smoking cessation is crucial for a better prognosis in patients with coronary heart disease ( chd)13 and copd.2,4,5 acute heart attacks are associated with high smoking cessation rates . in patients with a first myocardial infarction ( mi ) in the 1970s,3 among whom 78% were smoking , the quitting rate was 55% . in a systematic review from 2003 , the mean rate of smoking cessation within a year after a new diagnosis of chd was found to be 45%.1 a lower quitting rate was observed in patients with copd , in particular in subjects not participating in smoking cessation programs . among smoking copd patients in a swedish study , 10% of those receiving usual care had stopped smoking after 3 years , compared to 38% of those who took part in smoking cessation groups.6 among hospitalized patients with respiratory and cardiac diseases who took part in an intensive smoking cessation program in singapore , 60% of the cardiac patients and 40% of the respiratory patients were still abstinent from smoking after 2 months.7 the mortality due to chd has decreased considerably in the western world in the last few decades.8 evidence shows that decreased smoking prevalence in the general population , particularly among patients with heart disease , is an important reason for this decrease.811 the mortality due to copd has decreased less.12 a stronger tendency of persistent smoking among copd patients may partly explain this difference . copd patients reluctance to quit smoking may lead to a feeling of hopelessness among the doctors who treat them.13 our aim was to determine how the quitting rate in adults is influenced by getting a diagnosis of obstructive lung disease in the population - based troms study . we also wanted to investigate whether influence from this life event differs from being diagnosed with chd . a large proportion of the adult population in troms has participated in health surveys ( the troms study ) since 1974 . the troms study so far consists of six surveys , and this study deals with subjects who participated in both troms 5 ( 20012002 ) and troms 6 ( 20072008 ) . the attendance rates ( of those invited ) in troms 5 and troms 6 were 79% and 66% , respectively . details of the participants have previously been described.14 we included participants who answered the questions on smoking in both surveys . the regional committee for medical and health research ethics and the norwegian data inspectorate approved the troms 5 and troms 6 surveys with a license for further analysis on non - identifiable data , like this study . the invitation included a questionnaire with questions on smoking habits , education , and diseases . we classified subjects reporting daily smoking in troms 5 , but not in troms 6 , as quitters . we divided length of education into three categories , 12 years , 1316 years , and 17 years . we classified diseases reported in troms 6 and not in troms 5 as new diagnoses . we categorized mi and angina pectoris as  chd  and asthma and copd as  obstructive lung disease  . the frequencies of current smoking at baseline ( in troms 5 ) and smoking cessation among smokers were calculated by subject characteristics , and the statistical differences between subgroups were analyzed by chi - square statistics . significant variables in univariable analysis ( p<0.1 ) , as well as age and sex , were entered in the multivariable analysis . for the statistical analyses , we used the ibm spss statistic , version 21 ( ibm corporation , armonk , ny , usa ) . a large proportion of the adult population in troms has participated in health surveys ( the troms study ) since 1974 . the troms study so far consists of six surveys , and this study deals with subjects who participated in both troms 5 ( 20012002 ) and troms 6 ( 20072008 ) . the attendance rates ( of those invited ) in troms 5 and troms 6 were 79% and 66% , respectively . details of the participants have previously been described.14 we included participants who answered the questions on smoking in both surveys . the regional committee for medical and health research ethics and the norwegian data inspectorate approved the troms 5 and troms 6 surveys with a license for further analysis on non - identifiable data , like this study . in both surveys , the invitation included a questionnaire with questions on smoking habits , education , and diseases . we classified subjects reporting daily smoking in troms 5 , but not in troms 6 , as quitters . we divided length of education into three categories , 12 years , 1316 years , and 17 years . we classified diseases reported in troms 6 and not in troms 5 as new diagnoses . we categorized mi and angina pectoris as  chd  and asthma and copd as  obstructive lung disease  . the frequencies of current smoking at baseline ( in troms 5 ) and smoking cessation among smokers were calculated by subject characteristics , and the statistical differences between subgroups were analyzed by chi - square statistics . significant variables in univariable analysis ( p<0.1 ) , as well as age and sex , were entered in the multivariable analysis . for the statistical analyses , we used the ibm spss statistic , version 21 ( ibm corporation , armonk , ny , usa ) . a total of 4,631 subjects participated in both the fifth and the sixth surveys of the troms study , and 4,497 subjects comprising 1,852 men and 2,645 women answered the questions on smoking in both surveys . the mean time difference between attending the two surveys was 6.2 years ( standard deviation 0.5 years ) . the mean age at troms 5 was 61.1 years ( range 3081 years ) ; 1,150 ( 25.6% ) reported daily smoking and 1,753 ( 39.0% ) reported former smoking . the highest prevalence of smoking ( 43.8% ) was found in subjects with self - reported copd , whereas the frequency among those with self - reported chd was 19.0% . the characteristics of the population in troms 5 and the respective frequencies of smoking are listed in table 1 . in the sixth survey , 765 subjects ( 17.0% ) reported current smoking , and 428 of the 1,150 who had been smoking in troms 5 had quit ( 37.2% ) . a significantly higher quitting rate was found in men compared to women , and the quitting rate increased with the length of education . self - reported diseases registered in troms 5 had no significant impact on the quitting rate ( table 2 ) . the number of days between attending the two surveys had no impact on the quitting rate ( odds ratio = 1 , p=0.8 ) . table 3 shows the frequencies of new self - reported diseases reported in troms 6 , but not in troms 5 , and the association between a new diagnosis and smoking cessation . new diagnoses of asthma / copd ( n=79 ) and chd ( n=73 ) were both associated with increased frequency of quitting , 50.6% ( p=0.01 ) and 52.1% ( p=0.008 ) , respectively . both men and women belonging to any of these diagnostic groups showed increased quitting rates , 54.9% vs 39.8% ( p=0.02 ) in men and 47.1% vs 32.7% ( p=0.009 ) in women . the impact of getting these new diagnoses was particularly strong among the subjects with education length no longer than 12 years ( p=0.001 ; figure 1 ) . subjects with education length up to 12 years were also more frequently diagnosed with these diseases compared to those with higher education , 16.0% and 9.5% ( p=0.01 ) , respectively . among subjects with higher education , a new diagnosis of both chd and obstructive lung disease was significantly associated with smoking cessation when analyzed by logistic regression and also after adjusting for sex and education level in multivariable logistic regression analyses ( table 4 ) . half of the participants with a new diagnosis of asthma / copd or angina / mi quit smoking during the 6 years of follow - up . however , the association between these new diagnoses and smoking cessation was found only in participants with education length up to 12 years . the much higher smoking rate among those with asthma and , in particular , those with copd at baseline than in those with chd indicates a shift in attitude toward smoking cessation among subjects with copd . the high number of participants and the high attendance rates among those invited are strengths of the study . the prevalences of daily smoking among all the attendees in troms 5 and troms 6 were 31% and 22% , respectively,11 which are close to the national prevalences of 29% and 21% , as registered by statistics norway ( https://www.ssb.no)15 in 2002 and 2008 , respectively . in our study sample , the prevalence was lower at both points of time , 25.6% and 17.0% , respectively , and a healthy survivor effect may have contributed to the low frequency of daily smoking in our subsample . the study is based on questionnaires and not on objective measurements of smoking , such as cotinine and thiocyanate . in a previous norwegian study , self - reported smoking was strongly related to serum thiocyanate if the question was asked in a neutral setting.16 although the questions on smoking were included in a self - administered questionnaire , underreporting of daily smoking among those with a new diagnosis can not be ruled out . shift in diagnosis based on the same illness from troms 5 to troms 6 , for instance , between asthma and copd , may have taken place in some subjects . this is no longer a problem when asthma and copd are combined into one category ( asthma and/or copd ) and subjects with a new diagnosis of any of these diseases are compared with those with neither of the diagnoses at both troms 5 and troms 6 . although we have found associations between a new diagnosis and smoking cessation , we do not know for sure whether the extra cessations in the subgroups with a new diagnosis were really preceded by a new diagnosis . subjects in these subgroups could have stopped smoking before the diagnosis was given . in these cases , it is likely that symptoms from a pulmonary or heart disease had raised their awareness of the risk of continued smoking . no previous study has , to our knowledge , described smoking cessation in relation to a new diagnosis of heart or lung disease . most previous studies evaluated smoking cessation programs , and control groups in such studies can be compared with our participants . however , the quitting rate of 41.7% among subjects with a copd diagnosis reported in troms 5 was more similar to the rate of 38% among the copd patients , who had taken part in the smoking cessation program in a swedish study , than the rate of 10% among the copd patients on usual care.6 in a study from primary care , where smokers received smoking cessation advice and were followed up annually with spirometry , higher rates of abstinence were found among those with copd than among those with normal lung function.17 this result is in line with our findings . we found that the quitting rate increased with increasing length of education , and this association is well known from previous studies.18 qualitative studies have shown that patients with a copd diagnosis may have several reasons for not quitting despite the knowledge of harming themselves,19 and they do not always believe that quitting would give them a better life.20 copd patients often show little interest in receiving help from medication and describe unassisted quitting as the best method to stop smoking , based on willpower , strong motivation , and internal strength.21 in our study , a new diagnosis of copd or chd might have given many participants the motivation they needed to quit without assistance . in another qualitative study , the interviewees who had stopped smoking emphasized that persons close to them had a strong influence on their decision to quit.22 this gives a reason to believe that the decreasing acceptance of smoking in the society also influences copd patients . half of the participants with a new diagnosis of asthma / copd or angina / mi quit smoking during the 6 years of follow - up . however , the association between these new diagnoses and smoking cessation was found only in participants with education length up to 12 years . the much higher smoking rate among those with asthma and , in particular , those with copd at baseline than in those with chd indicates a shift in attitude toward smoking cessation among subjects with copd . the high number of participants and the high attendance rates among those invited are strengths of the study . the prevalences of daily smoking among all the attendees in troms 5 and troms 6 were 31% and 22% , respectively,11 which are close to the national prevalences of 29% and 21% , as registered by statistics norway ( https://www.ssb.no)15 in 2002 and 2008 , respectively . in our study sample , the prevalence was lower at both points of time , 25.6% and 17.0% , respectively , and a healthy survivor effect may have contributed to the low frequency of daily smoking in our subsample . the study is based on questionnaires and not on objective measurements of smoking , such as cotinine and thiocyanate . in a previous norwegian study , self - reported smoking was strongly related to serum thiocyanate if the question was asked in a neutral setting.16 although the questions on smoking were included in a self - administered questionnaire , underreporting of daily smoking among those with a new diagnosis can not be ruled out . all diagnoses were self - reported , and their correctness could not be confirmed . shift in diagnosis based on the same illness from troms 5 to troms 6 , for instance , between asthma and copd , may have taken place in some subjects . this is no longer a problem when asthma and copd are combined into one category ( asthma and/or copd ) and subjects with a new diagnosis of any of these diseases are compared with those with neither of the diagnoses at both troms 5 and troms 6 . although we have found associations between a new diagnosis and smoking cessation , we do not know for sure whether the extra cessations in the subgroups with a new diagnosis were really preceded by a new diagnosis . subjects in these subgroups could have stopped smoking before the diagnosis was given . in these cases , it is likely that symptoms from a pulmonary or heart disease had raised their awareness of the risk of continued smoking . no previous study has , to our knowledge , described smoking cessation in relation to a new diagnosis of heart or lung disease . most previous studies evaluated smoking cessation programs , and control groups in such studies can be compared with our participants . however , the quitting rate of 41.7% among subjects with a copd diagnosis reported in troms 5 was more similar to the rate of 38% among the copd patients , who had taken part in the smoking cessation program in a swedish study , than the rate of 10% among the copd patients on usual care.6 in a study from primary care , where smokers received smoking cessation advice and were followed up annually with spirometry , higher rates of abstinence were found among those with copd than among those with normal lung function.17 this result is in line with our findings . we found that the quitting rate increased with increasing length of education , and this association is well known from previous studies.18 qualitative studies have shown that patients with a copd diagnosis may have several reasons for not quitting despite the knowledge of harming themselves,19 and they do not always believe that quitting would give them a better life.20 copd patients often show little interest in receiving help from medication and describe unassisted quitting as the best method to stop smoking , based on willpower , strong motivation , and internal strength.21 in our study , a new diagnosis of copd or chd might have given many participants the motivation they needed to quit without assistance . in another qualitative study , the interviewees who had stopped smoking emphasized that persons close to them had a strong influence on their decision to quit.22 this gives a reason to believe that the decreasing acceptance of smoking in the society also influences copd patients . it has been suggested that a hard core of smokers will constitute an increasing proportion of copd patients who still smoke.23 the high quitting rates among subjects with both an established and a new diagnosis of copd in our study contradicts this pessimism . the study supports pursuit of early diagnosis of copd and gives reasons for a more optimistic attitude among health workers when they discuss smoking cessation with their copd patients .
backgroundpatients with copd have had a lower tendency to quit smoking compared to patients with coronary heart disease ( chd ) . 
 we wanted to investigate if this is still true in a norwegian population.methodsour data came from the fifth and sixth troms surveys , which took place in 20012002 and 20072008 . 
 the predictors of smoking cessation were evaluated in a cohort of 4,497 participants who had stated their smoking status in both surveys.resultsof the 4,497 subjects in the cohort , 1,150 ( 25.6% ) reported daily smoking in troms 5 . in troms 6 , 428 had quit ( 37.2% ) . 
 a new diagnosis of obstructive lung disease ( asthma or copd ) and chd were both associated with increased quitting rates , 50.6% ( p=0.01 ) and 52.1% ( p=0.02 ) , respectively . in multivariable logistic regression analysis with smoking cessation as outcome 
 , the odds ratios ( ors ) of a new diagnosis of obstructive lung disease and of chd were 1.7 ( 1.12.7 ) and 1.7 ( 1.02.9 ) , respectively . 
 male sex had an or of 1.4 ( 1.11.8 ) compared to women in the multivariable model , whereas the ors of an educational length of 1316 years and 17 years compared to shorter education were 1.6 ( 1.12.2 ) and 2.5 ( 1.54.1 ) , respectively.conclusionthe general trend of smoking cessation in the population was confirmed . 
 increased rates of smoking cessation were associated with a new diagnosis of heart or lung disease , and obstructive lung disease was just as strongly linked to smoking cessation as was chd . 
 this should encourage the pursuit of early diagnosis of copd .