limited to patients with mild COPD, since 85% of those with COPD had mild COPD. In addition, the cessation rates may be somewhat overestimated since data on smoking were self-reported and not conferred by a biochemical method. However, a study has indicated a deception rate of only 3% in both the control and the intervention group Citation[16]. In calculating our results, we chose to use the intention to treat model. This may underestimate our results, but was judged to have the closest similarity to daily practice.
Discussion with other studies
This study contained several components of interventions that might influence the smoker to stop smoking: spirometry, brief advice by the nurse, letter from the physician, each either once or three times. The information concerning the effects of smoking was similar when comparing those with COPD and those with normal lung function. The higher smoking cessation rate among smokers with COPD was probably influenced by information in the letter from the physician on the abnormal spirometry results and by receiving a diagnosis. This is in concordance with other studies, which showed that when smokers perceived that their symptoms were associated with their smoking habits or if they were identified as high-risk smokers and they had abnormal spirometry they were more likely to intend to stop smoking Citation[16–20]. Our study also indicated that the intervention had little additional effect on the smoking cessation of smokers with normal lung function when the spirometry and smoking advice was repeated yearly (see ).
The lung health study Citation[5] also used a multiple intervention design, using an intensive behavioural-intervention programme, which consisted of 12 cessation group meetings during a 10-week period and nicotine gum. Their population was of similar age and mild COPD, but had a higher number of mean pack-years, 40.4 (SD 19.7) as compared with our study population, 27 (SD 12.4). The similarities with our study were the annual relapse prevention by spirometry control and advice. The point-prevalence cessation rate for the first annual visit in our study was 18% in smokers with COPD and 5% in smokers with normal lung function; in the lung health study it was 35% in the intervention group and approximately 10% in the control group. In our study the rates increased at the second and third annual visit, point prevalence in smokers with COPD was 22% and 29% respectively and in smokers with normal lung function 9% and 14%, respectively. In the lung health study the rate of sustained non-smokers declined to 22% among those with COPD and in the control group to 5%. In our study the prolonged prevalence abstinence rate at 12 months were 10%, 20%, and 25% year 1, 2, and 3 respectively. So, the long-term effects seem comparable to our study but our results may have been achieved with less effort.
Tobacco dependence is a chronic condition that often requires repeated intervention Citation[21] and to stop smoking is a dynamic process. Most smokers go through several stages before they take the decision to make quitting attempts and at last succeed with their intentions and stop smoking. A large proportion of all smokers are in the stage of contemplation or the stage of preparation Citation[22]. Smoking cessation advice or other interventions appear to have their effect by triggering a quitting attempt Citation[23] and this might explain why as many as 18% of the smokers with COPD stopped smoking within the first year.
Studies have shown that a considerable number of all smokers want to stop smoking, but a significant proportion of smokers have never tried to stop smoking Citation[24]. Each year about 2% of smokers succeed in quitting on their own initiative Citation[25]. According to a review Citation[26], brief advice (up to 5 minutes) from a clinician given to all smokers encouraging a quitting attempt increases this proportion to 3%. In medical settings, the highest cessation rates were found when smoking cessation advice was combined with either nicotine replacement or bupropion and multiple components that include spirometry, physician and non-physician advice, and psychosocial support on multiple occasions over the longest possible time period Citation[27]. In our study, individuals who stopped smoking to a higher degree used nicotine replacement, or the Swedish tobacco, snuff.
Conclusions
There are several studies reporting a large under-diagnosis of COPD Citation[28], Citation[29]. In this study, a multiple-intervention approach, including annual spirometry, brief smoking cessation advice by a nurse, and a subsequent letter from the physician, showed high smoking cessation rates for smokers with mild COPD. A structured nurse-based COPD surgery offering smoking cessation advice and regular spirometry controls of smokers with COPD may increase the chances of successful smoking cessation in daily practice.
The authors would like to thank the asthma/COPD nurses Marian Areland, Birgitta Carlborg, Anna-karin Eriksson, Karin Eriksson, Gunilla Jansson, Kerstin Jonsson, Thurid Thoor, and Birgitta Wennblad who performed the pulmonary function tests. The Health Research Council in the Southeast of Sweden (FORSS) is acknowledged for its financial support. Additional support was gratefully received from AstraZeneca.
Related Research Data
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