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Biomedical subjects

John Britton

Publications and source records attributed to John Britton.

At least 19 recordsLinked to original sources
PubMed2007

Protocol for the smoking, nicotine and pregnancy (SNAP) trial: double-blind, placebo-randomised, controlled trial of nicotine replacement therapy in pregnancy.

BACKGROUND: Smoking in pregnancy remains a public health challenge. Nicotine replacement therapy (NRT) is effective for smoking cessation in non-pregnant people, but because women metabolise nicotine and cotinine much faster in pregnancy, it is unclear whether this will be effective for smoking cessation in pregnancy. The NHS Health Technology Assessment Programme (HTA)-funded smoking, nicotine and pregnancy (SNAP) trial will investigate whether or not nicotine replacement therapy (NRT) is effective, cost-effective and safe when used for smoking cessation by pregnant women. METHODS/DESIGN: Over two years, in 5 trial centres, 1050 pregnant women who are between 12 and 24 weeks pregnant will be randomised as they attend hospital for ante-natal ultrasound scans. Women will receive either nicotine or placebo transdermal patches with behavioural support. The primary outcome measure is biochemically-validated, self-reported, prolonged and total abstinence from smoking between a quit date (defined before randomisation and set within two weeks of this) and delivery. At six months after childbirth self-reported maternal smoking status will be ascertained and two years after childbirth, self-reported maternal smoking status and the behaviour, cognitive development and respiratory symptoms of children born in the trial will be compared in both groups. DISCUSSION: This trial is designed to ascertain whether or not standard doses of NRT (as transdermal patches) are effective and safe when used for smoking cessation during pregnancy.

Adolescent↗
PubMed2006

Barriers and motivators to gaining access to smoking cessation services amongst deprived smokers--a qualitative study.

BACKGROUND: Smoking is strongly associated with disadvantage and is an important contributor to inequalities in health. Smoking cessation services have been implemented in the UK targeting disadvantaged smokers, but there is little evidence available on how to design services to attract this priority group. METHODS: We conducted focus groups with 39 smokers aged 21-75 from the most socio-economically deprived areas of Nottingham UK who had made an unsuccessful attempt to quit within the last year without using smoking cessation services, to identify specific barriers or motivators to gaining access to these services. RESULTS: Barriers to use of existing services related to fear of being judged, fear of failure, a perceived lack of knowledge about existing services, a perception that available interventions--particularly Nicotine Replacement Therapy--are expensive and ineffective, and negative media publicity about bupropion. Participants expressed a preference for a personalized, non-judgemental approach combining counselling with affordable, accessible and effective pharmacological therapies; convenient and flexible timing of service delivery, and the possibility of subsidized complementary therapies. CONCLUSION: We conclude that smokers from these deprived areas generally had low awareness of the services available to help them, and misconceptions about their availability and effectiveness. A more personalized approach to promoting services that are non-judgemental, and with free pharmacotherapy and flexible support may encourage more deprived smokers to quit smoking.

Adult↗
PubMed2006

Poor sanitation and helminth infection protect against skin sensitization in Vietnamese children: A cross-sectional study.

BACKGROUND: Geohelminth infection and poor hygiene may be protective against allergic sensitization. OBJECTIVE: To determine whether current helminth infection is associated with a reduced prevalence of allergen skin test sensitization in a Southeast Asian population of children with a high prevalence of hookworm infection. METHODS: A total of 1742 Vietnamese schoolchildren were invited to take part in a cross-sectional survey. Allergen skin sensitization to house dust mites (Dermatophagoides pteronyssinus and Dermatophagoides farinae) and American cockroach (Periplaneta americana) were measured and stool samples for qualitative and quantitative geohelminth estimation collected. RESULTS: A total of 1601 children age 6 to 18 participated. Sensitization to dust mites was present in 14.4% and to cockroach in 27.6% of children. In a mutually adjusted model, the risk of sensitization to dust mites was reduced in those with higher hookworm burden (adjusted odds ratio [OR] for 350+ vs no eggs per gram, 0.61; 95% CI, 0.39-0.96) and with Ascaris infection (adjusted OR, 0.28; 0.10-0.78), and increased in those using flush toilets (adjusted OR for flush toilet vs none/bush/pit, 2.51; 1.00-6.28). In contrast, sensitization to cockroach was not independently related to geohelminth infection but was increased in those regularly drinking piped or well water rather than from a stream (adjusted OR, 1.33; 1.02-1.75). CONCLUSION: Geohelminth infection, sanitation, and water supply influence the risk of allergic sensitization in Vietnamese children. This is consistent with a protective effect against allergy by geohelminth or other gastrointestinal infection. CLINICAL IMPLICATIONS: If the inverse relationship between geohelminth infection, poor sanitation, and allergic sensitization proves to be causal, drugs derived from parasite products may help to alleviate clinical allergic disease.

Adolescent↗
PubMed2006

Associations of a novel IL4RA polymorphism, Ala57Thr, in Greenlander Inuit.

BACKGROUND: A novel IL4RA polymorphism, Ala57Thr, was identified in Greenlander Inuit. OBJECTIVE: We sought to determine whether the novel Thr57 allele is population specific and to assess the associations of Ala57Thr and Ile50Val with atopy in 2 Inuit populations. METHODS: Ala57Thr and Ile50Val were genotyped in 651 Inuit living in Denmark, 1295 Inuit living in Greenland, and 1329 individuals from 7 populations from widely differing global locations. In Inuit the polymorphisms were evaluated for associations with atopy, rhinitis, asthma, and pulmonary function. RESULTS: Thr57 was in linkage disequilibrium with Ile50 (D' = 1, r(2) = 0.13) and was common (33%) in the Inuit but rare (<0.6%) in all other populations. In Inuit living in Denmark, the Thr57 allele (in a dose-dependent manner) and the Ile50/Thr57 haplotype were associated with lower risk of atopy (P(linear) = .003 and P = .034, respectively), with similar trends observed for atopic rhinitis and atopic asthma. In Inuit living in Greenland, Thr57 was not associated with atopy or atopic diseases, but Ile50 was weakly associated with lower risk of atopy. CONCLUSION: The novel IL4RA Ala57Thr was common in and population specific to Greenlander Inuit, with Thr57 associated with a lower risk of atopy in those living in Denmark. Hence a full investigation of genotype-phenotype relationships in a given population can only be achieved if each gene is screened for novel polymorphisms in that population. CLINICAL IMPLICATIONS: Clinical risk attributable to variations in a gene in an ethnic group requires that all variations of the gene are known for that group.

Adult↗
PubMed2006

Asthma and current intestinal parasite infection: systematic review and meta-analysis.

RATIONALE: Epidemiologic studies suggest that intestinal parasite infections may protect against asthma. OBJECTIVES: A systematic review and meta-analysis of epidemiologic studies to determine whether total or species-specific current parasite infection is associated with a reduced risk of asthma or wheeze. METHODS: We searched MEDLINE, EMBASE, and CINAHL (up to January 2006); reviews; and reference lists from publications, with no language restrictions. We included studies that reported asthma or wheeze as an outcome measure and ascertained parasite infection by fecal examination. We estimated pooled odds ratios (OR) and 95% confidence intervals (CI) using data extracted from published papers, or where available, original data provided by authors, using random effect models. MEASUREMENTS AND MAIN RESULTS: Thirty-three studies met the inclusion criteria. Infection with any parasite was associated with a small, nonsignificant increase in asthma risk (OR, 1.24; 95% CI, 0.98-1.57; 29 studies). In species-specific analysis, Ascaris lumbricoides was associated with significantly increased odds of asthma (OR, 1.34; 95% CI, 1.05-1.71; 20 studies), while hookworm infection was associated with a significantly strong reduction (OR, 0.50; 95% CI, 0.28-0.90; 9 studies) that was directly and significantly related to infection intensity (p < 0.001; OR for highest tertile of infection, 0.34; 95% CI, 0.19-0.62). Other species had no significant effects on asthma. Infection effects on wheeze were derived from smaller numbers, but revealed a broadly similar pattern of results. CONCLUSIONS: Parasite infections do not in general protect against asthma, but infection with hookworm may reduce the risk of this disease.

Adult↗
PubMed2006

Smoking cessation.

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Behavior Therapy↗
PubMed2006

Designing smoking cessation services for school-age smokers: A survey and qualitative study.

To identify the preferred design characteristics of smoking cessation services for school-age smokers, we conducted focus groups with teenage smokers motivated to stop smoking. We surveyed all pupils in years 9-11 (aged 13-16) in a random sample of 10 schools in Nottinghamshire, United Kingdom, to elicit details of smoking behavior, and conducted 25 focus groups in 6 schools with current smokers who wanted to stop smoking. Of 4,065 pupils surveyed, 888 (22%) were current smokers, and 438 (50% of smokers) wanted to quit smoking. We sampled 226 of these individuals for focus group studies, and 135 (60%) participated. These participants were motivated to quit, and almost all had tried to do so but had found it too difficult. Many were aware of smoking cessation methods but had low perceptions of their effectiveness based on their own or others' poor experiences of these interventions, and few were aware of the possibility of professional cessation support. Given clear, nondirective information about interventions, participants reported a preference for confidential, nonjudgmental services delivered during school time by a trained counselor, allowed the option to attend with friends, and offered nicotine replacement therapy (NRT). School-age smokers in Nottinghamshire, United Kingdom, who are motivated to stop smoking have low knowledge and opinions of smoking cessation interventions. Our findings indicate that young smokers would favor school-based services offering confidential professional counseling and NRT.

Adolescent↗
PubMed2006

Use of nicotine replacement therapy in socioeconomically deprived young smokers: a community-based pilot randomised controlled trial.

BACKGROUND: Smoking is common in young people, particularly in disadvantaged groups, and continued smoking has a major impact on quality and quantity of life. Although many young smokers want to stop smoking, little is known about the design and effectiveness of cessation services for them. OBJECTIVE: To determine whether nicotine replacement therapy (NRT) when combined with counselling is effective in young smokers in a deprived area of Nottingham, UK. METHODS AND SUBJECTS: We surveyed smoking prevalence and attitudes to smoking and quitting in young people accessing an open access youth project in a deprived area of Nottingham, and used the information gained to design a community based smoking cessation service incorporating a randomised controlled trial of nicotine patches against placebo given in association with individual behavioural support. We resurveyed smoking prevalence among project attendees after completing the pilot study. RESULTS: Of 264 young people surveyed (median age 14 years, range 11-21), 49% were regular smokers. A total of 98 young people were recruited and randomised to receive either active nicotine patches on a six week reducing dose regimen (49 participants), or placebo (49 participants). Adherence to therapy was low, the median duration being one week, and 63 participants did not attend any follow up. At four weeks, five subjects receiving active NRT and two receiving placebo were abstinent, and at 13 weeks none were. Adverse effects were more common in the active group but none were serious. Smoking prevalence among 246 youth project attendees surveyed after the trial was 44%. CONCLUSIONS: This study suggests that NRT in this context is unlikely to be effective in young smokers, not least because of low adherence to therapy. It also suggests that young smokers want help with smoking cessation, but that establishing the efficacy of smoking cessation services for young people who need them most will be very difficult.

Administration, Cutaneous↗
PubMed2006

The pro-oxidant activity of high-dose vitamin E supplements in vivo.

BACKGROUND: A recent meta-analysis has demonstrated that the regular administration of high-dose vitamin E supplements may be associated with increased mortality. The biological mechanism for this effect is uncertain. METHODS: A ferrous oxidation xylenol assay was used to assess plasma oxidation activity levels in samples from a randomized, placebo-controlled, 6-week trial of daily vitamin E supplementation in adults with asthma (n = 72). RESULTS AND CONCLUSION: A 27% increase in plasma oxidation activity levels was observed in patients receiving vitamin E. We demonstrate a pro-oxidant effect of high-dose vitamin E supplementation that may explain the increase in mortality observed in intervention studies using this nutrient.

Adolescent↗
PubMed2006

Dose-ranging study for trials of therapeutic infection with Necator americanus in humans.

Epidemiological studies suggest that a hookworm infection producing 50 eggs/gram of feces may protect against asthma. We conducted a dose-ranging study to identify the dose of hookworm larvae necessary to achieve 50 eggs/gram of feces for therapeutic trials of asthma. Ten healthy subjects without asthma or airway hyperresponsiveness to inhaled methacholine received 10, 25, 50, or 100 Necator americanus larvae administered double blind to an area of skin on the arm. Subjects were seen weekly for 12 weeks and were then treated with mebendazole. Skin itching at the entry site and gastrointestinal symptoms were common at higher doses. Lung function did not change. Levels of blood eosinophils and IgE increased transiently, and levels of IgG increased progressively. All doses resulted in at least 50 eggs/gram of feces in the eight subjects who completed the study. Infection with 10 N. americanus larvae is well tolerated, elicits a modest host eosinophil response, and is potentially suitable for use in preliminary clinical therapeutic trials.

Adult↗
PubMed2005

Use of acetaminophen and the risk of self-reported allergic symptoms and skin sensitization in Butajira, Ethiopia.

BACKGROUND: Studies in developed countries suggest that acetaminophen use is associated with increased risk of asthma, but it is unclear whether this association is causal. OBJECTIVE: To determine the relation among acetaminophen use, asthma, and allergy, and to explore potential biases in acetaminophen use, in a developing country population. METHODS: We surveyed 7649 adults and children from Butajira, Ethiopia, collecting data on self-reported symptoms of allergic disease, skin sensitization to Dermatophagoides pteronyssinus and cockroach, acetaminophen use, and potential confounders. We then collected detailed data on indications for acetaminophen use and reasons for aspirin avoidance in a nested follow-up study. RESULTS: Allergic symptoms increased significantly with frequency of acetaminophen use, with odds ratios in those using >3 tablets in the past month relative to none 1.89 (95% CI, 1.51-2.36) for wheeze, 2.14 (1.72-2.67) for nocturnal shortness of breath, 2.52 (1.99-3.20) for rhinitis, and 1.90 (1.39-2.61) for eczema. Cockroach sensitization was also more common in the highest acetaminophen category (odds ratio, 1.40; 95% CI, 1.10-1.79), but D pteronyssinus sensitization was not. Less than 1% of participants with asthma or wheeze in our nested study reported avoidance of aspirin because of asthma symptoms. None volunteered using acetaminophen to treat allergic symptoms. CONCLUSION: There is a dose-related association between acetaminophen use and self-reported allergic symptoms in this population that is not a result of aspirin avoidance, reverse causation, or other bias. Acetaminophen may therefore be involved in the etiology of asthma and allergic disease.

Acetaminophen↗
PubMed2005

Corticosteroid sparing effects of vitamin C and magnesium in asthma: a randomised trial.

AIM: The study aims to assess the a priori hypothesis that regular supplementation with vitamin C or magnesium will permit a reduction in the corticosteroid dose required to maintain asthma control in adults. METHODS: We invited all participants recruited from primary care centres who completed a parallel-group, randomised, placebo-controlled, 16-week supplementation trial of 1g/day vitamin C or 450 mg/day magnesium to continue and participate in a structured corticosteroid reduction protocol over 10 weeks. RESULTS: A total of 92 participants (29 vitamin C, 31 magnesium and 32 placebo) entered the study. Assuming no reduction in corticosteroid dose in the 10 who subsequently withdrew, the geometric mean reductions in inhaled corticosteroid dose achieved with vitamin C, magnesium and placebo were 49, 13 and 11 microg, respectively. Relative to placebo, the unadjusted effect of vitamin C was significant, and remained at borderline significance after adjustment for baseline corticosteroid dose (relative reduction ratio=4.03, 95% CI 0.95 to 17.1, P=0.06). CONCLUSIONS: We conclude that while vitamin C supplements may have modest corticosteroid sparing effects and hence the potential to reduce exposure to their side effects, magnesium supplements have no effect on the inhaled corticosteroid dose required to maintain asthma control.

Administration, Inhalation↗
PubMed2005

Early life risk factors for atopic dermatitis in Ethiopian children.

BACKGROUND: Atopic dermatitis (AD) has increased in prevalence in many countries in recent decades, but the risk factors for AD in developing countries are unknown. Helminthic parasites may play a role in protecting against allergic disease, but few studies have investigated the association of AD with parasitic infection. OBJECTIVE: To establish the independent effects of parasitic infection and other early life factors on the risk of AD in Ethiopia. METHODS: We conducted a cross-sectional survey and nested case-control study of children age 1 to 5 years in Jimma and surrounding rural areas in southwest Ethiopia. Cases were defined according to the International Study of Asthma and Allergies in Childhood criteria for AD and confirmed by clinical examination. Information on lifestyle and other potential risk factors was collected by parental questionnaire, and stool samples were analyzed for parasites. RESULTS: Complete data were obtained on 306 AD cases defined by International Study of Asthma and Allergies in Childhood criteria (prevalence, 4.4%) and 426 controls. There was no reduction in the risk of AD in relation to intestinal parasite infection; in fact, AD was increased in subjects with Trichuris (1.61; 95% CI, 1.14-2.26). The risk of AD was also unrelated to family size, crowding in the home, or breast-feeding, but was related to previously unrecognized factors including malaria and access to piped drinking water. Similar findings were apparent in cases and controls confirmed by clinical examination. CONCLUSION: Neither intestinal parasite infection nor other proposed risk factors for AD appear to be related to the presence of the condition in young children in Ethiopia, suggesting that other factors may be more important in this population.

Allergens↗
PubMed2005

Exhaled carbon monoxide levels in atopic asthma: a longitudinal study.

Exhaled carbon monoxide (eCO) is a potential non-invasive marker of airway inflammation. We have investigated the cross-sectional and longitudinal relationship between eCO and lung function and bronchial reactivity in 69 adults with atopic asthma, in the course of participation in a 6-week randomised placebo-controlled trial of vitamin E supplementation. At baseline, there was no cross-sectional association between absolute eCO levels and either forced expiratory volume (FEV(1)), forced vital capacity (FVC) or bronchial reactivity. However, in the longitudinal analysis within the placebo group, a rise in mean eCO was significantly associated with improvement in bronchial reactivity (change in eCO (parts per million) per natural log unit change in bronchial hyperreactivity 0.498, 95% confidence interval 0.071 to 0.924, P=0.024). These findings suggest that, contrary to previous data, there is no cross-sectional relationship between eCO and lung function or bronchial reactivity, but that there may be a longitudinal trend with bronchial reactivity that is worth further investigation.

Adolescent↗
PubMed2005

U.K. general practitioners' beliefs, attitudes, and reported prescribing of nicotine replacement therapy in pregnancy.

Clinical guidelines recommend that U.K. health professionals prescribe NRT in pregnancy. The present study was conducted to determine (a) general practitioners' confidence in their ability to deliver a range of smoking cessation interventions, including NRT, in pregnancy, (b) the frequency with which general practitioners recall prescribing NRT in pregnancy, and (c) the factors that influence general practitioners to prescribe NRT in pregnancy. We conducted a mail survey of 368 general practitioners (family physicians) working in four districts of Nottingham, England (response rate = 68.6%). Some 27.1% of respondents recalled prescribing NRT to pregnant women (9.2% were unsure). General practitioners were less confident about their ability to prescribe NRT in pregnancy than they were of their ability to deliver other simple smoking cessation interventions in pregnancy. Most general practitioners (62%) believed NRT to be effective in pregnancy and safer than smoking (70%), but fewer (45%) believed NRT to be safe in pregnancy per se. Multiple logistic regression demonstrated that general practitioners who believed NRT use in pregnancy was safer than smoking were most likely to recall having prescribed it, OR = 4.94, 95% CI = 1.31-18.71. Many general practitioners were unsure about the safety of NRT in pregnancy, which may explain their relatively low confidence in their ability to prescribe NRT in pregnancy, compared with other interventions. The key factor influencing general practitioners' prescribing decisions was a belief that NRT use in pregnancy was likely to be safer than smoking. Empirical evidence about the safety and efficacy of NRT use in pregnancy is required to inform general practitioners' decisions about prescribing NRT to pregnant women who smoke.

Adult↗
PubMed2004

Recruiting pregnant smokers for a placebo-randomised controlled trial of nicotine replacement therapy.

BACKGROUND: Smoking in pregnancy is a public health problem and effective methods for reducing this are required. Although nicotine replacement therapy (NRT) is effective for smoking cessation in non-pregnant people, there is no direct evidence concerning its effectiveness in pregnancy. Despite this, clinical guidelines recommend the cautious use of NRT during pregnancy. Randomised controlled trials are needed to determine the safety and efficacy of NRT when used by pregnant women for smoking cessation, but the feasibility of recruiting women to such trials is unknown. Consequently, in this study we aimed to determine i) the feasibility of recruiting women to a RCT of NRT in pregnancy as they attend hospital antenatal ultrasound examinations, ii) the proportion of such women who are eligible for and interested in trial enrollment and iii) research staff perceptions of how one method of trial recruitment could be improved. METHODS: During a one month period, all women attending for antenatal ultrasound examination in an English teaching hospital were asked to complete a questionnaire which determined their eligibility to enroll in a proposed placebo controlled randomised trial investigating the effectiveness of NRT in pregnancy. Women who were eligible to participate were asked whether they would do so and those who accepted enrollment were offered an appointment with a smoking cessation advisor. RESULTS: Over 99% (851/858) of women agreed to complete a questionnaire about smoking habits whilst waiting for ultrasound examinations. 10.3% (88/851) of women attending for antenatal ultrasound fitted eligibility criteria for a proposed RCT of NRT in pregnancy, but only 3.6% [(31/851), 95% CI, 2.4 to 4.9%] indicated on the questionnaire that they would like to take part in a study involving randomisation to placebo or active patches. Researchers offered trial enrollment to 26 of these 31 women and 96% (25) accepted. Staff recruiting women believed that trial recruitment would be maximised if women attending the ultrasound department knew about trial recruitment before attending and greater staff resources were made available for this. It was also perceived that women generally under-reported the amount they smoked on questionnaires completed whilst waiting in ultrasound department areas. CONCLUSIONS: It is feasible to recruit women for a trial of NRT in pregnancy as they wait for antenatal ultrasound examinations. Using similar recruitment methods, researchers can expect to recruit between 24 and 49 women per 1000 approached.

Eligibility Determination↗
PubMed2004

Diet and asthma.

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Antioxidants↗