Characteristics Associated with Sustained Abstinence from Smoking Among Patients with COPD

Article Outline

• Abstract
• Materials and Methods
  • Study Subjects
  • Study Design
  • Measures
  • Analysis
• Results
• Discussion
• Limitations
• References
• Copyright

Abstract 

Purpose

Smoking cessation is the mainstay of recommended treatment for chronic obstructive pulmonary disease (COPD), yet many continue smoking. This study seeks to understand the characteristics of patients with COPD who have quit and those who have not quit to identify important factors to evaluate in smoking-cessation interventions.

Subjects/methods

A cross-sectional survey of a random sample of 1.5 million, predominantly male Veterans Administration enrollees. Of the respondents (63% [n = 887 775]), those with at least 1 COPD visit, a smoking history, and aged more than 34 years were included in this analysis (n = 89 337). Differences in demographics, functional status, comorbidities, and provider–patient interactions were evaluated for current and former smokers.

Results

Ninety-seven percent of the cohort with COPD was male. Former smokers (n = 58 482) were older (mean age of 69.6 vs 62.8, P<.001) and had more cardiac comorbidities, but better mental health (Mean Mental Component Summary score from the Veterans Short Form-36 ± standard deviation of 43.4 ± 13.2 vs 39.9 ± 13.7, P<.001) than current smokers (n = 25 595), respectively. In addition, former smokers more actively participated in their health care and had a better relationship with their provider than current smokers.

Conclusion

Former smokers with COPD were older, had more cardiac comorbidities, better mental health, and better perceived provider–patient interactions than active smokers. This study highlights the importance of screening participants with COPD who are enrolling in forthcoming smoking cessation trials for mental illnesses. In addition, developing interventions that address psychiatric comorbidities and potentially improve provider-patient communication may be other key areas to evaluate in future smoking cessation trials in patients with COPD.

Keywords:  Chronic obstructive pulmonary disease , Tobacco use disorder , Former and current smokers , Mental health , Cardiovascular disease

Approximately 50 million Americans continue to smoke, despite that approximately half of the living adults in the United States who ever smoked cigarettes have quit.¹ Smoking cessation has immediate health benefits for people of all ages. Smoking is the most important cause of chronic obstructive pulmonary disease (COPD) and is responsible for more than 90% of cases of COPD within the United States.² COPD is a serious public health problem that affects approximately 30 million Americans, represents the fourth leading cause of death, and costs $37.2 billion annually.³, ⁴ The morbidity and mortality associated with COPD are continuing to increase, and it is predicted to become the third leading cause of death by 2020.³, ⁵

Smoking cessation at all ages reduces the risk of premature death. After 10 to 15 years of abstinence, the risk of all-cause mortality returns nearly to that of persons who never smoked. Several studies have demonstrated that former smokers in the general population have better health-related quality of life than current smokers as measured in many ways, including days of illness, number of health complaints, and self-reported health status.¹, ⁶, ⁷ In addition, former smokers compared with current smokers practice more health-promoting and disease-preventing behaviors.¹

Some investigators have described a lower prevalence of respiratory symptoms in former smokers compared with current smokers from cross-sectional, population-based studies.⁸ In addition, with sustained abstinence, COPD mortality rates among former smokers decline in comparison with those who continue smoking.¹ Therefore, studies evaluating factors associated with sustained abstinence from smoking are important to help identify populations that may require more intensive smoking-cessation interventions.¹, ⁹

According to the 2000 National Health Interview Survey, 70% of adult smokers in the United States wanted to quit smoking.¹⁰ Predictors of success in smoking cessation in the general population include older age, male gender, higher income, lower levels of daily cigarette consumption, history of quit attempts, and a strong desire to stop smoking.¹¹, ¹² Whether the observed predictors of successful smoking cessation in the general population also apply to the population of smokers who have developed COPD needs further study. This study evaluates a number of these predictors, with the addition of psychiatric comorbidities and perceived provider-patient interactions, within a COPD population. In addition to the intrinsic characteristics of smokers themselves, it is known that smokers are more likely to successfully quit smoking when advised by a physician to stop.¹³, ¹⁴, ¹⁵, ¹⁶, ¹⁷ One might hypothesize that more satisfying and trusting provider–patient relationships would be associated with higher rates of successful smoking cessation. Therefore, we undertook this distinctive study to evaluate factors, including demographics, physical and psychiatric comorbidities, functional status, and patients’ perception of their quality of health care that are associated with being a former smoker in patients who already have a smoking-related disease, COPD.

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Materials and Methods 

Study Subjects 

The sample of predominantly male patients described in this study was taken from the 1999 Veterans Health Administration (VHA) Large Health Survey of Veteran Enrollees, and the sampling strategy for this survey has been described.¹⁸ Briefly, 1 500 000 of the 3 720 200 veteran enrollees were randomly selected to receive a survey. After deleting patients who had died and those who were ineligible because of inaccurate names or addresses, there were 1 406 048 veterans who were sampled. The overall response rate was 63.14% (887 775). The survey responses were evaluated, cleaned, and scanned to create ASCII files, which were then converted into SAS (SAS Institute Inc., Cary, NC) and STATA (StataCorp, College Station, Tex) files for statistical analysis. These files were merged with the national VHA databases to obtain International Classification of Diseases (ICD)-9-CM codes for diagnoses from the Patient Treatment Files and the Outpatient Clinic files. Individual identifiers were subsequently stripped to maintain confidentiality for the analyses. The local institutional review board approved the current study.

The cohort of patients with ICD-9 codes for COPD and asthma (15.9% of the total respondents) were selected for further analysis for this study. To select patients with likely COPD and to reduce the chance of including patients with asthma, patients were excluded if they were less than 35 years old or responded “no” to the question, “Have you smoked at least 100 cigarettes in your entire life?” In addition, there were approximately 6000 patients with spinal cord injuries who were excluded because of the high frequency of restrictive physiology, which may complicate the clinical picture of COPD.

Study Design 

The remaining cohort (89 337 predominantly male patients) was subdivided into groups consisting of current smokers, intermittent smokers, and former smokers on the basis of their response to 2 questions concerning smoking history. The first question considered for these strata was, “Do you now smoke cigarettes everyday, some days, or not at all?” The second question was, “About how long has it been since you last smoked cigarettes regularly, that is, daily?” Patients who responded “not at all” to the first question and who responded “1 to 5 months, 6 to 11 months, 1 to 5 years, or more than 5 years” to the second question were classified as “former smokers.” Those who responded “every day” to the first question and “still smoking” to the second question were classified as “current smokers.” Those who responded “some days” with any response to the second question were classified as “intermittent smokers.” However, those who responded “not at all” to the first question, but “still smoking” or “less than 1 month” to the second question were classified as “current smokers.”

Measures 

Data collection by the survey took place between July 1999 and January 2000. No results of pulmonary function tests (PFTs) or spirometry values were available from the survey or in the national Veterans Administration databases; therefore, no direct measures of COPD severity could be assigned. We were able to determine whether these patients had performed PFTs during the year before, the year of, and the year after the survey data were collected (by evaluating clinic stop codes from the national Veterans Administration databases) within the fiscal years 1998 to 2000 (eg, fiscal year 1998 was from October 1997 to September 1998). Therefore, functional status (obtained by survey questions from the Veterans Short Form-36 [V/SF-36], which is the short form health survey for veterans) was used as a surrogate for COPD severity. All patients received a set of core questions in the survey, including the V/SF-36. The V/SF-36 builds on a well-established widely used instrument, the Medical Outcomes Study SF-36, which has been modified for use in VHA ambulatory care patients.¹⁹, ²⁰, ²¹, ²² The V/SF-36 measures 8 concepts of health, using several items. Two summary components are then derived from these 8 scales, a Physical Component Summary (PCS) score and a Mental Component Summary (MCS) score. Each of the 2 component summary scales are standardized to the US population and norm-based so that the scores have a direct interpretation in relation to the distribution of scores in the US population with a mean of 50 and a standard deviation of 10. Higher scores indicate better health. The 2 summaries make an important contrast between the physical and psychologic health status of the veteran users. The PCS and MCS scores provide 90% of the reliable variance in the 8 V/SF-36 concepts. The changes to the SF-36 are well described and reported with increases to the precision and discriminant validity of the PCS and MCS.²⁰, ²³ Details of the scoring of the V/SF-36 have been published.¹⁸, ²¹, ²² In addition to the set of core questions (including the basic smoking questions mentioned above and the V/SF-36), patients randomly received 1 of 5 modules. One of which was satisfaction with care and patient evaluation of care. Therefore, the number of respondents to each of these modules is approximately one-fifth of the total sample.

Within the satisfaction with care and patient evaluation of care module, one of the questions evaluated trust and asked, “All things considered, how much do you trust your regular doctor?”²⁴ The options included choices from 1 to 10, with 1 being “completely” and 10 being “not at all.” Another question was related to whom patients could direct their questions about their own health care by asking, “Did you know who to ask when you had questions about your care?” The potential responses to this question included “yes, always,” “yes, sometimes,” “no,” and “didn’t have any questions.” Another question in this module stated, “Thinking about how well your regular doctor knows you, how would you rate your doctor’s knowledge of what worries you most about your health?” The possible responses included “very poor,” “poor,” “fair,” “good,” “very good,” and “excellent.”

Analysis 

The patients with COPD were categorized to 3 groups (ie, former smokers, intermittent smokers, and current smokers) as our outcome measure (response variable). Univariate analyses were performed to detect differences among the 3 groups of smokers. To describe the relationship of our interest variable (explanatory variable) to our outcome, we used simple logistic regression analysis. The assumptions of simple logistic regression analysis were verified with the Shapiro-Wilk test for normal distribution and a goodness-of-fit test for fitting the model. The odd ratios also were calculated to show the ratio of the odds that an event will occur in the smoker group to the odds that the event will occur in the former smoker group or intermittent group. Our simple logistic regression analysis results were used to construct our final model to predict the outcome of specific smoker group membership by multivariable logistic regression analysis. The dependent variable was assignment to former versus current smokers. For multivariable analysis with logistic regression, the associations of predicted probabilities and observed responses were indicated by the statistic c for each comparison. The largest area under the receiver operator characteristic curve was preferred. Greater than 0.85 was considered to be very good fit model. For this model, the odds ratios for age and the MCS were calculated for a change of 10 years and 10 points, respectively, which is considered a large effect. All analyses were carried out using Statistical Analysis System version 8.2 (SAS Institute Inc.).

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Results 

Twenty-nine percent (25 595/89 337) of the predominantly male patients were classified as current smokers, 6% (5260) were intermittent smokers, and 65% (58 482) were former smokers (Table 1). The majority of patients were male (97%). The former smokers were significantly older than the other groups (Table 1). Significantly fewer whites and more African Americans were in the intermittent smokers group than in the other 2 groups, and there were significantly fewer Hispanics in the current smokers group. Of note, less than one-half of these patients who had the diagnosis of COPD by ICD-9 codes had PFTs during fiscal years 1998, 1999, or 2000. Slightly more former smokers had clinic stop codes for PFTs during these 3 years than former smokers (former smokers: 27 333 [46.7%] vs current smokers: 11 325 [44.2%], P<.0001). The physical component summary scores from the V/SF-36 were not significantly different between groups; however, the mental component summary scores were higher (indicating better mental health) for the former smokers than for the other groups (Table 1).

Table 1. Demographics and Characteristics of Former Versus Intermittent Versus Current Smokers

	Former	Intermittent	Current
Number (percentage)	58482 (65%)	5260 (6%)	25595 (29%)
Age (mean years±SD)	69.6⁎ (±10.1)	64.3⁎ (±10.5)	62.8⁎ (±10.4)
Percentage of males	96.8%	96.6%	97.0%
Ethnicity: white	86.5%	79.4%⁎	87.0%
AA	8.0%	14.5%⁎	8.4%
Hispanic	3.4%	3.4%	2.2%⁎
Other	2.1%	2.7%	2.4%
PCS (mean±SD)	28.8 (±10.2)	28.8 (±9.6)	29.9 (±10.0)
MCS (mean±SD)	43.4⁎ (±13.2)	39.4 (±13.1)	39.9 (±13.7)

SD = standard deviation; AA = African American; PCS = Physical Component Summary; MCS = Mental Component Summary.

By univariate analysis, current smokers had the fewest self-reported cardiac comorbidities, including congestive heart failure, angina, and “heart attacks” (Table 2). However, some of these differences may be explained by the differences in age between the 3 groups (the current smokers are significantly younger and have the fewest cardiac comorbidities). In contrast with the cardiac comorbidities, the former smokers had the fewest self-reported mental comorbidities, including depression, posttraumatic stress disorder, and schizophrenia (Table 2).

Table 2. Distribution of Self-reported Comorbidities Among Former Versus Intermittent Versus Current Smokers

Because it is known that recommendations from physicians positively influence patients’ decisions to stop smoking, we explored whether aspects of patient satisfaction with care were associated with being a former smoker. Former smokers trusted their doctor more than the other 2 groups (Table 3). The intermittent and current smokers answered “no” more frequently to the question regarding whether they knew whom to ask about questions about their care, indicating that they were less likely to know whom they could direct their questions about their own health care than the former smokers. When asked whether they knew what the next step in their care would be, the intermittent and current smokers answered “no” significantly more often than the former smokers group (Table 3). The former smokers responded “very good” and “excellent” significantly more often than the other groups to the question regarding how they would rate their doctor’s knowledge of the patient’s worries. In addition, the current and intermittent smokers reported more difficulties in receiving care that they or their doctor believed necessary and more difficulties getting a referral to a specialist than the former smokers (Table 3).

Table 3. Results from Patient Care Satisfaction Module Among Former Versus Intermittent Versus Current Smokers by Univariate Analysis

	Former	Intermittent	Current	P value
Trust doctor (mean±SD)	4.20 (±3.25)	4.40 (±3.26)	4.41 (±3.22)	<.001
Did not know who to ask	8.1%	11.3%	11.8%	<.001
Did not know next step	18.0%	21.2%	22.1%	<.001
Knowledge of worries:
Very poor/poor	5.8%	7.8%	10.1%	<.001
Very good/excellent	50.7%	47.3%	44.0%
No difficulty receiving care	74.1%	71.6%	69.0%	<.001
No problem with specialist referral	76.4%	71.2%	72.7%	<.001

SD = standard deviation.

Because the intermittent smoking group was not similar to either the former or current smokers, we excluded these patients from further (multivariable) analysis. We included factors in the multivariable model with logistic regression that were clinically thought to possibly influence a patient’s decision to stop smoking, including age, cardiac and psychologic comorbidities, perception of quality of care (from the patient care satisfaction module), and scores from the PCS and MCS from the V/SF-36. Significant factors that were associated with former smoking included older age, the presence of angina, and better mental health (by MCS) (Table 4). In addition, the former smokers more often knew who to ask for questions about their care and believed that their physician had adequate knowledge of their worries.

Table 4. Multivariable Analysis with Logistic Regression of Former Versus Current Smokers Using Age, Comorbidities (Cardiac and Psychologic), Perception of Quality of Care, and the Physical Component Scale/Mental Component Scale from Veterans Short Form-36

	Former smokers versus current smokers
ROC curve with C statistic	0.704
Age (10 y): OR (95% CI)	1.77(1.71-1.84)⁎
Angina: OR (95% CI)	1.13(1.04-1.23)⁎⁎
Know who to ask	1.50(1.22-1.85)⁎⁎
Knowledge of worries:
Fair/good vs very poor	1.14(0.98-1.32)⁎⁎⁎
Fair/good vs excellent	0.92(0.84-0.99)⁎⁎
MCS (10 points)	1.15(1.12-1.19)⁎

ROC: receiver operator characteristic; OR: odds ratio; CI = confidence interval; MCS = Mental Component Summary score.

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Discussion 

In this unique cross-sectional study of functional status and perceptions of quality of health care in predominantly male patients with COPD, we found that former smokers were older and had more cardiac comorbidities, but had better mental health than current smokers. In addition, the former smokers more actively participated in their health care and had a better relationship with their provider than the current smokers.

Our findings regarding differences in mental health between a cohort of former and active smokers with COPD are similar to other cross-sectional²⁵, ²⁶ and longitudinal²⁷ studies evaluating these differences in the general population. Similar to our population, former smokers in the general population experience better perceived mental health than current smokers, especially after the initial period of smoking cessation.²⁶, ²⁷ The lower Mental Health Summary scores in the current smokers with COPD from our study might suggest greater psychologic needs in this subpopulation. A significant percentage of patients with COPD have psychiatric comorbidities, particularly depression and anxiety.²⁸, ²⁹ Several studies have evaluated smoking-cessation interventions in patients with COPD, but most did not measure functional status or address mental health/illness differences between those who continued to smoke and those who were able to stop smoking.³⁰, ³¹, ³², ³³, ³⁴, ³⁵, ³⁶ The Lung Health Study evaluated a smoking-cessation intervention in smokers with mild to moderate COPD, but did not measure functional status or mental health.³¹, ³² Another study evaluating a smoking-cessation intervention in patients with COPD did not measure functional status, but did find that 18% to 23% of participants, without a diagnosis of depression at entry, met criteria for depression when they were formally evaluated using a standardized instrument.³³ Although mental illnesses were not addressed in most of these studies of smoking-cessation interventions in patients with COPD, the management of psychiatric comorbidities may play an important role in the success of these smoking-cessation programs.²⁸, ³⁷ Overall, people with mental illness are approximately twice as likely to smoke and tend to smoke more heavily than the general population.³⁸ Although quit rates for patients with serious mental illnesses are marginally lower than the general population, smoking-cessation interventions are effective when they also included specific interventions addressing the mental illnesses, as well as the tobacco use.³⁹ Because studies in the general population have demonstrated success with smoking-cessation interventions in people with mental illnesses, it is reasonable to target this subgroup of patients within the actively smoking COPD population. Our findings provide evidence for the necessity of identifying patients with mental illnesses in clinical trials of smoking-cessation interventions in patients with COPD to study whether more intensive interventions (including psychologic counseling) may be of benefit and improve quit rates.

Former smokers with COPD in our study had more cardiovascular disease than the current smokers. The association between successful cessation of smoking and heart disease has been reported in 1 longitudinal analysis based on the Framingham Heart Study, in which the development of ischemic heart disease and recent hospitalization were predictive of subsequent smoking cessation within the 2 years after the hospitalization.⁴⁰ In addition, another study by Sherman and colleagues⁴¹ of veterans from southwestern and western states demonstrated that more smokers with self-reported COPD were advised to quit, prescribed nicotine replacement, and/or referred to a smoking-cessation program more often than smokers without COPD. The quit rates were similar for smokers with and without COPD; however, those with COPD were more likely to be depressed than smokers without COPD, which may explain the similar rates. These studies support the premise that patients with smoking-related illnesses, such as COPD and heart disease, likely receive the message to quit smoking more intensively than those without these conditions.

The association between older age and former smoking has been reported in the general population.¹¹, ¹², ⁴² Despite this association, it remains unclear whether older persons are more accepting of smoking cessation recommendations or other factors are responsible for the differences. Some investigators have postulated that older smokers may have higher cessation rates because they are more likely to experience health problems, which were often reported as a reason for stopping smoking.⁴² Another explanation may be that there is actually a survival benefit from quitting smoking, because current smokers are more likely to die than former smokers.¹

We were unable to find any published data regarding the characteristics of the provider–patient relationships between former and active smokers with COPD. In our study, the former smokers reported that they knew who to ask when they had questions about their care significantly more commonly than the current smokers. Patients who responded affirmatively to this question are likely to be more engaged in their own health care and are likely to take an active part in their health plan. These characteristics may be associated with patients who are more health conscious, are more empowered regarding their own health and health care, and may be more likely to successfully change their behavior, that is, quit smoking. In addition, former smokers were much more likely to respond “very good” or “excellent” when asked how they would rate their doctors’ knowledge of what worries patients the most about their health compared with current smokers. This question may reflect that former smokers have a higher level of communication with their health care provider than current smokers, which may also contribute to their success in quitting.

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Limitations 

Our study has several limitations that should be considered. First, these data are cross-sectional; therefore, no conclusions about direction of causality can be drawn from our results. As far as we know, this is the first study to describe the differences in functional status and mental health in current versus former smokers with COPD. However, our findings are consistent with other cross-sectional and longitudinal studies in smokers within the general population.²⁵, ²⁶, ²⁷ A second limitation is our predominately male population. In the general population, female smokers have been shown to be more at risk for continued smoking than males.¹¹, ⁴³ In addition, our sample included only patients within the Veterans Administration system, who are known to be older and have more chronic illnesses than the general population. Therefore, our results may not be generalizable to other populations. Another limitation is the nature of the questions about satisfaction with health care and whether these questions are a good proxy for the quality of the provider–patient relationship; however, prior work indicates that they may be a good measure of this.⁴⁴ The diagnosis of COPD was based on visits to a health care provider with at least 1 ICD-9 code for COPD, rather than by clinical history or spirometry. This is unfortunately a “real-world” setting in which patients with COPD are managed (often without any PFT confirmation of the diagnosis). Finally, we did not have data on health care use differences between the current and former smokers. It is possible that the former smokers had more contact with health care providers (“more attention”) because of having more comorbidities than the active smokers, which could possibly result in better perceived mental health.

In conclusion, we found that former, predominantly male smokers with COPD were older and had more cardiac comorbidities, but had better mental health than current smokers. In addition, the former smokers more actively participated in their health care and had a better relationship with their provider than the current smokers. The results of this study highlight the importance of screening participants enrolling in forthcoming smoking-cessation trials for mental illnesses (particularly anxiety and depression in patients with COPD). In addition, developing interventions that address these psychiatric comorbidities and that improve provider–patient communication may be other key areas to evaluate in future smoking-cessation trials in patients with COPD.

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References 

1. United States. Public Health Service. Office of the Surgeon General, Office on Smoking and Health . The Health Benefits of Smoking Cessation (a Report of the Surgeon General) . Rockville (MD): U.S. Dept. of Health and Human Services; 1999; Issued by the performing agencies: U.S. Dept. of Health and Human Services, Centers for Disease Control, Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health. DHHS Publication No: (CDC) 90-8416
   • View In Article
2. Global Initiative for Chronic Obstructive Lung Disease (GLOBAL). Global strategy for the diagnosis, management, and prevention of chronic obstructive pulmonary disease: workshop. Updated ed. 2004 July [cited: 2004 Sept. 1]. Available at: http://www.goldcopd.com/goldwr2004clean.pdf. Accessed March 30, 2005.
   • View In Article
3. Mannino DM , Homa DM , Akinbami LJ , Ford ES , Redd SC . Chronic obstructive pulmonary disease surveillance—United States, 1971-2000 . MMWR Surveill Summ . 2002;51:1–16
   • View In Article
   • MEDLINE
4. National Institutes of Health, National Heart Lung and Blood Institute . Morbidity and mortality (2004 chartbook on cardiovascular, lung, and blood diseases) . 2004; May [cited: 2005 July]. Available at: http://www.nhlbi.nih.gov/resources/docs/04a_chtbk.pdf. Accessed July 9, 2005
   • View In Article
5. Murphy SL . Deaths (final data for 1998) . Natl Vital Stat Rep . 2000;48:1–105
   • View In Article
   • MEDLINE
6. Mulder I , Tijhuis M , Smit HA , Kromhout D . Smoking cessation and quality of life (the effect of amount of smoking and time since quitting) . Prev Med . 2001;33:653–660
   • View In Article
   • MEDLINE
   • CrossRef
7. Wilson D , Parsons J , Wakefield M . The health-related quality-of-life of never smokers, ex-smokers, and light, moderate, and heavy smokers . Prev Med . 1999;29:139–144
   • View In Article
   • MEDLINE
   • CrossRef
8. Paoletti P , Camilli AE , Holberg CJ , Lebowitz MD . Respiratory effects in relation to estimated tar exposure from current and cumulative cigarette consumption . Chest . 1985;88:849–855
   • View In Article
   • MEDLINE
   • CrossRef
9. Hawthorne VM , Fry JS . Smoking and health (the association between smoking behaviour, total mortality, and cardiorespiratory disease in west central Scotland) . J Epidemiol Community Health . 1978;32:260–266
   • View In Article
   • MEDLINE
10. Centers for Disease Control and Prevention . Cigarette smoking among adults—United States, 2000 . MMWR Morb Mortal Wkly Rep . 2002;51:642–645
    • View In Article
    • MEDLINE
11. Hymowitz N , Cummings KM , Hyland A , Lynn WR , Pechacek TF , Hartwell TD . Predictors of smoking cessation in a cohort of adult smokers followed for five years . [abstract] Tob Control . 1997;6(Suppl 2):S57–S62
    • View In Article
    • CrossRef
12. Monso E , Campbell J , Tonnesen P , Gustavsson G , Morera J . Sociodemographic predictors of success in smoking intervention . Tob Control . 2001;10:165–169
    • View In Article
    • MEDLINE
    • CrossRef
13. Ossip-Klein DJ , McIntosh S , Utman C , Burton K , Spada J , Guido J . Smokers ages 50+ (who gets physician advice to quit?) . Prev Med . 2000;31:364–369
    • View In Article
    • MEDLINE
    • CrossRef
14. Duncan CL , Cummings SR , Hudes ES , Zahnd E , Coates TJ . Quitting smoking (reasons for quitting and predictors of cessation among medical patients) . J Gen Intern Med . 1992;7:398–404
    • View In Article
    • MEDLINE
    • CrossRef
15. Senore C , Battista RN , Shapiro SH , et al.   Predictors of smoking cessation following physicians’ counseling . Prev Med . 1998;27:412–421
    • View In Article
    • MEDLINE
    • CrossRef
16. Goldstein MG , Niaura R , Willey-Lessne C , et al.   Physicians counseling smokers. A population-based survey of patients’ perceptions of health care provider-delivered smoking cessation interventions . Arch Intern Med . 1997;157:1313–1319
    • View In Article
    • MEDLINE
17. Tessaro I , Lyna PR , Rimer BK , et al.   Readiness to change smoking behavior in a community health center population . J Community Health . 1997;22:15–31
    • View In Article
    • MEDLINE
    • CrossRef
18. Perlin J , Kazis LE , Skinner KM , et al.   Health Status and Outcomes of Veterans: Physical and Mental Component Summary Scores: Veterans SF-36; 1999 Large Health Survey of Veteran Enrollees; Executive Report . Washington, DC: Department of Veterans Affairs, Office of Quality and Performance; 2000; Bedford, MA: VHA Health Assessment Project, Center for Health Quality, Outcomes and Economic Research
    • View In Article
19. Ware JE , Sherbourne CD . The MOS 36-item short-form health survey (SF-36). I. Conceptual framework and item selection . Med Care . 1992;30:473–483
    • View In Article
    • MEDLINE
    • CrossRef
20. Kazis LE , Miller DR , Clark J , et al.   Health-related quality of life in patients served by the Department of Veterans Affairs (results from the Veterans Health Study) . Arch Intern Med . 1998;158:626–632
    • View In Article
    • MEDLINE
    • CrossRef
21. Kazis LE , Ren XS , Lee A , et al.   Health status in VA patients (results from the Veterans Health Study) . Am J Med Qual . 1999;14:28–38
    • View In Article
    • MEDLINE
    • CrossRef
22. Kazis LE . The veterans SF-36 health status questionnaire (development and application in the Veterans Health Administration) . Medical Outcomes Trust Monitor . 2000;5:1–2 13-14
    • View In Article
23. Ware JE , Kosinski M , Keller SD . SF-36 Physical and Mental Health Summary Scales (A User’s Manual) . Boston (MA): The Health Institute, New England Medical Center; 1994;
    • View In Article
24. Safran DG , Kosinski M , Tarlov AR , et al.   The Primary Care Assessment Survey (tests of data quality and measurement performance) . Med Care . 1998;36:728–739
    • View In Article
    • MEDLINE
    • CrossRef
25. Woolf SH , Rothemich SF , Johnson RE , Marsland DW . Is cigarette smoking associated with impaired physical and mental functional status? An office-based survey of primary care patients . Am J Prev Med . 1999;17:134–137
    • View In Article
    • Abstract
    • Full Text
    • Full-Text PDF (175 KB)
    • CrossRef
26. Tillmann M , Silcock J . A comparison of smokers’ and ex-smokers’ health-related quality of life . J Public Health Med . 1997;19:268–273
    • View In Article
    • MEDLINE
27. Mino Y , Shigemi J , Otsu T , Tsuda T , Babazono A . Does smoking cessation improve mental health? . Psychiatry Clin Neurosci . 2000;54:169–172
    • View In Article
    • MEDLINE
    • CrossRef
28. Wagena EJ , Kant I , Huibers MJ , et al.   Psychological distress and depressed mood in employees with asthma, chronic bronchitis or emphysema (a population-based observational study on prevalence and the relationship with smoking cigarettes) . Eur J Epidemiol . 2004;19:147–153
    • View In Article
    • MEDLINE
    • CrossRef
29. Kunik ME , Roundy K , Veazey C , et al.   Surprisingly high prevalence of anxiety and depression in chronic breathing disorders . Chest . 2005;127:1205–1211
    • View In Article
    • MEDLINE
    • CrossRef
30. Wagena EJ , van der Meer RM , Ostelo RJ , Jacobs JE , van Schayck CP . The efficacy of smoking cessation strategies in people with chronic obstructive pulmonary disease (results from a systematic review) . [Review] Respir Med . 2004;98:805–815
    • View In Article
    • Abstract
    • Full Text
    • Full-Text PDF (380 KB)
    • CrossRef
31. O’Hara P , Grill J , Rigdon MA , Connett JE , Lauger GA , Johnston JJ  The Lung Health Study Research Group . Design and results of the initial intervention program for the Lung Health Study . Prev Med . 1993;22:304–315
    • View In Article
    • MEDLINE
    • CrossRef
32. Anthonisen NR , Connett JE , Kiley JP , et al.   Effects of smoking intervention and the use of an inhaled anticholinergic bronchodilator on the rate of decline of FEV1. The Lung Health Study . JAMA . 1994;272:1497–1505
    • View In Article
    • MEDLINE
33. Tashkin D , Kanner R , Bailey W , et al.   Smoking cessation in patients with chronic obstructive pulmonary disease (a double-blind, placebo-controlled, randomised trial) . Lancet . 2001;357:1571–1575
    • View In Article
    • Abstract
    • Full Text
    • Full-Text PDF (89 KB)
    • CrossRef
34. Brandt CJ , Ellegaard H , Joensen M , Kallan FV , Sorknaes AD , Tougaard L  RYLUNG Group . Effect of diagnosis of “smoker’s lung.” . [comment] Lancet . 1997;349:253
    • View In Article
    • Full Text
    • Full-Text PDF (39 KB)
    • CrossRef
35. Crowley TJ , Macdonald MJ , Walter MI . Behavioral anti-smoking trial in chronic obstructive pulmonary disease patients . Psychopharmacology (Berl) . 1995;119:193–204
    • View In Article
    • MEDLINE
    • CrossRef
36. Pederson LL , Wanklin JM , Lefcoe NM . The effects of counseling on smoking cessation among patients hospitalized with chronic obstructive pulmonary disease (a randomized clinical trial) . Int J Addict . 1991;26:107–119
    • View In Article
    • MEDLINE
37. Wagena EJ , Huibers MJ , van Schayck CP . Antidepressants in the treatment of patients with COPD (possible associations between smoking cigarettes, COPD and depression) . Thorax . 2001;56:587–588
    • View In Article
    • MEDLINE
    • CrossRef
38. Lasser K , Boyd JW , Woolhandler S , Himmelstein DU , McCormick D , Bor DH . Smoking and mental illness (a population-based prevalence study) . JAMA . 2000;284:2606–2610
    • View In Article
    • MEDLINE
    • CrossRef
39. El-Guebaly N , Cathcart J , Currie S , Brown D , Gloster S . Smoking cessation approaches for persons with mental illness or addictive disorders . [Review] Psychiatr Serv . 2002;53:1166–1170
    • View In Article
    • MEDLINE
    • CrossRef
40. Freund KM , D’Agostino RB , Belanger AJ , Kannel WB , Stokes J . Predictors of smoking cessation (the Framingham Study) . Am J Epidemiol . 1992;135:957–964
    • View In Article
    • MEDLINE
41. Sherman SE , Lanto AB , Nield M , Yano EM . Smoking cessation care received by veterans with chronic obstructive pulmonary disease . J Rehabil R D . 2003;40:1–12
    • View In Article
42. Osler M , Prescott E . Psychosocial, behavioural, and health determinants of successful smoking cessation (a longitudinal study of Danish adults) . Tob Control . 1998;7:262–267
    • View In Article
    • MEDLINE
    • CrossRef
43. Monso E , Campbell J , Tonnesen P , Gustavsson G , Morera J . Sociodemographic predictors of success in smoking intervention . Tob Control . 2001;10:165–169
    • View In Article
    • MEDLINE
    • CrossRef
44. Safran DG . Defining the future of primary care (what can we learn from patients?) . Ann Intern Med . 2003;138:248–255
    • View In Article