Are self-reports of smoking rate biased? Evidence from the Second National Health and Nutrition Examination Survey

Neural activity during health messaging predicts reductions in smoking above and beyond self-report

OBJECTIVE

The current study tested whether neural activity in response to messages designed to help smokers quit could predict smoking reduction, above and beyond self-report.

DESIGN

Using neural activity in an a priori region of interest (a subregion of medial prefrontal cortex [MPFC]), in response to ads designed to help smokers quit smoking, we prospectively predicted reductions in smoking in a community sample of smokers (N = 28) who were attempting to quit smoking. Smoking was assessed via expired carbon monoxide (CO; a biological measure of recent smoking) at baseline and 1 month following exposure to professionally developed quitting ads.

RESULTS

A positive relationship was observed between activity in the MPFC region of interest and successful quitting (increased activity in MPFC was associated with a greater decrease in expired CO). The addition of neural activity to a model predicting changes in CO from self-reported intentions, self-efficacy, and ability to relate to the messages significantly improved model fit, doubling the variance explained (R²self-report = .15, R²self-report + neural activity = .35, R²change = .20).

CONCLUSION

Neural activity is a useful complement to existing self-report measures. In this investigation, we extend prior work predicting behavior change based on neural activity in response to persuasive media to an important health domain and discuss potential psychological interpretations of the brain-behavior link. Our results support a novel use of neuroimaging technology for understanding the psychology of behavior change and facilitating health promotion.

Using SMS text messaging to assess moderators of smoking reduction: Validating a new tool for ecological measurement of health behaviors

OBJECTIVE

Understanding the psychological processes that contribute to smoking reduction will yield population health benefits. Negative mood may moderate smoking lapse during cessation, but this relationship has been difficult to measure in ongoing daily experience. We used a novel form of ecological momentary assessment to test a self-control model of negative mood and craving leading to smoking lapse.

DESIGN

We validated short message service (SMS) text as a user-friendly and low-cost option for ecologically measuring real-time health behaviors. We sent text messages to cigarette smokers attempting to quit eight times daily for the first 21 days of cessation (N-obs = 3,811).

MAIN OUTCOME MEASURES

Approximately every two hours, we assessed cigarette count, mood, and cravings, and examined between- and within-day patterns and time-lagged relationships among these variables. Exhaled carbon monoxide was assessed pre- and posttreatment.

RESULTS

Negative mood and craving predicted smoking two hours later, but craving mediated the mood-smoking relationship. Also, this mediation relationship predicted smoking over the next two, but not four, hours.

CONCLUSION

Results clarify conflicting previous findings on the relation between affect and smoking, validate a new low-cost and user-friendly method for collecting fine-grained health behavior assessments, and emphasize the importance of rapid, real-time measurement of smoking moderators.

Validation of smoking cessation self-reported by patients with chronic obstructive pulmonary disease

PURPOSE

The present study reports on the biochemical validation of the self-reported smoking status of patients with chronic obstructive pulmonary disease (COPD). The objective is to establish the proportion of overestimation of self-reported success rates.

METHODS

A cross-sectional smoking-status validation study including 60 patients with COPD who reported that they had stopped smoking. In the analysis of urine samples, a cut-off point of 50 ng/mL of cotinine was used.

RESULTS

At the time of biochemical validation, 55 patients reported that they had quit smoking while five patients resumed smoking. Smoking status was biochemically confirmed for 43 patients (78%) and 12 patients (22%) were classified as smokers. The sensitivity of the self- report of smoking was 29% and the specificity was 100%.

CONCLUSION

Many primary care patients with COPD do not provide valid information on their smoking status, which hamper adequate therapeutic interventions. Integration of biochemical validation in daily care could overcome this problem, but may harm the doctor-patient relationship.

Determinants of heavy cigarette smoking: are there differences in men and women? Results from the population-based MONICA/KORA Augsburg surveys

INTRODUCTION

Heavy cigarette smoking is more frequent in men than in women. So far, little is known whether this sex-specific difference in cigarette consumption is modified by age at smoking onset, sociodemographical, and lifestyle factors. Therefore, we aimed to identify sex-specific characteristics associated with heavy daily cigarette smoking.

METHODS

The study population consisted of 3,178 daily smokers aged 25-74 years from the population-based MONICA/KORA Augsburg surveys conducted between 1984 and 1995. Subjects consuming at least 20 cigarettes daily were defined as heavy smokers. Multivariate logistic regression was used to identify sociodemographical, smoking-related, and lifestyle characteristics of heavy smokers.

RESULTS

A number of 1,576 subjects (49.6%) were identified as heavy smokers. Men were significantly more often heavy smokers than women with the exception of those women who have started smoking at an early age. Multivariate logistic regression revealed early age at smoking onset determines heavy smoking in women but not in men. While younger age at study examination and low educational level was associated with heavy smoking in men only, current employment was associated with heavy smoking in women only. Moreover, living alone, high alcohol or coffee consumption, and low physical leisure activity were associated with heavy smoking behavior in both sexes. Survey, obesity and parental history of smoking showed no association with heavy smoking.

CONCLUSIONS

The present study revealed sex-specific differences in heavy smoking by age at smoking onset, which was not shown before so far. These findings should be further investigated and addressed in future prevention campaigns.

Fagerstrom test for nicotine dependence vs heavy smoking index in a general population survey

BACKGROUND

The Fagerström Test for Nicotine Dependence (FTND) is used for assessing nicotine dependence. A shorter test derived from the FTND used for the general population is the Heavy Smoking Index (HSI) (six questions vs. two). The objective of this study is to compare the validity of the HSI versus the FTND.

METHODS

A survey of tobacco use in the general population was carried out in the northern Spanish region of Galicia using both the FTND and the HSI to study a representative sample of 1655 daily smokers. The HSI was compared with the FTND, considered the gold standard. Measures of sensitivity, specificity and predictive values were calculated. Concordance between the tests was also established (Cohen's kappa).

RESULTS

Cohen's kappa showed good agreement between measures (Kappa = 0.7); specificity values were also high (Sp = 96.2%). Sensitivity analysis in females (Se = 62.3%) did not show good agreement.

CONCLUSIONS

The HSI can be used as a reasonably good screening test in order to identify daily smokers with high nicotine dependence. Nevertheless, for populations or subpopulations having low nicotine dependence, such as women, the FTND is more reliable.

How many cigarettes did you smoke? Assessing cigarette consumption by global report, Time-Line Follow-Back, and ecological momentary assessment

OBJECTIVE

This study evaluated and compared several methods of assessing daily cigarette consumption.

DESIGN

Comparison of measures of daily cigarette consumption from several sources, from 232 smokers entering a smoking cessation program.

MAIN OUTCOME MEASURES

Global reports of average smoking, Time-Line Follow-Back (TLFB) recall for the week preceding the study (premonitoring TLFB), 2 weeks' cigarette recordings using electronic diaries and ecological momentary assessment (EMA), and TLFB recall of smoking during EMA (monitored TLFB).

RESULTS

Global reports and premonitoring TLFB showed severe digit bias: six times as many values as expected were rounded at 10. Monitored TLFB also showed substantial digit bias (four times). EMA data showed none. EMA averaged 2.6 cigarettes lower than monitored TLFB, but exceeded TLFB on 32% of days. Across days, EMA and TLFB only correlated 0.29. Daily variations in TLFB did not correlate with variations in carbon monoxide (CO) measures taken on 3 days, but EMA measures did; among participants whose CO varied, r = .69. CO correlated with EMA cigarettes recorded in the preceding 2 hours, suggesting timely recording of cigarettes.

CONCLUSION

TLFB measures are limited for precise assessment of cigarette consumption. EMA measures appear to be useful for tracking smoking, and likely other health-relevant events.

A method comparison study of timeline followback and ecological momentary assessment of daily cigarette consumption

INTRODUCTION

Uncertainty exists about how best to measure daily cigarette consumption. Two common measures are timeline followback (TLFB), which involves structured, prompted recall, and ecological momentary assessment (EMA), which involves recording consumption, as it occurs, on a handheld electronic device.

METHODS

We evaluated the agreement between TLFB and EMA measures collected for 14 days prior to the target quit date from 236 smokers in a smoking cessation program. We performed a Bland-Altman analysis to assess agreement of TLFB and EMA using a regression-based model that allows for a nonuniform difference between methods and limits of agreement that can vary with the number of cigarettes smoked.

RESULTS

For pairs of measurements taken on the same smoker, TLFB counts were on average 3.2 cigarettes higher than EMA counts; this difference increased for larger numbers of cigarettes. Using a model that allows for variable limits of agreement, the width of the 95% interval ranged from 8.7 to 61.8 cigarettes, with an average of 26.4 cigarettes. Variation between the methods increased substantially for larger cigarette counts, leading to wider limits and poorer agreement for heavy smokers.

DISCUSSION

Throughout the measurement range, the estimated limits of agreement were far wider than the limits of clinical significance, defined a priori to be 20% of the number of cigarettes smoked. We conclude that TLFB and EMA cannot be considered equivalent for the assessment of daily cigarette consumption, especially for heavy smokers.

Salivary cotinine concentrations in daily smokers in Barcelona, Spain: a cross-sectional study

BACKGROUND

Characterizing and comparing the determinant of cotinine concentrations in different populations should facilitate a better understanding of smoking patterns and addiction. This study describes and characterizes determinants of salivary cotinine concentration in a sample of Spanish adult daily smoker men and women.

METHODS

A cross-sectional study was carried out between March 2004 and December 2005 in a representative sample of 1245 people from the general population of Barcelona, Spain. A standard questionnaire was used to gather information on active tobacco smoking and passive exposure, and a saliva specimen was obtained to determine salivary cotinine concentration. Two hundred and eleven adult smokers (>16 years old) with complete data were included in the analysis. Determinants of cotinine concentrations were assessed using linear regression models.

RESULTS

Salivary cotinine concentration was associated with the reported number of cigarettes smoked in the previous 24 hours (R2 = 0.339; p < 0.05). The inclusion of a quadratic component for number of cigarettes smoked in the regression analyses resulted in an improvement of the fit (R2 = 0.386; p < 0.05). Cotinine concentration differed significantly by sex, with men having higher levels.

CONCLUSION

This study shows that salivary cotinine concentration is significantly associated with the number of cigarettes smoked and sex, but not with other smoking-related variables.

Adjusting for subgroup differences in extreme response tendency in ratings of health care: impact on disparity estimates

OBJECTIVE

Adjust for subgroup differences in extreme response tendency (ERT) in ratings of health care, which otherwise obscure disparities in patient experience.

DATA SOURCE

117,102 respondents to the 2004 Consumer Assessment of Healthcare Providers and Systems (CAHPS) Medicare Fee-for-Service survey.

STUDY DESIGN

Multinomial logistic regression is used to model respondents' use of extremes of the 0-10 CAHPS rating scales as a function of education. A new two-stage model adjusts for both standard case-mix effects and ERT. Ratings of subgroups are compared after these adjustments.

PRINCIPAL FINDINGS

Medicare beneficiaries with greater educational attainment are less likely to use both extremes of the 0-10 rating scale than those with less attainment. Adjustments from the two-stage model may differ substantially from standard adjustments and resolve or attenuate several counterintuitive findings in subgroup comparisons.

CONCLUSIONS

Addressing ERT may be important when estimating disparities or comparing providers if patient populations differ markedly in educational attainment. Failures to do so may result in misdirected resources for reducing disparities and inaccurate assessment of some providers. Depending upon the application, ERT may be addressed by the two-stage approach developed here or through specified categorical or stratified reporting.

Modeling heaping in self-reported cigarette counts

In studies of smoking behavior, some subjects report exact cigarette counts, whereas others report rounded-off counts, particularly multiples of 20, 10 or 5. This form of data reporting error, known as heaping, can bias the estimation of parameters of interest such as mean cigarette consumption. We present a model to describe heaped count data from a randomized trial of bupropion treatment for smoking cessation. The model posits that the reported cigarette count is a deterministic function of an underlying precise cigarette count variable and a heaping behavior variable, both of which are at best partially observed. To account for an excess of zeros, as would likely occur in a smoking cessation study where some subjects successfully quit, we model the underlying count variable with zero-inflated count distributions. We study the sensitivity of the inference on smoking cessation by fitting various models that either do or do not account for heaping and zero inflation, comparing the models by means of Bayes factors. Our results suggest that sufficiently rich models for both the underlying distribution and the heaping behavior are indispensable to obtaining a good fit with heaped smoking data. The analyses moreover reveal that bupropion has a significant effect on the fraction abstinent, but not on mean cigarette consumption among the non-abstinent.

End-digits preference for self-reported height depends on language

Background

When individuals report figures, they often prefer to round to specific end-digits (e.g. zero). Such preference has been found in reports of body weight, cigarette consumption or blood pressure measurements. Very little is known about self-reported body height. End-digit preference can distort estimates of prevalence and other statistical parameters. This study examines end-digit preference for self-reported height and how it relates with sex, age, educational level or cultural affiliation.

Methods

We analysed reports of height of 47,192 individuals (aged 15 years or older) living in Switzerland and participating in one of the three population-based Swiss Health Surveys carried out in 1992/93, 1997 and 2002 respectively. Digit preferences were analysed by sex, age group, educational level, survey, smoking status, interview language (only for Swiss nationals) and nationality. Adjusted odds ratios (OR) with 95% confidence interval were calculated by using multivariate logistic regression.

Results

Italian and French nationals (44.1% and 40.6%) and Italian and French Swiss (39.6% and 35.3%) more strongly preferred zero and five than Germans and German Swiss (29.2% and 30.3%). Two, four, six and eight were more popular in Germans and German Swiss (both 44.4%). Compared to German Swiss (OR = 1), for the end-digits zero and five, the OR were 1.50 (1.38–1.63) for Italian Swiss and 1.24 (1.18–1.30) for French Swiss; 1.73 (1.58–1.89) for Italian nationals and 1.61 (1.33–1.95) for French nationals. The end-digits two, four, six and eight showed an opposite pattern.

Conclusion

Different preferences for end-digits depending on language and nationality could be observed consistently in all three national health surveys. The patterns were strikingly similar in Swiss and foreign nationals speaking the same language, suggesting that preferences were specific to language rather than to nationality. Taking into account rounding preferences could allow more valid comparisons in analyses of self-reported data originating from different cultures.

Parental smoking and childhood obesity--is maternal smoking in pregnancy the critical exposure?

BACKGROUND

The concept of priming of childhood obesity by prenatal exposure to maternal smoking is based on a number of consistent studies. A recent paper found similar associations between paternal smoking and childhood obesity, questioning the presumed causal effect attributed to the prenatal exposure. Is the relation to paternal smoking consistent? Does it explain the effect of maternal smoking before or in pregnancy?

METHODS

Data from a cross sectional study on 5899 children in the setting of the 2005 school entrance health examinations in Bavaria were analysed. Associations between paternal smoking or maternal smoking before or in pregnancy and childhood obesity were assessed with adjustment for potential confounders.

RESULTS

The children's mean age was 5.8 years. The unadjusted odds ratio for obesity and paternal smoking was 2.0 (95% CI: 1.5, 2.6) and similar to that for maternal smoking before or in pregnancy with 2.3 (95% CI: 1.8, 3.1). After adjustment for a number of potential confounders and paternal smoking at interview the odds ratio for maternal smoking before or in pregnancy and childhood obesity was 1.9 (95% CI: 1.3, 2.7). There was no evidence for interaction between paternal smoking and maternal smoking before or in pregnancy (P = 0.38).

CONCLUSIONS

Although of similar magnitude, the association of paternal smoking could only partially explain the effect of maternal smoking before or in pregnancy on childhood obesity. Whether this persistent association reflects residual confounding or causality is unclear.

The association between self-reported acrylamide intake and hemoglobin adducts as biomarkers of exposure

BACKGROUND

The validity of epidemiological studies assessing a lifetime cancer risk due to environmental factors, such as nutrition or smoking behavior strongly depends on the validity of the patient's history.

OBJECTIVES

This study assesses whether a standardized questionnaire is a valid tool to identify exposure with acrylamide by relating the self-reported food and smoking history with a biomarker, namely hemoglobin-adduct levels of acrylamide.

METHODS

Objective parameters of previous exposure, such as hemoglobin-adduct levels of acrylamide and of the smoking-specific acrylonitrile, respectively, were related to self-reported data in 1,008 volunteers of the general population in bivariate analyses and a multiple linear regression analysis using the log-transformed biomarker levels as outcome.

RESULTS

Smoking was significantly associated with adduct levels of acrylamide (p < 0.0001) and had a main contribution to the internal burden with acrylamide. In cigarette smokers a strong correlation between the number of cigarettes smoked daily and the corresponding biomarkers was observed. Focusing on non-smokers (n = 828), a significant but weak correlation was found in bivariate analyses (Spearman rank correlation coefficient: 0.178 (95% CI: 0.089-0.268) in females and 0.168 (95% CI: 0.063-0.273) in males. A multiple linear regression analysis similarly yielded evidence of a significant association between the highest intake category and adduct levels; however, explained variability was very small (R(2) = 0.08).

CONCLUSION

Self-reported data concerning smoking behavior were highly valid, while self-reported food intake is apparently not as useful for estimating food-related acrylamide exposure.

Paternal smoking is associated with a decreased prevalence of type 1 diabetes mellitus among offspring in two national British birth cohort studies (NCDS and BCS70)

AIMS

An association between paternal age and type 1 diabetes (IDDM) among their offspring was recently reported as well as transgenerational responses in humans. This paper aims to assess the association of markers for prenatal exposures with IDDM.

METHODS

We analysed data from two birth cohorts in Great Britain on 5214 cohort members from the National Child Development Study (NCDS) and 6068 members of the 1970 British Birth Cohort Study (BCS70) with full information on IDDM and explanatory variables using multivariate logistic regression.

RESULTS

IDDM prevalence was 0.7% (95% CI 0.5-1.0%; n=38) in the NCDS and 0.4% (95% CI 0.3-0.6%; n=27) in the BCS70 cohort. Paternal age was not associated with IDDM possibly due to lack of sample power. Unexpectedly, a lowered prevalence of IDDM was observed among offspring of smoking fathers in both cohorts, with a combined odds ratio of 0.44 (95% CI 0.25-0.75). This association could not be explained by maternal smoking prior to, during or after pregnancy, number of siblings, parental social class, maternal and paternal age, or cohort. Maternal smoking in pregnancy did not alter the IDDM prevalence among offspring.

CONCLUSIONS

This unexpected finding may be explained by germ-line mutations or other mechanisms associated with paternal smoking. This phenomenon should be investigated and these results should not be used as a justification for smoking. Paternal exposures may be important in determining IDDM risk.

Are these emergency department performance data real?

We have recently demonstrated that the distribution of total time spent by patients in emergency departments (EDs) in England shows a peak immediately prior to the current Department of Health target of 4 hours. We aimed to investigate whether this suggested that performance data were being manipulated. We collected data from 117 EDs, and 616,067 patient episodes were included in the analysis. Evidence of manipulation of performance data appears to be present in a small proportion of episodes, but because of the numbers involved, it could equate to over 50,000 episodes per year in EDs in England.

Digit preference bias in the recording of emergency department times

OBJECTIVE

Digit preference bias has previously been described in a number of different clinical settings. The paper aimed to assess whether digit preference bias affects the recording of the time patients arrive and leave emergency departments.

METHOD

An observational study of 137 emergency departments in England and Wales was conducted. Each department was asked to submit details of the time of arrival and time of departure from the emergency department for each patient attending during April 2004. In addition, interviews with the lead clinician were undertaken to determine the method used to record the time of departure. The degree of digit preference bias was assessed using a modification of Whipple's index.

RESULTS

One hundred and twenty-three (86.9%) departments submitted data detailing 648,203 emergency department episodes. 114,875 (18.0%) episodes had a recorded minute of departure of '0' or '30', with a further 281,890 (44.1%) having other values with a terminal digit of '0' or '5'. The mean modified Whipple's index for time of departure was 316.9 (range 70.9-484.4). Linear regression demonstrates a small but significant inverse relationship between the modified Whipple's index and the mean total time in department (b = -0.05, 95% CIs -0.09 to -0.0004, P = 0.048).

CONCLUSION

Some departments show considerable digit preference bias in the recording of time of departure from the emergency department. Such bias may cause difficulty in assessing changes in the performance of departments.

Smoking cessation in patients with COPD in daily general practice (SMOCC): six months' results

BACKGROUND

Chronic Obstructive Pulmonary Disease (COPD) forms an increasing health problem. Despite smoking cessation improving the prognosis of the disease, many patients persist smoking. The present study presents the results of a smoking cessation counseling protocol in general practice (Smoking Cessation in patients with COPD in general practice (SMOCC)).

METHODS

A randomized controlled trial of patients with COPD compared smoking cessation counseling according to an intensified minimal intervention strategy with usual care. In total 43 general practices with 392 patients participated in Nijmegen, The Netherlands, in 2001-2002.

RESULTS

Significantly more smokers in the experimental group made a quit attempt (44.9% versus 36.5%) and actually quit smoking than in the control group (16.0% versus 8.8%). The motivation to stop smoking at baseline was not associated with smoking cessation.

CONCLUSION

The SMOCC strategy doubled the self-reported quit rates and was complied well by the general practitioners. Implementation in general practice is recommended.

Validation of the timeline follow-back in the assessment of adolescent smoking

The timeline follow-back instrument (TLFB) is a valid and reliable method of quantifying alcohol use patterns. The use of this instrument has been expanded to assess other behaviors, such as drug use, sexual behavior, binge eating, and panic attacks. Some evidence for the validity and reliability of this assessment instrument has emerged in the area of adult smoking. However, to date, there is no published evidence of its reliability and validity in the assessment of adolescent smoking. The purpose of this study is to present early evidence of the utility of the TLFB to collect information on adolescent smoking behavior. Through secondary data analysis of four studies on adolescent smokers, we examined the associations between the TLFB and measures of dependence, smoking history, respiratory symptoms, and saliva cotinine. Moreover, we examined the stability of the TLFB data across two 15-day time periods. Results provide preliminary evidence of the validity and reliability of the TLFB in the assessment of adolescent smoking. In particular, the TLFB instrument offered important data on the heterogeneity of adolescent smoking patterns beyond a global measure of cigarettes per day, and the reduction of digit bias. Implications of these findings for the assessment of adolescent smoking are discussed.

Carboxyhaemoglobin concentration, smoking habit, and mortality in 25 years in the Renfrew/Paisley prospective cohort study

OBJECTIVE

To investigate how carboxyhaemoglobin concentration is related to smoking habit and to assess whether carboxyhaemoglobin concentration is related to mortality.

DESIGN

Prospective cohort study.

SETTING

Residents of the towns of Renfrew and Paisley in Scotland.

PARTICIPANTS

The whole Renfrew/Paisley study, conducted between 1972 and 1976, consisted of 7048 men and 8354 women aged 45-64 years. This study was based on 3372 men and 4192 women who were screened after the measurement of carboxyhaemoglobin concentration was introduced about halfway through the study.

MAIN OUTCOME MEASURES

Deaths from coronary heart disease (CHD), stroke, chronic obstructive pulmonary disease (COPD), lung cancer, and all causes in 25 years after screening.

RESULTS

Carboxyhaemoglobin concentration was related to self reported smoking and for each smoking category was higher in participants who reported inhaling than in those who reported not inhaling. Carboxyhaemoglobin concentration was positively related to all causes of mortality analysed (relative rates associated with a 1 SD (2.93) increase in carboxyhaemoglobin for all causes, CHD, stroke, COPD, and lung cancer were 1.26 (95% confidence interval (CI) 1.19 to 1.34), 1.19 (95% CI 1.13 to 1.26), 1.19 (95% CI 1.13 to 1.26), 1.64 (95% CI 1.47 to 1.84), and 1.69 (95% CI 1.60 to 1.79), respectively). Adjustment for self reported cigarette smoking attenuated the associations but they remained relatively strong.

CONCLUSIONS

Self reported smoking data were validated by the objective measure of carboxyhaemoglobin concentration. Since carboxyhaemoglobin concentration remained associated with mortality after adjustment for smoking, carboxyhaemoglobin seems to capture more of the risk associated with smoking tobacco than does self reported tobacco consumption alone. Analysing mortality by self reported cigarette smoking underestimates the strength of association between smoking and mortality.

Heterogeneity of cardiovascular risk among smokers is related to degree of carbon monoxide exposure

BACKGROUND

Between smokers matched for daily tobacco consumption there are marked variations of the cardiovascular risk. This follow up of the population based cohort "Men born in 1914" from Malmö, Sweden, explored whether this is accounted for by the levels of carbon monoxide (CO).

METHODS

Three hundred and sixty-five men without history of cardiovascular disease (CVD) were followed over 27 years. Leg artery disease was defined as a systolic ankle-arm pressure ratio (ABPI) below 0.9 in either leg. Incidence of myocardial infarction (MI), stroke and deaths is based on linkage with regional and national registers. The distribution of CO in blood and expired air, respectively, was divided into quartiles.

RESULTS

There was a significant inverse relation between ABPI and CO in blood and expired air. Incidence of CVD events and deaths increased progressively with degree of CO exposure. Men with CO in the top quartile had significantly increased risks of CVD events (RR: 2.2; 95% CI: 1.00-4.6) and cardiovascular deaths (RR: 3.2, CI: 1.2-8.3), adjusted for daily tobacco consumption and other potential confounders.

CONCLUSIONS

In smokers, the prevalence of leg atherosclerosis and incidence of cardiovascular disease is related to the amount of carbon monoxide in blood or expired air.

Cost-effectiveness of screening for coronary artery disease in asymptomatic patients with Type 2 diabetes and additional atherogenic risk factors

OBJECTIVE

Screening for coronary artery disease (CAD) in asymptomatic diabetic patients with two additional atherogenic risk factors has been recommended by the American College of Cardiology/American Diabetes Association, but its cost-effectiveness is yet to be determined. The present study aims to evaluate the cost-effectiveness of screening and determine acceptable strategies.

DESIGN

Cost-effectiveness analysis using a Markov model was performed from a societal perspective to measure the clinical benefit and economic consequences of CAD screening in asymptomatic men with diabetes and two additional atherogenic risk factors. We evaluated cohorts of patients stratified by different age groups, and 10 possible combination pairs of atherogenic risks. Incremental cost-effectiveness of no screening, exercise electrocardiography, exercise echocardiography, or exercise single-photon emission-tomography (SPECT) was calculated. Input data were obtained from the published literature. Outcomes were expressed as U.S. dollars per quality-adjusted life-year (QALY).

MEASUREMENTS AND MAIN RESULTS

Compared with no screening, incremental cost-effectiveness ratio of exercise electrocardiography was $41,600/QALY in 60-year-old asymptomatic diabetic men with hypertension and smoking, but was weakly dominated by exercise echocardiography. Exercise echocardiography was most cost-effective, with an incremental cost-effectiveness ratio of $40,800/QALY. Exercise SPECT was dominated by other strategies. Sensitivity analyses found that results varied depending on age, combination of additional atherogenic risk factors, and diagnostic test performance.

CONCLUSIONS

Incremental cost-effectiveness ratio of CAD screening in asymptomatic patients with diabetes and two or more additional atherogenic risk factors is shown to be acceptable from a societal perspective. Exercise echocardiography was the most cost-effective strategy, followed by exercise electrocardiography.

Concordance of different measures of nicotine dependence: two pilot studies

Two samples of adult daily smokers completed a structured interview to determine nicotine dependence according to generic (DSM-IV/ICD-10), Fagerström [Fagerström Tolerance Questionnaire (FTQ), Fagerström Test for Nicotine Dependence (FTND), Heavy Smoking Index (HSI), and time to first cigarette after awakening (TFC)], consumption [e.g., cigarettes/day (CPD)], and self-rating (e.g., "how addicted are you") measures. One sample was a population-based sample of 43 smokers from the Vermont site of the DSM-IV field trial for substance use disorders. The other sample consisted of 50 smokers evenly distributed across a wide range of CPD to study biochemical markers of smokers. In the first study, DSM/ICD criteria were only slightly correlated with Fagerström (r =.24-.35) and consumption (r =.06-0.33) criteria. Self-rating criteria were correlated moderately with most other criteria (r =.24-.60). In the second study, generic, Fagerström, and self-rating criteria increased with increasing CPD up to 30 CPD but not thereafter. One interpretation of these results is that generic, Fagerström, consumption, and self-rating criteria each tap different aspects of nicotine dependence.

Bias induced by self-reported smoking on periodontitis-systemic disease associations

Non-causal associations between periodontitis and systemic diseases may be spuriously induced by smoking because of its strong relationship to both. The goal of this study was to evaluate whether adjustment for self-reported smoking removes tobacco-related confounding and eliminated such spurious confounding. Using NHANES III data, we evaluated associations between attachment loss and serum cotinine after adjustment by self-reported number of cigarettes smoked. Cotinine, a metabolite of nicotine, should not be related to attachment loss, if self-reported smoking captures the effect of tobacco on attachment levels. Adjustment for self-reported cigarette smoking did not completely remove the correlation between attachment loss and serum-cotinine level (r = 0.075, n= 1507, p = 0.003). Simulation studies indicated similar results for time-to-event data. These findings demonstrate the difficulty in distinguishing the effects of periodontitis from those of smoking with respect to a smoking-related outcome. Future studies should report results of analyses on separate subcohorts of never-smokers and smokers.

Nicotine replacement to reduce cigarette consumption in smokers who are unwilling to quit: a randomized trial

The objective of this study was to assess whether nicotine replacement therapy, administered in a real-life situation, could reduce cigarette consumption in smokers who were not prepared to quit smoking. Daily smokers of more than 20 cigarettes per day who had no intention to quit smoking in the next 6 months were recruited from the general population and randomly assigned to either a 6-month treatment of nicotine (choice among a 15-mg nicotine patch, a 4-mg nicotine gum, a 10-mg nicotine inhaler, or a combination of these, N = 265), matching placebo products (N = 269), or no intervention (N = 389). Products were sent to participants by mail. Education was limited to a booklet. Of 923 participants, 879 (95%) were followed up after 6 months. Mean baseline consumption was 30 cigarettes per day in all groups. At 6 months, cigarette consumption decreased by a median of 10 cigarettes per day in the nicotine group, 7.5 in the placebo group, and 2.5 among controls ( < 0.04 for all pair-wise comparisons). Smoking cessation rates were low (2%-4%) and did not differ significantly between groups. Quit attempts were less frequent among controls (21%) than among the nicotine (28%, = 0.04) and placebo (27%, = 0.08) subjects. In conclusion, nicotine replacement therapy helped smokers reduce their cigarette consumption and maintain this reduction over 6 months, but a large part of this reduction was attributable to a placebo effect. Nicotine treatment for smoking reduction had no detectable impact on smoking cessation.

Smoking and risk of premature death among middle-aged Japanese: ten-year follow-up of the Japan Public Health Center-based prospective study on cancer and cardiovascular diseases (JPHC Study) cohort I

To update the evidence on the association between smoking and mortality, we analyzed data from a population-based prospective study in Japan. In total, 19950 men and 21534 women aged 40 - 59 who reported their smoking history and had no serious disease at baseline survey were followed. During 1990 - 1999, 1014 men and 500 women died. Smokers were associated with an unhealthy lifestyle. Relative risks (RRs) for selected cause of death due to smoking were slightly attenuated by adjusting for possible confounding factors. Age- and area-adjusted RRs of male current smokers compared with never smokers were 1.66 (95% confidence intervals (CI): 1.40, 1.95) for all causes, 1.69 (1.31, 2.18) for all cancers, 1.67 (1.20, 2.34) for all circulatory system disease, and 1.63 (1.24, 2.15) for other causes, while those of females were 2.03 (1.52, 2.73), 2.06 (1.35, 3.15), 2.99 (1.75, 5.11), 1.31 (0.69, 2.51), respectively. After adjusting for multivariate variables, the corresponding RRs of male smokers were 1.55 (1.29, 1.86), 1.61 (1.20, 2.15), 1.41 (0.97, 2.03), and 1.61 (1.17, 2.19), against 1.89 (1.36, 2.62), 1.83 (1.14, 2.95), 2.72 (1.45, 5.07), and 1.39 (0.71, 2.73) for females. Twenty-two percent of death from all causes, 25% of all cancer, and 17% of all circulatory system disease deaths, could be attributed to cigarette smoking in males, and 5%, 4%, and 11% in females, respectively. Cumulative dose as indicated by pack-years was clearly associated with cancer death. These findings provided information as to the quantitative risk for premature death due to smoking among middle-aged Japanese men and women, and showed that the elevated risk was not explained by the unhealthy lifestyle of smokers.

Ages at initiation of cigarette smoking and quit attempts among women: a generation effect

OBJECTIVES

This study sought to determine whether the age at initiation of regular cigarette smoking and the likelihood of quitting smoking through age 35 differ among women from younger versus older generations.

METHODS

Annual population-based, random surveys (total of 3676 female residents of Geneva, Switzerland, aged 35-74 years) were conducted from 1992 to 1998.

RESULTS

Women younger than 55 years were more likely to be past or current smokers, began smoking earlier (median age < 20 years), and smoked more cigarettes per day than older women, yet attempted to quit smoking more often before age 35 (log-rank P <.001).

CONCLUSIONS

Young female smokers have a higher propensity to quit smoking compared with older women. Encouraging young smokers to quit-in addition to preventing nonsmokers from starting-may be an important facet of reducing cigarette smoking prevalence among adolescents.

The effect of risk factor reductions between 1981 and 1990 on coronary heart disease incidence, prevalence, mortality and cost

OBJECTIVES

We sought to estimate the impact and cost-effectiveness of risk factor reductions between 1981 and 1990.

BACKGROUND

Coronary heart disease (CHD) mortality rates have declined dramatically, partly as a result of reductions in CHD risk factors.

METHODS

We used the CHD Policy Model, a validated computer-simulation model, to estimate the effects of actual investments made to change coronary risk factors between 1981 and 1990, as well as the impact of these changes on the incidence, prevalence, mortality and costs of CHD during this period and projected to 2015.

RESULTS

Observed changes in risk factors between 1981 and 1990 resulted in a reduction of CHD deaths by approximately 430,000 and overall deaths by approximately 740,000, with an estimated cost-effectiveness of about $44,000 per year of life saved during this period, based on the estimated actual costs of the interventions used. However, because much of the benefit of risk factor reductions is delayed, the estimated reductions for the 35-year period of 1981 to 2015 were 3.6 million CHD deaths and 1.2 million non-CHD deaths, at a cost of only about $5,400 per year of life saved.

CONCLUSIONS

Aggregate efforts to reduce risk factors between 1981 and 1990 have led to substantial reductions in CHD and should be well worth the cost, largely because of population-wide changes in life-style and habits. Some interventions are much better investments than others, and attention to such issues could lead to better use of resources and better outcomes in the future.

Measurement of self reported active exposure to cigarette smoke

STUDY OBJECTIVE

The number of cigarettes smoked per day is an imprecise indicator of exposure to cigarette smoke, and biochemical assessment of exposure is not always feasible. The aim of this study was to develop more accurate measures of self reported active exposure to cigarette smoke.

DESIGN

Mail survey in 386 smokers, retest at one month in 94 participants (24%), analysis of saliva cotinine in 98 participants (25%), collection of empty cigarette packs in 214 participants (55%), collection of cigarette butts in 107 participants (28%). Ten questions and items intended to assess active exposure to cigarette smoke were tested and compared with saliva cotinine, the Fagerström test for nicotine dependence, and self rated dependence.

SETTING

A population sample in Geneva, Switzerland, in 1999.

PARTICIPANTS

323 daily smokers and 63 occasional smokers.

MAIN RESULTS

Measures that were associated with saliva cotinine included the number of cigarettes smoked per day (r(2)=0.36), smoking intensity (r(2)=0.40), the type of cigarettes smoked (regular versus light) (r(2)=0.04), smoking when ill (r(2)=0.15) and a single item rating of the total quantity of smoke inhaled (r(2)=0.27). A multivariate model combining the first four items explained the largest proportion of the variance in cotinine (r(2)=0.63), substantially more than was explained by the number of cigarettes per day alone, by 75% in all smokers and by 110% in daily smokers.

CONCLUSIONS

The study identified measures of exposure to smoke that reflect saliva cotinine better than the number of cigarettes per day. These measures can be used in studies of the dose related risk of smoking and in smoking reduction studies.

Serum thiocyanate concentration as an indicator of smoking in relation to deaths from cancer

All residents aged 40 years or more in Oyabe City, Toyama Prefecture, Japan were involved in an annual medical check-up between 1987 and 1988. The cohort was followed and death certificates from cancers were confirmed prospectively. During follow-up to December 31 st, 1994, 100 deaths (28 gastric, 17 lung and 55 other cancers) from cancers occurred, and these subjects were included in this study as the case group. Subjects in the control group, matched for gender and age with the cases, were selected randomly from participants whose serum samples had been stocked during annual medical check-up. The concentration of serum thiocyanate in all (79.8 μmol/l), gastric (86.7 μmol/l) and lung (90.0 μmol/l) cancer patients were significantly higher than that of relevant controls (64.3 μmol/l, 59.0 μmol/l and 61.0 μmol/l, respectively; and p<0.001, p<0.001 and p<0.05, respectively). After adjusting for BMI, blood pressure and total serum cholesterol, the results of multiple logistic regression analysis showed that the risk of all cancers (OR=3.40, 95% confidence interval (95% Cl): 1.67-6.96, p<0.01), gastric cancer (OR=7.98, 95% CI: 1.91-33.34, p<0.05) and lung cancer (OR=8.83, 95% CI: 1.19-65.65, p<0.05) were elevated significantly with logarithm transformed values of serum thiocyanate increased. The present findings suggested that in epidemiological studies confirmation of smoking status with biomarkers such as serum thiocyanate may be important, although considering the small sample size, a relatively weaker risk to interested factors rather than the strong relationship between smoking and cancer was noted.

[Smoking in the general population: a description of prevalence, degree of consolidation and phase of cessation]

Smoking is a risk factor associated with high and preventable mortality and morbidity. An understanding of smoking consolidation and the desire to quit in specific subgroups of the general population will facilitate appropriate planning of health care resource utilization. We performed a multistage, random, stratified cross-sectional study in the general population of Valladolid (Spain) during 1998 and 1999 as part of a cardiovascular disease risk survey. Data collected by questionnaire and interview included number of cigarettes smoked per day, nicotine dependence and stage in the process of smoking cessation. Venous carboxyhemoglobin was also measured. The percentage of reported smokers in the general population was 29.3% (95% CI: 25.7-32.9%). Prevalence was 41.8% (95% CI: 39.2-44.5%) in the 26-to-45-year-old age group and fell to 6% (95% CI: 5.6-6.5%) among subjects over 66 years of age. Analysis by sex, 31.2% (95% CI: 26.1-36.4%) of men and 27.4% (95% CI: 24.1-30.7%) of women were smokers. In rural areas the percentage of smokers was 26.9% (95% CI: 20.2-33.5%) whereas the percentage in urban areas was 31.2% (95% CI: 26.1-36.4%). The number of cigarettes/day, venous carboxyhemoglobin and nicotine dependence differed by age range, sex and place of residence and helped to describe the degree of consolidation of smoking by strata. Phases of cessation were distributed similarly by age range but not by sex. The prevalence of smoking is still high, particularly among young people and women, although it is tending to decrease. Smoking is better established in the 26-45 year-old age range, among men, among those living in rural areas and among older smokers who, probably, can not quit smoking alone.

Age at starting smoking and number of cigarettes smoked in Catalonia, Spain

BACKGROUND

Few studies have investigated the association between age at starting smoking and the average number of cigarettes smoked per day in adulthood. To provide further evidence on this issue, we analyzed data from the Catalan Health Interview Survey (CHIS).

METHODS

The CHIS was conducted in 1994 on a randomly selected sample (N = 15,000) of the population of Catalonia, Spain. A total of 4,897 current or exsmokers (3,276 males and 1,621 females) were included for analysis. Age-standardized proportions of subjects smoking <15, 15-24, and >/=25 cigarettes/day, age-standardized mean number of cigarettes smoked per day, and multivariate odds ratios (OR) of being a heavy smoker (>/=25 cigarettes/day) according to age at starting smoking (<15, 15-17, 18-19, >/=20 years) were computed.

RESULTS

Men who started smoking before the age of 15 smoked on average 5.5 cigarettes more than those who started at age 19 or over. Women who started smoking early in life smoked, on average, 6.8 cigarettes/day more than women who started later. The proportion of smokers of <15 cigarettes/day was higher among subjects who started smoking later. Both for males and for females, the OR of being a heavy smoker significantly increased with decreasing age at starting smoking (OR = 2.4 for males and 4.5 for females who started at age <15 versus >/=20 years). The level of education did not modify the relationship in males, whereas the association with age at starting was only apparent for more educated women.

CONCLUSIONS

This study confirms that age at starting smoking is inversely and strongly associated to the number of cigarettes smoked per day. Thus, actions aimed at the prevention or delay of smoking onset among adolescents would have an important beneficial effect.

Smoking habits and risk of cancers other than lung cancer: 28 years' follow-up of 26,000 Norwegian men and women

The impact of tobacco smoking on lung cancer risk has been investigated thoroughly since the 1950s, but other types of cancer also have been associated with smoking. In the present study, the aim was to explore the variation in risk connected with cigarette, cigar, and pipe smoking of suspected smoking-associated cancers other than lung cancer. Data were obtained from a survey of a random sample of the Norwegian population. A self-administered mailed questionnaire, which included questions about smoking habits, was completed by 26,000 men and women in 1965 (response rate: 76 percent). The cohort was followed from 1966 through 1993, including registration of all incident cancer cases. A dose-response relationship of cigarette smoking to the risk of urinary bladder cancer and cancers of the upper digestive and respiratory tract was observed. For the latter forms of cancer, a dose-response relationship of pipe smoking also was observed. In cancer of the pancreas, a stronger association between cigarette smoking and cancer risk was observed when the analysis was confined to histologically confirmed cases only. Current cigarette smokers at baseline had a significantly higher risk of cervical cancer than those who never smoked cigarettes. In cancers of the stomach, colon, rectum, breast, corpus uteri, ovary, and prostate, and in leukemia, no association between smoking and cancer risk was observed.

The impact of smoking habits on lung cancer risk: 28 years' observation of 26,000 Norwegian men and women

While factory-made cigarettes dominate the market in most countries, the use of handrolled cigarettes accounts for a substantial proportion of the tobacco consumption in Norway. In the present study, we examined the impact of tobacco smoking on lung cancer in general, and the effect of handrolled cigarettes in particular. The data used was from a self-administered mailed questionnaire which included questions about smoking habits and which was completed by about 26,000 men and women in 1964-65. During the follow-up from 1966 to 1993, 333 lung cancers in men and 102 in women were registered. The analysis was performed by use of the Cox proportional hazards regression models. A clear dose-response relationship was found both for cigarette smoking, and for pipe smoking (in men). The dose-response relationship of cigarette smoking was seen in all the three histologic groups considered-squamous cell carcinoma, adenocarcinoma, and small cell carcinoma. The highest relative risks were noted in squamous cell and small cell carcinoma. A higher risk of lung cancer was found for cigarette-smoking women who started cigarette smoking before the age of 30 compared with similar groups of men. In a combined analysis of men and women, an elevated relative risk of 1.9 (95 percent confidence interval = 1.2-3.3) was found for those smoking only handrolled cigarettes compared with those smoking factory-made filter cigarettes only.