Validation of self-reported cigarette smoking in a remote Australian Aboriginal community

OBJECTIVE: To examine the relationship between self-reported tobacco smoking and urinary cotinine concentrations in the setting of a remote Aboriginal community. METHODS: In a remote Northern Territory (NT) Aboriginal community the relationship between self-reported tobacco smoking and urinary cotinine concentrations was examined as part of a cross-sectional survey of cardiovascular risk factors. Current tobacco smoking was assessed as part of a questionnaire. The concentration of cotinine and cotinine/creatinine ratio (CCR) in a spot urine sample were used as a biochemical marker of nicotine exposure. RESULTS: A total of 237 people took part in the survey, although completed questionnaires and urine results were available for 184 people. Current tobacco smoking was reported by 161 (69 [95% CI 63 to 75]%) people, with higher rates among males (84/104, 81 [95% CI 72 to 88]%) than females (77/129, 60 [95% CI 51 to 68]%, p < 0.001). There was good agreement of self report with current tobacco smoking using categories based on urinary cotinine (agreement 94%, kappa = 0.84) and urinary CCR (agreement 94%, kappa = 0.86). Quantitative agreement between cotinine measures and self-reported number of cigarettes per day was better for CCR than cotinine, but the correlation was relatively weak for both. CONCLUSIONS: Self-reported cigarette smoking is a valid qualitative measure in this environment. The relatively weak correlation between the biomarker and number of reported cigarettes smoked illustrates problems both with questionnaire and urinary markers of nicotine exposure. IMPLICATIONS: As a qualitative measure of tobacco smoking in this setting, self-report appears adequate but the validity of quantitative self-report is unclear.     

Effects of smoking reduction during pregnancy on the birth weight of term infants

This study was undertaken to determine 1) whether reducing tobacco exposure during pregnancy increases the birth weight of term infants and 2) the relative effects of early- and late-pregnancy exposure to tobacco on infant birth weight. Data were obtained from the Smoking Cessation in Pregnancy project, conducted in public clinics in three states (Colorado, Maryland, and Missouri) between 1987 and 1991. Self-reported cigarette use and urine cotinine concentration were collected from 1,583 pregnant smokers at study enrollment and in the third trimester. General linear models were used to generate mean adjusted birth weights for women who reduced their tobacco exposure by 50 percent or more and for those who did not change their exposure. Regression smoothing techniques were used to characterize the relation between birth weight and early exposure and birth weight and third-trimester exposure. Reducing cigarette use was associated with an increase in mean adjusted birth weight of only 32 g, which was not significant (p = 0.33). As third-trimester cigarette use increased, birth weight declined sharply but leveled off at more than eight cigarettes per day. Findings were similar when urine cotinine concentration was used. Women who smoke during pregnancy may need to reduce to low levels of exposure (less than eight cigarettes per day) to improve infant birth weight.     

Children's exposure to environmental tobacco smoke in the home: comparison of urine cotinine and parental reports

The authors examined the relationship between parent-reported estimates of children's exposure to environmental tobacco smoke (ETS) in the home and children's urinary cotinine levels. Data were collected from a largely ethnic minority, low-income, urban sample of households in which a child had asthma and at least 1 household member smoked. Information about level of household smoking restriction, parental smoking status, and number of cigarettes smoked per day accounted for approximately 45% of the variance in cotinine concentration. Detailed information about the duration of household smoking or children's ETS exposure added no additional significant information. Questionnaires eliciting detailed information about smoking habits and children's ETS exposure may be no better at predicting children's urinary cotinine levels than simpler surveys that inquire about smoking restrictions in the home, parental smoking status, and number of cigarettes smoked at home per day.     

Children's Exposure to Environmental Tobacco Smoke in the Home: Comparison of Urine Cotinine and Parental Reports

The authors examined the relationship between parent-reported estimates of children's exposure to environmental tobacco smoke (ETS) in the home and children's urinary cotinine levels. Data were collected from a largely ethnic minority, low-income, urban sample of households in which a child had asthma and at least 1 household member smoked. Information about level of household smoking restriction, parental smoking status, and number of cigarettes smoked per day accounted for approximately 45% of the variance in cotinine concentration. Detailed information about the duration of household smoking or children's ETS exposure added no additional significant information. Questionnaires eliciting detailed information about smoking habits and children's ETS exposure may be no better at predicting children's urinary cotinine levels than simpler surveys that inquire about smoking restrictions in the home, parental smoking status, and number of cigarettes smoked at home per day.     

Determinants of salivary cotinine concentrations in Chinese male smokers

BACKGROUND: Identifying factors that affect cotinine levels in smokers may be useful for smoking cessation programs. Our aims were to characterize the distribution of salivary cotinine levels in Chinese smokers and to investigate factors that influence cotinine concentrations. METHODS: In a cross-sectional study, 600 Chinese adult smokers answered a questionnaire on smoking habits and provided a saliva sample for cotinine analysis. Modification of the relation between number of cigarettes smoked and cotinine concentration by individual characteristics, smoking behavior, and type of tobacco was evaluated. RESULTS: Quadratic model provided the best fit for the relation between number of cigarettes smoked in the previous 24 hours and salivary cotinine concentration. Among those smoking up to 20 cigarettes, the median cotinine concentration was higher among younger subjects, those smoking cigarettes without filter and regular rather than light cigarettes, and those inhaling frequently and deeply. Such trends were not observed among heavier smokers. The increase in cotinine per cigarette tended to be larger in those with lower median cotinine level. CONCLUSIONS: Our findings show that smoking behavior-related factors modify the relation between number of cigarettes smoked and salivary cotinine concentration. This suggests that smokers may regulate their smoking behavior to achieve a certain optimum nicotine level.     

Saliva cotinine levels in smokers and nonsmokers

The authors collected by mail self-reported data on smoking habits and saliva samples that were analyzed for cotinine concentration in 222 smokers and 97 nonsmokers. Participants were members of the University of Geneva (Switzerland) in 1995. The 207 cigarette-only smokers smoked on average 10.7 cigarettes/day and had a median concentration of cotinine of 113 ng/ml. The cotinine concentration was moderately associated with the number of cigarettes smoked per day (+14 ng/ml per additional cigarette, p < 0.001, R2 = 0.45) and was 54 ng/ml higher in men than in women after adjustment for cigarettes per day and for the Fagerstr?m Test for Nicotine Dependence. The cotinine level was not associated with the nicotine yield of cigarettes (r= 0.08). In nonsmokers, the median concentration of cotinine was 2.4 ng/ml. The cotinine concentration was 1.5 times higher in nonsmokers whose close friends/spouses were smokers than in nonsmokers whose close friends/spouses were nonsmokers (p = 0.05). A cutoff of 7 ng/ml of cotinine distinguished smokers from nonsmokers with a sensitivity of 92.3% and a specificity of 89.7%; a cutoff of 13 ng/ml provided equally satisfactory results (sensitivity, 86.5%; specificity, 95.9%). This study provides evidence for the construct validity of both questionnaires and saliva cotinine for the assessment of active and passive exposure to tobacco smoke.     

Smoking and pregnancy outcome among African-American and white women in central North Carolina.

Despite extensive research on tobacco smoking during pregnancy, few studies address risks among African-American and white women, groups that differ in brand preference and smoking habits. The Pregnancy, Infection, and Nutrition Study is a prospective cohort study that included 2,418 women with detailed information on smoking during pregnancy, including brand, number of cigarettes per day, and changes during pregnancy. We analyzed risk of preterm birth (<37 and <34 weeks' gestation) and small-for-gestational-age deliveries in relation to tobacco use. Pregnant African-American smokers differed markedly from whites in brand preference (95% vs 26% smoked menthol cigarettes) and number of cigarettes per day (1% of African-Americans and 12% of whites smoked 20+ cigarettes per day). Smoking was not related to risk of preterm birth overall, but cotinine measured at the time of delivery was (adjusted odds ratio = 2.2, 95% confidence interval = 1.1-4.5). A clear association and dose-response gradient was present for risk of fetal growth restriction (risk ratio for 20+ cigarettes/day = 2.4, 95% confidence interval = 1.4-4.0). Associations of tobacco use with preterm premature rupture of amniotic membrane resulting in preterm birth were notably stronger than the associations with other types of preterm birth.     

Questionnaire and hair measurement of exposure to tobacco smoke

To assess the relation between nicotine and cotinine levels in hair and reported exposure to environmental tobacco smoke (ETS), hair samples from 112 children (aged 3 months to 10 years) and 76 of their mothers were analyzed and information on the smoking habits of household adults in the preceding 6 months recorded. It was found that the levels of nicotine in children's hair were related to the number of smokers in the house, and increased with the total number of cigarettes smoked by all household adults (P<0.0001). In a multiple regression analysis, mother's smoking was much more a contributor to children's nicotine levels than smoking by the father or other household adults. Cotinine levels were less strongly associated with reported ETS exposure than nicotine. There was a strong correlation between nicotine hair levels in children and mothers (r(s)=0.7, P<0.0001). However, nicotine levels in the hair of active smokers were not correlated with the reported number of cigarettes they smoked per day. In this population, there was a consistent relation between exposure to ETS (assessed by questionnaire) and dose (as measured by nicotine in hair). We conclude that hair nicotine levels rather than hair cotinine levels provide an informative and objective measure of ETS exposure. The number of cigarettes smoked by active smokers may not be an accurate measure of the total nicotine levels in their bodies.     

Estimating Cotinine Associations and a Saliva Cotinine Level to Identify Active Cigarette Smoking in Alaska Native Pregnant Women

Studies indicate nicotine metabolism varies by race and can change during pregnancy. Given high rates of tobacco use and limited studies among Alaska Native (AN) women, we estimated associations of saliva cotinine levels with cigarette use and second-hand smoke (SHS) exposure and estimated a saliva cotinine cutoff to distinguish smoking from non-smoking pregnant AN women. Using questionnaire data and saliva cotinine, we utilized multi-variable linear regression (n = 370) to estimate cotinine associations with tobacco use, SHS exposure, demographic, and pregnancy-related factors. Additionally, we estimated an optimal saliva cotinine cutoff for indication of active cigarette use in AN pregnant women using receiver operating characteristic (ROC) curve analysis (n = 377). Saliva cotinine significantly decreased with maternal age and significantly increased with cigarettes smoked per day, SHS exposure, and number of previous full term pregnancies. Using self-reported cigarette use in the past 7 days as indication of active smoking, the area under the ROC curve was 0.975 (95 % CI: 0.960–0.990). The point closest to 100 % specificity and sensitivity occurred with a cotinine concentration of 1.07 ng/mL, which corresponded to sensitivity of 94 % and specificity of 94 %. We recommend using a saliva cotinine cutoff of 1 ng/mL to distinguish active smoking in pregnant AN women. This cutoff is lower than used in other studies with pregnant women, most likely due to high prevalence of light or intermittent smoking in the AN population. Continued study of cotinine levels in diverse populations is needed.     

Variation of serum and urine cotinine in passive and active smokers and applicability in preconceptional smoking cessation counseling

This study assessed the applicability of serum and urine cotinine as a biochemical marker of self-reported smoking habits for use in a preconceptional smoking cessation program. The variation of serum and urine cotinine over the course of the day was investigated in a sample of 21 smokers and 8 passive smokers who reported their smoking habits and exposure to smoke daily in a questionnaire for 10 consecutive days. Blood and urine samples were collected on two sampling days, 1 week apart. Both serum and urine cotinine assay could distinguish between passive and active smokers, but not between higher categories of smokers (10-19 and > or = 20 cigarettes per day) due to significant intersubject overlap. In serum, no significant differences were found between morning and afternoon cotinine concentrations on either day, in contrast to urine cotinine (with lower excretions observed in the morning). An overall coefficient of variation of 22% was observed for both specimens in smokers. Because serum cotinine is subject to lower variability over the course of the day, it is more practical for use in a clinical setting where appointments are scheduled throughout the day in order to confirm smoking status.     

Spontaneous cigarette brand switching: consequences for nicotine and carbon monoxide exposure.

A group of smokers who had participated in smoking-related studies three to six years earlier were re-studied to assess changes in their smoking practices. Individuals who smoked the same brands of cigarettes showed no change in plasma cotinine (reflecting exposure to nicotine) or expired carbon monoxide (CO) concentration. Those who switched to cigarettes of lower nicotine yield (average decrease 38 per cent) showed reduced plasma cotinine concentrations, due primarily to smoking fewer cigarettes per day. The intake of nicotine per cigarette was not different. Subjects who smoked cigarettes of higher yield (102 per cent increase) had higher cotinine and CO levels, due to greater intake per cigarette.     

Heterogeneity in Smokers' Responses to Tobacco Control Policies

This paper uses unconditional quantile regression to estimate whether smokers' responses to tobacco control policies change across the distribution of smoking levels. I measure smoking behavior with the number of cigarettes smoked per day and also with serum cotinine levels, a continuous biomarker of nicotine exposure, using individual‐level repeated cross‐section data from the National Health and Nutrition Examination Surveys. I find that the cigarette taxes lead to reductions in both the number of cigarettes smoked per day and in smokers' cotinine levels. These reductions are most pronounced in the middle quantiles of both distributions in terms of marginal effects, but most pronounced in the lower quantiles in terms of tax elasticities. I do not find that higher cigarette taxes lead to statistically significant changes in the amount of nicotine smokers ingest from each cigarette. Copyright © 2015 John Wiley & Sons, Ltd.     

Self-reported smoking, cotinine levels, and patterns of smoking in pregnancy

Non-pregnant adult smokers generally exhibit fairly stable smoking behaviour over time. In studies of this population, cotinine assays are considered a 'gold standard' measure of exposure to cigarette smoke; current smoking status can be validated with high sensitivity and specificity. In contrast, there is substantial within-person fluctuation in pregnancy smoking, as women try repeatedly to quit or cut down. As a result, cotinine measures may be of limited use for validation of amount smoked, as they are informative only about recent exposure, vary with individual smoking topography and are dependent on time lapsed since the last cigarette smoked. Thus, in reproductive epidemiology, where timing, intensity and duration of exposure are critical, self-reported history of cigarette consumption may be a more relevant fetal exposure than current smoking status. If there were substantial within-person variation over the course of pregnancy, numerous measures of cotinine would be needed to characterise patterns of fetal exposure and would not be feasible in many studies. We examined self-reported smoking patterns and compared them to patterns of urinary cotinine levels in a prospective study of 998 pregnant women, recruited 1988-92. Fluctuations in smoking were considerable and, while cotinine measures and self-reported number of cigarettes were highly correlated at any given time point across women (r=0.70), the within-person correlation between the patterns of self-reported number of cigarettes and cotinine levels was weaker (r=0.33). For researchers interested in fetal outcomes in which intensity and timing of exposure are critical, we conclude that self-reported variations in smoking during pregnancy may be a valid way to characterise detailed patterns of fetal exposure in epidemiological studies.     

Measuring exposure to environmental tobacco smoke (ETS): a developing country's perspective

AIMS: To assess exposure to ETS among nonsmokers in the community and examine the relation between various subjective and objective measures of exposure to ETS in a developing country's setting. METHODS: An interviewer-administered population-based survey of adults 18-65 years residing in Aleppo, Syria. From a total number of 2038 participants, a sub-sample of 419 nonsmokers (27.2% men, 72.8% women, mean age 34 years) underwent subjective and objective assessment of exposure to ETS (saliva cotinine, breath CO, self-reported measures of exposure combined into ETS exposure scale). RESULTS: Overall, 97.6% of adults nonsmokers assessed in this study, 72.9% of whom were women, have detectable saliva cotinine levels (mean +/- SD 1.7 +/- 1.5 ng/ml). Correlation between self-reported exposure measures and saliva cotinine was moderate with the strongest observed for number of cigarette smokers in the house, average number of cigarettes smoked daily in the house, house policy regarding smoking, and total ETS score (r 0.3-0.4). These same variables were among the best predictors of saliva cotinine according to stepwise linear regression analysis, but their individual relevance differed between men and women reflecting underlying differences in gender-based behavior-mobility patterns. Generally, subjective measures could explain 22% of the variability in cotinine levels in men and 19% in women. CONCLUSIONS: Exposure to ETS is universal among adult nonsmokers in Syria. Saliva cotinine correlated moderately with self-reported measures, whereby selected subjective measures can be as informative as composite scores incorporating multiple measures. Even in this environment of omnipresence of smoking, household restrictions seem to offer protection against ETS exposure.     

The effect of paternal smoking on the birthweight of newborns whose mothers did not smoke. Group Health Medical Associates.

We examined the relationship of paternal smoking habits to birthweight in a cohort of infants enrolled at birth (n = 1219). To assess validity of parental smoking reports, cord serum levels of cotinine were measured in 175 newborns. A mean birthweight deficit of 88 g was found in newborns of nonsmoking mothers whose fathers smoked more than 20 cigarettes/day. Only 2 of 138 newborns whose mothers said they were nonsmokers had cotinine levels indicating that their mothers were active smokers. Among infants of nonsmoking mothers, detectability of cotinine in cord blood was significantly correlated with the number of cigarettes smoked daily by fathers. These data suggest that fetal growth may be adversely affected when the mother is passively exposed to tobacco smoke during pregnancy.     

Association between trauma exposure and smoking in a population-based sample of young adults

PURPOSE: To evaluate the relation between smoking and trauma exposure in a population-based, longitudinal sample. Contrary to current smoking trends in the general population, recent findings indicate continued high smoking rates in trauma-exposed samples. METHODS: A nationally representative sample of 15,197 adolescents was followed from 1995 (mean age, 15.6 years) to 2002 (mean age, 22 years) as part of three waves of The National Longitudinal Study of Adolescent Health (Add Health). We examined the relation between self-reported trauma exposure and smoking behaviors (lifetime regular, current regular), nicotine dependence based on the Fagerstr?m Test of Nicotine Dependence (FTND), number of cigarettes smoked per day, and age of onset of regular smoking. RESULTS: Controlling for demographics and depressive symptoms, exposure to traumatic events yielded a significant increase in the odds of lifetime regular smoking. Nicotine dependence and cigarettes smoked per day was also significantly related to exposure to childhood physical and sexual abuse. Decreased age of regular smoking onset was seen for those reporting childhood physical abuse and childhood sexual abuse. CONCLUSIONS: Exposure to traumatic life events during childhood and young adulthood increases the risk of smoking, highlighting the need to prevent and treat tobacco use in this vulnerable population.     

Fetal Exposure to Secondhand Tobacco Smoke Assessed by Maternal Self-reports and Cord Blood Cotinine: Prospective Cohort Study in Krakow

Objectives While the validity of self-reported smoking habits is generally judged as satisfactory, objective markers of secondhand smoke (SHS) exposure may be more useful in validating the causal links between prenatal SHS and health effects. The cohort study in Krakow provided an opportunity for comparative assessment of fetal exposure to SHS based upon questionnaires and cord blood cotinine measurements. Methods The study sample included 467 newborns born to women recruited in the first and second trimester of pregnancy. To compare the validity of self-reported SHS and cord blood cotinine levels in assessing the association between fetal passive smoking and health effects of newborns, we separately examined the regression coefficients of birthweight on self-reported number of cigarettes smoked by other household members during the entire pregnancy and cord blood cotinine levels. Results In the non-exposed newborns the geometric mean of cord blood cotinine was 0.077 ng/ml and was significantly lower than in newborns with a maternal report of SHS. Cord cotinine levels were more highly correlated with a self-reported number of cigarettes smoked daily at home in the third trimester of pregnancy. The two measures of SHS (number of cigarettes and number of hours of daily exposure) were equally well correlated with cord blood cotinine levels. Using cotinine as the exposure variable, overall the association was not significant; but among the subgroup with cord cotinine levels above the median (≥0.083 ng/ml), the association with birthweight was significant (beta coefficient = −113.65, P = 0.041). Conclusion The study provides evidence that the assessment of fetal SHS exposure based on cord blood cotinine produced better estimates of the association between exposure and birth outcomes. The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the Centers for Disease Control and Prevention.     

Cigarette smoking and body weight in the Cancer Prevention Study I.

To investigate the generality of the association of heavy cigarette smoking with increased body weight, the relation of number of cigarettes smoked per day to relative body weight was examined in baseline data for 891,589 participants in a prospective study initiated in 1959. Although the relative weight of cigarette smokers was consistently lower than that of never and exsmokers, men and women smoking two or more packs of cigarettes per day were more likely to be categorized as moderately or severely overweight and less likely to be categorized as underweight than those smoking 10-20 cigarettes per day, despite somewhat greater educational attainment by heavier smokers. These analyses offer support for the temporal generality of the relation between heavier cigarette smoking and greater body weight, and suggest that this phenomenon cannot be explained by historic trends in the socioeconomic stratification of smoking prevalence or smoking dose.     

Tobacco smoke and formation of N-(2-hydroxyethyl)valine in human hemoglobin

Human exposure to ethylene oxide (EtO) occurs mainly through inhalation of polluted air in occupational workplaces and/or via tobacco smoke. A significant biochemical reaction of EtO converts the terminal valine of hemoglobin into N-(2-hydroxyethyl)valine (HOEtVal). In the present study, the extent of HOEtVal formation in 360 healthy adults who were not occupationally exposed to EtO was measured with a gas chromatograph/mass spectrometer in the electron-capture negative chemical ionization mode. This parameter was correlated with smoking habits and urinary cotinine concentration, exhibiting a positive relationship between HOEtVal and the number of cigarettes smoked (r2 = .4416). Urinary cotinine measurements also correlated with HOEtVal and the number of cigarettes smoked. This positive correlation between urinary cotinine and HOEtVal (r2 = .3893) provides a new perspective on the early stages of carcinogenic processes.     

Cord serum cotinine as a biomarker of fetal exposure to cigarette smoke at the end of pregnancy

This study investigated the association between biomarkers of fetal exposure to cigarette smoke at the end of pregnancy, cotinine in cord serum and in maternal and newborn urine samples, and quantitative measurement of smoking intake and exposure evaluated by maternal self-reported questionnaire. Study subjects were 429 mothers and their newborns from a hospital in Barcelona, Spain. A questionnaire including smoking habits was completed in the third trimester of pregnancy and on the day of delivery. Cotinine concentration in cord serum was associated with daily exposure to nicotine in nonsmokers and with daily nicotine intake in smokers. The geometric mean of cotinine concentration in cord serum statistically discriminated between newborns from nonexposed and exposed nonsmoking mothers, and between these two classes and smokers, and furthermore was able to differentiate levels of exposure to tobacco smoke and levels of intake stratified in tertiles. Urinary cotinine levels in newborns from nonsmoking mothers exposed to more than 4 mg nicotine daily were statistically different from levels in two other categories of exposure. Cotinine concentration in urine from newborns and from mothers did not differentiate between exposure and nonexposure to environmental tobacco smoke (ETS) in nonsmoking mothers. Cord serum cotinine appeared to be the most adequate biomarker of fetal exposure to smoking at the end of pregnancy, distinguishing not only active smoking from passive smoking, but also exposure to ETS from nonexposure.