Expired air carbon monoxide and serum thiocyanate as objective measures of cigarette exposure

The validity of self-reported smoking: a review and meta-analysis

OBJECTIVES

The purpose of this study was to identify circumstances in which biochemical assessments of smoking produce systematically higher or lower estimates of smoking than self-reports. A secondary aim was to evaluate different statistical approaches to analyzing variation in validity estimates.

METHODS

Literature searches and personal inquiries identified 26 published reports containing 51 comparisons between self-reported behavior and biochemical measures. The sensitivity and specificity of self-reports of smoking were calculated for each study as measures of accuracy.

RESULTS

Sensitivity ranged from 6% to 100% (mean = 87.5%), and specificity ranged from 33% to 100% (mean = 89.2%). Interviewer-administered questionnaires, observational studies, reports by adults, and biochemical validation with cotinine plasma were associated with higher estimates of sensitivity and specificity.

CONCLUSIONS

Self-reports of smoking are accurate in most studies. To improve accuracy, biochemical assessment, preferably with cotinine plasma, should be considered in intervention studies and student populations.

The validity of self-reported smoking: a review and meta-analysis

OBJECTIVES

The purpose of this study was to identify circumstances in which biochemical assessments of smoking produce systematically higher or lower estimates of smoking than self-reports. A secondary aim was to evaluate different statistical approaches to analyzing variation in validity estimates.

METHODS

Literature searches and personal inquiries identified 26 published reports containing 51 comparisons between self-reported behavior and biochemical measures. The sensitivity and specificity of self-reports of smoking were calculated for each study as measures of accuracy.

RESULTS

Sensitivity ranged from 6% to 100% (mean = 87.5%), and specificity ranged from 33% to 100% (mean = 89.2%). Interviewer-administered questionnaires, observational studies, reports by adults, and biochemical validation with cotinine plasma were associated with higher estimates of sensitivity and specificity.

CONCLUSIONS

Self-reports of smoking are accurate in most studies. To improve accuracy, biochemical assessment, preferably with cotinine plasma, should be considered in intervention studies and student populations.

Assessing nicotine dependence: a comparison of the Fagerström Tolerance Questionnaire (FTQ) with the Fagerström Test for Nicotine Dependence (FTND) in a clinical sample

A recent effort to improve the psychometric properties of the Fagerström Tolerance Questionnaire (FTQ) resulted in the revised Fagerström Test for Nicotine Dependence (FTND). We endeavored to replicate and extend findings suggesting the superiority of the FTND by examining the psychometric properties of both instruments, as well as their relationship to self-report and biochemical variables associated with nicotine dependence in 110 smoking clinic participants. Results verified that the FTND represents a modest improvement over the FTQ, however, the need for continued development of self-report measures of nicotine dependence is noted.

Biochemical validation of smoking status: pros, cons, and data from four low-intensity intervention trials

Biochemical validation of smoking status has long been considered essential, but recent reports have questioned its utility in certain kinds of field trials. We describe efforts to biochemically validate self-reports of smoking cessation from participants in four large-scale randomized trials in outpatient clinics, hospitals, worksites, and dental clinics. These studies included over 5,000 adults smokers who participated in the population-based low-intensity intervention evaluations. At a 1-year follow-up, 798 subjects reported no tobacco use. We attempted to verify these reports using saliva continine/carbon monoxide validation procedures. Overall, there was a moderately high nonparticipation rate (27%), a low disconfirmation rate (4%), and a high self-reported relapse rate (12%) in the interval between survey and biochemical validation. There were no differences between intervention and control conditions on any of the above variables. Longer durations of self-reported abstinence were strongly related to increased probability of biochemical confirmation. Differences in results across projects were related to how biochemical validation was conducted. These results, as well as statistical power considerations, raise questions about whether biochemical validation procedures are practical, informative, or cost-effective in such population-based, low-intensity intervention research.

Comparison of a mechanized version of the 'König' reaction and a fluorescence polarization immunoassay for the determination of nicotine metabolites in urine

Smoking can be detected by the determination of cotinine in urine. We compared the performance of an automated modification of the 'König' reaction adapted to a centrifugal analyzer with an automated commercial fluorescence polarization immunoassay (TDX system). In the latter assay, cotinine, as the primary metabolite of nicotine, can be measured with high specificity. In contrast, the 'König' reaction also detects nicotine metabolites other than cotinine by a group colour reaction. Analysis speed of the 'König' reaction was about 66 samples/h with a detection limit 2 S.D. above the mean value of urine samples of non-smokers. Analysis speed of the TDX system was 41 samples/h. The coefficient of variation (C.V.) of both methods in smokers' urine was 8.6% ('König' reaction) vs. 3.4% (TDX system) in the high range and 16.4% vs. 9.5% in the low range. In a controlled, prospective study recruiting 86 cigarette-smoking volunteers, 83.7% were correctly classified as being smokers by both systems, 13.9% were classified as smokers by the 'König' reaction only and 2.4% were misclassified as non-smokers by both systems. Thus, the sensitivity of the 'König' reaction seems to be higher than in the TDX system (97.6% vs. 83.7%). Of 33 non-smoking individuals, 81.8% were correctly classified as non-smokers by both systems, 18.2 were misclassified as smokers by the 'König' reaction and no person was misclassified by the fluorescence polarization immunoassay. Thus, the specificity of the TDX system seems to be higher than that of the 'König' reaction (100% vs. 81.8%). We conclude that both systems are applicable to detect individuals who smoke regularly by simple urine testing. The higher specificity of the TDX system is outweighed by the higher sensitivity of the 'König' reaction at much lower cost.

Effects of the multiple risk factor intervention trial smoking cessation program on pulmonary function. A randomized controlled trial

To determine whether the decline in pulmonary function in smokers is modified by stop-smoking intervention, a randomized controlled study (the Multiple Risk Factor Intervention Trial) was done comparing participants in a special intervention group that included an intensive smoking cessation program with those assigned to usual care. The subjects were 6,347 middle-aged male smokers who had serial measurements of pulmonary function--principally the forced expiratory volume in 1 second (FEV1)--during 6 to 7 years of follow-up. No overall differences were detected in the rate of loss of FEV1 in the two groups. The use of beta-blockers, which had detrimental effects on FEV1, was significantly more common in the intervention group. Among nonusers of beta-blockers, heavy smokers lost FEV1 at a rate about 11 ml per year slower in the intervention group than in the control group (2P = .09) and ended the trial with an FEV1 about 90 ml higher (2P = .05). These results support the inference from observational studies that smoking cessation has a beneficial effect on pulmonary function in heavy smokers.

Discrepancies between self-reported smoking and carboxyhemoglobin: an analysis of the second national health and nutrition survey

Environmental, self-report, and demographic factors mediated the relationship between self-reported cigarette smoking and carboxyhemoglobin among 2114 smokers and 3918 nonsmokers. Self-reported nonsmokers with carboxyhemoglobin levels between 2% and 3% were more likely to be self-reported ex-smokers, to live in a larger community, and to be younger, less educated, and male than were self-reported nonsmokers with carboxyhemoglobin levels of less than 2%. Self-reported nonsmokers with strong evidence of cigarette consumption (carboxyhemoglobin level greater than 3%) were more likely to be self-reported ex-smokers, younger, less educated, and non-White than were nonsmokers with carboxyhemoglobin levels of less than 2%.

Do smokers of lower tar cigarettes consume lower amounts of smoke components? Results from the Scottish Heart Health Study

Data on 1133 men and 1621 women who smoke solely cigarettes with a known tar yield are extracted from the baseline population survey of the Scottish Heart Health Study. The expired-air carbon monoxide (CO-E), serum thiocyanate and serum cotinine values are compared between smokers in three tar groups: low (below 13 mg/cig.), middle (14-15 mg/cig.) and high tar (above 15 mg/cig.). An index of tar consumption is calculated assuming that the intake of different smoke components relative to one another is in proportion to their concentration in the smoke. CO-E and cotinine are found to peak in the middle tar group. Thiocyanate only tends to increase from low to middle tar group for women and from middle to high tar group for men. Tar consumption increases with tar yield of the cigarette smoked, but the increase is much lower than would be expected. We conclude that the tar yield of a cigarette is not an accurate guide to the amount of smoke components consumed by its smoker. Health professionals should be aware of these limitations of tar yield as a measure of cigarette strength.

An iterative technique for identifying smoking deceivers with application to the Scottish Heart Health Study

BACKGROUND

The study population consists of 3,977 self-declared nonsmokers for whom complete data on smoking biochemistry were available. Data were obtained from the Scottish Heart Health Study, a random cross-sectional population sample of 40- to 59-year-old men and women.

METHODS

Three biochemical markers of smoking (expired-air carbon monoxide, serum thiocyanate, and serum cotinine) are used together to derive optimum cut-points for distinguishing true nonsmokers from self-declared nonsmokers who are smoking deceivers, using an iterative procedure via a computer program.

RESULTS

The cut-points derived are, for carbon monoxide, 6 ppm (sensitivity, 0.81, and specificity, 0.94, when compared with the other two biochemical markers combined), for thiocyanate, 63.4 mumol/liter (sensitivity, 0.75; specificity, 0.92), and, for cotinine, 17.5 ng/ml (sensitivity, 0.77; specificity, 0.98). These cut-points are generally lower than those reported previously, primarily because other studies have taken self-reported smoking status to be the truth. The presence of deceivers among declared nonsmokers would tend to raise the biochemical levels of this group and hence of the cut-points.

CONCLUSION

The prevalence of smoking deception in the Scottish population is low: the frequency of those at or above all three cut-points is 1.2%, at or above two or more (the preferred definition of a smoking deceiver) is 2.2%, and at or above at least one is 16.4%.

Stability of salivary cotinine sent through the U.S. mail for verification of smoking status

Until now mass media smoking cessation studies have relied almost exclusively on self-reports of smoking cessation because biochemical confirmation has not seemed practical. This study investigated the reliability of mailed salivary cotinine specimens for the determination of smoking status. Two simultaneous saliva specimens were obtained from 10 smokers and 10 nonsmokers. One of each pair was frozen immediately. The other was sent through the local U.S. mail and then subjected to additional physical agitation and heat before being frozen. All specimens were subsequently analyzed for cotinine. No cotinine was detectable in any of the nonsmokers' specimens. There was excellent correlation between the paired smokers' specimens. These results show that the mailing of saliva specimens for cotinine analysis is practical and provides accurate data on smoking status. It is an approach which could easily be used in mass media smoking cessation studies to biochemically confirm smoking behavior.

Evaluation of two biological markers of tobacco exposure. MRFIT Research Group

This study assesses serum thiocyanate and expired-air carbon monoxide based on findings for 8,895 participants in the Multiple Risk Factor Intervention Trial. For each marker and combination of markers, a logistic probability model was used to generate a plot of true positive vs false positive rates (an operating characteristic curve), an optimal cutpoint, and the positive predictive value for discriminating tobacco smokers (cigarettes, pipes, cigars, or cigarillos) from non-tobacco smokers. Optimal cutpoints were 83 mumols/liter for thiocyanate and 10 ppm for carbon monoxide. These cutpoints were applied to the entire group to evaluate accuracy. Specificity was higher for carbon monoxide than for thiocyanate (91.8 vs 87.3%) and sensitivity was lower (85.7% for carbon monoxide vs 88.8% for thiocyanate). When carbon monoxide and thiocyanate were both used, specificity was 92.7% and sensitivity was 89.1%. The estimated cutpoints derived from the Multiple Risk Factor Intervention Trial result in predictive values greater than 87% when the prevalence of smokers is greater than 50%. Cutpoints should be modified to maximize the predictive value when the prevalence of smokers is less than 50%. Both serum thiocyanate and carbon monoxide are good markers of smoking exposure. Serum thiocyanate may be preferable to carbon monoxide because of its longer half-life.

Smoking characteristics and inhalation biochemistry in the Scottish population

Data from a cross-sectional random population sample of 10,359 middle-aged Scottish men and women are used to investigate the relationships between self-reported tobacco consumption and three biochemical markers of tobacco inhalation: expired air carbon monoxide (CO), serum thiocyanate and serum cotinine. These data represent one of the largest samples of these biochemical markers yet analysed. The results show that, for each sex, the biochemical markers are highly correlated for smokers and for the entire sample of mixed smokers and non-smokers. CO is the preferred biochemical marker, in such groups, because it is the cheapest, is non-invasive and gives virtually instantaneous results. Self-reported daily cigarette consumption also correlates well with each of these biochemical markers, and so it appears that people are, in the context of population studies, mainly truthful about their smoking. The relationships with self-reported cigarette consumption are curvilinear with apparent levelling out of the gradient at around 25 cigarettes/day for cotinine and thiocyanate and at greater than 40 cigarettes/day for CO. Sex differences are small, although thiocyanate is generally higher and cotinine generally lower in women with the same self-reported cigarette consumption as men. Amongst non-smokers, only cotinine is able to discriminate between self-reported levels of exposure to passive smoking. CO and thiocyanate are not suitable for measuring low levels of smoke inhalation, such as found in passive smokers.

Identification of exposure markers in smokers' breath

Volatile organic compounds present in the exhaled breath of 26 smokers and 43 non-smokers were evaluated in an effort to identify possible biochemical markers resulting from the exposure to cigarette smoke. The total ion current profiles obtained from gas chromatography-mass spectrometry (GC-MS), which contained about 230 GC-MS peaks, were first analyzed by using standard statistical procedures to select a subset of 22 peaks. The importance of the peaks was ranked using factor analysis, which further reduced the dimensionality of the data, and discriminant analysis served to develop classification functions. One peak, 2,5-dimethyl furan, had sufficient discriminatory power in the GC-MS profiles to allow almost complete differentiation (96% correct classification) between the smokers and non-smokers groups. In addition, several other compounds were able to separate the groups with a high level of accuracy.

Effects of smoking cessation on consumption of alcohol and sweet, high-fat foods

Smoking cessation may have significant effects on consumption of certain foods and other substances which may influence health. This study of seven young female smokers examined consumption of alcohol, coffee, soda, and sweets (sweet, high-fat foods) across 3 weeks, involving baseline ad lib smoking (week 1), complete cessation (week 2), and resumption of smoking (week 3). TV watching (i.e., nondietary activity) and subjective measures of craving and tension-anxiety also were assessed. Results showed increased intake of sweets and, to a lesser extent, alcohol after cessation which was reversed upon resumption of smoking. There were no significant changes across weeks in other substances. The changes in alcohol and sweet intake did not appear to be related directly to the subjective changes. These findings indicate that smoking cessation, a behavior change which promotes health, may lead to alterations in consumption of other substances, which may have adverse effects on health risk.

Carbon monoxide assessment of smoking in chronic obstructive pulmonary disease

Chronic Obstructive Pulmonary Disease (COPD) is a major, often fatal, drain on health-care resources. Most cases of COPD result from Tobacco Dependence, and smoking cessation slows COPD's progression. But there is very little information on treating Tobacco Dependence in COPD patients. In preparation for clinical trials using monetary payments to motivate reduced smoking, as assessed by breath carbon monoxide (CO) levels in COPD patients, we have addressed three issues. First, surveying 182 advanced COPD patients, we found that CO levels above 8 parts per million (ppm) were strongly associated with a self-report of current smoking, and that CO levels correlated neither with COPD severity, nor with age: about one-third of these patients were currently smoking. Second, among 12 still-smoking COPD patients serially observed for 8 h. CO half-life averaged about 6.5 h. Third, 8 patients reinforced with lottery tickets for CO reductions significantly reduced CO levels during 2 test weeks, mainly by deferring smoking before scheduled CO measurements.

Skin surface sampling for nicotine: a rapid, noninvasive method for identifying smokers

We evaluated a novel, rapid, noninvasive method of skin surface air sampling that detects the presence of nicotine and therefore can identify smokers. The principle of the methodology involved is skin surface air sampling and ion-mobility spectrometry. We studied 93 volunteers and patients; 50 of these gave a positive history for smoking. Skin surface sampling identified 49 of these 50 individuals. Fifty of the 93 individuals provided urine samples. Nicotine was detected in 22 of these urine samples by thin-layer chromatography. Skin surface sampling identified all of these patients. The combination of skin surface air sampling and ion-mobility spectrometry is a rapid, noninvasive screening method for separating smokers from nonsmokers.

Passive smoking and the seasonal difference of severity of asthma in children

To learn whether asthmatic children are affected by passive smoking, we studied 240 unselected consecutively referred asthmatic subjects, aged 7 to 17 years. To discover whether children of smokers are affected more severely during the cold, wet season, when windows are closed and children are indoors, than during the warm, dry season, when houses are well ventilated and children spend more time outdoors, we compared lung function tests recorded during the two seasons. If seen during the cold, wet season, children of smoking mothers compared with those of nonsmoking mothers had a lower FEV1% (74 vs 86, p = .00), FEF25-75 percent (56 vs 75, p = .00) and PC20 histamine (0.85 vs 1.95, p = .01). There was a highly significant correlation between the number of cigarettes the mother smoked in the house and each of these lung function test results, indicating a dose-response relationship. Those seen during the warm, dry season, by contrast, did not have lower mean spirometric test results if their mothers were smokers than if nonsmokers, and there was no correlation between the number of cigarettes the mother smoked in the house and the result of any lung function test. Our results strongly support the hypothesis that cigarette smoke from the mother aggravates her child's asthma.

Optimum cutoff points for biochemical validation of smoking status

Selection of cutoff points for tests to validate smoking cessation should take account of the prevalence of deception. When the prevalence of deception is relatively low, the cutoff points to validate quitting should be relatively high. Many studies have used cutoff points that are too low and may have underestimated cessation rates. We present a method for determining the best cutoff points that takes account of the prevalence of deception.

Evaluation of nicotine, cotinine, thiocyanate, carboxyhemoglobin, and expired carbon monoxide as biochemical tobacco smoke uptake parameters

In a cross-sectional study on 236 individuals in Japan (174 males, 62 females; 149 smokers, 87 non-smokers) plasma nicotine (pnic), cotinine (pcot) and thiocyanate (pSCN), urinary creatinine ratios of nicotine (unic), cotinine (ucot) and thiocyanate (uSCN) as well as carboxyhemoglobin (COHb) and expired carbon monoxide (COex) were determined. All tobacco smoke uptake parameters (TSUP) were significantly elevated in smokers as compared to nonsmokers. The discriminant power (smokers vs nonsmokers) rank in the following order: ucot approximately pcot approximately unic greater than pSCN approximately COHb approximately pnic greater than COex approximately uSCN. All parameters except for pnic are significantly correlated with the self-reported number of cigarettes smoked per day. The reason for the poor correlation of pnic with daily cigarette consumption is the short half-life of pnic coupled with the arbitrary time of blood drawing in relation to the last time of smoking.

Effect of the Johnson & Johnson Live for Life program on employee smoking

Smoking-cessation programs at the worksite hold the potential to reduce the national prevalence of smoking. This article presents the 2-year results of a broad-spectrum smoking-cessation initiative that was part of the comprehensive Johnson & Johnson LIVE FOR LIFE wellness program. In a quasi-experimental design, four companies offered the complete LIVE FOR LIFE program to their employees, and three comparison companies offered only annual health screen assessments. Smoking status was assessed by self-report and serum thiocyanate at baseline and at a 2-year follow-up. At the LIVE FOR LIFE companies, 22.6% of all smokers quit versus 17.4% of smokers at the health screen only companies. The LIVE FOR LIFE program was particularly effective with smokers at high risk for coronary heart disease: 32% of all high-risk smokers quit at the LIVE FOR LIFE companies versus 12.9% at the health screen only companies. These results demonstrate that a company-wide smoking-cessation initiative can produce significant changes in smoking behavior.

Evaluation of a portable measure of expired-air carbon monoxide

There are a variety of independent methods of estimating smoking status; measurement of expired air carbon monoxide has proven to be reliable and convenient. This article describes a new, inexpensive, portable analyzer for measuring expired-air carbon monoxide --the Bedfont EC50. We have compared this analyzer with the standard instrument for measuring expired-air carbon monoxide in 138 normal subjects and found good correlation and agreement. The Bedfont was demonstrated to be better at identifying smoking status, and the relevance of this finding for classification of smokers and nonsmokers by fixed-threshold carbon monoxide levels is discussed. The features of the Bedfont EC50 are particularly appealing for field and clinical use.

Effects of cigarette smoking on resting EEG, visual evoked potentials and photic driving

The effects of smoking a cigarette (1.3 mg nicotine delivery) versus sham smoking were studied using EEG, visual evoked potentials (VEP), photic driving (PD) and heart rate (HR) in thirty young healthy male and female habitual cigarette smokers. Heart rate (HR) and exhaled carbon monoxide (CO) level were significantly increased by real as opposed to sham smoking. Real versus sham smoking significantly increased relative power in the beta bands, reduced alpha and theta activity to a small but significant extent, but had no effect on delta activity. Dominant EEG alpha frequency was significantly increased by real as opposed to sham smoking. Smoking produced no significant mean change in PD or VEP. However, correlational analysis indicated that variables such as basal CO level, residual butt filter nicotine, basal electrocortical response level and personality, predicted to varying degrees the magnitude and direction of the effect of smoking on VEP, PD and EEG.

Comparison of tests used to distinguish smokers from nonsmokers

Questionnaire and biochemical measures of smoking were studied in 211 hospital outpatients. Eleven different tests of smoke intake were compared for their ability to categorize smokers and nonsmokers correctly. The concentration of cotinine, whether measured in plasma, saliva, or urine, was the best indicator of smoking, with sensitivity of 96-97 per cent and specificity of 99-100 per cent. Thiocyanate provided the poorest discrimination. Carbon monoxide measured as blood carboxyhaemoglobin or in expired air gave sensitivity and specificity of about 90 per cent. Sensitivities of the tests were little affected by the presence among the claimed nonsmokers of a group of 21 "deceivers" who concealed their smoking. It is concluded that cotinine is the measure of choice, but for most clinical applications carbon monoxide provides an acceptable degree of discrimination and is considerably cheaper and simpler to apply.

Evaluation of biochemical validation measures in determination of smoking status

This study was designed to evaluate the use of salivary cotinine, salivary thiocyanate, and expired-air carbon monoxide as biochemical validation measures for assessing the smoking status of adults. The participants were 20 known non-smokers plus 216 admitted smokers and 102 proclaimed quitters participating in a clinical trial of approaches to facilitate smoking cessation. Conventional analytical procedures were utilized. By use of data from known non-smokers and admitted smokers, the sensitivity and specificity of the validation measures were as follows: salivary cotinine, 99% and 100%; expired-air carbon monoxide, 96% and 100%; and salivary thiocyanate, 67% and 95%, respectively. The salivary cotinine and expired-air carbon monoxide tests confirmed smoking cessation for 55% and 74%, respectively, of the proclaimed quitters. The length of time since quitting was significantly related to the results observed with the latter measures. Consideration of these observations along with various practical factors suggests that expired-air carbon monoxide assays may be the validation measure of choice for most clinical trials.

Nicotine yield and measures of cigarette smoke exposure in a large population: are lower-yield cigarettes safer?

We examined the relationship of machine-estimated nicotine yield by cigarette brand with the level of cigarette consumption and two biochemical measures of smoke exposure (expired-air carbon monoxide and plasma thiocyanate) in a large, population-based sample of smokers (N = 713). The lower the nicotine yield of the cigarette, the greater the number of cigarettes smoked per day. Prior to adjusting for number of cigarettes smoked per day, nicotine yield was not related to the actual measures of smoke exposure. Smokers of ultralow-yield cigarettes had laboratory tests of smoke exposure which were not significantly different from those of smokers of higher-yield brands. Only after adjustment for number of cigarettes smoked per day did nicotine yield become significantly related to expired-air carbon monoxide and to plasma thiocyanate. In multivariate analysis, the number of cigarettes smoked per day accounted for 28 per cent and 22 per cent of the variance in observed expired-air carbon monoxide and plasma thiocyanate levels, respectively, whereas nicotine yield accounted for only 1 per cent and 2 per cent of the variance, respectively. The relative lack of an effect of nicotine yield on the biochemical measure appears to be due to the fact that smokers of lower nicotine brands smoked more cigarettes per day, thereby compensating for reduced delivery of smoke products. Our data do not support the concept that ultralow-yield cigarettes are less hazardous than others. Machine estimates suggesting low nicotine yield underrepresent actual human consumption of harmful cigarette constituents.

Cotinine validation of self-reported smoking in commercially run community surveys

A validation study was carried out on self-reported smoking for 1177 people in Sydney and Melbourne in 1983. Because of its long half life and the fact that smoking is its only source in body fluids, saliva cotinine was chosen as the validation measure. Cotinine levels above 250 nmol/l were used to classify people as smokers. The sensitivity of self-reported smoking was 92.6% and the specificity was 93.4%. There was some evidence that people in the process of changing their smoking status might be slow in updating their self-classification. The smoking prevalence estimate based on cotinine levels was found to be 1.7% lower than that for self-reported smoking status. The small proportion of false negatives and false positives suggests that commercially collected data banks can be valid sources of prevalence data. Correlation between cotinine level and reported cigarette consumption was not affected by sample volume, and was similar to that achieved for carbon monoxide and thiocyanate at a low 0.34. Regression analysis using self-reported cigarette consumption filter/non-filter cigarettes, and time since last cigarette as predictors, explained 13.6% of the variance in cotinine level.

Guidelines and methodological standards for smoking cessation intervention research among pregnant women: improving the science and art

While the evidence confirming the risks of smoking during pregnancy is unequivocal, smoking rates for U.S. women remain high. From 1965 to 1975 the proportion of women smokers, aged 18 to 35, rose from 34% to 36%. Rates of heavy smoking increased from 51% to 61%. Significant increases were noted in the United States, especially for teenaged girls, with 1979 data showing higher smoking rates among girls aged 17 to 18 (26%), than among the same-aged boys (19%). Moreover, adolescents have one-fifth of all U.S. births. Exact rates of smoking during pregnancy are unknown but several reports suggest 20-40% of pregnant U.S. women smoke at the onset of pregnancy. A national survey showed 35% of young women smokers able to quit smoking during pregnancy, with another 32% cutting down. Although 62% believed that smoking could harm the fetus, the majority were unable to stop smoking during their pregnancy. Most women who succeed in quitting or cutting down revert to their usual smoking habits late in pregnancy or after delivery. Since almost all data are based on self-reports, some degree of inaccuracy and underreporting can be assumed.

Relationship between baseline risk factors and coronary heart disease and total mortality in the Multiple Risk Factor Intervention Trial. Multiple Risk Factor Intervention Trial Research Group

The relationship between selected baseline risk factors and subsequent coronary heart disease (CHD) death and total mortality among participants in the Multiple Risk Factor Intervention Trial (MRFIT) was studied in order to determine whether the three risk factors used to identify high-risk men for the trial were associated with CHD death; whether other risk factors measured at baseline, especially lipoprotein cholesterol levels, were associated with CHD and total mortality; and whether there were any differences between special intervention (SI) and usual care (UC) participants in the relationship of the specific levels of risk factors to CHD or total mortality. The three main risk factors (blood cholesterol, cigarette smoking, and diastolic blood pressure) and age were significantly associated with CHD mortality; age, diastolic blood pressure, and cigarette smoking were associated with total mortality. The risk score based on the multiple logistic equation developed from the Framingham Study was also strongly associated with CHD mortality. When the joint associations of selected baseline risk factors with CHD and total mortality were considered, age, diastolic blood pressure, cigarette smoking, and low- and high-density lipoprotein cholesterol were significantly associated with CHD mortality; age, cigarette smoking, and low-density lipoprotein cholesterol were positively associated with total mortality. Systolic blood pressure significantly improved the prediction of CHD mortality for SI and UC men when it was added to a regression model that included age, diastolic blood pressure, cigarettes smoked per day, body mass index, and lipoprotein levels, but improved the prediction of total mortality only for SI men. In similar analyses, serum thiocyanate improved the prediction of both CHD and total mortality for UC men. Among SI men the improved prediction gained by considering serum thiocyanate was less pronounced and not significant for CHD death. This latter finding may be due in part to the changes made in smoking behavior by SI participants during the course of the study. The estimated regression coefficients for CHD and total mortality endpoints were not significantly different between the SI and UC groups.

Serum thiocyanate and smoking: interpretation of serum thiocyanate levels observed in a large health study

In a Norwegian health study involving 25,300 persons the mean serum thiocyanate level in non-smokers was 33.9 mumol/l for males and 33.5 mumol/l for females. In moderate smokers (five to nine cigarettes per day) the mean level was 59.6 mumol/l for males and 70.9 mumol/l for females. In heavy smokers (greater than 25 cigarettes per day) the mean level was 87.3 mumol/l in males and 99.7 mumol/l in females. The difference between the thiocyanate levels in females and males smoking the same number of cigarettes can be explained by the sex difference in distribution volume for thiocyanate. Among non-smokers the mean level of serum thiocyanate was the same whether the persons had been indirectly exposed to tobacco smoke or not. The mean serum thiocyanate levels were up to 10 mumol/l higher in the last half part of the year than in the first part. This can be explained by seasonal variations in the content of thiocyanate in the diet. The range of the individual thiocyanate level was great both in non-smokers and in smokers, resulting in a large overlap. Serum thiocyanate can therefore not distinguish all non-smokers from all smokers. However, by choosing suitable 'cut-off levels' it is possible to extract from the total population groups consisting of a large majority of smokers and only a few non-smokers and vice versa.

Highlighting specific patient education needs in an aging cardiac population

Given the utility of a multifactoral approach to cardiac rehabilitation and the importance of tailoring such an approach to the needs of the specific cardiac population being treated, early assessment of targeted risk factors and health-related practices is becoming increasingly indicated. The present article describes how, by using a paper-and-pencil multiple-risk-factor assessment instrument referred to as the Heart Health Assessment Questionnaire, the specific educational needs of an aging veteran population were more clearly identified. Among the health areas found in need of particular attention were patient smoking behavior, medication education, and reported tension and worry over health problems. In addition, given the large unemployment rate within this population, the need for the adoption of activities such as physical exercise and hobbies that could have a positive impact on self-esteem and quality of life was strongly indicated. These and other findings are discussed in relation to the pivotal role of the health education professional for older cardiac populations.

Monoamine oxidase B, smoking, and Parkinson's disease

Idiopathic Parkinson's disease (PD) has been reported to occur more commonly among non-smokers than among cigarette smokers, for reasons that are unknown. PD may possibly be caused by one or more unidentified neurotoxins which chemically resemble N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), a substance which after conversion to an active neurotoxin by monoamine oxidase B (MAO-B) can extensively damage dopaminergic nigrostriatal neurons in humans, lower primates and mice. We measured MAO-B in autopsied brain of PD patients and control subjects and found enzyme activities similar. Inhibition of rat liver MAO-B by the urines of PD patients was greater than by urines of control subjects. These observations do not favour the hypothesis that idiopathic PD is due to excessive conversion of a precursor compound to an active neurotoxin by MAO-B. On the other hand, we found that MAO-B activity was significantly lower in the platelets of heavy cigarette smokers than in platelets of non-smokers. Finally, we found that hydrazine, a compound present in tobacco smoke, had a significant effect in mice in protecting dopaminergic nigrostriatal neurons from damage by MPTP. If idiopathic PD is caused by MPTP-like neurotoxins, accumulation of hydrazine in the tissues of cigarette smokers might explain their reduced likelihood of developing PD.

Verification of smoking status by thiocyanate in unrefrigerated, mailed saliva samples

A simple method of obtaining an unbiased verification of smoking status was developed for use in a randomized clinical trial. At the end of smoking cessation intervention for pregnant women, each participant mailed a saliva sample to a laboratory for the determination of thiocyanate. For comparison, salivary thiocyanate also was measured by a standard collection method in a reference group of non-study women who did not smoke during pregnancy. Although there may have been up to a 1-week delay between collection and analysis, results show that thiocyanate from unrefrigerated, mailed samples of saliva distinguishes reported smokers from nonsmokers, is positively associated with the amount of smoking, and is negatively associated with the length of cessation. These study findings are consistent with results from other studies in which samples of serum or saliva were collected and shipped under conditions requiring the presence of a staff member. The ability to perform an unbiased smoking status verification using a simple, inexpensive, and noninvasive collection method expands study possibilities, as it eliminates the need for direct, face-to-face contact with study subjects, and for being at their location.

Contingent payment procedures for smoking reduction and cessation

We assessed the ability of a combined contingent reinforcement and intensive monitoring procedure to promote and sustain temporary smoking cessation among 34 hired research volunteers, and the ability of a smoking reduction test to predict the subsequent initiation of abstinence. During the 5-day cutdown test, subjects were paid from $0 to $6 per day depending on the extent of reduction from baseline CO levels. During the abstinence test, breath samples were obtained three times daily and subjects were paid $4 for each CO reading less than or equal to 11 ppm. Sixty-eight percent of subjects initiated abstinence. Of the breath samples collected during the abstinence test (91% of scheduled samples), 96.5% were less than or equal to 11 ppm and 80.5% were less than or equal to 8 ppm. Subjects who earned more money during the cutdown test were more likely to abstain (r = -0.51, p less than .001). Contingent reinforcement and intensive monitoring procedures appear to have usefulness for analog studies of smoking reduction and cessation.

Agreement between laboratory tests and self-reports of alcohol, tobacco, caffeine, marijuana and other drug use in post-partum women

The agreement between self-reported consumption of several drugs and laboratory tests used to detect their use is examined. Post-partum women (N = 108) enrolled in a research study participated in a detailed interview covering alcohol and caffeine ingestion, tobacco smoking and use of marijuana and other psychoactive drugs. They also kept a 4-day record of their use of these substances. Blood and urine samples were taken and a physical exam done at the close of the record period. Laboratory tests to detect use of alcohol, tobacco, caffeine, marijuana and other drugs were carried out and the results compared to self-reported drug use in the interview and the record. The degree of agreement depended on the drug taken, the test used and the pattern of drug use in the sample. Sporadic or infrequent consumption related poorly to laboratory tests, especially those that were designed as screening tools. Regular consumption could be identified with greater accuracy. However, the group associations evident between self-reports of drug use and laboratory results were not sufficient to guarantee that subjects were correctly classified. Error in both self-report and the decision made from laboratory values must be taken into account in determining the confidence that should be placed in the data and the conclusions drawn from it.

Social influences and constraints on the initiation and cessation of adolescent tobacco use

This research examines the viability of a theoretical perspective which combines social bonding theory and differential association theory in explaining the initiation and cessation of adolescent tobacco use. Three-year panel data collected from seventh- to twelfth-grade adolescents were analyzed using differences in means tests and discriminant analysis. The findings indicate overall support for the theoretical model in discriminating between (1) initiators and stable nonsmokers and (2) cessators and stable smokers. However, there were some differences in the variables found to be important at each stage of adolescent smoking. Commitment to education, attachment to father and mother, and association with female smoking friends were the most effective discriminators for the initiation stage, while attachment to father, beliefs, and association with both male and female smoking friends were important for the cessation stage. Findings are also discussed for males and females and for junior and senior high-school adolescents.

Self-reported physical health practices and health care utilization: findings from the National Health Interview Survey

Cross-sectional physical health practice and health care utilization data from the 1977 National Health Interview Survey were analyzed. After adjusting for the effects of age, sex, race, income, education, and marital status, there were significant relationships between hours of sleep and both doctor visits and hospital days; increased physical activity was associated with fewer doctor visits. Prospective intervention studies are needed to determine whether changes in health practices will lead to decreased utilization.

Skills intervention to prevent cigarette smoking among adolescents

Skills intervention to prevent cigarette smoking was evaluated with 689 adolescents. At 24-month follow-up, youths who received health information and skills intervention had lower intentions to smoke and less cigarette use than youths who received health information alone and youths who received no intervention. Conclusions about the effects of skills intervention are strengthened by the common preparation and random assignment of intervention leaders and by process measurement data.

Biomedical applications of cotinine quantitation in smoking related research

Two studies were undertaken to assess the variability of cotinine concentrations in different biological fluids and to determine the most desirable fluid to use for specific experimental protocols. For protocols validating smoking cessation, plasma or urinary cotinine determinations provided the most accurate indicators of compliance. In studies where smokers switched from high yield to low yield cigarettes, plasma cotinine determinations were good indicators of smoker behavior. Correct interpretation of smoker status is dependent on the biological fluid selected for cotinine analysis.

A simple, inexpensive urine test of smoking

Three novel colorimetric methods of detecting urinary nicotine metabolites called the barbituric acid, diethylthiobarbituric acid (DETB), and DETB extraction methods were evaluated for use as a simple, cheap, objective test of smoking. Urine samples were collected from 103 male smokers and 78 male non-smokers working at two London factories. The smokers recorded the number of cigarettes smoked over the previous 36 hours. All three methods correctly classified the smokers. The DETB extraction method had a lower false positive rate (averaging 3% on morning and afternoon urine samples) than either the DETB or the barbituric acid method (12% and 6% respectively) and was the best procedure for classifying subjects as "smokers" or "non-smokers." When a quantitative variant of the barbituric acid method was used there was a significant correlation (r = 0.85, p less than 0.001) between the ratios of urinary nicotine metabolites to creatinine and the number of cigarettes smoked. The ratios for smokers of 6-15, 16-25, and 26 or more cigarettes, however, overlapped considerably. The methods can be performed very rapidly and the reagent cost is equivalent to less than 1p per test.

Comparisons of various salivary parameters in smokers before and after the use of a nicotine-containing chewing gum

This study was designed to compare various salivary parameters between smokers and non-smokers and to determine the influence of a nicotine-containing chewing gum (used to aid in quit-smoking efforts) upon these same parameters. At the baseline examination, subjects were assigned to one of three groups: non-smokers who did not utilize any gum, smokers provided a nicotine-containing gum, and smokers provided a placebo gum. Saliva was collected from all subjects and analyzed for acidogenicity and buffer pH as well as for levels of thiocyanate, lactoperoxidase, lysozyme, lactoferrin, and secretory IgA. After 15 weeks of gum usage, saliva was again collected from each subject and the identical analyses performed. Significant differences were observed between smokers and non-smokers with regard to three parameters: The saliva of smokers contained greater concentrations of thiocyanate and lower concentrations of lactoferrin, at the baseline examination and after the 15-week test period. In addition, the CO content of alveolar air was higher in smokers at both examination periods. In contrast, the use of the nicotine gum per se had no effect on any of the test parameters.

Marijuana smoking: effect on expired air carbon monoxide levels

A group of regular marijuana smokers was given expired air carbon monoxide (CO) tests before and after smoking low-dose, high-dose, and placebo marijuana cigarettes. Expired air CO doubled following smoking. There were no significant differences in CO levels in the different dose categories. Studies of the effects of marijuana on the body should attempt to separate effects of the drug from the effects that are secondary to the method of intake.

Alcohol increases cigarette smoking: a laboratory demonstration

Most people would agree that a relationship exists between drinking alcohol and smoking cigarettes, but there is very little empirical evidence demonstrating a direct causal association. Study of the relationship has been hampered by the lack of a simple laboratory methodology. This article describes an efficient experimental paradigm. Fourteen male narcotic addicts in methadone maintenance treatment volunteered to come to the laboratory for two smoking sessions, during which each subject was given either an alcoholic drink or orange juice, followed by three cigarettes at 20-minute intervals. Drinking alcohol significantly increased the amount and rate of smoking. However, not all subjects reacted to alcohol with increased smoking, and we were unable to account for those individual differences. Our finding supports the theory that a direct causal mechanism linking smoking and drinking exists. That link probably has clinical significance, because there is evidence that ex-smokers are at particularly high risk when they drink alcohol.