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Biomedical subjects

D P Strachan

Publications and source records attributed to D P Strachan.

At least 109 records · Page 6Linked to original sources
PubMed1995

Mortality from cardiovascular disease among interregional migrants in England and Wales.

OBJECTIVE: To investigate the extent to which geographical variations in mortality from ischaemic heart disease and stroke in Britain are influenced by factors in early life or in adulthood. DESIGN: Longitudinal study of migrants. SUBJECTS: 1% sample of residents in England and Wales born before October 1939 and enumerated at the 1971 census (the Office of Population Censuses and Surveys' longitudinal study). MAIN OUTCOME MEASURE: 18,221 deaths from ischaemic heart disease and 9899 deaths from stroke during 1971-88 were analysed by areas of residence in 1939 and 1971. These included 2928 deaths from ischaemic heart disease and 1608 deaths from stroke among individuals moving between 14 areas defined by the major conurbations and nine standard administrative regions of England and Wales. RESULTS: The southeast to northwest gradient in mortality from ischaemic heart disease was related significantly to both the 1939 area (chi 2 = 6.09, df = 1) and area in 1971 (chi 2 = 5.05, df = 1). Geographical variations in mortality from stroke were related significantly to the 1939 area (chi 2 = 4.09, df = 1) but the effect of area in 1971 was greater (chi 2 = 8.07, df = 1). The effect of 1971 area on mortality from stroke was largely due to a lower risk of death from stroke among individuals moving into Greater London compared with migrants to the rest of the South East region (chi 2 = 4.54, df = 1). CONCLUSIONS: Geographical variations in mortality from cardiovascular disease in Britain may be partly determined by genetic factors, environmental exposures, or lifestyle acquired early in life, but the risk of fatal ischaemic heart disease and stroke changes on migration between areas with differing mortality. The low risk of death from stroke associated with residence in Greater London is acquired by individuals who move there.

Adult↗
PubMed1995

Health effects of an air pollution episode in London, December 1991.

BACKGROUND: In December 1991 London experienced a unique air pollution episode during which concentrations of nitrogen dioxide rose to record levels, associated with moderate increases in black smoke. The aim of this study was to investigate whether this episode was associated with adverse health effects and whether any such effects could be attributed to air pollution. METHODS: The numbers of deaths and hospital admissions occurring in Greater London during the week of the episode were compared with those predicted using data from the week before the episode and from equivalent periods from the previous four years. Relative risks (RR) (episode week versus predicted) for adverse health events were estimated using log linear modelling and these were compared with estimates from control areas which had similar cold weather but without increased air pollution. RESULTS: In all age groups mortality was increased for all causes (excluding accidents) (relative risk = 1.10) and cardiovascular diseases (1.14); non-significant increases were observed for all respiratory diseases (1.22), obstructive lung diseases (1.23), and respiratory infections (1.23). In the elderly (65 + years) the relative risk of hospital admission was increased for all respiratory diseases (1.19) and for obstructive lung diseases (1.43), and a non-significant increase was observed for ischaemic heart disease (1.04). In children (0-14 years) there was no increase in admissions for all respiratory diseases and only a small non-significant increase for asthma. When compared with control areas the relative risks became non-significant but remained increased. CONCLUSIONS: The air pollution episode was associated with an increase in mortality and morbidity which was unlikely to be explained by the prevailing weather, a coincidental respiratory epidemic, or psychological factors due to publicity. Air pollution is a plausible explanation but the relative roles of nitrogen dioxide and particulates cannot be distinguished.

Adolescent↗
PubMed1995

Vegetarian diet as a risk factor for tuberculosis in immigrant south London Asians.

BACKGROUND: In a previous retrospective study of tuberculosis in south London among Asian immigrants from the Indian subcontinent Hindu Asians were found to have a significantly increased risk for tuberculosis compared with Muslims. This finding has been further investigated by examining the role of socioeconomic and lifestyle variables, including diet, as risk factors for tuberculosis in Asian immigrants from the Indian subcontinent resident in south London. METHODS: Using a case-control study technique Asian immigrants from the Indian subcontinent diagnosed with tuberculosis during the past 10 years and two Asian control groups (community and outpatient clinic controls) from the Indian subcontinent were investigated. Cases and community controls were approached by letter. A structured questionnaire concerning a range of demographic, migration, socioeconomic, dietary, and health topics was administered by a single trained interviewer to subjects (56 cases and 100 controls) who agreed to participate. RESULTS: The results confirmed earlier findings that Hindu Asians had an increased risk of tuberculosis compared with Muslims. However, further analysis revealed that religion had no independent influence after adjustment for vegetarianism (common among Hindu Asians). Unadjusted odds ratios for tuberculosis among vegetarians were 2.7 (95% CI 1.1 to 6.4) using community controls, and 4.3 (95% CI 1.8 to 10.4) using clinic controls. There was a trend of increasing risk of tuberculosis with decreasing frequency of meat or fish consumption. Lactovegetarians had an 8.5 fold risk (95% CI 1.6 to 45.4) compared with daily meat/fish eaters. Adjustment for a range of other socioeconomic, migration, and lifestyle variables made little difference to the relative risks derived using either community or clinic controls. CONCLUSIONS: These results indicate that a vegetarian diet is an independent risk factor for tuberculosis in immigrant Asians. The mechanism is unexplained. However, vitamin D deficiency, common among vegetarian Asians in south London, is known to affect immunological competence. Decreased immunocompetence associated with a vegetarian diet might result in increased mycobacterial reactivation among Asians from the Indian subcontinent.

Adult↗
PubMed1995

Effect of ambient levels of smoke and sulphur dioxide on the health of a national sample of 23 year old subjects in 1981.

BACKGROUND: There is concern that, despite the fall in air pollution levels since the 1950s, there may still be adverse effects at current levels. A study was carried out to investigate the association between air pollution and respiratory symptoms in 23 year old subjects in 1981. METHODS: Data on cough, phlegm, and wheeze were available on 11,552 members of the 1958 national birth cohort. Counties in the UK were ranked by annual average level of black smoke and sulphur dioxide (SO2), and then divided into five groups. The subject's county of residence determined their categorisation of pollution exposure. The association between air pollution exposure and respiratory symptoms was examined by logistic regression, adjusting for social class, sex, and smoking. RESULTS: The ranges of the air pollution groups were 2.0-13.0, 13.1-18.7, 19.6-20.8, 21.0-25.8, and 26.1-55.1 micrograms/m3 for black smoke, and 7.0-36.4, 36.7-42.7, 43.0-50.5, 52.0-59.3, and 60.9-87.7 micrograms/m3 for SO2. The overall prevalences of cough, phlegm, wheezing since age 16, and wheezing in the past year were 13.3%, 10.3%, 9.4%, and 4.4%, respectively. Phlegm symptoms increased with increasing smoke levels with evidence of a plateau. Cough and wheeze were not associated with black smoke; no symptom was associated with SO2. In the subgroup with wheeze at ages 16-23 there was no effect of smoke level on phlegm. CONCLUSIONS: Low ambient levels of black smoke were associated with decreased prevalence of phlegm symptoms in young adults in the UK in 1981. The effect was evident below the current EC guideline of 34-51 micrograms/m3 annual black smoke. In 1991 the annual mean smoke level for each county ranged from 3.4 to 26.5 micrograms/m3, spanning all but the last exposure group used here. This is consistent with the existence of adverse and possibly chronic effects at current levels.

Adult↗
PubMed1994

Helicobacter pylori infection in childhood: risk factors and effect on growth.

OBJECTIVE: To investigate the current prevalence of Helicobacter pylori infection in childhood, the risk factors for infection, and the effect of infection on growth in preadolescent schoolchildren. DESIGN: Population based sample of 7 year old schoolchildren followed up at age 11; data on risk factors for infection collected at age 7; presence of infection at age 11 determined by measurement of salivary IgG against H pylori by a newly developed enzyme linked immunosorbent assay (ELISA). Height was measured at 7 and 11 years of age. SUBJECTS: 554 schoolchildren from Edinburgh. RESULTS: 62 (11%) children had H pylori infection. Independent risk factors for infection were single parent families (adjusted odds ratio = 2.5; 95% confidence interval 1.1 to 5.7), the 10% most crowded homes (3.1; 1.3 to 7.2), and schools serving predominantly rented housing estates (2.5; 1.0 to 6.5). School catchment area was more important than parental social class or housing tenure. Growth in height between 7 and 11 was diminished in infected children by a mean of 1.1 cm (0.3 to 2.0 cm) over four years. This growth reduction was largely confined to girls (1.6 cm over four years), among whom it correlated with salivary IgG (P = 0.015). CONCLUSION: Data from salivary assay to investigate the epidemiology of H pylori suggest that factors relating to the type of community in which the child lives may now be as important for acquisition of this infection as features of the family home. The greater reduction of growth among infected girls raises the possibility that H pylori infection may delay or diminish the pubertal growth spurt.

Child↗
PubMed1994

Trends in prevalence and severity of childhood asthma.

OBJECTIVE: To test the null hypothesis that there has been no change in the prevalence or severity of childhood asthma over recent years. DESIGN: Repeated population prevalence survey with questionnaires completed by parents followed by home interviews with parents. SETTING: London borough of Croydon, 1978 and 1991. SUBJECTS: All children in one year of state and private primary schools aged 7 1/2 to 8 1/2 years at screening survey. MAIN OUTCOME MEASURES: Trends in symptoms, acute severe attacks, and chronic disability. RESULTS: For 1978 and 1991 respectively, the response rates were 4147/4763 and 3070/3786, and home interviews were obtained from 273/288 and 319/395 parents of currently wheezy children. Between 1978 and 1991 there were significant relative increases in prevalence ratios in the 12 month prevalence of attacks of wheezing or asthma (1.16; 95% confidence interval 1.02 to 1.31), the one month prevalence of wheezing episodes (1.78; 1.15 to 2.74), and the one month prevalence of night waking (1.81; 1.01 to 3.23) but not in frequent (> or = 5) attacks over the past year (1.05; 0.79 to 1.40). There were substantial and significant decreases in the 12 month prevalence of absence from school of more than 10 days due to wheezing (0.52; 0.30 to 0.90), any days in bed (0.67; 0.44 to 1.01), and restriction of activities at home (0.51; 0.31 to 0.83) and an equivalent but not significant fall in speech limiting attacks (0.51; 0.24 to 1.11). CONCLUSION: The small increase in the prevalence of wheezy children and relatively greater increase in persistent wheezing suggests a change in the environmental determinants of asthma. In contrast and paradoxically the frequency of wheezing attacks remains unchanged and there are indications that severe attacks and chronic disability have fallen by about half; this may be due to an improvement in treatment received by wheezy children.

Activities of Daily Living↗
PubMed1994

Childhood eczema: disease of the advantaged?

OBJECTIVE: To determine whether the increased prevalence of childhood eczema in advantaged socioeconomic groups is due to increased parental reporting. DESIGN: Comparison of parental reports of eczema with visible eczema recorded by medical officers during a detailed physical examination. SETTING: National birth cohort study. SUBJECTS: 8279 children from England, Wales, and Scotland born during 3-9 March 1958 and followed up at the ages of 7, 11, and 16. MAIN OUTCOME MEASURES: Prevalence of eczema according to parental report compared with medical officer's examination at the ages of 7, 11, and 16. RESULTS: Prevalence of both reported and examined eczema increased with rising social class at the ages of 7, 11, and 16 years. The point prevalence of examined eczema at age 7 was 4.8%, 3.6%, 3.6%, 2.4%, 2.2%, and 2.4% in social classes I, II, III non-manual, III manual, IV, and V respectively (chi 2 value for linear trend 12.6, P < 0.001). This trend persisted after adjustment for potential confounders such as region and family size and was not present for examined psoriasis or acne. CONCLUSIONS: Eczema is more prevalent among British schoolchildren in social classes I and II than those in lower classes. Exposures associated with social class are probably at least as important as genetic factors in the expression of childhood eczema.

Adolescent↗
PubMed1994

Passive exposure to tobacco smoke in children aged 5-7 years: individual, family, and community factors.

OBJECTIVE: To examine the importance of parental smoking on passive exposure to tobacco smoke in children and the social and geographical patterns of exposure. DESIGN: Cross sectional study. SETTING: Schools in 10 towns in England and Wales; five towns with high adult cardiovascular mortality and five with low rates. SUBJECTS: 4043 children aged 5-7 years of European origin. MAIN OUTCOME MEASURES: Salivary cotinine concentration and parents self reported smoking habits. RESULTS: 1061 (53.0%) children were exposed to cigarette smoke at home or by an outside carer. Geometric mean cotinine rose from 0.29 (95% confidence interval 0.28 to 0.31) ng/ml in children with no identified exposure to 4.05 (3.71 to 4.42) ng/ml in households where both parents smoked and 9.03 (6.73 to 12.10) ng/ml if both parents smoked more than 20 cigarettes a day. The effect of mothers' smoking was greater than that of fathers', especially at high levels of consumption. After adjustment for known exposures geometric mean cotinine concentrations rose from 0.52 ng/ml in social class I to 1.36 ng/ml in social class V (P < 0.0001); and were doubled in high mortality towns compared with the low mortality towns (P = 0.002). In children with no identified exposure similar trends by social class and town were observed and the cotinine concentrations correlated with the prevalence of parental smoking, both between towns (r = 0.69, P = 0.02) and between schools within towns (r = 0.50, P < 0.001). CONCLUSIONS: Mothers' smoking is more important that fathers' despite the lower levels of smoking by mothers. Children not exposed at home had low cotinine concentration, the level depending on the prevalence of smoking in the community.

Age Factors↗
PubMed1994

Patient characteristics associated with the labelling of asthma.

Patient characteristics associated with the asthma label were investigated in 262 children, aged 8 years, who reported wheezing illness in the previous 12 months. Children were first identified by a screening questionnaire administered to the parents of all 8 year old schoolchildren in Croydon, south London. Interviews were conducted with those reported to have had a wheezing illness in the previous 12 months to obtain details of the child's illness, medical care, demographic and socioeconomic characteristics. Multivariate analysis showed that the likelihood of being labelled asthmatic was increased in those who had a parental history of hayfever [odds ratio (OR) = 2.24, 95% confidence interval (CI) = 1.22-4.14] or at least two allergic provoking factors (OR = 3.83, 95% CI = 1.44-10.15). No significant associations were found between asthma labelling and children's socioeconomic characteristics or use of general practitioner services. These findings suggest that wheeze is likely to be labelled asthma when the clinical history suggests an allergic aetiology.

Asthma↗
PubMed1994

Chest illness in infancy and chronic respiratory disease in later life: an analysis by month of birth.

BACKGROUND: Cohorts born at different times of year differ in their risk of exposure to seasonal respiratory infections in early life, but are likely to have similar socioeconomic status and lifestyle thereafter. METHODS: We investigated the long-term consequences of acute chest illness in infancy for later development of chronic respiratory disease by analysing variations by month of birth in hospital admissions for respiratory illness (total n = 49,866), chronic respiratory symptoms and ventilatory function among British school children (n = 11,482) and middle-aged adults (total n = 55,829). RESULTS: Admission for bronchiolitis in the first year of life was three times more common for infants born September to November (autumn) than those born March to May, yet people born in the autumn experienced fewer respiratory symptoms and had better ventilatory function. In two surveys of middle-aged men, forced expiratory volume in one second/forced ventilatory capacity (FEV1/FVC) was significantly (P = 0.025) higher among autumn births. Hospital admissions for chronic bronchitis/emphysema and pneumonia varied little with season of birth. Admissions for asthma were significantly (P < 0.05) more common among children and young adults born in the autumn. CONCLUSIONS: These findings do not support the hypothesis of a causal link between chest illness in infancy and the later development of chronic bronchitis and emphysema. The variation in asthma admissions with month of birth deserves further investigation.

Adult↗
PubMed1994

A national survey of asthma prevalence, severity, and treatment in Great Britain.

Parents of 5472 children aged 5-17 years from 3209 families were interviewed in a nationwide household survey. In the past year, 15.0% of children had wheezed, 2.2% had more than 12 attacks, and 2.3% had experienced a speech limiting attack. Altogether 4.3% were woken more than once a week by wheezing, 13.1% had doctor diagnosed asthma, and 13.6% had been prescribed antiasthmatic drugs in the past year. With increasing age, morbidity related to wheezing declined to a greater extent than annual period prevalence. The prevalence of wheeze varied little by socioeconomic group, but there were marked trends in all three indices of severity towards increased morbidity in poorer families. Diagnostic labelling and drug treatment of wheezy children did not differ substantially with socioeconomic status. Thus, a degree of socioeconomic equality exists in the process of medical care for childhood asthma in Britain. This does not appear to have resulted in equality of outcome.

Adolescent↗
PubMed1994

Psoriasis and eczema are not mutually exclusive diseases.

BACKGROUND: Some reports have suggested that psoriasis and eczema are seldom found together. Knowledge of disease co-occurrence could lead to improved understanding of shared or opposing pathological mechanisms. OBJECTIVE: We sought to determine whether psoriasis and eczema could exist simultaneously and consecutively in the same individuals. METHODS: Skin examination data relating to 9,263 British children born during March 3rd to 9th, 1958 (the National Child Development Survey), were analysed for the co-occurrence of eczema and psoriasis. RESULTS: Of 354 children with visible eczema at the ages of 11 or 16 years, 5 (1.4%) were also noted to have visible psoriasis, compared to 89 (1.0%) of 8,909 children who did not have visible eczema at 11 or 16 years. The relative risk of psoriasis in a case of eczema was 1.41, 95% confidence intervals from 0.58 to 3.46. CONCLUSION: Contrary to some hospital-based studies which have suggested that the two diseases are seldom found together, this study of a large and representative population suggests that eczema and psoriasis may co-occur concurrently and consecutively in the same individual.

Adolescent↗
PubMed1993

Time trends in respiratory symptoms in childhood over a 24 year period.

Two cross sectional surveys, 24 years apart, using the same respiratory questionnaire, were carried out to examine changes in prevalence rates of cough, phlegm, and wheeze and to relate changes in wheeze to objective peak expiratory flow rates (PEFRs). The surveys were done in towns in southern and northern England and South Wales in schoolchildren aged 6.0-7.5 years; n = 1655 in 1966 and n = 2323 in 1990. Parents reported on winter cough and winter phlegm (early morning or day/night) and wheeze; PEFRs were also measured. The proportion of children reported as wheezing on most days or nights increased from 3.9% to 6.1% (95% confidence interval (CI) for increase -0.2 to 4.6), with a smaller increase in the prevalence of those who had ever wheezed. The proportion of children with day or night time cough increased from 21.1% to 33.3% (95% CI for increase 3.8 to 20.6) and the proportion with day or night time phlegm increased from 5.8% to 10.0% (95% CI for increase 0.4 to 8.0). Smaller increases in the prevalence of persistent cough (from 9.0% to 12.4%) and persistent phlegm (from 2.4% to 3.5%) were also observed, while morning cough and morning phlegm showed little change. The increases in cough and phlegm were apparent in subjects with and without a history of wheeze. Both absolute and proportional changes in symptom prevalence were generally greater in the north than in the south. Similar social class trends were seen in each survey. The mean difference in PEFR between subjects with and without wheeze was smaller in 1990 than in 1966, but this result could be influenced by a greater proportion of subjects receiving antiasthmatic treatment in the 1990 survey. These apparent increases in the prevalence of persistent wheeze, day and night time cough and phlegm, occurring over a period during which outdoor air pollution levels have decreased substantially, deserve further investigation.

Child↗