To determine the relation between body mass index and the development of asthma in children.
Prospective study of 4393 asthma-free children followed for up to 14 years.
Children of participants in ...the National Longitudinal Survey of Youth.
Analysis was limited to children who were followed from birth and were asthma-free during the first 24 months of life. The outcome was the development of asthma during follow-up (incident asthma). Body mass index (BMI) was our main predictor of interest. Survival analyses, using time to development of asthma as the main endpoint, were stratified by sex and controlled for race/ethnicity, poverty status, and prenatal maternal smoking.
Asthma developed in 218 (5.0 %) children during the follow-up period. The relation between BMI and incident asthma varied by sex. A BMI > or =85th percentile at age 2-3 years was a risk factor for subsequent asthma development in boys (hazard ratio (HR) 1.6 95% confidence interval (CI) 1.1, 2.4) but not girls (HR 0.8, 95% CI 0.5, 1.4). Similarly, boys with BMIs always > or =85th percentile were at increased risk for subsequent asthma development (HR 2.4, 95% CI 1.4, 4.4) but not girls (HR 1.5, 95% CI 0.7, 2.9).
Boys with high body masses may be at an increased risk for developing asthma.
The present study investigates the interfacial properties of carbon nanotube (CNT) reinforced polymer composites by simulating a nanotube pull-out experiment. An atomistic description of the problem ...is achieved by implementing constitutive relations that are derived solely from interatomic potentials. Specifically, we adopt the Lennard-Jones (LJ) interatomic potential to simulate a non-bonded interface, where only the van der Waals (vdW) interactions between the CNT and surrounding polymer matrix are assumed to exist. The effects of such parameters as the CNT embedded length, the number of vdW interactions, the thickness of the interface, the CNT diameter and the cut-off distance of the LJ potential on the interfacial shear strength (ISS) are investigated and discussed. The problem is formulated for both a generic thermoset polymer and a specific two-component epoxy based on a diglycidyl ether of bisphenol A (DGEBA) and triethylene tetramine (TETA) formulation. The study further illustrates that by accounting for different CNT capping scenarios and polymer morphologies around the embedded end of the CNT, the qualitative correlation between simulation and experimental pull-out profiles can be improved.
Background
An important question in the valuation of children’s health is whether the preferences of younger individuals should be captured within value sets for measures that are aimed at them. This ...depends on whether younger individuals can complete valuation exercises and whether their preferences differ from those of adults. This study compared the preferences of adults and adolescents for EQ-5D-Y-3L health states using latent scale values elicited from a discrete choice experiment (DCE).
Methods
An online DCE survey, comprising 15 pairwise choices, was provided to samples of UK adults and adolescents (aged 11–17 y). Adults considered the health of a 10-year-old child, whereas adolescents considered their own health. Mixed logit models were estimated, and comparisons were made using relative attribute importance (RAI) scores and a pooled model.
Results
In total, 1000 adults and 1005 adolescents completed the survey. For both samples, level 3 in pain/discomfort was most important, and level 2 in self-care the least important, based on the relative magnitudes of coefficients. The RAI scores (normalized on self-care) indicated that adolescents gave less weight relative to adults to usual activities (1.18 v. 1.51; P < 0.05), pain/discomfort (1.77 v. 3.12; P < 0.01), and anxiety/depression (1.64 vs. 2.65; P < 0.01). The pooled model indicated evidence of differences between the two samples in both levels in pain/discomfort and anxiety/depression.
Limitations
The perspective of the DCE task differed between the 2 samples, and no data were collected to anchor the DCE data to generate value sets.
Conclusions
Adolescents could complete the DCE, and their preferences differed from those of adults taking a child perspective. It is important to consider whether their preferences should be incorporated into value sets.
Wilderness therapy is a specialized approach to adolescent substance use and mental health treatment. While empirical evidence of positive outcomes grows to support this approach, qualitative ...understandings are lacking in the literature, thereby limiting theoretical explanations. Additionally, the voice of adolescent clients is hardly present, and was therefore the focus for this research. A sample of 148 adolescent wilderness therapy clients at one Canadian residential treatment program for addictive behaviour and mental health issues participated in the study. A realist approach utilizing thematic analysis of written open-ended responses produced six major themes; three depicting participant experiences (social dynamics, wilderness, catalyst for change) and three for perceived outcomes (skill development, self-concept, health). These findings are discussed in relationship to the development of a clinical model of wilderness therapy and the potential of wilderness interventions in adolescent residential treatment. Recommendations for practice and future research are discussed.
•Social dynamics and outdoor living and travel presented significant opportunities and challenges to youth in wilderness therapy.•Youth reported positive and negative experiences suggesting further inquiry of assessment and ‘fit’ for this treatment approach.•Theoretical development of a clinical model of change in wilderness therapy is needed.
The provision of informal (unpaid) care can impose significant ‘spillover effects’ on carers, and accounting for these effects is consistent with the efficiency and equity objectives of health ...technology assessment (HTA). Inclusion of these effects in health economic models, particularly carer health-related quality of life (QOL), can have a substantial impact on net quality-adjusted life year (QALY) gains and the relative cost effectiveness of new technologies. Typically, consideration of spillover effects improves the value of a technology, but in some circumstances, consideration of spillover effects can lead to situations whereby life-extending treatments for patients may be considered cost ineffective due to their impact on carer QOL. In this piece we revisit the classic ‘QALY trap’ and introduce an analogous ‘carer QALY trap’ which may have practical implications for economic evaluations where the inclusion of carer QOL reduces incremental QALY gains. Such results may align with a strict QALY-maximisation rule, however we consider the extent to which this principle may be at odds with the preferences of carers themselves (and possibly society more broadly), potentially leading decision makers into the carer QALY trap as a result. We subsequently reflect on potential solutions, highlighting the important (albeit limited) role that deliberation has to play in HTA.
The usual radical radiotherapy treatment prescribed for head and neck squamous cell carcinoma (HNSCC) is 70 Gy (in 2 Gy per fraction equivalent) administered to the high-risk target volume (TV). This ...can be planned using either a forward-planned photon-electron junction technique (2P) or a single-phase (1P) forward-planned technique developed in-house. Alternatively, intensity-modulated radiotherapy (IMRT) techniques, including helical tomotherapy (HT), allow image-guided inversely planned treatments. This study was designed to compare these three planning techniques with regards to TV coverage and the dose received by organs at risk.
We compared the dose-volume histograms and conformity indices (CI) of the three planning processes in five patients with HNSCC. The tumour control probability (TCP), normal tissue complication probability (NTCP) and uncomplicated tumour control probability (UCP) were calculated for each of the 15 plans. In addition, we explored the radiobiological rationality of a dose-escalation strategy.
The CI for the high-risk clinical TV (CTV1) in the 5 patients were 0.78, 0.76, 0.82, 0.72 and 0.81 when HT was used; 0.58, 0.56, 0.47, 0.35 and 0.60 for the single-phase forward-planned technique and 0.46, 0.36, 0.29, 0.22 and 0.49 for the two-phase technique. The TCP for CTV1 with HT were 79.2%, 85.2%, 81.1%, 83.0% and 53.0%; for single-phase forward-planned technique, 76.5%, 86.9%, 73.4%, 81.8% and 31.8% and for the two-phase technique, 38.2%, 86.2%, 42.7%, 0.0% and 3.4%. Dose escalation using HT confirmed the radiobiological advantage in terms of TCP.
TCP for the single-phase plans was comparable to that of HT plans, whereas that for the two-phase technique was lower. Centres that cannot provide IMRT for the radical treatment of all patients could implement the single-phase technique as standard to attain comparable TCP. However, IMRT produced better UCP, thereby enabling the exploration of dose escalation.
Discrete choice experiments (DCEs) are becoming increasingly used to elicit preferences for children’s health states. However, DCE data need to be anchored to produce value sets, and composite time ...trade-off (cTTO) data are typically used in the context of EQ-5D-Y-3L valuation. The objective of this paper is to compare different anchoring methods, summarise the characteristics of the value sets they produce, and outline key considerations for analysts. Three anchoring methods were compared using data from published studies: (1) rescaling using the mean value for the worst health state; (2) linear mapping; and (3) hybrid modelling. The worst state rescaling value set had the largest range. The worst state rescaling and linear mapping value sets preserved the relative importance of the dimensions from the DCE, whereas the hybrid model value set did not. Overall, the predicted values from the hybrid model value set were more closely aligned with the cTTO values. These findings are relatively generalisable. Deciding upon which anchoring approach to use is challenging, as there are numerous considerations. Where cTTO data are collected for more than one health state, anchoring on the worst health state will arguably be suboptimal. However, the final choice of approach may require value judgements to be made. Researchers should seek input from relevant stakeholders when commencing valuation studies to help guide decisions and should clearly set out their rationale for their preferred anchoring approach in study outputs.
Many researchers have conceptualized smoking uptake behavior in adolescence as progressing through a sequence of developmental stages. Multiple social, psychological, and biological factors influence ...this process, and may play different functions at different points in the progression, and play different roles for different people. The major objective of this paper is to review empirical studies of predictors of transitions in stages of smoking progression, and identify similarities and differences related to predictors of stages and transitions across studies. While a number of factors related to stage of progression replicated across studies, few variables uniquely predicted a particular stage or transition in smoking behavior. Subsequently, theoretical considerations related to stage conceptualization and measurement, inter-individual differences in intra-individual change, and the staged or continuous nature of smoking progression are discussed.
To determine the occurrence of the human pathogen, Vibrio vulnificus, in south Texas coastal waters. Coastal waters were sampled monthly between August 2006 and July 2007. Water temperature, ...dissolved oxygen, pH, salinity, conductivity and turbidity were measured during each sampling event. Culture-based techniques utilizing Vibrio vulnificus agar (VVA) and membrane-Enterococcus indoxyl-β- d-glucoside agar (mEI) were used to assess the occurrence and levels of V. vulnificus and the faecal contamination indicator group, enterococci, respectively. Vibrio vulnificus isolates were confirmed using colony-blot hybridization with the species-specific VVAP probe. Vibrio vulnificus was isolated at all sites throughout the year even when the water temperature dropped to 9·71°C. Significant correlations were found between concentrations of V. vulnificus and the abiotic factors, water temperature (P = 0·002) and dissolved oxygen (P = 0·028), as well as between concentrations of V. vulnificus and enterococci (P < 0·001). This study demonstrated the year-round presence of V. vulnificus in coastal waters of south Texas. These findings indicate that the potential for human exposure to the pathogen, V. vulnificus, exists throughout the year. It also suggests that routinely monitored data might be used to predict the occurrence of the pathogen.
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