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Biomedical subjects

D P Strachan

Publications and source records attributed to D P Strachan.

At least 127 records · Page 7Linked to original sources
PubMed1993

Relation of passive smoking as assessed by salivary cotinine concentration and questionnaire to spirometric indices in children.

BACKGROUND: Previous studies of the effects of passive exposure to smoke on spirometric indices in children have largely relied on questionnaire measures of exposure. This may have resulted in underestimation of the true effect of passive smoking. Biochemical measures offer the opportunity to estimate recent exposure directly. METHODS: The relation between spirometric indices and passive exposure to tobacco smoke was examined in a large population sample of 5-7 year old children from 10 towns in England and Wales. The effects of passive exposure to smoke on lung function were assessed by means of both salivary cotinine concentration and questionnaire measurements of exposure. Analyses of the relation between spirometric values and cotinine concentrations were based on 2511 children and of the relation between spirometric values and questionnaire measures on 2000 children. RESULTS: Cotinine concentration was negatively associated with all spirometric indices after adjustment for confounding variables, which included age, sex, body size, and social class. The strongest association was with mid expiratory flow rate (FEF50), the fall between the bottom and top fifths of the cotinine distribution being 6%, equivalent to a reduction of 14.3 (95% confidence limits (CL) 8.6, 20.0) ml/s per ng/ml cotinine. Salivary cotinine concentrations were strongly related to exposure to cigarette smoke at home but 88% of children who were from non-smoking households and not looked after by a smoker had detectable cotinine concentrations, 5% being in the top two fifths of the cotinine distribution. A composite questionnaire score based on the number of regular sources of exposure was as strongly related to mid and end expiratory flow rates as the single cotinine measure. The fall in FEF50 per smoker to whom the child was exposed was 51.0 (26.5, 75.5) ml/s. The relationships between the questionnaire score and forced vital capacity (FVC) or forced expiratory volume in one second (FEV1) were not statistically significant. CONCLUSIONS: These effects of passive smoking on respiratory function are consistent with the results of previous studies and, although small in absolute magnitude, may be important if the effects of exposure are cumulative. In children aged 5-7 years the use of a single salivary cotinine concentration as a marker of passive exposure to smoke resulted in clear relationships between exposure and FVC and FEV1, whereas the associations were much weaker and not significant when based on the questionnaire score. The associations between exposure and mid or end expiratory flow rates were of similar magnitude for cotinine concentration and the questionnaire score. The use of salivary cotinine concentration in longitudinal studies may help to determine the extent to which these effects are cumulative or reversible.

Biomarkers↗
PubMed1993

Socioeconomic characteristics of interregional migrants in England and Wales, 1939-71.

"Data from the Longitudinal Study (LS) of the Office of Population Censuses and Surveys are used to examine patterns of regional migration in England and Wales between 1939 and 1971. The source of information on region in 1939 is from a national population register established shortly after the start of the Second World War." The results suggest that "overall, 18% of persons in the analysis moved between regions from 1939 to 1971. Migrants tended to be socioeconomically advantaged compared with nonmigrants. Moreover, those moving to regions where the nonmigrants were the most advantaged, were themselves the most advantaged of the migrants. This paper illustrates a new source of data on long-term migration that deserves further exploration."

Demography↗
PubMed1992

Ventilatory function, height, and mortality among lifelong non-smokers.

STUDY OBJECTIVE: The aims were to determine the relationship between spirometric indices and mortality among lifelong non-smokers, and to investigate whether the association of short stature with increased risk of death is explained by reduced levels of ventilatory function in shorter men. DESIGN: The study was a nested (within cohort) case-control analysis of an 18 year prospective study of mortality. SUBJECTS: Participants were 3452 male civil servants aged 40-64 years at entry who denied ever having smoked tobacco. MEASUREMENTS AND MAIN RESULTS: 408 men who died were matched to 2874 controls of the same age and height. Reduced one second forced expiratory volume (FEV1) was associated with mortality from non-respiratory causes (rate ratio per litre decrease = 1.44, 95% confidence interval 1.196-1.73). The ratio of FEV1 to forced vital capacity was a weak predictor of mortality. Among 397 case-control sets matched for age and FEV1, mortality was unrelated to height. Comparing mortality differentials across age adjusted tertiles of each risk factor, height adjusted FEV1 was a stronger predictor of death than height, body mass index, or plasma cholesterol. FEV1 adjusted for age but not for height was almost as strong a predictor as systolic blood pressure. CONCLUSIONS: The determinants of ventilatory function in lifelong non-smokers may include causes of premature death. FEV1 may be a more sensitive indicator than height of early life influences upon mortality.

Adult↗
PubMed1992

Asthma from birth to age 23: incidence and relation to prior and concurrent atopic disease.

BACKGROUND: Few studies present prospective data on the incidence of asthma. Its associations with sex and with prior and concurrent hay fever and eczema were examined in a nationally representative sample followed from birth to 23 years of age (British 1958 birth cohort). METHODS: Reports of asthma or wheezy bronchitis, hay fever and eczema were obtained by interview of parents of children at ages 7, 11, and 16 years, and of cohort members at age 23 years. Linked data from all four interviews were available on 7225 subjects (43% of the original birth cohort). RESULTS: The cumulative incidence of asthma or wheezy bronchitis was 18.2%, 21.8%, 24.5%, and 28.6% by the ages of 7, 11, 16, and 23 years respectively. Over the four incidence periods examined (0 to 7 years, 8 to 11 years, 12 to 16 years, 17 to 23 years) the average annual incidence of new cases was 2.6%, 1.1%, 0.71%, and 0.76% respectively. The male:female incidence ratio rose from 1.23 in the 0 to 7 year period to 1.48 at 12 to 16 years but had reversed to 0.59 at 17 to 23 years. A prior report of hay fever or eczema each increased the subsequent incidence of asthma or wheezy bronchitis by a factor of 1.7 to 2.0 independently of sex. This effect of prior atopic illness, however, was largely explained by the strong independent association of incidence of asthma and wheezy bronchitis with atopic disease at the end of each incidence period (odds ratios 2.0 to 2.5 per atopic condition, p < 0.01). CONCLUSIONS: Gender differences in the incidence of asthma or wheezy bronchitis vary with age and are not explained by atopy. The incidence of asthma or wheezy bronchitis can be predicted from a clinical history of hay fever or eczema but is more strongly associated with the presence of atopic disease at the time of onset.

Adolescent↗
PubMed1992

Determinants of passive smoking in children in Edinburgh, Scotland.

OBJECTIVES: Using saliva cotinine as a quantitative marker, we examined the contribution of factors other than parental smoking to children's passive exposure to tobacco smoke. METHODS: Saliva specimens from a random sample of 734 7-year-old schoolchildren in Edinburgh, Scotland, were analyzed for cotinine. Their parents completed a questionnaire covering smoking habits and conditions in the home. RESULTS: A number of independent predictors of cotinine were identified in addition to the main one of smoking by household members. These predictors included home ownership, social class, day of the week, season of the year, number of parents present, crowding in the home, the number of children in the household, and sex. Cotinine was higher in children from less advantaged backgrounds, during winter, on Mondays, in girls, and when fewer other children were present. The effects were similar between children from nonsmoking and smoking homes. CONCLUSIONS: Questionnaire measures of parental smoking are insufficient to fully characterize young children's exposure to passive smoking. Because socioeconomic variables contribute to measured exposure, passive-smoking studies that treat class as a confounder and control for it may be overcontrolling.

Child↗
PubMed1991

Ventilatory function as a predictor of fatal stroke.

OBJECTIVE: To investigate the relation between ventilatory function and subsequent mortality due to cerebrovascular disease. DESIGN: Prospective longitudinal study. SUBJECTS: A total of 18,403 male civil servants aged 40-64 years at entry examination for the Whitehall study. MAIN OUTCOME MEASURE: Mortality from cerebrovascular disease (ICD8 430-438) after 18 years of follow up. RESULTS: In all, 262 men with sinus rhythm at entry died due to stroke during the 18 years of follow up. Compared with men with a forced expiratory volume in one second of greater than or equal to 3.5 litres those with a value of less than 3.0 litres were almost twice as likely to die of cerebrovascular disease (rate ratio adjusted for age and systolic blood pressure = 1.88, 95% confidence interval 1.32 to 2.69). This increased risk occurred within each tertile of systolic blood pressure. Nested case-control analyses were used to control precisely for confounding effects of age, height, and smoking (by matching) and employment grade and physiological risk factors (by modelling). The effect of forced expiratory volume in one second was independent of age, height, smoking habits, employment grade, blood pressure, weight, cholesterol concentration, glucose tolerance, electrocardiographic abnormalities, history of chest pain, and history of intermittent claudication. CONCLUSIONS: Measurements of ventilatory function may assist clinical decisions about whether to treat mild hypertension. Impaired ventilatory function and stroke may share common causes.

Adult↗
PubMed1991

Predictors of death from aortic aneurysm among middle-aged men: the Whitehall study.

Among 18,403 male civil servants examined at age 40-64 years there were 99 deaths attributed to aortic aneurysm during 18 years of follow-up. Each case was matched by age to ten controls who survived longer than the case. The risk of all types of fatal aneurysm was substantially increased for current smokers of manufactured cigarettes (rate ratio compared with lifelong non-smokers = 6.5; 95 per cent confidence interval 2.3-18.7), pipe or cigars (6.7; 1.7-26.5) and hand-rolled cigarettes (25.0; 7.5-83.3). Diastolic blood pressure was strongly associated with dissecting aneurysm (rate ratio per 10 mmHg increase = 2.4; 95 per cent confidence interval 1.7-3.2) and abdominal aneurysm (1.5; 1.2-1.9) but not other aneurysms (1.0; 0.7-1.5). The independent effects of height, adiposity, plasma cholesterol, glucose intolerance, reported angina and intermittent claudication were not significant. Hypertension and smoking, particularly of hand-rolled cigarettes, are confirmed as major and potentially remediable risk factors for fatal aortic aneurysm.

Aged↗
PubMed1991

Ventilatory function and winter fresh fruit consumption in a random sample of British adults.

The relation between ventilatory function and the reported frequency of consumption of fresh fruit and fruit juice was studied among 1502 lifelong non-smokers and 1357 current smokers aged 18-69 with no history of chronic respiratory disease. Forced expiratory volume in one second (FEV1) was assessed by turbine spirometry. As winter fruit consumption was more widely dispersed than summer consumption and few subjects ate fruit more frequently in the winter, winter fruit consumption was taken as an indicator of habitual (year round) consumption. After adjustment for sex, age, height, cigarette consumption, region of residence, and household socioeconomic group, FEV1 was associated with winter fruit consumption. The mean adjusted FEV1 among those who never drank fresh fruit juice and ate fresh fruit less than once a week during the winter was 78 ml lower (95% confidence interval 24-132 ml) than the mean for the other subjects. A similar difference was found in all age-sex groups and among both current smokers and lifelong non-smokers. Antioxidant and other actions of vitamin C may protect against pulmonary emphysema, or reduce bronchoconstrictor responses to environmental pollutants.

Adolescent↗
PubMed1990

Impedance tympanometry and the home environment in seven-year-old children.

The distribution of tympanogram types among 872 seven-year-old children from a random population sample was related to 14 features of the home environment reported by parents in a questionnaire. Parental smoking was an important determinant of middle ear underpressure and effusion, and accounted for much of the associations observed with dampness, crowding and rented accommodation. Gas cooking was associated with a higher prevalence of effusion, but a lower prevalence of underpressure; this may deserve further study. After adjustment for seasonal variation, tenure and household smokers, the weekly mean temperature in the bedrooms of 34 children with Type B tympanograms was 18.2 degrees C, compared to 17.9 degrees C for 190 children with Type A tympanograms. The equivalent figures for bedroom relative humidity were 51.8 per cent and 52.7 per cent. It is unlikely that heating or ventilation of the home is an important determinant of middle ear effusion and underpressure in this age-group.

Acoustic Impedance Tests↗
PubMed1990

Regional variations in wheezing illness in British children: effect of migration during early childhood.

STUDY OBJECTIVE: The aim was to examine the regional distribution of wheezing illness among British children, and the age at which geographical differences may be determined. DESIGN: Cross sectional analyses and study of interregional migrants were used. SUBJECTS: The subjects were national cohorts of British children born in 1958 and 1970. MEASUREMENTS AND MAIN RESULTS: The regional distribution of wheezing illness showed significant heterogeneity at age 5 (1970 cohort) and 7 (1958 cohort). In both cohorts, children in Scotland had a low prevalence of wheeze, which could not be attributed to underreporting of mild cases. There was a less consistent tendency for high prevalence in Wales, and in the South Western and Midlands regions of England. In the 1958 cohort, the regional differentials diminished progressively with age and were negligible at age 23. There was a poor correlation between the regional distribution of childhood asthma and the common geographical pattern shown by eczema in infancy and hay fever at age 23. Analysis of interregional migrants suggested that the regional variation in each cohort at age 5-7 was primarily related to the region of current residence, and not to the region of birth. CONCLUSIONS: Genetic constitution, perinatal exposures, or early childhood experiences are unlikely to account for the regional variation in wheezing illness. Although local patterns of symptom reporting or disease labelling may be acquired by parents who move to a new region, environmental factors operating at a regional level probably determine the prevalence of asthma in primary school children. These influences do not appear to have long lasting effects upon the tendency to wheeze in adolescence and early adulthood.

Adolescent↗
PubMed1990

Quantification of airborne moulds in the homes of children with and without wheeze.

A population survey of 1000 7 year old children found a significant excess of wheeze among children whose homes were reported to be mouldy (odds ratio 3.70, 95% confidence limits 2.22, 6.15). The airborne mould flora was quantified by repeated volumetric sampling during the winter in three rooms of the homes of 88 children. All of these had previously completed spirometric tests before and after a six minute free running exercise challenge. Total airborne mould counts varied from 0 to 41,000 colony forming units (CFU)/m3, but were generally in the range 50-1500 CFU/m3, much lower than the concentrations found outdoors in summer. The principal types of fungi identified are all known to be common out of doors, and most were found on at least one occasion in most of the homes. Median and geometric mean total mould counts were not related to reports of visible mould in the home, or to a history of wheeze in the index child. The heterogeneous group of non-sporing fungi (mycelia sterilia) were the only airborne fungi present at significantly higher concentrations in the homes of wheezy children (geometric mean 2.1 v 0.7 CFU/m3. A non-significant increase in total mould counts was observed in the homes of children with a 10% or greater decline in FEV1 after exercise (geometric mean 354 v 253 CFU/m3). Questionnaire reports of mould in the home may be a poor indicator of exposure to airborne spores. The total burden of inhaled mould spores from indoor sources is probably not an important determinant of wheeze among children in the general population. Although the association with mycelia sterilia could be a chance finding, these non-sporing isolates may include a potent source of allergen.

Bronchi↗
PubMed1990

The relationship of salivary cotinine to respiratory symptoms, spirometry, and exercise-induced bronchospasm in seven-year-old children.

The effects of passive tobacco smoke exposure upon respiratory symptoms and lung function were assessed in a cross-sectional survey of 770 children 7 yr of age, using cotinine as a quantitative biochemical marker of exposure. Salivary cotinine levels were strongly related to the number of smokers in the home, but three-quarters of children from nonsmoking households had detectable salivary cotinine, and 10% of this group were in the upper two-fifths of the distribution of measured tobacco smoke exposure. Smoking by persons other than members of the household may deserve greater attention in future studies of young children. After adjustment for housing tenure, most respiratory symptoms were unrelated to salivary cotinine, but a "tendency for colds to go to the chest" was twice as prevalent in the upper two-fifths as in the lower two-fifths of the cotinine distribution. No association was found between salivary cotinine and reports of wheeze or measured reduction in FEV1 after 6 min of free running. After adjustment for sex, height, test conditions, and housing tenure, all baseline spirometric indices except FVC were inversely associated with salivary cotinine. Only FEF75-85 and FEF75 were significantly reduced, the difference for each index between the top and bottom quintiles of the cotinine distribution being about 7%, equivalent to a reduction of 1.1% (95% CL, 0.1 to 2.1%) per doubling of cotinine concentration. These changes may be evidence of small airways damage, which could later progress to more severe respiratory impairment.

Asthma↗
PubMed1989

Passive smoking, salivary cotinine concentrations, and middle ear effusion in 7 year old children.

OBJECTIVE: To assess the contribution of passive exposure to tobacco smoke to the development of middle ear underpressure and effusion. DESIGN: Cross sectional observational study. SETTING: One third of the primary schools in Edinburgh. SUBJECTS: 892 Children aged 6 1/2 to 7 1/2 were examined, and satisfactory tympanograms were obtained in 872. Results of assay of salivary cotinine concentrations were available for 770 children, and satisfactory tympanograms were available for 736 of these. END POINT: Correlation of the prevalence of middle ear underpressure and effusion with concentrations of the marker of nicotine, cotinine, in the saliva of the children. MEASUREMENTS AND MAIN RESULTS: Middle ear pressure and compliance were measured in both ears by impedance tympanometry. Salivary cotinine concentrations were assayed by gas-liquid chromatography. Cotinine concentrations increased with the number of smokers in the household. Girls had higher concentrations than boys, and children living in rented housing had higher concentrations than those living in housing owned by their parents. There was a trend towards more abnormal tympanometric findings with increasing cotinine concentration, the odds ratio for a doubling of the cotinine concentration being 1.14 (95% confidence interval 1.03 to 1.27). After adjustment for the sex of the child and housing tenure the odds ratio for a doubling of the cotinine concentration was 1.13 (1.00 to 1.28). CONCLUSIONS: The results of this study are consistent with those of case-control studies of children attending for an operation to relieve middle ear effusion. They indicate that the disease should be added to the list of recognised hazards associated with passive smoking. About one third of the cases of middle ear effusion in this study were statistically attributable to exposure to tobacco smoke.

Acoustic Impedance Tests↗