Automated homogeneous immunoassay analysis of cotinine in urine

Secondhand tobacco smoke, does it have an impact on the neurobehavioral performance of the exposed children?

Secondhand tobacco smoke (SHS) is a significant public health problem for all ages worldwide. Children are more vulnerable to the health effects of SHS because of the inhalation of more air per body volume compared to adults. The study aimed to assess neurobehavioral performance among SHS exposed Egyptian basic school children (10-12 years) and its relationship with urinary cotinine levels. Multistage cluster sampling was carried out, where 181 children (80 exposed and 101 non-exposed children) were recruited. A questionnaire on SHS exposure was sent to students' parents/caregivers. Urine samples were taken for assessment of cotinine levels by enzyme immunoassay. A Neurobehavioral test battery was measured. The exposed children had significantly lower performance in tests of attention (PASAT) [5.22 ± 5.10 vs. 6.98 ± 5.87, p = 0.035], visuomotor speed (Digit Symbol and Trail making A) [41.40 ± 18.01 vs. 46.53 ± 15.89 and 107.92 ± 44.34 vs. 92.44 ± 37.09; respectively] than non-exposed subjects. The neurobehavioral effects were correlated with urinary cotinine levels among children exposed to SHS compared to unexposed children. The study revealed poor performance in neurobehavioral domains of attention and visuomotor skills among children exposed to SHS. This necessitates the implementation of antismoking media awareness programs on the harmful effects of SHS and how to protect children from it.

Isotope dilution-LC-MS/MS method for quantification of the urinary cotinine-to-creatinine ratio

Background

Appropriate monitoring of tobacco smoking is extremely important in several areas of medicine, e.g. management of chronic obstructive pulmonary disease (COPD), epidemiological surveys, and allocation of heart or lung transplants. The major metabolite of nicotine is cotinine that is increasingly used as a laboratory parameter for assessing tobacco smoke exposure.

Methods

Creatinine and cotinine were analyzed simultaneously in urine by ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) in one run within 3 min using a biphenyl column. For quantification, the respective stable-isotope-labeled standards were used.

Results

Detuning and measuring a natural isotope of creatinine as precursor and product ion allowed a simultaneous quantification of creatinine and cotinine. The method revealed robust validation results. For both analytes, inaccuracy and imprecision of the quality control and external quality assessment (EQA) samples were ≤-11.1%.

Conclusions

One essential novelty of the method presented here is the simultaneous quantification of creatinine and cotinine covered by one analytical method. Despite the very different natural concentrations of creatinine and cotinine, this allows the immediate reporting of the cotinine-to-creatinine ratio without the need for a separate creatinine analysis.

Long-term Results From the FRESH RCT: Sustained Reduction of Children's Tobacco Smoke Exposure

INTRODUCTION

Standard care interventions to reduce children's tobacco smoke exposure (TSE) may not be sufficient to promote behavior change in underserved populations. A previous study demonstrated the short-term efficacy of an experimental counseling intervention, Family Rules for Establishing Smokefree Homes (FRESH) compared with standard care on boosting low-income children's TSE reduction and maternal smoking at 16-week end of treatment (EOT). This study tested long-term posttreatment efficacy of this treatment through a 12-month follow-up.

STUDY DESIGN

This study was a two-arm RCT.

SETTING/PARTICIPANTS

Maternal smokers (n=300) not seeking cessation treatment were recruited from low-income, urban communities. Participants exposed their <4-year-old children to tobacco smoke daily. Data collection and analyses occurred from 2006 to 2018.

INTERVENTION

The FRESH behavioral intervention included 2 home visits and 7 phone sessions. FRESH used cognitive behavioral skills training, support, problem-solving, and positive social reinforcement to facilitate the adoption of increasingly challenging TSE-protection behaviors. No nicotine-replacement therapy or medication was provided.

MAIN OUTCOME MEASURES

Primary outcomes were child cotinine (TSE biomarker) and reported TSE from EOT through 12 months after treatment. A secondary outcome was bioverified maternal smoking cessation.

RESULTS

Compared with controls, children in FRESH had significantly lower cotinine (β= -0.31, p<0.01) and lower maternal-reported TSE (β= -1.48, p=0.001) through the 12-month follow-up. A significant effect of time (β= -0.03, p=0.003) reflected a posttreatment decrease in cotinine. There was no treatment × time interaction, suggesting the treatment effect at EOT was sustained after treatment. Compared with controls, FRESH mothers maintained significantly higher odds of quitting smoking from EOT through 12-month follow-up (OR=8.87, 95% CI=2.33, 33.75).

CONCLUSIONS

Study results with a sample of underserved maternal smokers demonstrated that the short-term effect of FRESH counseling at 16-week EOT was maintained through 12 months after treatment-for both bioverified child TSE reduction and maternal smoking cessation. Smokers in low-income communities demonstrate elevated challenges to success in standard smoking treatment. FRESH follow-up results suggest the high potential value of more-intensive behavioral intervention for vulnerable smokers.

TRIAL REGISTRATION

This study is registered at www.clinicaltrials.gov NCT02117947.

Increasing Home Smoking Restrictions Boosts Underserved Moms' Bioverified Quit Success

Objectives: Standard smoking cessation treatments remain relatively ineffective in vulnerable populations. This study tested whether efforts to restrict residential smoking mediated the counseling treatment - smoking cessation association in a child tobacco smoke exposure (TSE) reduction trial. Methods: Maternal smokers (N = 300) with young children from low-income minority communities were randomized to counseling or standard care control to promote child TSE reduction. Secondary mediation analyses controlled for factors associated with smoking cessation. Results: Counseling group mothers were more likely than controls to increase home smoking restrictions (OR = 1.9, 95% CI 1.1-3.4) and quit smoking (OR = 11.0, 95% CI 6.3-19.2). As hypothesized, increasing home smoking restrictions improved likelihood of bioverified quit status at end of treatment (OR = 2.5, 95% CI 1.1-5.9) and partially mediated the association between counseling intervention and quit status. Conclusions: Results suggest that among maternal smokers known to experience increased challenges to quitting smoking, encouraging efforts to protect children from TSE by increasing home smoking restrictions may be an important counseling intervention element that facilitates smoking cessation.

Reducing Underserved Children's Exposure to Tobacco Smoke: A Randomized Counseling Trial With Maternal Smokers

INTRODUCTION

Addressing maternal smoking and child tobacco smoke exposure is a public health priority. Standard care advice and self-help materials to help parents reduce child tobacco smoke exposure is not sufficient to promote change in underserved populations. We tested the efficacy of a behavioral counseling approach with underserved maternal smokers to reduce infant's and preschooler's tobacco smoke exposure.

DESIGN

A two-arm randomized trial: enhanced behavior counseling (experimental) versus enhanced standard care (control). Assessment staff members were blinded.

SETTING/PARTICIPANTS

Three hundred randomized maternal smokers were recruited from low-income urban communities. Participants had a child aged <4 years exposed to two or more maternal cigarettes/day at baseline.

INTERVENTION

Philadelphia Family Rules for Establishing Smoke-free Homes (FRESH) included 16 weeks of counseling. Using a behavioral shaping approach within an individualized cognitive-behavioral therapy framework, counseling reinforced efforts to adopt increasingly challenging tobacco smoke exposure-protective behaviors with the eventual goal of establishing a smoke-free home.

MAIN OUTCOME MEASURES

Primary outcomes were end-of-treatment child cotinine and reported tobacco smoke exposure (maternal cigarettes/day exposed). Secondary outcomes were end-of-treatment 7-day point-prevalence self-reported cigarettes smoked/day and bioverified quit status.

RESULTS

Participation in FRESH behavioral counseling was associated with lower child cotinine (β=-0.18, p=0.03) and reported tobacco smoke exposure (β=-0.57, p=0.03) at the end of treatment. Mothers in behavioral counseling smoked fewer cigarettes/day (β=-1.84, p=0.03) and had higher bioverified quit rates compared with controls (13.8% vs 1.9%, χ(2)=10.56, p<0.01). There was no moderating effect of other smokers living at home.

CONCLUSIONS

FRESH behavioral counseling reduces child tobacco smoke exposure and promotes smoking quit rates in a highly distressed and vulnerable population.

TRIAL REGISTRATION

This study is registered at www.clinicaltrials.gov NCT02117947.

Determination of the nicotine metabolites cotinine and trans-3'-hydroxycotinine in biologic fluids of smokers and non-smokers using liquid chromatography-tandem mass spectrometry: biomarkers for tobacco smoke exposure and for phenotyping cytochrome P450 2A6 activity

The nicotine metabolite cotinine is widely used to assess the extent of tobacco use in smokers, and secondhand smoke exposure in non-smokers. The ratio of another nicotine metabolite, trans-3'-hydroxycotinine, to cotinine in biofluids is highly correlated with the rate of nicotine metabolism, which is catalyzed mainly by cytochrome P450 2A6 (CYP2A6). Consequently, this nicotine metabolite ratio is being used to phenotype individuals for CYP2A6 activity and to individualize pharmacotherapies for tobacco addiction. In this paper we describe a highly sensitive liquid chromatography-tandem mass spectrometry method for determination of the nicotine metabolites cotinine and trans-3'-hydroxycotinine in human plasma, urine, and saliva. Lower limits of quantitation range from 0.02 to 0.1ng/mL. The extraction procedure is straightforward and suitable for large-scale studies. The method has been applied to several thousand biofluid samples for pharmacogenetic studies and for studies of exposure to low levels of secondhand smoke. Concentrations of both metabolites in urine of non-smokers with different levels of secondhand smoke exposure are presented.

Dipstick tests for secondhand smoke exposure

INTRODUCTION

We tested TobacAlert and NicAlert immunochromatographic strips for use as indicators of secondhand smoke (SHS) exposure.

METHODS

Urine samples collected from SHS-unexposed volunteers were spiked with cotinine to concentrations of 5, 8, 13, and 23 ng cotinine/ml urine. One sample was not spiked and used as a control. According to manufacturer's instructions, 45 NicAlert and 45 TobacAlert dipsticks were prepared. The exercise was repeated once. Cotinine levels in urine samples were measured using liquid chromatography/mass spectrometry (LC/MS). STATA was used for statistical analyses.

RESULTS

Ninety NicAlert and 90 TobacAlert dipsticks were tested. Each strip was read by 3 different readers, for 270 NicAlert and 270 TobacAlert readings; 98/270 (36%) NicAlert and 104/270 (39%) TobacAlert readings agreed with the readings predicted by LC/MS-determined cotinine levels. Spearman's rho for the NicAlert strips was .13 and for the TobacAlert strips .23. Both were statistically significant. Using a dichotomous scheme to interpret any strip reading >or=1 as "positive," indicating SHS exposure, NicAlert strips were 94% sensitive and 31% specific, while TobacAlert strips were 89% sensitive and 60% specific.

DISCUSSION

NicAlert and TobacAlert strips performed poorly at low cotinine levels. While the strips could be used to prescreen samples prior to more accurate testing, their use in the clinical or research setting to indicate SHS exposure should be restricted to carefully selected scenarios.

GC-MS determined cotinine in an epidemiological study on smoking status at delivery

The objective of this study was to measure the plasma cotinine levels in pregnant women and their newborns using a gas chromatography-mass spectrometry (GC-MS) method in an epidemiological-delivered population with a wide range of tobacco intakes. Nearly 1000 pregnant women from regional maternity wards (n=1007) were selected for the study. Each patient kept a tobacco diary and underwent a blood test to assess cotinine levels and at the same time that the newborns' cordonal plasma was taken. These values were then cross-checked. Cotinine was estimated using a selected-ion monitoring mode with a 1.5 ng/ml quantification limit. The cotinine levels in mothers and newborns were highly correlated, whatever the mother's smoking status, with a calculated cut-off for cotinine levels in active smokers of 21.5 ng/ml. Finally, the cotinine determined through this GC-MS method offered a sensitive and accurate measure of tobacco exposition of the pregnant women and their babies.

Risks for Heart Disease and Lung Cancer from Passive Smoking by Workers in the Catering Industry

Workers in the catering industry are at greater risk of exposure to secondhand smoke (SHS) when smoke-free workplace policies are not in force. We determined the exposure of catering workers to SHS in Hong Kong and their risk of death from heart disease and lung cancer. Nonsmoking catering workers were provided with screening at their workplaces and at a central clinic. Participants reported workplace, home, and leisure time exposure to SHS. Urinary cotinine was estimated by enzyme immunoassay. Catering facilities were classified into three types: nonsmoking, partially restricted smoking (with nonsmoking areas), and unrestricted smoking. Mean urinary cotinine levels ranged from 3.3 ng/ml in a control group of 16 university staff through 6.4 ng/ml (nonsmoking), 6.1 ng/ml (partially restricted), and 15.9 ng/ml (unrestricted smoking) in 104 workers who had no exposures outside of work. Workers in nonsmoking facilities had exposures to other smoking staff. We modeled workers' mortality risks using average cotinine levels, estimates of workplace respirable particulates, risk data for cancer and heart disease from cohort studies, and national (US) and regional (Hong Kong) mortality for heart disease and lung cancer. We estimated that deaths in the Hong Kong catering workforce of 200,000 occur at the rate of 150 per year for a 40-year working-lifetime exposure to SHS. When compared with the current outdoor air quality standards for particulates in Hong Kong, 30% of workers exceeded the 24-h and 98% exceeded the annual air quality objectives due to workplace SHS exposures.

Design options for molecular epidemiology research within cohort studies

Past discussions of the relative strengths of nested case-control and case-cohort designs have not fully considered cohorts with stored biological samples in which biomarker analyses are planned. Issues related to biomarker analyses can affect an investigator's choice of design and the conduct of these two designs. The key issues identified are effects of analytic batch, long-term storage, and freeze-thaw cycles on biomarkers. In comparison with the nested case-control design, the case-cohort design is less able to handle these challenges. Problems arise because most implementations of the case-cohort design do not allow for simultaneous evaluation of biomarkers in cases and reference group members, and there is no matching. By design, the nested case-control study controls for storage duration and the batching of biological samples from cases and controls is logistically simple. The allowance for matching also means that subjects can be matched on the number of freeze-thaw cycles experienced by the biological sample. However, the matching generates complex data sets that can be more difficult to analyze, and the costly biomarker data generated from the controls has few uses outside of testing the specific hypotheses of the study. In addition, because the same subject can serve as a control and a case, or multiple times as a control, biomarker analyses and sample batching can be more complex than initially anticipated. However, in total, of the two designs, the nested case-control study is better suited for studying biomarkers that can be influenced by analytic batch, long-term storage, and freeze-thaw cycles.

Assessment of Sources of Second-Hand Smoke Exposure in a Putatively Unexposed Population

The authors sought to determine levels of urinary cotinine and its association with collateral exposure to second-hand smoke in public health workers. Urinary cotinine was measured twice at 1-wk intervals in 28 public health workers or their spouses. Information on sources of second-hand smoke exposure and a dietary history were obtained from each participant. Geometric mean and median cotinine levels were 2.74 and 2.33 ng/mL, respectively. Only 6 instances of second-hand smoke exposure were reported from a combined 204 days of potential exposure, and these did not correspond to higher cotinine values. There was no association between consumption of foods containing nicotine and log-transformed urine cotinine levels (p = .80). The authors' analysis indicates dietary sources of nicotine are not important, even for persons with very low urinary cotinine levels. Further study is needed to determine sources of variation in urinary cotinine among largely unexposed populations.