0306~160319’ $5.00 + .OO
.-lddicrive Behaviors. Vol. Il. pp. 301-306. 1992 Printed
Copyright
in the USA. All rights reserved.
IMPROVEMENT
F 1992 Pergamon
Press Ltd.
IN PULMONARY FUNCIlOiV FOLLOlVING SMOKING CESSATION KAREN M. EMMONS
The Miriam
Hospital/Brown
University
School of Medicine
GERDI WEIDNER and W. MICHAEL FOSTER State University
of New York at Stony Brook
R. LORRAINE COLLINS Research
Institute
on Alcoholism
Abstract - This study investigated improvement in pulmonary function following smoking cessation. It employed three indices of lung function that are sensitive to improvement following smoking cessation and that can be easily assessed within a clinical setting: maximum midexpiraton flow (MMF), forced expiratory volume in I second (FEV I ). and forced vital capacity (FVC). Smoking status was verified by saliva thiocyanate analysis. Signihcant improvement in MMF was evident after 3 months of cessation and was maintained at the 6-month follow-up. This study demonstrates that signiticant improvement in at least one parameter of lung function occurs within the time span typically used in smoking cessation programs.
The recalcitrant nature of smoking suggests that typical community-based treatment clinics may not be sufficient to address the needs of many smokers who want to quit smoking (Abrams, Emmons, Niaura, Goldstein, & Sherman, 1991; DiFranza & Guerrera, 1989: Pierce, Fiore, Novotny, Hatziandreu. & Davis. 1989a, 1989b). Adoption of a biobehavioral approach to smoking intervention may more adequately address mechanisms that are pertinent to cessation for a substantial proportion of the smoking population. For many smokers, the primary goal of smoking cessation is improvement ofcurrent health and/or prevention ofdisease. Therefore, it is conceivable that accurate feedback concerning improvement in physiological parameters resulting from smoking cessation would serve to reinforce abstinence. There is some initial evidence available suggesting that providing smokers with information about carbon monoxide levels and pulmonary function prior to smoking cessation may enhance short-term abstinence rates (Walker & Franzini, 1985). However, there have been no evaluations to date of the impact of repeated feedback about improvements in physiological functioning following cessation on long-term outcome. It is well-documented that improvement in pulmonary function results from smoking cessation (USDHHS, 1984). In particular, measures such as maximum midexpiratory flow (MMF) and derivatives of forced vital capacity (FVC) have been found to be most sensitive to improvement following smoking cessation (McCarthy, Craig, & Cherniack, 1976; McFadden & Linden, 1972). Most investigations of the impact of This research was supported in part by funds from the American Lung Association. the American Heart Association (Suffolk County). the Veterans Administration. NIH (HL3141903. HL3426103. HL4036801). the National Cancer Institute (I-R03-CA-48437). and Biomedical Research Suta~ort RR0706721. The .. authors would like to thank Joanne Wood. David Abrams. and Charles Sherman for their contributions to this project. .Address correspondence to Karen M. Emmons. Ph.D., The Miriam Hospital. Division of Behavioral Medicine, RISE Building. I64 Summit Avenue, Providence. RI 01906. 301
smoking cessation on pulmonary function have utilized long-term follow-ups evaluating change over 5 to 10 years. These studies primarily employ complex physiological tests (e.g.. single-breath nitrogen test) which require expensive and sophisticated equipment, as well as trained pulmonary technicians (Buist, Nagy, & Sexton. 1979; Dirksen, Janzon. & Lindell, 1974; McCarthy, et al., 1976). The complexity of these measures may limit their generalizability and preclude their use in smoking cessation programs. Thus. it is important to investigate approaches that are more likely to be utilized within clinical settings. Several studies have examined short-term pulmonary response to smoking cessation using more easily assessed lung function parameters (e.g., spirometric measurements), but they do not offer conclusive results (e.g., Bode, Dosman, Martin. & Macklem, 1975; Buist. Sexton, Nagy, RcRoss, 1976). For example, Bode et al. (1975) studied 10 subjects prior to and following smoking cessation. No significant changes in spirometric measures of forced expiratory volume in 1 second (FEVl) or maximum midexpiratory flow (MMF) vvere found. A number of methodological factors may have impacted on the results. For example, follow-up assessments were made over a broad time span. In addition, subjects did not participate in a formal smoking cessation clinic but were only asked to quit smoking. No biochemical validation of subjects’ self-reported abstinence was made. A large body of literature suggests that self-report is not a reliable indicator of smoking behavior (e.g., Brockway. Kleinmann, Edleson. &r Gruenewald, 1977; McFall Rc Hammen, 1971). Therefore, it is likely that some of the subjects who were presumed to be abstinent were still smoking. McFadden and Linden (1972) examined changes in total lung capacity (TLC) and MMF following cessation among 23 smokers with chronic bronchitis. A reversal of abnormalities in MMF was found among the abstinent subjects. However, only 4 participants reported abstinence by the l-month assessment, and no biochemical validation ofsmoking status was made. In addition, all subjects were placed on bronchodilator therapy following cessation, which may have confounded the results. One of the few studies of lung function to be associated with a formal smoking cessation program was conducted by Buist et al. (1976). A group of 75 smokers was monitored for 1 year following cessation using both simple spirometry and the more complicated single breath nitrogen test. Improvement was found among the 13 abstainers with the single breath nitrogen test. although no change was evident in the spirometric measurements. In summary, studies utilizing more easily obtained measures of pulmonary function to document the changes in function following smoking cessation have not yielded consistent results. Several factors that may account for these discrepant findings include failure to verify self-reported smoking status, non-uniform follow-up intervals, and different forms of cessation treatment. In light of these limitations. the present study was designed (a) to investigate the temporal nature of short-term changes in lung function employing biochemical verification of smoking status, and (b) to determine if the type of lung function parameters that can be easily measured within a clinical setting are sensitive enough to reflect significant short-term improvement following cessation. METHOD
Subjects Fifty-eight respondents to advertisements for a smoking cessation clinic were screened for asthma and advanced respiratory disease by a pulmonologist. Nine subjects were excluded because they had either one or both of these conditions. Of the 49
Pulmonan
function
and smoking
cessation
303
participants in the smoking cessation program, 25 persons ( 17 abstainers, 8 relapsers) participated in the cessation treatment and a 6-month follow-up. The subjects for the present study were these 17 abstainers who participated in the pre-treatment and 6month assessments. Data from a 3-month follow-up, available for 11 of these abstainers, will also be presented. The subjects smoked an average of 3 1.6 (SD = 11.62; range = 1j-40) cigarettes per day, and had been smoking an average of 19.7 (SD = 8.00: range = 8-40) years. The average age ofthe sample was 39.7 (SD = 7.80, range = 24-55) and the average weight was 67.7 kg. (SD = 12.3). There were no gender differences on any of the demographic variables or pre-treatment pulmonary measures. At treatment onset subjects were asymptomatic and had near normal lung function: FVC and FEV 1 were 87.7% and 85.4%, respectively of the predicted values, calculated as a function of age, height, and gender (Crapo, Morris, & Gardner. 198 1). Smoking cessation treatment This study was part of a larger project investigating the comparative efficacy of two approaches to smoking cessation (relapse prevention and broad spectrum). Details of the treatment are reported elsewhere (Emmons, Emont, Collins, & Weidner, 1988; Emmons, Weidner, & Collins, 1989). Outcome variables Smoking behavior. Smoking history and current rate of cigarette consumption were assessed via a 3 1-item questionnaire (a copy of the questionnaire can be obtained from the first author). Self-reports of smoking status following smoking cessation were verified by carbon monoxide and saliva thiocyanate analysis. A cut-off of 5 ppm for carbon monoxide (Ohlin, Lundh, & Westling, 1976) and 85 pg/mL for saliva thiocyanate (Pechacek, Fox, Murray, & Luepker, 1984) were used as indicants of abstinence. Based on these criteria, 4 of the subjects were categorized as relapsers, and 1 1 were categorized as abstainers at the 3-month follow-up. At the 6-month follow-up, 8 of the subjects were categorized as relapsers, and 17 were categorized as abstainers. Lungparameters. Spirometric measurements oflung function (forced expiratory volume in 1 second expressed as a percentage of forced vital capacity (FEV I/FVC), forced vital capacity (FVC), and maximum midexpiratory flow (MMF) were used as dependent variables. These parameters were selected because they have been found to be sensitive to improvement following smoking cessation (McCarthy et al., 1976; McFadden & Linden, 1972). All spirometric measurements were made according to American Thoracic Society criteria, using a water-sealed spirometer (Collins, 9-L Vitalmeter, Braintree, MA) (Gainsler & Wrighter, 1966). All volumes were expressed in liters adjusted to barometric pressure. PROCEDURE
Spirometric measurement of pulmonary function was completed approximately 1 week prior to initiation of the 8-week smoking cessation program, and 3- and 6-months following cessation. Smoking history, medical history, and demographic information were obtained prior to measurement of pulmonary function. Height, assumed to be constant throughout the 6-month study period, was assessed at pre-treatment following removal of shoes. Weight was assessed both at pre-treatment and at follow-up. Pre-
KAREN
304
Xl. EMMONS
et al.
treatment and follow-up assessments for a given subject were performed at the same time of day, at times when subjects were in good health. Any assessments planned for times when a subject was not feeling.welI were rescheduled in order to minimize the impact on effort expended while completing the spirometric measurements. Verification of smoking status was completed at the follow-up assessments. In order to minimize the impact of nicotine on acute physiological responses, a 1-hour period of abstinence was imposed prior to pulmonary testing. During this period. subjects completed questionnaire measures and other assessments.
RESULTS
Pulmonary function values for the entire sample were examined with repeated measured analysis of variance. The mean values for the lung parameters at the baseline and 6-month follow-up assessments are presented in Table 1. Analyses indicated that there was significant improvement in MMF by the 6-month fo!low-up (F( 1) = 5.23. p 5 .Oj). There was no change in FVC or FEVl/FVC values following 6 months of smoking cessation. Analyses were also performed on the data for the 1 1 subjects who participated in both the 3- and 6-month follovv-ups. MMF was significantly improved at both follow-up points. vvhen compared to pre-treatment (F(2) = 3.48. p I .05). There was no significant change in FVC or FEV I /FVC following 3 or 6 months of abstinence. Inspection of the data regarding the number of subjects that esperienced improvement in pulmonary function revealed that 90% of the abstainers who completed all three assessments showed improvement on at least one parameter at one or more ofthe time points investigated. Similar proportions were found among subjects \vho completed only the pre-treatment and 6-month assessments. Although the relapsers per se were not of interest in the present study, this group does provide a comparison for evaluating the level of change among the abstainers. There was no change in any of the pulmonary function parameters among the relapsers over the study period.
DISCUSSION
The primary goal of this study was to investigate the temporal nature of short-term changes in lung function following biochemically-verified smoking cessation. The results indicated that statistically significant improvement in one parameter of lung
Table I. Mean values of lung function parameters for abstainers who completed the pre-treatment and 6-month assessments (n = 17)
Pm-treatment FEV I/FVC (%I) (*SD) FVC (L) (&SD) MMF(L/s) (LSD) */I I
.01. Z-tailed.
.79 .I0 3.94 I .05 3.71 2.46
h-month follow-up .89 .Ol 3.71 .95 4.36* 2.34
Pulmonaq
function and smoking cessation
305
function occurs within the typical time span of smoking cessation programs and followups. Further, it was found that improvement can be easily and quickly measured (e.g., lo- 15 min) in a clinical context. It should also be noted that improvement was evident in 90% of the abstainers across one or more of the time periods investigated. Although the ability to detect statistically significant improvement may have been affected by the small sample size, the clinical significance of these findings should not be overlooked. Feedback about such improvements may prove to be a powerful reinforcer of abstinence efforts. The present study demonstrates that measurement of lung function within the context of a cessation program represents a means of providing direct physiological feedback about health status. Further research is warranted to determine the role that this type of physiological feedback might play in relapse prevention. The findings of the present study should be interpreted with caution due to the considerable attrition that occurred over the study period. Although subjects who did not complete the follow-ups did not differ from those who did attend follow-up assessments on a number of baseline demographic and physiological characteristics, it is still possible that differences between these groups may have been found had all subjects been re-assessed. It should be noted that the attrition rate found in this study is typical ofmost smoking cessation studies (c.f. Abrams et al., 199 1). Another limitation of this study was the lack of a control group that would make it possible to estimate the influence that motivation may have had on abstainers’ pulmonary function results. If a motivational effect was operating. the improvement in abstainers’ lung function could have been an artifact. Although it was not possible to include a continuous smoking control group, analyses of the relapsers’ lung function data indicated that there were no significant changes in lung function among this group during the study period. Since the relapsers may also have been motivated to have improved lung function resulting from their limited period of abstinence, it is unlikely that the improvements among the abstainers were solely a function of motivation. In summary, this study offers improvements over the existing literature by utilizing a formal smoking cessation program and including biochemical verification ofsmoking status. The verification techniques allowed for assessment of abstinence several days in duration. Although more sophisticated and sensitive techniques have recently become available (e.g., cotinine assays), the measures chosen were considered to be state-of-theart at the time the study was conducted (Abueg, Colletti, & Rizzo, 1986; Pechacek et al., 1981; Stookey, Katz. Olson, Drook, & Cohen, 1987). In addition, there is a substantial literature documenting the impact of simply participating in biochemical measurement of abstinence on accuracy of self-report, e.g., bogus pipeline effect (e.g., Jones & Sigall, 197 1). The results ofthis study suggest that, following smoking cessation, there are significant improvements in physiological parameters that can be measured in a clinical context. Feedback about improvements in lung function could potentially be utilized in a feedback model within cessation programs as a strategy for decreasing relapse. The potential benefits of adopting an interdisciplinary perspective for the design of smoking cessation programs and the prevention of relapse indicate that the inclusion of biobehavioral mechanisms in smoking cessation programs deserve further research attention. REFERENCES Abrams. D. B., Emmons. K. M.. Niaura. R. S.. Goldstein. M. G., Sherman. & C. B. (199 I). Tobacco dependence. In P. E. Nathan, J. W. Langenbucher, B. S. McCrady, & W. Frankenstein (Eds.). The antural revie~v of nddiciions frealnw~t and research (Vol. I, pp. 39 I-436). Elmsford. NY: Pergamon Press.
KAREN
306
M. EXiMONS
et al.
Abueg. F. R.. Colletti. G.. & Rizzo. A. A. (1986). Thesaliva thiocyanateanalvsis: A methodological extension and its relationship to CO and self-report in moderate smokers. .4ddic& Behaviors. I I, 55-58. Bode. F. R.. Dosman. J.. Martin. R.. & Macklem. P. T. ( 1975). Reversibility of pulmonary function abnormalities in smokers: A prospective study ofearly diagnostic tests ofsmall airway disease. The.4tncricat1
Jownu/ c~/.tledicinr. 59. 43-52. Brockvvay. B. S., Kleinmann. G.. Edleson. J.. Br Gruenewald. K. (1977). Non-aversive procedures and their effect on cigarette smoking. .-lddicfive Behuviors. I 1. I 2 I - 128. Buist. A. S.. Nagy. J. M.. & Sexton. G. J. (I 979). The effect of smoking cessation on pulmonary function: A 30-month follow-up of two smoking cessation clinics. .4merican Review q/ Respiruroq~ Disease. 120.
953-957. Buist. ‘4. S.. Sexton, G. J.. Nagy. J. M.. & Ross. B. B. (1976). Theeffect ofsmokingcessation and modification on lung function. .-lmerricarr Rt,vicn,clfRespirulor?, Disease. 11-I. I 14-122. Crapo. R. 0.. Morris. A. H.. & Gardner. R. M. ( 198 I). Reference spirometric values using techniques and equipment that meet ATS recommendations. American Review c!l‘Respirulorj~Disease. 123. 659-664. DiFranza. J. R., & Guerrera. M. P. ( 1989). Hard core smokers (letter). Jolrrnulqf~/2t’.-Ir,2erit.un.\/edicu/A WI-
ciuiicln. 261( 18). 7634. Dirksen. H.. Janzon. L.. & Lindell. S. E. ( 1973). Influence ofsmoking and cessation ofsmoking on lung function. Scundinuriun Jownal ql’Respiruioq~ Diseuse. 85, 266. Emmons. K. M.. Emont. S. L.. Collins. R. L.. & Weidner. G. (1988). Relapse prevention versus broad spectrum treatment for smoking cessation: A comparison ofefficacy. J~~~rmu/ofS~thsianc~~.4h~rte. 1. 79-89. Emmons. K. M.. Weidner. G.. R: Collins. R. L. (1989). Smoking cessation and cardiovascular reactivity to stress. Jownul ol‘Behavioru/ .\ledkne. 12(6). 587-598. Gainsler. E. A., & \
.-lddicrive Behaviors. Vol. Il. pp. 301-306. 1992 Printed
Copyright
in the USA. All rights reserved.
IMPROVEMENT
F 1992 Pergamon
Press Ltd.
IN PULMONARY FUNCIlOiV FOLLOlVING SMOKING CESSATION KAREN M. EMMONS
The Miriam
Hospital/Brown
University
School of Medicine
GERDI WEIDNER and W. MICHAEL FOSTER State University
of New York at Stony Brook
R. LORRAINE COLLINS Research
Institute
on Alcoholism
Abstract - This study investigated improvement in pulmonary function following smoking cessation. It employed three indices of lung function that are sensitive to improvement following smoking cessation and that can be easily assessed within a clinical setting: maximum midexpiraton flow (MMF), forced expiratory volume in I second (FEV I ). and forced vital capacity (FVC). Smoking status was verified by saliva thiocyanate analysis. Signihcant improvement in MMF was evident after 3 months of cessation and was maintained at the 6-month follow-up. This study demonstrates that signiticant improvement in at least one parameter of lung function occurs within the time span typically used in smoking cessation programs.
The recalcitrant nature of smoking suggests that typical community-based treatment clinics may not be sufficient to address the needs of many smokers who want to quit smoking (Abrams, Emmons, Niaura, Goldstein, & Sherman, 1991; DiFranza & Guerrera, 1989: Pierce, Fiore, Novotny, Hatziandreu. & Davis. 1989a, 1989b). Adoption of a biobehavioral approach to smoking intervention may more adequately address mechanisms that are pertinent to cessation for a substantial proportion of the smoking population. For many smokers, the primary goal of smoking cessation is improvement ofcurrent health and/or prevention ofdisease. Therefore, it is conceivable that accurate feedback concerning improvement in physiological parameters resulting from smoking cessation would serve to reinforce abstinence. There is some initial evidence available suggesting that providing smokers with information about carbon monoxide levels and pulmonary function prior to smoking cessation may enhance short-term abstinence rates (Walker & Franzini, 1985). However, there have been no evaluations to date of the impact of repeated feedback about improvements in physiological functioning following cessation on long-term outcome. It is well-documented that improvement in pulmonary function results from smoking cessation (USDHHS, 1984). In particular, measures such as maximum midexpiratory flow (MMF) and derivatives of forced vital capacity (FVC) have been found to be most sensitive to improvement following smoking cessation (McCarthy, Craig, & Cherniack, 1976; McFadden & Linden, 1972). Most investigations of the impact of This research was supported in part by funds from the American Lung Association. the American Heart Association (Suffolk County). the Veterans Administration. NIH (HL3141903. HL3426103. HL4036801). the National Cancer Institute (I-R03-CA-48437). and Biomedical Research Suta~ort RR0706721. The .. authors would like to thank Joanne Wood. David Abrams. and Charles Sherman for their contributions to this project. .Address correspondence to Karen M. Emmons. Ph.D., The Miriam Hospital. Division of Behavioral Medicine, RISE Building. I64 Summit Avenue, Providence. RI 01906. 301
smoking cessation on pulmonary function have utilized long-term follow-ups evaluating change over 5 to 10 years. These studies primarily employ complex physiological tests (e.g.. single-breath nitrogen test) which require expensive and sophisticated equipment, as well as trained pulmonary technicians (Buist, Nagy, & Sexton. 1979; Dirksen, Janzon. & Lindell, 1974; McCarthy, et al., 1976). The complexity of these measures may limit their generalizability and preclude their use in smoking cessation programs. Thus. it is important to investigate approaches that are more likely to be utilized within clinical settings. Several studies have examined short-term pulmonary response to smoking cessation using more easily assessed lung function parameters (e.g., spirometric measurements), but they do not offer conclusive results (e.g., Bode, Dosman, Martin. & Macklem, 1975; Buist. Sexton, Nagy, RcRoss, 1976). For example, Bode et al. (1975) studied 10 subjects prior to and following smoking cessation. No significant changes in spirometric measures of forced expiratory volume in 1 second (FEVl) or maximum midexpiratory flow (MMF) vvere found. A number of methodological factors may have impacted on the results. For example, follow-up assessments were made over a broad time span. In addition, subjects did not participate in a formal smoking cessation clinic but were only asked to quit smoking. No biochemical validation of subjects’ self-reported abstinence was made. A large body of literature suggests that self-report is not a reliable indicator of smoking behavior (e.g., Brockway. Kleinmann, Edleson. &r Gruenewald, 1977; McFall Rc Hammen, 1971). Therefore, it is likely that some of the subjects who were presumed to be abstinent were still smoking. McFadden and Linden (1972) examined changes in total lung capacity (TLC) and MMF following cessation among 23 smokers with chronic bronchitis. A reversal of abnormalities in MMF was found among the abstinent subjects. However, only 4 participants reported abstinence by the l-month assessment, and no biochemical validation ofsmoking status was made. In addition, all subjects were placed on bronchodilator therapy following cessation, which may have confounded the results. One of the few studies of lung function to be associated with a formal smoking cessation program was conducted by Buist et al. (1976). A group of 75 smokers was monitored for 1 year following cessation using both simple spirometry and the more complicated single breath nitrogen test. Improvement was found among the 13 abstainers with the single breath nitrogen test. although no change was evident in the spirometric measurements. In summary, studies utilizing more easily obtained measures of pulmonary function to document the changes in function following smoking cessation have not yielded consistent results. Several factors that may account for these discrepant findings include failure to verify self-reported smoking status, non-uniform follow-up intervals, and different forms of cessation treatment. In light of these limitations. the present study was designed (a) to investigate the temporal nature of short-term changes in lung function employing biochemical verification of smoking status, and (b) to determine if the type of lung function parameters that can be easily measured within a clinical setting are sensitive enough to reflect significant short-term improvement following cessation. METHOD
Subjects Fifty-eight respondents to advertisements for a smoking cessation clinic were screened for asthma and advanced respiratory disease by a pulmonologist. Nine subjects were excluded because they had either one or both of these conditions. Of the 49
Pulmonan
function
and smoking
cessation
303
participants in the smoking cessation program, 25 persons ( 17 abstainers, 8 relapsers) participated in the cessation treatment and a 6-month follow-up. The subjects for the present study were these 17 abstainers who participated in the pre-treatment and 6month assessments. Data from a 3-month follow-up, available for 11 of these abstainers, will also be presented. The subjects smoked an average of 3 1.6 (SD = 11.62; range = 1j-40) cigarettes per day, and had been smoking an average of 19.7 (SD = 8.00: range = 8-40) years. The average age ofthe sample was 39.7 (SD = 7.80, range = 24-55) and the average weight was 67.7 kg. (SD = 12.3). There were no gender differences on any of the demographic variables or pre-treatment pulmonary measures. At treatment onset subjects were asymptomatic and had near normal lung function: FVC and FEV 1 were 87.7% and 85.4%, respectively of the predicted values, calculated as a function of age, height, and gender (Crapo, Morris, & Gardner. 198 1). Smoking cessation treatment This study was part of a larger project investigating the comparative efficacy of two approaches to smoking cessation (relapse prevention and broad spectrum). Details of the treatment are reported elsewhere (Emmons, Emont, Collins, & Weidner, 1988; Emmons, Weidner, & Collins, 1989). Outcome variables Smoking behavior. Smoking history and current rate of cigarette consumption were assessed via a 3 1-item questionnaire (a copy of the questionnaire can be obtained from the first author). Self-reports of smoking status following smoking cessation were verified by carbon monoxide and saliva thiocyanate analysis. A cut-off of 5 ppm for carbon monoxide (Ohlin, Lundh, & Westling, 1976) and 85 pg/mL for saliva thiocyanate (Pechacek, Fox, Murray, & Luepker, 1984) were used as indicants of abstinence. Based on these criteria, 4 of the subjects were categorized as relapsers, and 1 1 were categorized as abstainers at the 3-month follow-up. At the 6-month follow-up, 8 of the subjects were categorized as relapsers, and 17 were categorized as abstainers. Lungparameters. Spirometric measurements oflung function (forced expiratory volume in 1 second expressed as a percentage of forced vital capacity (FEV I/FVC), forced vital capacity (FVC), and maximum midexpiratory flow (MMF) were used as dependent variables. These parameters were selected because they have been found to be sensitive to improvement following smoking cessation (McCarthy et al., 1976; McFadden & Linden, 1972). All spirometric measurements were made according to American Thoracic Society criteria, using a water-sealed spirometer (Collins, 9-L Vitalmeter, Braintree, MA) (Gainsler & Wrighter, 1966). All volumes were expressed in liters adjusted to barometric pressure. PROCEDURE
Spirometric measurement of pulmonary function was completed approximately 1 week prior to initiation of the 8-week smoking cessation program, and 3- and 6-months following cessation. Smoking history, medical history, and demographic information were obtained prior to measurement of pulmonary function. Height, assumed to be constant throughout the 6-month study period, was assessed at pre-treatment following removal of shoes. Weight was assessed both at pre-treatment and at follow-up. Pre-
KAREN
304
Xl. EMMONS
et al.
treatment and follow-up assessments for a given subject were performed at the same time of day, at times when subjects were in good health. Any assessments planned for times when a subject was not feeling.welI were rescheduled in order to minimize the impact on effort expended while completing the spirometric measurements. Verification of smoking status was completed at the follow-up assessments. In order to minimize the impact of nicotine on acute physiological responses, a 1-hour period of abstinence was imposed prior to pulmonary testing. During this period. subjects completed questionnaire measures and other assessments.
RESULTS
Pulmonary function values for the entire sample were examined with repeated measured analysis of variance. The mean values for the lung parameters at the baseline and 6-month follow-up assessments are presented in Table 1. Analyses indicated that there was significant improvement in MMF by the 6-month fo!low-up (F( 1) = 5.23. p 5 .Oj). There was no change in FVC or FEVl/FVC values following 6 months of smoking cessation. Analyses were also performed on the data for the 1 1 subjects who participated in both the 3- and 6-month follovv-ups. MMF was significantly improved at both follow-up points. vvhen compared to pre-treatment (F(2) = 3.48. p I .05). There was no significant change in FVC or FEV I /FVC following 3 or 6 months of abstinence. Inspection of the data regarding the number of subjects that esperienced improvement in pulmonary function revealed that 90% of the abstainers who completed all three assessments showed improvement on at least one parameter at one or more ofthe time points investigated. Similar proportions were found among subjects \vho completed only the pre-treatment and 6-month assessments. Although the relapsers per se were not of interest in the present study, this group does provide a comparison for evaluating the level of change among the abstainers. There was no change in any of the pulmonary function parameters among the relapsers over the study period.
DISCUSSION
The primary goal of this study was to investigate the temporal nature of short-term changes in lung function following biochemically-verified smoking cessation. The results indicated that statistically significant improvement in one parameter of lung
Table I. Mean values of lung function parameters for abstainers who completed the pre-treatment and 6-month assessments (n = 17)
Pm-treatment FEV I/FVC (%I) (*SD) FVC (L) (&SD) MMF(L/s) (LSD) */I I
.01. Z-tailed.
.79 .I0 3.94 I .05 3.71 2.46
h-month follow-up .89 .Ol 3.71 .95 4.36* 2.34
Pulmonaq
function and smoking cessation
305
function occurs within the typical time span of smoking cessation programs and followups. Further, it was found that improvement can be easily and quickly measured (e.g., lo- 15 min) in a clinical context. It should also be noted that improvement was evident in 90% of the abstainers across one or more of the time periods investigated. Although the ability to detect statistically significant improvement may have been affected by the small sample size, the clinical significance of these findings should not be overlooked. Feedback about such improvements may prove to be a powerful reinforcer of abstinence efforts. The present study demonstrates that measurement of lung function within the context of a cessation program represents a means of providing direct physiological feedback about health status. Further research is warranted to determine the role that this type of physiological feedback might play in relapse prevention. The findings of the present study should be interpreted with caution due to the considerable attrition that occurred over the study period. Although subjects who did not complete the follow-ups did not differ from those who did attend follow-up assessments on a number of baseline demographic and physiological characteristics, it is still possible that differences between these groups may have been found had all subjects been re-assessed. It should be noted that the attrition rate found in this study is typical ofmost smoking cessation studies (c.f. Abrams et al., 199 1). Another limitation of this study was the lack of a control group that would make it possible to estimate the influence that motivation may have had on abstainers’ pulmonary function results. If a motivational effect was operating. the improvement in abstainers’ lung function could have been an artifact. Although it was not possible to include a continuous smoking control group, analyses of the relapsers’ lung function data indicated that there were no significant changes in lung function among this group during the study period. Since the relapsers may also have been motivated to have improved lung function resulting from their limited period of abstinence, it is unlikely that the improvements among the abstainers were solely a function of motivation. In summary, this study offers improvements over the existing literature by utilizing a formal smoking cessation program and including biochemical verification ofsmoking status. The verification techniques allowed for assessment of abstinence several days in duration. Although more sophisticated and sensitive techniques have recently become available (e.g., cotinine assays), the measures chosen were considered to be state-of-theart at the time the study was conducted (Abueg, Colletti, & Rizzo, 1986; Pechacek et al., 1981; Stookey, Katz. Olson, Drook, & Cohen, 1987). In addition, there is a substantial literature documenting the impact of simply participating in biochemical measurement of abstinence on accuracy of self-report, e.g., bogus pipeline effect (e.g., Jones & Sigall, 197 1). The results ofthis study suggest that, following smoking cessation, there are significant improvements in physiological parameters that can be measured in a clinical context. Feedback about improvements in lung function could potentially be utilized in a feedback model within cessation programs as a strategy for decreasing relapse. The potential benefits of adopting an interdisciplinary perspective for the design of smoking cessation programs and the prevention of relapse indicate that the inclusion of biobehavioral mechanisms in smoking cessation programs deserve further research attention. REFERENCES Abrams. D. B., Emmons. K. M.. Niaura. R. S.. Goldstein. M. G., Sherman. & C. B. (199 I). Tobacco dependence. In P. E. Nathan, J. W. Langenbucher, B. S. McCrady, & W. Frankenstein (Eds.). The antural revie~v of nddiciions frealnw~t and research (Vol. I, pp. 39 I-436). Elmsford. NY: Pergamon Press.
KAREN
306
M. EXiMONS
et al.
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