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Validation of smoking abstinence in newly diagnosed cardiovascular patients
Addictive Behaviors, Printed in the USA.
Vol. 18, pp. 421-429, All rights reserved.
1993 Copyright
0306-4603193 $6.00 + .OO @Z1993 Pergamon Press Ltd.
VALIDATION OF SMOKING ABSTINENCE IN NEWLY DIAGNOSED CARDIOVASCULAR PATIENTS DAWN Department
KENNETH
of Pediatrics.
A. WALLSTON, School
K. WILSON University
JOAN
E. KING,
of Nursing,
Vanderbilt
CRAIG School
of Medicine,
of Tennessee,
Memphis
and M. SHELTON
SMITH
University
HEIM Vanderbilt
University
Abstract -Three methods of assessing smoking status among newly diagnosed cardiovascular (CV) patients were compared: self-reports, collateral reports (spouse. friend, etc.). and saliva cotinine assays. Self-reported smoking status was assessed as the average number of cigarettes smoked per day at baseline, 3, 6. 9, and I2 months into treatment, and at a 6. month posttreatment follow-up. The majority of patients had quit smoking within 6 months prior to participating in the program. All participants were informed at the onset of the study and at the time of each assessment that their self-reports of smoking abstinence would be validated through collateral reports and possibly saliva cotinine analyses. Less than 5% (I 3 of 274) of the subjects’ self-reports showed discrepancies with collateral reports. Analyses of saliva cotinine assays in a subsample of subjects, however. indicated that 16% (I3 of Xl) of the saliva cotinine tests were discrepant with the collateral reports. Thus, the saliva cotinine analyses picked up an additional 11% false negatives, as compared to collateral reports. It is concluded that the use of collateral reports as an index of smoking status may be an overestimate of actual quit rates. The overall discrepancy rate for this study, however, was fairly low and suggests that patients’ self-reports may be reliable when they have already quit on their own and/or are notified in advance of verification procedures.
An increasing number of studies have examined the relationship between biochemical validation and self-reports of smoking status (Abrams, Follick, Biener, Carey, & Hitti, 1987; Carey & Abrams, 1988; Pechacek, Fox, Murray, & Leupker, 1984). In general, three biochemical measures have been compared to self-report measures: expired carbon monoxide (CO) or carboxyhemoglobin (COHb), thiocyanate (SCN). and cotinine. Cotinine, unlike the other biochemical measures has been shown to be other than nicotine expounaffected by factors (i.e., certain foods, air pollutants) sure. Hill, Haley, and Wynder (1983) compared COHb, SCN, plasma nicotine, and plasma cotinine with cardiovascular (CV) patients’ self-reports of smoking level in order to determine which measures were most reliable for specifying a dose-related measure of smoking inhalation to CV risk. Smokers who were using low-nicotine brands had lower levels of nicotine and cotinine than did regular-brand smokers: however, both types of smokers had similar COHb and SCN levels. Haley, Axelrad, and Tilton (1983) also found that saliva cotinine was more accurate than SCN for differentiating smokers from nonsmokers. Pojer et al. (1984) also concluded that This project was funded by a Grant from the National Institute of Heart, Lung, and Blood. NIH, Grant #2ROl HL35310-03 to Kenneth A. Wallston. Principal Investigator. The authors wish to thank Michael P. Carey, Ph.D. for his helpful suggestions on earlier’drafts of this paper. Requests for reprints should be sent to Dawn K. Wilson, Department of Internal Medicine, Medical College of Virginia, Box 160, MCV Station, Richmond, VA 23298-0160. 421
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D. K. WILSON
et al
cotinine measures were more sensitive than COHb and SCN in classifying smokers with no illness. Previous research has demonstrated discrepancies between biochemical measures and patients’ self-reports of smoking abstinence. In one study (Ronan. Ruane, Graham. Hickey, & Mulcahy, 1981). post-myocardial infarction (Ml) patients were given detailed advice on stopping smoking as part of a secondary prevention program. At a long term follow-up visit (M = 8.6 years), subjects provided a blood sample without knowledge of its’ purpose. Only 5 of 57 (8.8%) patients who reported abstinence had COHb levels above the nonsmoking cutoff. Sillett, Wilson. Malcolm. and Ball (1978) compared post-Ml patients’ reports of smoking with COHb measures at a l-year routine follow-up assessment in an ongoing drug trial. Eleven of 5 I (22%) patients who reported abstinence had elevated levels of COHb. In another study (Wilcox, Hughes, & Roland, 1979). urine samples and self-reports of smoking status were obtained from patients after attending an infarction clinic. Whether subjects were warned in advance about the purpose of the urine collection was not indicated. Thirteen of 49 (27%‘) patients who reported quitting smoking while attending the clinic had urinary nicotine and cotinine levels indicative of smoking. In contrast to secondary prevention studies, CV patients who quit smoking on their own, in general, have demonstrated lower false negative rates. Scott and Lamparski (1985) examined smoking cessation rates in patients who had a major cardiac event at least 3 months prior to assessment. The study was described as a survey of general lifestyle changes in patients who had developed cardiac problems. After obtaining information about smoking status. weight change, exercise, and so forth. each subject provided a CO sample for alveolar CO analysis. Whether the purpose of the CO sample was given in advance was not stated. Three of 26 (12%) patients who reported quitting had CO levels above nonsmoking cutoffs. Finally, Baile, Bigelow. Gottlieb. Stitzcr. and Sacktor (1982) reported that in their previous unpublished work, 9% of the hospitalized MI patients who claimed they had stopped smoking on their own had elevated CO concentrations. This paper evaluates collateral reports as an alternative method of smoking validation that is less costly than biochemical measures. Collateral reports involve contacting a spouse, friend. or family member in order to verify a subject’s self-report of smoking status. McIntyre-Kingsolver, Lichtenstein. and Mermelstein (1986) compared subjects’ self-reports of smoking abstinence with spouse reports after completposttreatment, there ing a smoking cessation program. At I-, 2-, 5, and I?-months was a 05% discrepancy rate between the two reports. In another study (Havik & Maeland, 198X), Ml patients’ reports of smoking status were compared to spouse reports after attending an in-hospital teaching program. Three of S2 (6%) patients reported smoking even though their collaterals reported they had quit. In part. this result could have occurred because collateral reports were obtained several months prior to patient reports of smoking status. In contrast, Cummings, Emont. Jaen. and Sciandra (1988) found. in a sample of adults who were I8 years or older, that SS of 266 (21%) of those who reported abstinence were not corroborated by collaterals. This report is an ancillary analysis of an intervention study in which we assessed the validity of self-reported abstinence among newly diagnosed CV patients who were either currently trying to quit smoking or had recently quit on their own. Three methods of assessing smoking status were compared: self-reports of smoking status, collateral reports of subjects’ smoking status. and saliva cotinine assays. All participants were told at the beginning of the study and at each follow-up assessment that
Validation
of smoking abstinence
423
collateral information and, possibly, saliva samples would be obtained to verify their smoking reports. This “pipeline” method has been used in a wide variety of studies in public health settings (i.e., schools). In general, previous research has demonstrated mixed results regarding the effectiveness of the “bogus pipeline” on increasing the accuracy of self-reported smoking, especially among adult populations (Akers, Massey, Clarke, & Lauer, 1983; Bauman & Dent, 1982; Evans, Hansen, & Mittlemark. 1977; Gillies, Wilcox, Coates, Kristmundsdottir, & Reid, 1982; Glynn, Gruder, & Jegerski, 1986). For example, one study demonstrated a 9% “bust” rate among MI patients who did not know in advance that their self-reports would be validated (Ronan et al., 1981). In another study (Sillett et al., 1978), there was a 22% “bust” rate when the biochemical measure was taken in the context of another unrelated study. Some investigators have demonstrated that the “bogus pipeline” method does result in greater reporting of smoking status among children (Evans et al., 1977). Other researchers (e.g., Glynn et al., 1986), however, found no effect for the “bogus pipeline” procedure upon improving accuracy of self-reported smoking among adults. Wilson, King, and Wallston (1987) also found that, for adults, it may be important to assess whether subjects believe the “bogus pipeline” procedure is valid before differences in self-reports emerge.
METHOD
Subjects
Participants were recruited through referral from cardiologists, or in response to newspaper and radio announcements. Diagnostic criteria included having one or more of the following conditions diagnosed by a physician within 6 months prior to participating in the study: hypertension, circulation problems, angina, irregular heart beat, coronary blockage, coronary artery bypass, MI, heart failure, and/or stroke. Participants were 79 CV patients (55 males, 24 females) who currently smoked or who had a previous history of smoking.’ The study was designed to examine smoking cessation and prevention of relapse in recent quitters and, therefore, targeted both current as well as previous smokers. Fifty-one of the participants had quit smoking within 6 months prior to entering the study, and 28 subjects reported smoking an average of 20 cigarettes per day at the study onset. Subjects ranged in age from 26 to 76 (M = 53 years) and had an average education level of 12 years of schooling. Procedure
Volunteers were told the general purpose of the study was to evaluate the efficacy of several smoking-cessation interventions, and it was emphasized that they did not have to want to change their smoking behavior to participate. All participants gave written informed consent and were mailed a questionnaire that assessed demographic and background smoking information. After returning the questionnaire, subjects were randomly assigned to either a contingency contracting treatment group or an education-only control group (see Wilson, Wallston, & King, 1990, for a description). The intervention program lasted 12 months and was conducted entirely ‘The focus of this paper is on the validation of smoking abstinence and therefore excludes subjects who did not report quitting smoking at any point during the larger study. Validation of self-reported smoking was not obtained on subjects who did not report abstinence because of cost limitations.
424
0.
K. WILSON
et al
by telephone. There were no significant differences in smoking-abstinence rates (based on biochemical verification and/or collateral reports of abstinence) across the treatment and control groups: thus, subjects were collapsed into one group for these analyses. Information about smoking status was obtained at baseline, 3, 6, 9. and I2 months into treatment, and at a 6-month posttreatment follow-up. unless otherwise indicated below.
Slrrokirr~~ statrrs. Smoking status was assessed by asking subjects to indicate how many cigarettes they currently smoked per day, on the average, and the number of days they remained abstinent ifthey had quit. Abstinence was defined as having quit for a 7-day period of time including the day of the assessment. Co//rrro.tr/ WJXM.S. Prior to participation, all subjects were requested to provide the names and telephone numbers of two collaterals whom they were told would be contacted during the study to verify their reports of smoking abstinence. In addition, at each assessment, subjects were reminded that their collaterals would be contacted to verify their reports of nonsmoking status. Approximately 50%~ of the collaterals were family members (e.g., spouses). 33% were close friends or co-workers. and the remainder were in-laws. Excluding baseline, collaterals were contacted within I to 2 days for all subjects who reported abstinence. Collaterals were told their responses were strictly confidential and were asked to indicate the subject’s smoking status and, if applicable, the number of days the subject remained abstinent. If both collaterals verified that the subject was abstinent, then only one collateral was contacted throughout the remainder of the study. If either one of the two collaterals indicated that the subject was smoking. it was defined as a discrepancy between subject and collateral reporting. Furthermore. if the subject subsequently reported abstinence, both collaterals were contacted for verification. StrliuLl c.oti/ritrcJ. All subjects were informed at the onset of the study that. throughout the project, they might be required to provide us with saliva samples to validate their reports of smoking abstinence. In addition. at each assessment. subjects were reminded that if they currently were not smoking, a saliva sample would probably be obtained to verify their reports. Those who reported abstinence at any of the assessments (except baseline and 3 months) and who lived within 30 miles of the project office were asked to provide a saliva sample.’ Research assistants went to the home of each subject who met the above criteria to collect the saliva sample. Subjects’ were asked if they were using nicotine gum or any other forms of nicotine replacement therapy at each assessment prior to obtaining the saliva samples. None of these participants reported using nicotine gum or replacement therapy at any time during the study. All saliva samples were immediately refrigerated and were analyzed for cotinine levels to determine each subject’s smoking status. A cutoff was established through a pilot study done in collaboration with the American Health Foundation Laboratory (New York, NY). Cotinine assays showing less than 20 ngiml were considered to be indicative of a nonsmoking status, while assays above this criterion were considered to be indicative of smoking. ‘Saliva wmples were not obtained from subjects at the fir51 3-month aaxe\wlent because the laboratory procedure had not yet been established. Subject\ were informed. however. at the onset of the study. that wliva sunple~ would be obtained to verify their smoking statu\ throughout the program.
Validation
Table
1. Subject and collateral
reports assays
of smoking
abstinence
425
of abstinence (expressed as absolute within nonsmoking cutoff Assessment
Method
of assessment
Subject reports Collateral validation Discrepancies across
3-Month
methods
6-Month Subject SO 48 2
55 49 6 Subject
Subject reports Collateral validation Cotinine validation;’ Discrepancies across “Assays
methods
g-Month vs. collateral 54 53
vs. collateral I7 17 I4 3
I
values).
and cotinine
period
12-Month (N = 274) 59 56 3
vs. biochemical (N = XI) 20 ?I 20 21 I8 I6 2 5
h-Month follow-up
56 55
I 23 23 20 3
< 20 ng/ml
RESULTS
Table I (top) provides data comparing subjects’ self-reports of abstinence with collateral reports of abstinence over time. The data presented in Table 1 are not independent. That is, some subjects may be represented as many as five times or as few as one. Overall, less than 5% (13 of 274) of the subjects’ reports of abstinence were not validated by their collaterals.’ Discrepancies between subjects’ self-reports and collateral reports were greatest at the 3-month assessment. Also depicted in Table I (bottom) are the comparisons of collateral reports of abstinence to saliva cotinine assays within the nonsmoking cutoff established by our laboratory (~20 ngl ml). In this subsample, the saliva cotinine results disagreed with the collateral reports in I3 of 81 (16%) instances. Of these 13 instances, only one subject demonstrated a discrepancy between collateral and cotinine measures across two assessments. The remaining I1 discrepancies were independent data points that represented different individuals in each case. Thus. saliva cotinine analyses picked up an additional 11% false negatives as compared with collateral reports. Over 80% of the subjects who were initially classified as recent quitters remained abstinent for the full 18 months of the study, while less than 12% of the subjects who were initially smokers remained abstinent over the course of the study (Table 2). Thus, a very small number of the subjects who quit during the study remained abstinent, making comparisons of initial smokers to recent quitters on accuracy of self-reporting not feasible for the present study. Generulizahility of cotinine jindings Demographics and background smoking variables were generalizability of the cotinine findings across subjects with dation. Table 3 provides the means and standard deviations smoked per day, age, education level, and age first smoked, baseline. Differences were not significant across the two
compared to assess the and without saliva valifor number of cigarettes across the two groups at groups for any of these
‘Note that the sample size (number of observations) presented in Table I exceed the original sample 51 nonsmokers and 28 smokers because these are repeated measure data and represent the total number reports, not subjects.
of of
426
II.
Table
K. WILSON
et al
2. Percentage of subjects validated abstinent,’ at 6. I?. and 18 months by initial smoking status
Initial smoker\ Recent quitters
6 month\
12 month\
IX month\
4.6 x1.3
IO. I 87.1
I I.5 Xl.3
,‘Only subjects whobe self-reports of abstinence here validated ba\ed on biochemical and/or collateral report\ of abstinence are all other\. including those lo’;1 to counted in the numerators: follow-up. Lvere considered to be nonahztinent for thehe caIcuI~~tion\.
variables. Gender and initial the two groups at baseline.
smoking
D
status
also did not significantly
I S C U S S I 0
differ across
N
The results of this study indicated that CV patients’ self-reports of smoking abstinence were discrepant 5% of the time as compared to their collaterals. Analyses of saliva cotininc assays in a subsample of subjects, however, indicated that 16% of the saliva cotinine tests were discrepant with the collateral reports. Thus. collateral reports as a single index of subjects’ smoking status were less stringent than saliva cotinine measures. The findings in this study suggest that, overall, discrepancies in reporting were relatively small. These results are consistent with previous studies of patients’ who quit smoking on their own (Baile et al.. 1982: Scott & Lamparski, 1985) and with treatment studies that included long term follow-up (e.g., Ronan et al., 1981; Sillett et al.. 197X). In general. these two types of studies have shown discrepancies ranging from 8.8% to 22%‘. The majority of patients included in the current analyses had already quit smoking prior to participating in the study. Thus, patients with CV disease, who have already abstained for up to 6 months may be more likely to give valid information than those who have quit more recently or who quit as part of a treatment program. Furthermore, our study did. in essence. include “follow-up” assessments over an I&month time period because the majority of patients had already quit prior to participating. The discrepancy rate of 16% in the present study is noteworthy given that it is consistent with a recent report which indicates that the discrepancy rate of self-reporting among high-risk medical samples typically exceeds 20% (USDHHS, 1990). Unfortunately, the relationship between initial smoking status and accuracy of self-report could not be examined in our study due to the small number of initial smokers who remained abstinent throughout the study. Additional research is needed to replicate these findings in a larger sample of adults across different stages of the quitting process (i.e., early vs. late maintenance). Table 3. Mean and standard deviations (SD) of background variables for subjects with and without saliva validation No saliva Variables Cigarette\ pel- da) Age lyr\.) Education (yr\.) Age first smoked (yrs.)
Mean 7.3 52.4 12.3 17.7
? SD 2 f t *
6.3 9.6 2.x 3.7
Saliva Mean x.0 52.1 12.2 16.6
t
SD
-t 12.0 i II.7 5 2.x -t 7.5
I
Value 0.X 0. I2 0. I2 0.74
Validation
of smoking
abstinence
427
The fact that the majority of the sample in our study who remained abstinent over the course of the program were initial quitters is important. Previous research on temporal patterns of relapse has indicated that many groups of ex-smokers return to smoking over a l-year period. Hunt and Bespalec (1974) found that 66% of the exsmokers they studied relapsed in less than 3 months. Furthermore, Prochaska, DiClemente, Velicer, and Rossi (1985) reported that a group of self-quitters who recycled from relapse to contemplation stages of change, over a 2-year period, benefited in several ways. First, they were more convinced of the cons of smoking which helped them in their efforts to maintain abstinence. Second, they used more stimulus-control techniques to aid them in controlling their smoking behavior. In light of these data, the results of the present study suggest that including former smokers in a smoking-cessation program can benefit them by aiding them in maintaining cessation through the difficult first 2 years of change. Another possible explanation for the relatively small degree of discrepancies in reporting could be that subjects knew in advance that their self-reports would be verified. Previous studies have shown mixed results regarding the effects of prior “bogus pipeline”) on improving the accuracy of self-reported knowledge (e.g., smoking (Akers et al., 1983; Bauman & Dent, 1982; Evans et al., 1977; Gillies et al., 1982; Glynn et al., 1986). Although the adult studies have not indicated that the “bogus pipeline” consistently increases the validity of self-reported smoking cessation, the results of the present study demonstrated reasonably low discrepancies between subjects and verification procedures. Perhaps one implication of the present study is that self-report generally can be relied upon to confirm posttreatment abstinence in CV patients who are notified that some objective confirmation will be of collateral or biochemical verification obtained. It is possible that the “threat” alone might also be effective for increasing the truthfulness of self-reports. Unfortunately, this study design, for feasibility reasons, was not able to separate out the effects of the “bogus pipeline” procedure from the spontaneously low rates of false reporting found among self-quitters. Further research is necessary to better understand if knowledge about having self-reports validated improves accuracy of reporting among patient populations. There are several limitations of the present study. First, the generalizability of our findings is limited because our population was a small subsample of CV patients in a medical setting who were participants in an ongoing smoking-cessation trial. Our study population did differ, however, from previous studies in that it incorporated a broader range of CV diagnoses and included both smokers and recent quitters. Another limitation of the present study was that only a subsample of the patients who reported abstinence were validated through biochemical methods. To determine if this subsample was comparable to those who did not live within the 30-mile radius. demographic and background information was compared across the two groups. Overall, differences on these variables were not significant, suggesting that the degree of discrepancies between collateral reports and cotinine assays would potentially generalize to participants who did not provide saliva validation, given the variables that we took into account. A final limitation of the present study was that we did not obtain collateral validation on subjects who reported smoking. A basic assumption in our study, given that it was conducted in the context of a treatment program, was that subjects who reported smoking were still actually smoking. Cost limitations did not allow us to conduct a more rigorous design. Given these limitations, the findings in the present study remain intriguing primarily because, to the
42x
D. K. WILSON
et al.
best of our knowledge. no previous study has compared collateral reports to saliva cotinine assays. In conclusion, the use of collateral reports as an index of smoking abstinence among CV patients may be of limited value. Despite the fact that they are less costly to obtain, collateral reports are possibly biased in that they overestimate the rate of abstinence as compared to biochemical measures. In part, the low discrepancy rate among collaterals and patients could be due to subjects being in collusion with their spouses/co-workers. Further research is needed replicating these findings among larger, more diverse populations to determine their generalizability. In addition. investigators should further explore the conditions and potential factors (e.g., prior knowledge of validation) that may underlie whether adults and patient populations will provide valid self-reports of smoking status. At present, collateral reports appear to be somewhat unreliable as the only means of validating self-reported smoking abstinence.
K E I- E It E N C E S .4brams, D. B., Follick. M. J.. Biener, L.. Care). K. H., & Hitti. J. (1987). Saliva cotinine a\ a measure of smoking status in field settings. Amc~Yc~tr/r Joor/rrr/ r:fP/rh/ic, Hco/rh. 77. X46-848. Aker\. R. L.. Massey. J.. Clarke, W.. & L,auer. R. M. (1983). Are self-reporta of adolescent deviance valid? Biochemical measure. randomized response and the hogu\ pipeline in smoking behavior. Srx~itrl Fowc,.\ _62. 234-25 I Baile. W. F.. Jr., Bigelokv. G. E.. Gottlieb. S. H., Stitzer. M. I_.. & Sacktor. J. D. (I982). Kapid resumption of cigarette smoking following myocardial infarction: Inverse relation to MI severity. Acldic~rivc Bchrrvior.t . 7. 373-M). Bauman. K. E.. & Dent. C. W. (1982). Infuence of an object measure on self-reports behavior. J,jrrr/ltr/ c~f‘App/icd P.vyhh~,~~. 67. 623-62X. Carey. K. 13.. & Ahrams. D. B. (1988). Propel-tie\ of wliva cotinine in young adult light smokers. Arllc~r-ic~rrn Jortr,ru/ of‘P//h/ic~ ffc,tr//h. 7x. X42-843, Cummings, K. M.. Emont. S. I... Jaen. C.. & Sciandr-a. R. (198X). Format and quitting instructions as factors influencing the impact of ;L wlf-administered quit smoking program. Hetrlfh Edr~rrriruz Qrcc~~.rc’r./J, 15. 199-216. bvan\. K. I., Hansen. W. H.. & Mittlemark. M. H. (1977). Increasing the validity of self-rrportj of smoking behavior in children. Jorr/./rtr/ r!f’Appiicd P.syc~lrcdr~py. 62. 521-523. Gillie\. P. A.. Wilcox. H.. CoateT. C.. Kristmund\dottir. F.. Rr Reid. D. J. (1981). L:\e of objective measurement in the validation of \elf-reported smoking in children aged IO and I I year\: Saliva thiocyanate. Jo/rr,rtr/ c!f Epidcmio/r~,~y trrfd Commr/rriry ffctrlllr, 36. 20.5-208. Flynn. S. M., Cruder. C. L.. & Jeger\kt. J. A. (1986). Effect\ of biochemical validation of \elf-reported cigarette smoking on treatment success and on misreporting abstinence. Heultl~ P.~~c~holog~. 5. I?136. Haley. N. J.. Axelrad. C. M.. & Tilton. K. A. (1983). Validation of self-reported smoking behavior: Biochemical analysw of cotinine and thiocyanate. i\/wc~ric~rrn Jo~rrrtrl of‘ P~th/ic~ Hrtrlrh. 73. 12041207. Havik, 0. E.. & Maeland. J. G. (1988). Changes in smoking hehavior after a myocardial infarction. Hctrlfh P.\ldlO/Oj,?‘. 7. 403-420. Hill. I’.. Haley. N. T.. & Wynder. E. L. (1983). Cigarette smoking: Carboxyhemoglobin. plasma nicotine. cotinine. and thiocyanate versus self-reported smoking data and cardiovascular disease. Jrwrjlctl of Cllrowic f~i.sc~tr.t~. 36. 439-449. Hunt, W. A.. & Bespalec. D. A. (1974). An evaluation ofcurrent methods of modifying smoking behavior. Jolrrrlcll of‘C/inic~tr/ P.\~c~llo/o‘qy. 30. 43 I -43x. McIntyre-Kingsolver, K.. Lichtenhtein. E.. & Mermelstcin. R. J. (1986). Spouse training in a multicomponent smoking cessation program. Bchvior Tlrcrtrp?. 17. 67-74. D. M., & Leupker. R. V. 119x4). Kevieu of techniques for Pechacek. T. F., Fox. B. H.. Murray, measurement of smoking behavior. In J. D. Matara/ro. S. M. Weiss. J. A. Herd. N. E. Miller. & S. M. Weiss (Eds.), Bchcwiortrl Irc,c~lrh: A Ircr~rdhod of‘i~ctrlth (,ni~(~tf(.l’t)~(‘t~~ cind tli~c~tr.tc pr-evc~t?tio~r (pp 729-754). Pojer. R.. Whitfield. J. B.. Poulos, V.. Eckhard, I. F.. Richmond, R.. & Hen\ley. W. J. ( 19X4). Carhoxyhemoglobin. cotinine, and thiocyanate assay compared for distinguishing smoker\ from non+mokers. Clitlictrl C/?cmi.ttr~. 30. I377- 13x0.
of
Validation
of smoking
abstinence
429
Prochaska, J. O., DiClemente, C. C., Velicer, W. F., & Rossi, J. (1985). Puftrms c?f‘chun~et If. Lon&rcdinul unulyses ofself--c,hunge processes uc’w~s sruges of .\moking c~es.sution. Unpublished manuscript, University of Rhode Island. Kingston, RI. Ronan. G., Ruane, P., Graham, I. M., Hickey, N., & Mulcahy. R. (1981). The reliability of smoking history amongst survivors of myocardial infarction. Brirish Journrrl ofAddiction. 76, 425-428. Scott, R. R., & Lamparski. D. (1985). Variables related to long-term smoking status following cardiac events. Addicriue Behaviors, 10,257-264. Sillett, R. W.. Wilson. M. B., Malcolm, R. E., & Ball. K. P. (1978). Deception among smokers. British Medicul Journul, 2, 1185-I 186. Wilcox, R. G., Hughes, J., & Roland. J. ( 1979). Verification of smoking history in patients after infarction using urinary nicotine and cotinine measurements. British Medicul Jorwnul, 2. 1026-1028. Wilson, D. K.. King, J. E., & Wallston. K. A. (1987). The cffec,r.s of u hogus pipclinc prwedure on ,scJ(fL reported smoking ubstinrnce. Paper presented at the meeting of the Annual Society of Behavioral Medicine, Boston, MA. Wilson. D. K.. Wallston, K. A.. & King, J. E. (1990). Effects of contract framing. motivation to quit. and self-efficacy on smoking reduction. Jordmcrl qf Applied Sociul Psychology, 20. 53 l-547. U.S. Department of Health and Human Services [USDHHS]. (1990). The heulth benrjts of smoking c,essurion (DHHS Publication No. CDC 90-8416). Washington. DC: U.S. Government Printing Office.
Vol. 18, pp. 421-429, All rights reserved.
1993 Copyright
0306-4603193 $6.00 + .OO @Z1993 Pergamon Press Ltd.
VALIDATION OF SMOKING ABSTINENCE IN NEWLY DIAGNOSED CARDIOVASCULAR PATIENTS DAWN Department
KENNETH
of Pediatrics.
A. WALLSTON, School
K. WILSON University
JOAN
E. KING,
of Nursing,
Vanderbilt
CRAIG School
of Medicine,
of Tennessee,
Memphis
and M. SHELTON
SMITH
University
HEIM Vanderbilt
University
Abstract -Three methods of assessing smoking status among newly diagnosed cardiovascular (CV) patients were compared: self-reports, collateral reports (spouse. friend, etc.). and saliva cotinine assays. Self-reported smoking status was assessed as the average number of cigarettes smoked per day at baseline, 3, 6. 9, and I2 months into treatment, and at a 6. month posttreatment follow-up. The majority of patients had quit smoking within 6 months prior to participating in the program. All participants were informed at the onset of the study and at the time of each assessment that their self-reports of smoking abstinence would be validated through collateral reports and possibly saliva cotinine analyses. Less than 5% (I 3 of 274) of the subjects’ self-reports showed discrepancies with collateral reports. Analyses of saliva cotinine assays in a subsample of subjects, however. indicated that 16% (I3 of Xl) of the saliva cotinine tests were discrepant with the collateral reports. Thus, the saliva cotinine analyses picked up an additional 11% false negatives, as compared to collateral reports. It is concluded that the use of collateral reports as an index of smoking status may be an overestimate of actual quit rates. The overall discrepancy rate for this study, however, was fairly low and suggests that patients’ self-reports may be reliable when they have already quit on their own and/or are notified in advance of verification procedures.
An increasing number of studies have examined the relationship between biochemical validation and self-reports of smoking status (Abrams, Follick, Biener, Carey, & Hitti, 1987; Carey & Abrams, 1988; Pechacek, Fox, Murray, & Leupker, 1984). In general, three biochemical measures have been compared to self-report measures: expired carbon monoxide (CO) or carboxyhemoglobin (COHb), thiocyanate (SCN). and cotinine. Cotinine, unlike the other biochemical measures has been shown to be other than nicotine expounaffected by factors (i.e., certain foods, air pollutants) sure. Hill, Haley, and Wynder (1983) compared COHb, SCN, plasma nicotine, and plasma cotinine with cardiovascular (CV) patients’ self-reports of smoking level in order to determine which measures were most reliable for specifying a dose-related measure of smoking inhalation to CV risk. Smokers who were using low-nicotine brands had lower levels of nicotine and cotinine than did regular-brand smokers: however, both types of smokers had similar COHb and SCN levels. Haley, Axelrad, and Tilton (1983) also found that saliva cotinine was more accurate than SCN for differentiating smokers from nonsmokers. Pojer et al. (1984) also concluded that This project was funded by a Grant from the National Institute of Heart, Lung, and Blood. NIH, Grant #2ROl HL35310-03 to Kenneth A. Wallston. Principal Investigator. The authors wish to thank Michael P. Carey, Ph.D. for his helpful suggestions on earlier’drafts of this paper. Requests for reprints should be sent to Dawn K. Wilson, Department of Internal Medicine, Medical College of Virginia, Box 160, MCV Station, Richmond, VA 23298-0160. 421
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cotinine measures were more sensitive than COHb and SCN in classifying smokers with no illness. Previous research has demonstrated discrepancies between biochemical measures and patients’ self-reports of smoking abstinence. In one study (Ronan. Ruane, Graham. Hickey, & Mulcahy, 1981). post-myocardial infarction (Ml) patients were given detailed advice on stopping smoking as part of a secondary prevention program. At a long term follow-up visit (M = 8.6 years), subjects provided a blood sample without knowledge of its’ purpose. Only 5 of 57 (8.8%) patients who reported abstinence had COHb levels above the nonsmoking cutoff. Sillett, Wilson. Malcolm. and Ball (1978) compared post-Ml patients’ reports of smoking with COHb measures at a l-year routine follow-up assessment in an ongoing drug trial. Eleven of 5 I (22%) patients who reported abstinence had elevated levels of COHb. In another study (Wilcox, Hughes, & Roland, 1979). urine samples and self-reports of smoking status were obtained from patients after attending an infarction clinic. Whether subjects were warned in advance about the purpose of the urine collection was not indicated. Thirteen of 49 (27%‘) patients who reported quitting smoking while attending the clinic had urinary nicotine and cotinine levels indicative of smoking. In contrast to secondary prevention studies, CV patients who quit smoking on their own, in general, have demonstrated lower false negative rates. Scott and Lamparski (1985) examined smoking cessation rates in patients who had a major cardiac event at least 3 months prior to assessment. The study was described as a survey of general lifestyle changes in patients who had developed cardiac problems. After obtaining information about smoking status. weight change, exercise, and so forth. each subject provided a CO sample for alveolar CO analysis. Whether the purpose of the CO sample was given in advance was not stated. Three of 26 (12%) patients who reported quitting had CO levels above nonsmoking cutoffs. Finally, Baile, Bigelow. Gottlieb. Stitzcr. and Sacktor (1982) reported that in their previous unpublished work, 9% of the hospitalized MI patients who claimed they had stopped smoking on their own had elevated CO concentrations. This paper evaluates collateral reports as an alternative method of smoking validation that is less costly than biochemical measures. Collateral reports involve contacting a spouse, friend. or family member in order to verify a subject’s self-report of smoking status. McIntyre-Kingsolver, Lichtenstein. and Mermelstein (1986) compared subjects’ self-reports of smoking abstinence with spouse reports after completposttreatment, there ing a smoking cessation program. At I-, 2-, 5, and I?-months was a 05% discrepancy rate between the two reports. In another study (Havik & Maeland, 198X), Ml patients’ reports of smoking status were compared to spouse reports after attending an in-hospital teaching program. Three of S2 (6%) patients reported smoking even though their collaterals reported they had quit. In part. this result could have occurred because collateral reports were obtained several months prior to patient reports of smoking status. In contrast, Cummings, Emont. Jaen. and Sciandra (1988) found. in a sample of adults who were I8 years or older, that SS of 266 (21%) of those who reported abstinence were not corroborated by collaterals. This report is an ancillary analysis of an intervention study in which we assessed the validity of self-reported abstinence among newly diagnosed CV patients who were either currently trying to quit smoking or had recently quit on their own. Three methods of assessing smoking status were compared: self-reports of smoking status, collateral reports of subjects’ smoking status. and saliva cotinine assays. All participants were told at the beginning of the study and at each follow-up assessment that
Validation
of smoking abstinence
423
collateral information and, possibly, saliva samples would be obtained to verify their smoking reports. This “pipeline” method has been used in a wide variety of studies in public health settings (i.e., schools). In general, previous research has demonstrated mixed results regarding the effectiveness of the “bogus pipeline” on increasing the accuracy of self-reported smoking, especially among adult populations (Akers, Massey, Clarke, & Lauer, 1983; Bauman & Dent, 1982; Evans, Hansen, & Mittlemark. 1977; Gillies, Wilcox, Coates, Kristmundsdottir, & Reid, 1982; Glynn, Gruder, & Jegerski, 1986). For example, one study demonstrated a 9% “bust” rate among MI patients who did not know in advance that their self-reports would be validated (Ronan et al., 1981). In another study (Sillett et al., 1978), there was a 22% “bust” rate when the biochemical measure was taken in the context of another unrelated study. Some investigators have demonstrated that the “bogus pipeline” method does result in greater reporting of smoking status among children (Evans et al., 1977). Other researchers (e.g., Glynn et al., 1986), however, found no effect for the “bogus pipeline” procedure upon improving accuracy of self-reported smoking among adults. Wilson, King, and Wallston (1987) also found that, for adults, it may be important to assess whether subjects believe the “bogus pipeline” procedure is valid before differences in self-reports emerge.
METHOD
Subjects
Participants were recruited through referral from cardiologists, or in response to newspaper and radio announcements. Diagnostic criteria included having one or more of the following conditions diagnosed by a physician within 6 months prior to participating in the study: hypertension, circulation problems, angina, irregular heart beat, coronary blockage, coronary artery bypass, MI, heart failure, and/or stroke. Participants were 79 CV patients (55 males, 24 females) who currently smoked or who had a previous history of smoking.’ The study was designed to examine smoking cessation and prevention of relapse in recent quitters and, therefore, targeted both current as well as previous smokers. Fifty-one of the participants had quit smoking within 6 months prior to entering the study, and 28 subjects reported smoking an average of 20 cigarettes per day at the study onset. Subjects ranged in age from 26 to 76 (M = 53 years) and had an average education level of 12 years of schooling. Procedure
Volunteers were told the general purpose of the study was to evaluate the efficacy of several smoking-cessation interventions, and it was emphasized that they did not have to want to change their smoking behavior to participate. All participants gave written informed consent and were mailed a questionnaire that assessed demographic and background smoking information. After returning the questionnaire, subjects were randomly assigned to either a contingency contracting treatment group or an education-only control group (see Wilson, Wallston, & King, 1990, for a description). The intervention program lasted 12 months and was conducted entirely ‘The focus of this paper is on the validation of smoking abstinence and therefore excludes subjects who did not report quitting smoking at any point during the larger study. Validation of self-reported smoking was not obtained on subjects who did not report abstinence because of cost limitations.
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by telephone. There were no significant differences in smoking-abstinence rates (based on biochemical verification and/or collateral reports of abstinence) across the treatment and control groups: thus, subjects were collapsed into one group for these analyses. Information about smoking status was obtained at baseline, 3, 6, 9. and I2 months into treatment, and at a 6-month posttreatment follow-up. unless otherwise indicated below.
Slrrokirr~~ statrrs. Smoking status was assessed by asking subjects to indicate how many cigarettes they currently smoked per day, on the average, and the number of days they remained abstinent ifthey had quit. Abstinence was defined as having quit for a 7-day period of time including the day of the assessment. Co//rrro.tr/ WJXM.S. Prior to participation, all subjects were requested to provide the names and telephone numbers of two collaterals whom they were told would be contacted during the study to verify their reports of smoking abstinence. In addition, at each assessment, subjects were reminded that their collaterals would be contacted to verify their reports of nonsmoking status. Approximately 50%~ of the collaterals were family members (e.g., spouses). 33% were close friends or co-workers. and the remainder were in-laws. Excluding baseline, collaterals were contacted within I to 2 days for all subjects who reported abstinence. Collaterals were told their responses were strictly confidential and were asked to indicate the subject’s smoking status and, if applicable, the number of days the subject remained abstinent. If both collaterals verified that the subject was abstinent, then only one collateral was contacted throughout the remainder of the study. If either one of the two collaterals indicated that the subject was smoking. it was defined as a discrepancy between subject and collateral reporting. Furthermore. if the subject subsequently reported abstinence, both collaterals were contacted for verification. StrliuLl c.oti/ritrcJ. All subjects were informed at the onset of the study that. throughout the project, they might be required to provide us with saliva samples to validate their reports of smoking abstinence. In addition. at each assessment. subjects were reminded that if they currently were not smoking, a saliva sample would probably be obtained to verify their reports. Those who reported abstinence at any of the assessments (except baseline and 3 months) and who lived within 30 miles of the project office were asked to provide a saliva sample.’ Research assistants went to the home of each subject who met the above criteria to collect the saliva sample. Subjects’ were asked if they were using nicotine gum or any other forms of nicotine replacement therapy at each assessment prior to obtaining the saliva samples. None of these participants reported using nicotine gum or replacement therapy at any time during the study. All saliva samples were immediately refrigerated and were analyzed for cotinine levels to determine each subject’s smoking status. A cutoff was established through a pilot study done in collaboration with the American Health Foundation Laboratory (New York, NY). Cotinine assays showing less than 20 ngiml were considered to be indicative of a nonsmoking status, while assays above this criterion were considered to be indicative of smoking. ‘Saliva wmples were not obtained from subjects at the fir51 3-month aaxe\wlent because the laboratory procedure had not yet been established. Subject\ were informed. however. at the onset of the study. that wliva sunple~ would be obtained to verify their smoking statu\ throughout the program.
Validation
Table
1. Subject and collateral
reports assays
of smoking
abstinence
425
of abstinence (expressed as absolute within nonsmoking cutoff Assessment
Method
of assessment
Subject reports Collateral validation Discrepancies across
3-Month
methods
6-Month Subject SO 48 2
55 49 6 Subject
Subject reports Collateral validation Cotinine validation;’ Discrepancies across “Assays
methods
g-Month vs. collateral 54 53
vs. collateral I7 17 I4 3
I
values).
and cotinine
period
12-Month (N = 274) 59 56 3
vs. biochemical (N = XI) 20 ?I 20 21 I8 I6 2 5
h-Month follow-up
56 55
I 23 23 20 3
< 20 ng/ml
RESULTS
Table I (top) provides data comparing subjects’ self-reports of abstinence with collateral reports of abstinence over time. The data presented in Table 1 are not independent. That is, some subjects may be represented as many as five times or as few as one. Overall, less than 5% (13 of 274) of the subjects’ reports of abstinence were not validated by their collaterals.’ Discrepancies between subjects’ self-reports and collateral reports were greatest at the 3-month assessment. Also depicted in Table I (bottom) are the comparisons of collateral reports of abstinence to saliva cotinine assays within the nonsmoking cutoff established by our laboratory (~20 ngl ml). In this subsample, the saliva cotinine results disagreed with the collateral reports in I3 of 81 (16%) instances. Of these 13 instances, only one subject demonstrated a discrepancy between collateral and cotinine measures across two assessments. The remaining I1 discrepancies were independent data points that represented different individuals in each case. Thus. saliva cotinine analyses picked up an additional 11% false negatives as compared with collateral reports. Over 80% of the subjects who were initially classified as recent quitters remained abstinent for the full 18 months of the study, while less than 12% of the subjects who were initially smokers remained abstinent over the course of the study (Table 2). Thus, a very small number of the subjects who quit during the study remained abstinent, making comparisons of initial smokers to recent quitters on accuracy of self-reporting not feasible for the present study. Generulizahility of cotinine jindings Demographics and background smoking variables were generalizability of the cotinine findings across subjects with dation. Table 3 provides the means and standard deviations smoked per day, age, education level, and age first smoked, baseline. Differences were not significant across the two
compared to assess the and without saliva valifor number of cigarettes across the two groups at groups for any of these
‘Note that the sample size (number of observations) presented in Table I exceed the original sample 51 nonsmokers and 28 smokers because these are repeated measure data and represent the total number reports, not subjects.
of of
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II.
Table
K. WILSON
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2. Percentage of subjects validated abstinent,’ at 6. I?. and 18 months by initial smoking status
Initial smoker\ Recent quitters
6 month\
12 month\
IX month\
4.6 x1.3
IO. I 87.1
I I.5 Xl.3
,‘Only subjects whobe self-reports of abstinence here validated ba\ed on biochemical and/or collateral report\ of abstinence are all other\. including those lo’;1 to counted in the numerators: follow-up. Lvere considered to be nonahztinent for thehe caIcuI~~tion\.
variables. Gender and initial the two groups at baseline.
smoking
D
status
also did not significantly
I S C U S S I 0
differ across
N
The results of this study indicated that CV patients’ self-reports of smoking abstinence were discrepant 5% of the time as compared to their collaterals. Analyses of saliva cotininc assays in a subsample of subjects, however, indicated that 16% of the saliva cotinine tests were discrepant with the collateral reports. Thus. collateral reports as a single index of subjects’ smoking status were less stringent than saliva cotinine measures. The findings in this study suggest that, overall, discrepancies in reporting were relatively small. These results are consistent with previous studies of patients’ who quit smoking on their own (Baile et al.. 1982: Scott & Lamparski, 1985) and with treatment studies that included long term follow-up (e.g., Ronan et al., 1981; Sillett et al.. 197X). In general. these two types of studies have shown discrepancies ranging from 8.8% to 22%‘. The majority of patients included in the current analyses had already quit smoking prior to participating in the study. Thus, patients with CV disease, who have already abstained for up to 6 months may be more likely to give valid information than those who have quit more recently or who quit as part of a treatment program. Furthermore, our study did. in essence. include “follow-up” assessments over an I&month time period because the majority of patients had already quit prior to participating. The discrepancy rate of 16% in the present study is noteworthy given that it is consistent with a recent report which indicates that the discrepancy rate of self-reporting among high-risk medical samples typically exceeds 20% (USDHHS, 1990). Unfortunately, the relationship between initial smoking status and accuracy of self-report could not be examined in our study due to the small number of initial smokers who remained abstinent throughout the study. Additional research is needed to replicate these findings in a larger sample of adults across different stages of the quitting process (i.e., early vs. late maintenance). Table 3. Mean and standard deviations (SD) of background variables for subjects with and without saliva validation No saliva Variables Cigarette\ pel- da) Age lyr\.) Education (yr\.) Age first smoked (yrs.)
Mean 7.3 52.4 12.3 17.7
? SD 2 f t *
6.3 9.6 2.x 3.7
Saliva Mean x.0 52.1 12.2 16.6
t
SD
-t 12.0 i II.7 5 2.x -t 7.5
I
Value 0.X 0. I2 0. I2 0.74
Validation
of smoking
abstinence
427
The fact that the majority of the sample in our study who remained abstinent over the course of the program were initial quitters is important. Previous research on temporal patterns of relapse has indicated that many groups of ex-smokers return to smoking over a l-year period. Hunt and Bespalec (1974) found that 66% of the exsmokers they studied relapsed in less than 3 months. Furthermore, Prochaska, DiClemente, Velicer, and Rossi (1985) reported that a group of self-quitters who recycled from relapse to contemplation stages of change, over a 2-year period, benefited in several ways. First, they were more convinced of the cons of smoking which helped them in their efforts to maintain abstinence. Second, they used more stimulus-control techniques to aid them in controlling their smoking behavior. In light of these data, the results of the present study suggest that including former smokers in a smoking-cessation program can benefit them by aiding them in maintaining cessation through the difficult first 2 years of change. Another possible explanation for the relatively small degree of discrepancies in reporting could be that subjects knew in advance that their self-reports would be verified. Previous studies have shown mixed results regarding the effects of prior “bogus pipeline”) on improving the accuracy of self-reported knowledge (e.g., smoking (Akers et al., 1983; Bauman & Dent, 1982; Evans et al., 1977; Gillies et al., 1982; Glynn et al., 1986). Although the adult studies have not indicated that the “bogus pipeline” consistently increases the validity of self-reported smoking cessation, the results of the present study demonstrated reasonably low discrepancies between subjects and verification procedures. Perhaps one implication of the present study is that self-report generally can be relied upon to confirm posttreatment abstinence in CV patients who are notified that some objective confirmation will be of collateral or biochemical verification obtained. It is possible that the “threat” alone might also be effective for increasing the truthfulness of self-reports. Unfortunately, this study design, for feasibility reasons, was not able to separate out the effects of the “bogus pipeline” procedure from the spontaneously low rates of false reporting found among self-quitters. Further research is necessary to better understand if knowledge about having self-reports validated improves accuracy of reporting among patient populations. There are several limitations of the present study. First, the generalizability of our findings is limited because our population was a small subsample of CV patients in a medical setting who were participants in an ongoing smoking-cessation trial. Our study population did differ, however, from previous studies in that it incorporated a broader range of CV diagnoses and included both smokers and recent quitters. Another limitation of the present study was that only a subsample of the patients who reported abstinence were validated through biochemical methods. To determine if this subsample was comparable to those who did not live within the 30-mile radius. demographic and background information was compared across the two groups. Overall, differences on these variables were not significant, suggesting that the degree of discrepancies between collateral reports and cotinine assays would potentially generalize to participants who did not provide saliva validation, given the variables that we took into account. A final limitation of the present study was that we did not obtain collateral validation on subjects who reported smoking. A basic assumption in our study, given that it was conducted in the context of a treatment program, was that subjects who reported smoking were still actually smoking. Cost limitations did not allow us to conduct a more rigorous design. Given these limitations, the findings in the present study remain intriguing primarily because, to the
42x
D. K. WILSON
et al.
best of our knowledge. no previous study has compared collateral reports to saliva cotinine assays. In conclusion, the use of collateral reports as an index of smoking abstinence among CV patients may be of limited value. Despite the fact that they are less costly to obtain, collateral reports are possibly biased in that they overestimate the rate of abstinence as compared to biochemical measures. In part, the low discrepancy rate among collaterals and patients could be due to subjects being in collusion with their spouses/co-workers. Further research is needed replicating these findings among larger, more diverse populations to determine their generalizability. In addition. investigators should further explore the conditions and potential factors (e.g., prior knowledge of validation) that may underlie whether adults and patient populations will provide valid self-reports of smoking status. At present, collateral reports appear to be somewhat unreliable as the only means of validating self-reported smoking abstinence.
K E I- E It E N C E S .4brams, D. B., Follick. M. J.. Biener, L.. Care). K. H., & Hitti. J. (1987). Saliva cotinine a\ a measure of smoking status in field settings. Amc~Yc~tr/r Joor/rrr/ r:fP/rh/ic, Hco/rh. 77. X46-848. Aker\. R. L.. Massey. J.. Clarke, W.. & L,auer. R. M. (1983). Are self-reporta of adolescent deviance valid? Biochemical measure. randomized response and the hogu\ pipeline in smoking behavior. Srx~itrl Fowc,.\ _62. 234-25 I Baile. W. F.. Jr., Bigelokv. G. E.. Gottlieb. S. H., Stitzer. M. I_.. & Sacktor. J. D. (I982). Kapid resumption of cigarette smoking following myocardial infarction: Inverse relation to MI severity. Acldic~rivc Bchrrvior.t . 7. 373-M). Bauman. K. E.. & Dent. C. W. (1982). Infuence of an object measure on self-reports behavior. J,jrrr/ltr/ c~f‘App/icd P.vyhh~,~~. 67. 623-62X. Carey. K. 13.. & Ahrams. D. B. (1988). Propel-tie\ of wliva cotinine in young adult light smokers. Arllc~r-ic~rrn Jortr,ru/ of‘P//h/ic~ ffc,tr//h. 7x. X42-843, Cummings, K. M.. Emont. S. I... Jaen. C.. & Sciandr-a. R. (198X). Format and quitting instructions as factors influencing the impact of ;L wlf-administered quit smoking program. Hetrlfh Edr~rrriruz Qrcc~~.rc’r./J, 15. 199-216. bvan\. K. I., Hansen. W. H.. & Mittlemark. M. H. (1977). Increasing the validity of self-rrportj of smoking behavior in children. Jorr/./rtr/ r!f’Appiicd P.syc~lrcdr~py. 62. 521-523. Gillie\. P. A.. Wilcox. H.. CoateT. C.. Kristmund\dottir. F.. Rr Reid. D. J. (1981). L:\e of objective measurement in the validation of \elf-reported smoking in children aged IO and I I year\: Saliva thiocyanate. Jo/rr,rtr/ c!f Epidcmio/r~,~y trrfd Commr/rriry ffctrlllr, 36. 20.5-208. Flynn. S. M., Cruder. C. L.. & Jeger\kt. J. A. (1986). Effect\ of biochemical validation of \elf-reported cigarette smoking on treatment success and on misreporting abstinence. Heultl~ P.~~c~holog~. 5. I?136. Haley. N. J.. Axelrad. C. M.. & Tilton. K. A. (1983). Validation of self-reported smoking behavior: Biochemical analysw of cotinine and thiocyanate. i\/wc~ric~rrn Jo~rrrtrl of‘ P~th/ic~ Hrtrlrh. 73. 12041207. Havik, 0. E.. & Maeland. J. G. (1988). Changes in smoking hehavior after a myocardial infarction. Hctrlfh P.\ldlO/Oj,?‘. 7. 403-420. Hill. I’.. Haley. N. T.. & Wynder. E. L. (1983). Cigarette smoking: Carboxyhemoglobin. plasma nicotine. cotinine. and thiocyanate versus self-reported smoking data and cardiovascular disease. Jrwrjlctl of Cllrowic f~i.sc~tr.t~. 36. 439-449. Hunt, W. A.. & Bespalec. D. A. (1974). An evaluation ofcurrent methods of modifying smoking behavior. Jolrrrlcll of‘C/inic~tr/ P.\~c~llo/o‘qy. 30. 43 I -43x. McIntyre-Kingsolver, K.. Lichtenhtein. E.. & Mermelstcin. R. J. (1986). Spouse training in a multicomponent smoking cessation program. Bchvior Tlrcrtrp?. 17. 67-74. D. M., & Leupker. R. V. 119x4). Kevieu of techniques for Pechacek. T. F., Fox. B. H.. Murray, measurement of smoking behavior. In J. D. Matara/ro. S. M. Weiss. J. A. Herd. N. E. Miller. & S. M. Weiss (Eds.), Bchcwiortrl Irc,c~lrh: A Ircr~rdhod of‘i~ctrlth (,ni~(~tf(.l’t)~(‘t~~ cind tli~c~tr.tc pr-evc~t?tio~r (pp 729-754). Pojer. R.. Whitfield. J. B.. Poulos, V.. Eckhard, I. F.. Richmond, R.. & Hen\ley. W. J. ( 19X4). Carhoxyhemoglobin. cotinine, and thiocyanate assay compared for distinguishing smoker\ from non+mokers. Clitlictrl C/?cmi.ttr~. 30. I377- 13x0.
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Prochaska, J. O., DiClemente, C. C., Velicer, W. F., & Rossi, J. (1985). Puftrms c?f‘chun~et If. Lon&rcdinul unulyses ofself--c,hunge processes uc’w~s sruges of .\moking c~es.sution. Unpublished manuscript, University of Rhode Island. Kingston, RI. Ronan. G., Ruane, P., Graham, I. M., Hickey, N., & Mulcahy. R. (1981). The reliability of smoking history amongst survivors of myocardial infarction. Brirish Journrrl ofAddiction. 76, 425-428. Scott, R. R., & Lamparski. D. (1985). Variables related to long-term smoking status following cardiac events. Addicriue Behaviors, 10,257-264. Sillett, R. W.. Wilson. M. B., Malcolm, R. E., & Ball. K. P. (1978). Deception among smokers. British Medicul Journul, 2, 1185-I 186. Wilcox, R. G., Hughes, J., & Roland. J. ( 1979). Verification of smoking history in patients after infarction using urinary nicotine and cotinine measurements. British Medicul Jorwnul, 2. 1026-1028. Wilson, D. K.. King, J. E., & Wallston. K. A. (1987). The cffec,r.s of u hogus pipclinc prwedure on ,scJ(fL reported smoking ubstinrnce. Paper presented at the meeting of the Annual Society of Behavioral Medicine, Boston, MA. Wilson. D. K.. Wallston, K. A.. & King, J. E. (1990). Effects of contract framing. motivation to quit. and self-efficacy on smoking reduction. Jordmcrl qf Applied Sociul Psychology, 20. 53 l-547. U.S. Department of Health and Human Services [USDHHS]. (1990). The heulth benrjts of smoking c,essurion (DHHS Publication No. CDC 90-8416). Washington. DC: U.S. Government Printing Office.