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Biomedical subjects

D P Strachan

Publications and source records attributed to D P Strachan.

At least 73 records · Page 4Linked to original sources
PubMed1998

Epidemiology of Epstein-Barr virus infection in pre-adolescent children: application of a new salivary method in Edinburgh, Scotland.

STUDY OBJECTIVE: To describe the epidemiology of Epstein-Barr virus (EBV) among primary school children by testing saliva with a new EBV capsid antigen "G" antibody capture radioimmunoassay (GACRIA). DESIGN: A population based sample of 7 year old schoolchildren were followed up at age 11. SETTING: 30 randomly chosen primary schools in Edinburgh, Scotland. PARTICIPANTS: 552 schoolchildren. MEASUREMENTS: Data on risk factors for infection were collected by questionnaire at ages 7 and 11. Saliva samples collected at age 11 were examined by GACRIA for evidence of previous infection with EBV. For 102 subjects, a second salivary specimen collected approximately one month after the first sample was available for testing as a measure of the repeatability of the method. MAIN RESULTS: Unequivocal results were found in 91% of samples and the repeatability of the test was good (kappa = 0.71). Fifty six per cent of children had antibodies to EBV. In a logistic regression analysis, independent risk factors for infection were sharing a room (odds ratio 1.78, 1.14, 2.79), head of household's social class IV/V compared with I (odds ratio 2.87, 1.08, 7.34), and schools serving predominantly rented housing estates (odds ratio 2.3, 1.09, 4.84). CONCLUSION: This study is the first application of EBV viral capsid GACRIA to salivary samples. The method was successfully used to describe the epidemiology of EBV. In this study, characteristics of the home seemed to be more important than those of the school in determining the likelihood of infection with EBV.

Adult↗
PubMed1998

Health effects of passive smoking. 4. Parental smoking, middle ear disease and adenotonsillectomy in children.

BACKGROUND: A systematic quantitative review was conducted of evidence relating parental smoking to acute otitis media, recurrent otitis media, middle ear effusion, and adenoidectomy and/or tonsillectomy. METHODS: Forty five relevant publications were identified after consideration of 692 articles selected by electronic search of the Embase and Medline databases using keywords relevant to passive smoking in children. The search was completed in April 1997 and identified 13 studies of acute otitis media, nine of recurrent otitis media, five of middle ear effusion, nine of glue ear surgery, and four of adenotonsillectomy. A quantitative meta-analysis was possible for all outcomes except acute otitis media, using random effects modelling where appropriate to pool odds ratios from each study. RESULTS: Evidence for middle ear disease is remarkably consistent, with pooled odds ratios if either parent smoked of 1.48 (95% CI 1.08 to 2.04) for recurrent otitis media, 1.38 (1.23 to 1.55) for middle ear effusion, and 1.21 (0.95 to 1.53) for outpatient or inpatient referral for glue ear. Odds ratios for acute otitis media are in the range 1.0 to 1.6. No single study simultaneously addresses selection bias, information bias and confounding, but where these have been investigated or excluded in the design or analysis, the associations with parental smoking persist virtually unchanged. Large French and British studies are inconsistent with regard to the association of parental smoking and tonsillectomy. CONCLUSIONS: There is likely to be a causal relationship between parental smoking and both acute and chronic middle ear disease in children.

Acute Disease↗
PubMed1998

Air pollution, pollens, and daily admissions for asthma in London 1987-92.

BACKGROUND: A study was undertaken to investigate the relationship between daily hospital admissions for asthma and air pollution in London in 1987-92 and the possible confounding and modifying effects of airborne pollen. METHODS: For all ages together and the age groups 0-14, 15-64 and 65+ years, Poisson regression was used to estimate the relative risk of daily asthma admissions associated with changes in ozone, sulphur dioxide, nitrogen dioxide and particles (black smoke), controlling for time trends, seasonal factors, calendar effects, influenza epidemics, temperature, humidity, and autocorrelation. Independent effects of individual pollutants and interactions with aeroallergens were explored using two pollutant models and models including pollen counts (grass, oak and birch). RESULTS: In all-year analyses ozone was significantly associated with admissions in the 15-64 age group (10 ppb eight hour ozone, 3.93% increase), nitrogen dioxide in the 0-14 and 65+ age groups (10 ppb 24 hour nitrogen dioxide, 1.25% and 2.96%, respectively), sulphur dioxide in the 0-14 age group (10 micrograms/m3 24 hour sulphur dioxide, 1.64%), and black smoke in the 65% age group (10 micrograms/m3 black smoke, 5.60%). Significant seasonal differences were observed for ozone in the 0-14 and 15-64 age groups, and in the 0-14 age group there were negative associations with ozone in the cool season. In general, cumulative lags of up to three days tended to show stronger and more significant effects than single day lags. In two-pollutant models these associations were most robust for ozone and least for nitrogen dioxide. There was no evidence that the associations with air pollutants were due to confounding by any of the pollens, and little evidence of an interaction between pollens and pollution except for synergism of sulphur dioxide and grass pollen in children (p < 0.01). CONCLUSIONS: Ozone, sulphur dioxide, nitrogen dioxide, and particles were all found to have significant associations with daily hospital admissions for asthma, but there was a lack of consistency across the age groups in the specific pollutant. These associations were not explained by confounding by airborne pollens nor was there convincing evidence that the effects of air pollutants and airborne pollens interact in causing hospital admissions for asthma.

Adolescent↗
PubMed1998

Health effects of passive smoking. 9. Parental smoking and spirometric indices in children.

BACKGROUND: A systematic quantitative review was conducted of the evidence relating parental smoking to spirometric indices in children. METHODS: An electronic search of the Embase and Medline databases was completed in April 1997 and identified 692 articles from which we included four studies in neonates, 42 cross-sectional studies in school aged children (22 were included in a meta-analysis), and six longitudinal studies of lung function development. RESULTS: In a pooled analyses of 21 surveys of school aged children the percentage reduction in forced expiratory volume in one second (FEV1) in children exposed to parental smoking compared with those not exposed was 1.4% (95% CI 1.0 to 1.9). Effects were greater on mid expiratory flow rates (5.0% reduction, 95% CI 3.3 to 6.6) and end expiratory flow rates (4.3% reduction, 95% CI 3.1 to 5.5). Adjustment for potential confounding variables had little effect on the estimates. A number of studies reported clear evidence of exposure response. Where exposure was explicitly identified it was usually maternal smoking. Two studies in neonates have reported effects of prenatal exposure to maternal smoking. Of five cross sectional studies that compared effects of perinatal exposure (retrospectively assessed) with current exposure to maternal smoking in later childhood, the three largest concluded that the major effect was in utero or neonatal exposure. Longitudinal studies suggest a small effect of current exposure on growth in lung function, but with some heterogeneity between studies. CONCLUSIONS: Maternal smoking is associated with small but statistically significant deficits in FEV1 and other spirometric indices in school aged children. This is almost certainly a causal relationship. Much of the effect may be due to maternal smoking during pregnancy.

Adolescent↗
PubMed1998

Health effects of passive smoking .5. Parental smoking and allergic sensitisation in children.

BACKGROUND: A systematic review was conducted of the effects of parental smoking on immunoglobulin (IgE) levels, skin prick positivity, and allergic rhinitis or eczema in children. Asthma was excluded in order to distinguish more clearly the effect of passive smoke exposure on allergic sensitisation. METHODS: Thirty six relevant publications were identified after consideration of 692 articles selected by electronic search of the Embase and Medline databases using keywords relevant to passive smoking in children. The search was completed in April 1997 and identified nine studies of IgE in neonates, eight of IgE in older children, 12 which included skin prick tests, and 10 describing symptoms of allergic disease other than asthma or wheezing. A quantitative meta-analysis was possible only for the studies reporting skin prick tests. RESULTS: Several large studies failed to confirm early reports of a substantial or statistically significant association of maternal smoking with concentrations of total serum IgE in neonates or in older children. No consistent association emerged between parental smoking and allergic rhinitis or eczema. Few of these studies adjusted for potential confounding variables. The quantity and quality of evidence was greatest for skin prick tests, and studies of parental smoking during pregnancy or infancy were broadly consistent in showing no adverse effect on prick positivity (pooled odds ratio 0.87, 95% confidence interval 0.62 to 1.24). There was much greater and statistically significant (p = 0.002) heterogeneity of odds ratios relating current parental smoking to skin prick positivity. CONCLUSIONS: Parental smoking, either before or immediately after birth, is unlikely to increase the risk of allergic sensitisation in children.

Adolescent↗
PubMed1998

Health effects of passive smoking. 6. Parental smoking and childhood asthma: longitudinal and case-control studies.

BACKGROUND: The relation of parental smoking to wheezing and asthma occurring after the first year of life was assessed by a systematic quantitative review of case-control and longitudinal studies, complementing earlier reviews of cross sectional surveys and wheezing in early childhood. METHODS: Fifty one relevant publications were identified after consideration of 1593 abstracts selected by electronic search of the Embase and Medline databases using keywords relevant to passive smoking in children. The search was completed in April 1997 and identified six studies of asthma incidence, seven of prognosis, 22 case-control studies, and 10 case series addressing disease severity. RESULTS: Maternal smoking was associated with an increased incidence of wheezing illness up to age 6 (pooled odds ratio 1.31, 95% CI 1.22 to 1.41), but less strongly thereafter (1.13, 95% CI 1.04 to 1.22). The long term prognosis of early wheezing illness was better if the mother smoked. The pooled odds ratio for asthma prevalence from 14 case-control studies was 1.37 (95% CI 1.15 to 1.64) if either parent smoked. Four studies suggest that parental smoking is more strongly associated with wheezing among non-atopic children. Indicators of disease severity including symptom scores, attack frequency, medication use, hospital attendance, and life threatening bronchospasm were in general positively related to household smoke exposure. CONCLUSIONS: The excess incidence of wheezing in smoking households appears to be largely non-atopic "wheezy bronchitis" with a relatively benign prognosis, but among children with established asthma, parental smoking is associated with more severe disease. This apparent paradox may be reconciled if environmental tobacco smoke is considered a co-factor provoking wheezing attacks, rather than a cause of the underlying asthmatic tendency.

Asthma↗
PubMed1998

Parental smoking, bronchial reactivity and peak flow variability in children.

BACKGROUND: A systematic quantitative review was conducted of the evidence relating environmental tobacco smoke to bronchial hyperresponsiveness (BHR) during childhood. METHODS: Twenty-nine relevant studies were identified after consideration of 1593 articles selected by electronic search of the Embase and Medline databases using keywords relevant to passive smoking in children. The search was completed in April 1997. RESULTS: Of 19 studies using challenge tests in children of school age, 10 (5759 children) could be summarised as the odds ratio of being bronchial hyperreactive in children exposed to environmental tobacco smoke compared with those not exposed. The pooled odds ratio for maternal smoking was 1.29 (95% confidence limits 1.10 to 1.50) with no evidence of heterogeneity between studies. However, in five further studies of 3531 children providing some evidence, but not odds ratios, none were statistically significant. A further four studies on 5233 children have collected data but are not published. In contrast, all four studies of circadian variation in peak expiratory flow found increased variation in children exposed to environmental tobacco smoke. CONCLUSIONS: A clear effect of exposure to environmental tobacco smoke on BHR in the general population has not been established. While the meta-analysis suggests a small but real increase in BHR in school aged children, it seems likely that this estimate is biased upwards due to publication bias. In contrast, limited evidence suggests greater variation in peak expiratory flow in children of smoking parents.

Adolescent↗
PubMed1998

Effects of changes in fresh fruit consumption on ventilatory function in healthy British adults.

Cross-sectional studies have shown frequent fresh fruit consumption to be associated with higher lung function in both children and adults. This relationship is investigated longitudinally in a national sample of 2,171 British adults age 18 to 73 initially examined in 1984, who were reexamined 7 yr later, and had no reported history of chronic respiratory disease throughout. Outcome was assessed by change in forced expiratory volume in one second (FEV1) between the two examinations, standardized for age, height, and sex and related to fresh fruit consumption estimated by food frequency questionnaires at both examinations. After adjustment for region, social class, and smoking, changes in fresh fruit consumption levels were positively associated with changes in FEV1 (p = 0.002), highlighted by a more marked fall in FEV1 (107 ml; 95% confidence interval, 36 to 178 ml) in subjects who reduced their fresh fruit consumption the greatest compared with those with no change. In contrast, average levels of fruit intake were not associated with change in FEV1 (p = 0.695). The implication is that the cross-sectional effects of fresh fruit consumption on ventilatory function appear to be reversible and not progressive, such that consistently low levels of fresh fruit intake do not appear to increase lung function decline.

Adolescent↗
PubMed1997

Investigation into the increase in hay fever and eczema at age 16 observed between the 1958 and 1970 British birth cohorts.

OBJECTIVE: To investigate whether changes in certain perinatal and social factors explain the increased prevalence of hay fever and eczema among British adolescents between 1974 and 1986. DESIGN: Two prospective birth cohort studies. SETTING: England, Wales, and Scotland. SUBJECTS: 11,195 children born 3-9 March 1958 and 9387 born 5-11 April 1970. MAIN OUTCOME MEASURES: Parental reports of eczematous rashes and of hay fever or allergic rhinitis in the previous 12 months at age 16. RESULTS: The prevalence of the conditions over the 12 month period increased between 1974 and 1986 from 3.1% to 6.4% (prevalence ratio 2.04 (95% confidence interval 1.79 to 2.32)) for eczema and from 12.0% to 23.3% (prevalence ratio 1.93 (1.82 to 2.06)) for hay fever. Both conditions were more commonly reported among children of higher birth order and those who were breast fed for longer than 1 month. Eczema was more commonly reported among girls and hay fever among boys. The prevalence of hay fever decreased sharply between social classes I and V, increased with maternal age up to the early 30s, and was lower in children whose mothers smoked during pregnancy. Neither condition varied significantly with birth weight. When adjusted for these factors, the relative odds of hay fever (1986 v 1974) increased from 2.23 (2.05 to 2.43) to 2.40 (2.19 to 2.63). Similarly, the relative odds of eczema rose from 2.02 (1.73 to 2.36) to 2.14 (1.81 to 2.52). CONCLUSIONS: Taken together, changes between cohorts in sex, birth weight, birth order, maternal age, breast feeding, maternal smoking during pregnancy, and father's social class at birth did not seem to explain any of the observed rise in the prevalence of hay fever and eczema. However, correlates of these factors which have changed over time may still underlie recent increases in allergic disease.

Adolescent↗
PubMed1997

The social origins of infantile colic: questionnaire study covering 76,747 infants.

OBJECTIVE: To describe risk factors for infantile colic. DESIGN: Questionnaire administered by health visitors. SETTING: Sheffield. SUBJECTS: Mothers of 76,747 infants born between 1 August 1975 and 31 May 1988, interviewed when the infant was 1 month old. MAIN OUTCOME MEASURES: Reporting of infantile colic and its duration; weight of infant leeding, state of the home, socioeconomic characteristics of the parents, parents' age, and mother's parity. RESULTS: The odds of reporting infantile colic were increased with breast feeding (odds ratio of breast v bottle feeding 1.35 (95% confidence interval 1.28 to 1.43)), increasing parental age, lower parity, increasing parental age at leaving full time education, and more affluent homes and districts of residence. In a logistic regression analysis, mother's age and parity and socioeconomic factors remained the most important risk factors for the reporting of infantile colic (each P < 0.005), and the effect of breast feeding was attenuated (odds ratio of breast v bottle feeding 1.09 (1.02 to 1.15)). CONCLUSION: At a population level, dietary factors contribute little to mothers' reporting of infantile colic, and dietary change should not be the primary intervention.

Age Factors↗
PubMed1997

Childhood antecedents of allergic sensitization in young British adults.

OBJECTIVE: This study was designed to investigate whether associations of self-reported hay fever with sibship size, birth order, infant feeding, and childhood socioeconomic status reflect variations in sensitization to common aeroallergens. METHODS: One thousand three hundred sixty-nine persons born throughout Britain in 1958 were followed up to age 34 to 35 years. The cohort included 1050 subjects with a history of asthma, wheezy bronchitis, wheezing, or pneumonia and 319 with no history of wheezing illness at ages 7, 11, 16, 23, or 33 years. Skin prick tests with extracts of mixed grass pollen, house dust mite (Der p 1), and cat fur were performed; and wheal diameters were measured. RESULTS: The prevalence of positive skin test results (> or = 3 mm wheal) was independently related (p < 0.01) to male sex, reduced numbers of older siblings (but not younger siblings), and higher socioeconomic status in childhood. Current cigarette smoking and maternal smoking during pregnancy were independently associated (p < 0.01) with a reduced prevalence of skin prick test positivity. No significant independent effects (p > 0.10) were found for adult social class, maternal age, birth weight, gestation, breast feeding, preschool nursery attendance, urban birthplace, or gas stove exposure. CONCLUSION: Factors related to small families and relative affluence in childhood promote atopic sensitization to a variety of aeroallergens in later life. These observations are consistent with the suggestion that early infection may protect against subsequent allergic disease.

Adult↗
PubMed1997

Relation of serum cytokine concentrations to cardiovascular risk factors and coronary heart disease.

OBJECTIVE: To determine whether serum concentrations of the cytokines tumour necrosis factor alpha (TNF alpha) and interleukin 6 (IL-6), which regulate C reactive protein, are associated with cardiovascular risk factors and prevalent coronary heart disease. DESIGN: A population based cross sectional study. SUBJECTS AND METHODS: 198 men aged 50 to 69 years were part of a random population sample drawn from south London. Serum cytokine and C reactive protein concentrations were determined by enzyme linked immunosorbent assay. The presence of coronary heart disease was determined by Rose angina questionnaire and Minnesota coded electrocardiogram. RESULTS: Serum TNF alpha concentrations were positively related to body mass index and Helicobacter pylori infection, but inversely related to alcohol consumption. IL-6 concentrations were positively associated with smoking, symptoms of chronic bronchitis, age, and father having a manual occupation. TNF alpha was associated with increased IL-6 and triglycerides, and reduced high density lipoprotein cholesterol. IL-6 was associated with raised fibrinogen, sialic acid, and triglycerides. ECG abnormalities were independently associated with increases in IL-6 and TNF alpha, each by approximately 50% (P < 0.05 for TNF alpha, P < 0.1 for IL-6). The corresponding increases in men with an abnormal ECG or symptomatic coronary heart disease were 28% for TNF alpha and 36% for IL-6 (P = 0.14 for TNF alpha and P < 0.05 for IL-6). CONCLUSIONS: This study confirms that many of the phenomena with which C reactive protein is associated, are also associated with serum levels of cytokine, which may be the mechanism.

Aged↗
PubMed1997

Systematic identification of twins by computerised searches of NHS patient registers in the UK.

OBJECTIVES: This study aimed to assess the feasibility, sensitivity, and specificity of a systematic search of the NHS central register for twins of the same sex. DESIGN, SETTING, AND SUBJECTS: Computerised searches by alphanumeric NHS number, sex, and date of birth of 1.6 million patients registered with general practitioners in Kent, followed by validation by postal questionnaire sent to 66 pairs of children, 129 pairs of adult twins, and one set of triplets. MAIN OUTCOME MEASURES: These were as follows: confirmed twin status, previous involvement in research, and willingness to participate in future research based on a twin register. RESULTS: The procedure was most efficient at identifying twins among children, in males born from 1930 onwards, and females born before 1940. Altogether 2397 male sets and 1684 female sets were identified as probable twins, triplets, or quadruplets with identical surnames, same dates of birth, and consecutive NHS numbers. Among a further 4004 pairs of adult females with the same dates of birth (1940-79), consecutive NHS numbers, but different (married) surnames, an estimated third are twins. Response to the postal questionnaire was 60% (197/327), including only one singleton. Only 10% of responders had previously participated in medical research, but 63% (65/103) of complete sets who responded expressed a willingness to participate in a twin register. CONCLUSIONS: A systematic search of the NHS central register could identify large numbers of British twins. The procedure is efficient, reasonably sensitive, and highly specific, if supplemented by additional information from birth records for adult females born after 1939. The potential exists to create an important new resource for twin studies in Britain.

Electronic Data Processing↗
PubMed1997

Trends in stroke mortality in Greater London and south east England--evidence for a cohort effect?

OBJECTIVE AND SETTING: To examine time trends in stroke mortality in Greater London compared with the surrounding South East Region of England. DESIGN: Age-cohort analysis based on routine mortality data. SUBJECTS: Resident population aged 45 years or more. MAIN OUTCOME MEASURE: Age specific stroke mortality rates, 1951-92. MAIN RESULTS: In 1951, stroke mortality was lower in Greater London than the surrounding South East Region in all age bands over 45. It has been declining in both areas but the rate of decline has been significantly slower in Greater London (p < 0.0001). The differences in rates of decline were such that stroke mortality is now higher in Greater London for people under 75. The crossover of age specific stroke mortality rates occurred at different periods in different age bands and is consistent with a cohort effect, with similar rates in Greater London and the surrounding south east for men and women born around 1916-21. This cohort effect does not appear to be consistent with past maternal and neonatal mortality rates in these areas, nor, within the limitations of the data, with the ethnic composition of cohorts. CONCLUSIONS: There seems to be a cohort effect on stroke mortality which is not explained by past maternal and neonatal mortality. If the decline in stroke mortality continues at its current rate, the Health of the Nation stroke target is unlikely to be achieved in Greater London.

Age Distribution↗
PubMed1997

Socioeconomic deprivation, ethnicity, and stroke mortality in Greater London and south east England.

OBJECTIVE AND SETTING: To examine geographical variation in stroke mortality in Greater London compared with the surrounding South East Region of England. DESIGN: Cross sectional, ecological analysis based on electoral wards. SUBJECTS: Resident population aged 45 years or more. MAIN OUTCOME MEASURE: Age specific stroke mortality rates in five age bands, 1986-92. MAIN OUTCOME MEASURE: Age specific stroke mortality rates in five age bands, 1986-92. MAIN RESULTS: In the 45-54 years age band, stroke mortality rate ratios (95% confidence intervals) relative to the surrounding south east were 2.09 (1.81, 2.4) for Inner London and 1.31 (1.15, 1.5) for Outer London for men and 1.64 (1.4, 1.93) and 1.13 (0.98, 1.31) respectively for women. This gradient diminished and reversed with increasing age. In the 85+ age band, rate ratios were 0.82 (0.76, 0.89) for Inner London and 0.89 (0.84, 0.94) for Outer London for men and 0.8 (0.75, 0.85) and 0.88 (0.84, 0.92) respectively for women. Carstairs deprivation index and the percentages of Afro-Caribbean men and women and Irish born men were significantly and positively correlated with stroke mortality at the ward level. The Carstairs effect diminished with increasing age. Adjustment for these variables diminished or abolished the higher stroke mortality risks in London for younger people but had little effect on the lower risks for older Londoners. CONCLUSIONS: Higher rates of stroke mortality among middle aged adults in Greater London, compared with the surrounding South East Region, are associated with socioeconomic deprivation and ethnicity. These factors do not explain the relatively lower stroke mortality among older Londoners.

Black or African American↗
PubMed1997

Health effects of passive smoking. 1. Parental smoking and lower respiratory illness in infancy and early childhood.

BACKGROUND: A systematic quantitative review was conducted of evidence relating parental smoking to acute lower respiratory illness in the first three years of life. METHODS: Fifty relevant publications were identified after consideration of 692 articles selected by electronic search of the Embase and Medline databases using keywords relevant to passive smoking in children. The search, completed in April 1997, identified 24 studies ascertaining illnesses in a community setting, including five surveys of schoolchildren with retrospective ascertainment of early chest illness, and 17 studies of admissions to hospital for lower respiratory illness in early life. Thirty eight studies were included in a quantitative overview using random effects modelling to derive pooled odds ratios. RESULTS: The results of community and hospital studies are broadly consistent, with only one publication reporting a reduced risk among children of smokers. The pooled odds ratios were 1.57 (95% CI 1.42 to 1.74) for smoking by either parent and 1.72 (95% CI 1.55 to 1.91) for maternal smoking. There is a significantly increased risk of early chest illness associated with smoking by other household members in families where the mother does not smoke (1.29, 95% CI 1.16 to 1.44). The associations with parental smoking are robust to adjustment for confounding factors, and show evidence of a dose-response relationship in most studies in which this has been investigated. CONCLUSIONS: The relationship between parental smoking and acute lower respiratory illness in infancy is very likely to be causal. Although it is impossible to distinguish the independent contributions of prenatal and postnatal maternal smoking, the increased risk associated with smoking by other household members suggests that exposure to environmental tobacco smoke after birth is a cause of acute chest illness in young children.

Acute Disease↗