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Assessing tobacco smoke exposure in pregnancy from self-report, urinary cotinine and NNAL: a validation study using the New Hampshire Birth Cohort Study

Por: Peacock · J. L. · Palys · T. J. · Halchenko · Y. · Sayarath · V. · Takigawa · C. A. · Murphy · S. E. · Peterson · L. A. · Baker · E. R. · Karagas · M. R.

Accurate assessment of tobacco smoke exposure is key to evaluate its effects. We sought to validate and establish cut-offs for self-reported smoking and secondhand smoke (SHS) exposure during pregnancy using urinary cotinine and 4-(methylnitrosamino)-1-(-3-pyridyl)-1-butanol (NNAL) in a large contemporary prospective study from the USA, with lower smoking prevalence than has previously been evaluated.


Prospective birth cohort.


Pregnancy clinics in New Hampshire and Vermont, USA.


1396 women enrolled in the New Hampshire Birth Cohort Study with self-reported smoking, urinary cotinine, NNAL and pregnancy outcomes.

Primary and secondary outcome measures

Cut-offs for urinary cotinine and NNAL concentrations were estimated from logistic regression models using Youden’s method to predict SHS and active smoking. Cotinine and NNAL were each used as the exposure in separate multifactorial models for pregnancy outcomes.


Self-reported maternal smoking was: 72% non-smokers, 5.7% ex-smokers, 6.4% SHS exposure, 6.2% currently smoked, 10% unreported. Cotinine and NNAL levels were low and highly intercorrelated (r=0.91). Geometric mean cotinine, NNAL were 0.99 ng/mL, 0.05 pmol/mL, respectively. Cotinine cut-offs for SHS, current smoking were 1.2 ng/mL and 1.8 ng/mL (area under curve (AUC) 95% CI: 0.52 (0.47 to 0.57), 0.90 (0.85 to 0.94)). NNAL cut-off for current smoking was 0.09 pmol/mL (AUC=0.82 (95% CI 0.77 to 0.87)). Using cotinine and NNAL cut-offs combined gave similar AUC to cotinine alone, 0.87 (95% CI 0.82 to 0.91). Cotinine and NNAL gave almost identical effect estimates when modelling pregnancy outcomes.


In this population, we observed high concordance between self-complete questionnaire smoking data and urinary cotinine and NNAL. With respect to biomarkers, either cotinine or NNAL can be used as a measure of tobacco smoke exposure overall but only cotinine can be used to detect SHS.

Minimal clinically important difference in means in vulnerable populations: challenges and solutions

Por: Peacock · J. L. · Lo · J. · Rees · J. R. · Sauzet · O.
Introduction and motivation

Many health studies measure a continuous outcome and compare means between groups. Since means for biological data are often difficult to interpret clinically, it is common to dichotomise using a cut-point and present the ‘percentage abnormal’ alongside or in place of means. Examples include birthweight where ‘abnormal’ is defined as 140 mm Hg (high blood pressure) and lung function with varying definitions of the ‘limit of normal’. In vulnerable populations with low means, for example, birthweight in a population of preterm babies, a given difference in means between two groups will represent a larger difference in the percentage with low birthweight than in a general population of babies where most will be full term. Thus, in general, the difference in percentage of patients with abnormal values for a given difference in means varies according to the reference population’s mean value. This phenomenon leads to challenges in interpreting differences in means in vulnerable populations and in defining an outcome-specific minimal clinically important difference (MCID) in means since the proportion abnormal, which is useful in interpreting means, is not constant—it varies with the population mean. This has relevance for study power calculations and data analyses in vulnerable populations where a small observed difference in means may be difficult to interpret clinically and may be disregarded, even if associated with a relatively large difference in percentage abnormal which is clinically relevant.


To address these issues, we suggest both difference in means and difference in percentage (proportion) abnormal are considered when choosing the MCID, and that both means and percentages abnormal are reported when analysing the data.


We describe a distributional approach to analyse proportions classified as abnormal that avoids the usual loss of precision and power associated with dichotomisation.

Womens acceptability of and experience with primary human papillomavirus testing for cervix screening: HPV FOCAL trial cross-sectional online survey results

Por: Smith · L. W. · Racey · C. S. · Gondara · L. · Krajden · M. · Lee · M. · Martin · R. E. · Stuart · G. · Peacock · S. · Coldman · A. J. · Franco · E. L. · van Niekerk · D. · Ogilvie · G. S.

To study participant’s acceptability of and attitudes towards human papillomavirus (HPV) testing compared with cytology for cervical cancer screening and what impact having an HPV positive result may have in future acceptability of screening.


Cross-sectional online survey of clinical trial participants.


Primary care, population-based Cervix Screening Program, British Columbia, Canada.


A total of 5532 participants from the HPV FOCAL trial, in which women received HPV and cytology testing at study exit, were included in the analysis. Median age was 54 years. The median time of survey completion was 3 years after trial exit.

Outcome measures

Acceptability of HPV testing for primary cervical cancer screening (primary); attitudes and patient perceptions towards HPV testing and receipt of HPV positive screen results (secondary).


Most respondents (63%) were accepting of HPV testing, with the majority (69%) accepting screening to begin at age 30 years with HPV testing. Only half of participants (54%) were accepting of an extended screening interval of 4–5 years. In multivariable logistic regression, women who received an HPV positive screen test result during the trial (OR=1.41 95% CI 1.11 to 1.80) or were older (OR=1.01, 95% CI 1.00 to 1.02) were more likely to report HPV testing as acceptable.


In this evaluation of acceptability and attitudes regarding HPV testing for cervix screening, most are accepting of HPV testing for screening; however, findings indicate heterogeneity in concerns and experiences surrounding HPV testing and receipt of HPV positive results. These findings provide insights for the development of education, information and communication strategies during implementation of HPV-based cervical cancer screening.

Trial registration numbers

ISRCTN79347302 and NCT00461760.

Impact of a cancer diagnosis on the income of adult cancer survivors: a scoping review protocol

Por: El Adam · S. · Bentley · C. · McQuarrie · L. · Teckle · P. · Peacock · S.

While the socioeconomic impact of a cancer diagnosis on cancer survivors has gained some attention in the literature, to our knowledge, a review of the evidence on changes in income due to cancer has yet to be undertaken. In this paper, we describe a scoping review protocol to review the evidence on the effect of a cancer diagnosis on the income of individuals diagnosed with cancer during adulthood (≥18 years). The purpose is to summarise existing evidence, identify gaps in current research and highlight priority areas for future research.

Methods and analysis

This study will follow the methodological framework for conducting scoping reviews by the Joanna Briggs Institute In collaboration with a health science librarian, we developed a search strategy to be performed in Ovid MEDLINE, PsycINFO, Cumulative Index to Nursing and Allied Health Literature, EMBASE, Econ-Literature and Evidence-Based Medicine Reviews. This scoping review will search the scientific literature published in English from 1 January 2000 to 31 December 2020. Studies that measured the impact of cancer on income of adults will be eligible for inclusion. Studies exclusively focused on employment outcomes (eg, return to work, unemployment, productivity loss), financial expenditures, childhood cancer survivors and/or the caregivers of cancer survivors will be excluded. Three independent reviewers will conduct screening and extract data. Descriptive information will be reported following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) extension for Scoping Reviews.

Ethics and dissemination

This scoping review will analyse data from publicly available materials and thus does not require ethics approval. Results from this review will be disseminated through a peer-reviewed publication and/or conference presentation with the potential to identify gaps in the literature, suggest strategies for standardised terminology and provide directions for future research.