The beginnings of chronic airflow obstruction

Early childhood lower respiratory tract infection and premature adult death from respiratory disease in Great Britain: a national birth cohort study

BACKGROUND

Lower respiratory tract infections (LRTIs) in early childhood are known to influence lung development and lifelong lung health, but their link to premature adult death from respiratory disease is unclear. We aimed to estimate the association between early childhood LRTI and the risk and burden of premature adult mortality from respiratory disease.

METHODS

This longitudinal observational cohort study used data collected prospectively by the Medical Research Council National Survey of Health and Development in a nationally representative cohort recruited at birth in March, 1946, in England, Scotland, and Wales. We evaluated the association between LRTI during early childhood (age <2 years) and death from respiratory disease from age 26 through 73 years. Early childhood LRTI occurrence was reported by parents or guardians. Cause and date of death were obtained from the National Health Service Central Register. Hazard ratios (HRs) and population attributable risk associated with early childhood LRTI were estimated using competing risks Cox proportional hazards models, adjusted for childhood socioeconomic position, childhood home overcrowding, birthweight, sex, and smoking at age 20-25 years. We compared mortality within the cohort studied with national mortality patterns and estimated corresponding excess deaths occurring nationally during the study period.

FINDINGS

5362 participants were enrolled in March, 1946, and 4032 (75%) continued participating in the study at age 20-25 years. 443 participants with incomplete data on early childhood (368 [9%] of 4032), smoking (57 [1%]), or mortality (18 [<1%]) were excluded. 3589 participants aged 26 years (1840 [51%] male and 1749 [49%] female) were included in the survival analyses from 1972 onwards. The maximum follow-up time was 47·9 years. Among 3589 participants, 913 (25%) who had an LRTI during early childhood were at greater risk of dying from respiratory disease by age 73 years than those with no LRTI during early childhood (HR 1·93, 95% CI 1·10-3·37; p=0·021), after adjustment for childhood socioeconomic position, childhood home overcrowding, birthweight, sex, and adult smoking. This finding corresponded to a population attributable risk of 20·4% (95% CI 3·8-29·8) and 179 188 (95% CI 33 806-261 519) excess deaths across England and Wales between 1972 and 2019.

INTERPRETATION

In this prospective, life-spanning, nationally representative cohort study, LRTI during early childhood was associated with almost a two times increased risk of premature adult death from respiratory disease, and accounted for one-fifth of these deaths.

FUNDING

National Institute for Health and Care Research Imperial Biomedical Research Centre, Royal Brompton and Harefield National Health Service (NHS) Foundation Trust, Royal Brompton and Harefield Hospitals Charity and Imperial College Healthcare NHS Trust, UK Medical Research Council.

Effects of Smoking and Physical Activity on the Pulmonary Function of Young University Nursing Students in Cáceres (Spain)

Background:

The simultaneous effect of physical activity (PA) and smoking on pulmonary function in young people remains unclear.

Propose:

The aim of this study was to determine the influence of smoking and PA on pulmonary function in young university students in Cáceres, Spain.

Methods:

A sample of 120 young nursing students was studied (60 smokers and 60 nonsmokers). All subjects underwent spirometry with a COPD-6 portable device, and their level of PA was quantified using the International Physical Activity Questionnaire. The influence of PA and smoking on pulmonary function was determined by comparing hypotheses.

Results:

Significant differences were observed between smokers and nonsmokers in terms of percent forced expiratory volume in 1 second, percent forced expiratory volume in 6 seconds, lung age, and the difference between lung age and chronological age (LA–CA) in those who practiced mild PA. In the subjects who performed moderate and vigorous PA, these differences were not noted. In the intragroup analysis, significant differences were observed in smokers in terms of percent forced expiratory volume in 1 second, percent forced expiratory volume in 6 seconds, lung age, and LA–CA; however, in the control group, differences were only observed in terms of lung age and LA–CA. These findings were confirmed in the multivariate analysis.

Conclusions/Implications for Practice:

Our findings confirmed a deterioration in pulmonary function in smokers who did not perform moderate or vigorous PA. The level of PA performed was positively related to pulmonary function in smokers, whereas in nonsmokers, improvements were only significant in LA–CA.

Combined Impact of Smoking and Early-Life Exposures on Adult Lung Function Trajectories

RATIONALE

Both adverse early-life exposures and adult smoking can negatively influence adult lung function trajectory, but few studies consider how the impact of early-life exposures may be modified by subsequent smoking.

METHODS

The Medical Research Council National Survey of Health and Development is a nationally representative cohort, initially of 5,362 individuals, followed since enrollment at birth in March 1946. Using data collected prospectively across life and multilevel modeling, we investigated how the relationships between early-life exposures (infant lower respiratory infection, manual social class, home overcrowding, and pollution exposure) and FEV₁ and FVC trajectories between ages 43 and 60-64 years were influenced by smoking behavior.

MEASUREMENTS AND MAIN RESULTS

Among 2,172 individuals, there were synergistic interactions of smoking with infant respiratory infection (P = 0.04) and early-life home overcrowding (P = 0.009), for FEV₁ at 43 years. Within smoker-stratified models, there were FEV₁ deficits among ever-smokers associated with infant lower respiratory infection (-108.2 ml; P = 0.001) and home overcrowding (-89.2 ml; P = 0.002), which were not evident among never-smokers (-15.9 ml; P = 0.69 and -13.7 ml; P = 0.70, respectively). FVC modeling, including 1,960 individuals, yielded similar results. FEV₁ decline was greater in smokers (P < 0.001), but there was no effect of any early-life exposure on FEV₁ decline. Neither smoking nor early-life exposures were associated with FVC decline.

CONCLUSIONS

Besides accelerating adult FEV₁ decline, cigarette smoking also modifies how early-life exposures impact on both midlife FEV₁ and FVC. These findings are consistent with smoking impairing pulmonary development during adolescence or early adulthood, thereby preventing catch-up from earlier acquired deficits.

Pediatric bronchiectasis: No longer an orphan disease

Bronchiectasis is described classically as a chronic pulmonary disorder characterized by a persistent productive cough and irreversible dilatation of one or more bronchi. However, in children unable to expectorate, cough may instead be wet and intermittent and bronchial dilatation reversible in the early stages. Although still considered an orphan disease, it is being recognized increasingly as causing significant morbidity and mortality in children and adults in both affluent and developing countries. While bronchiectasis has multiple etiologies, the final common pathway involves a complex interplay between the host, respiratory pathogens and environmental factors. These interactions lead to a vicious cycle of repeated infections, airway inflammation and tissue remodelling resulting in impaired airway clearance, destruction of structural elements within the bronchial wall causing them to become dilated and small airway obstruction. In this review, the current knowledge of the epidemiology, pathobiology, clinical features, and management of bronchiectasis in children are summarized. Recent evidence has emerged to improve our understanding of this heterogeneous disease including the role of viruses, and how antibiotics, novel drugs, antiviral agents, and vaccines might be used. Importantly, the management is no longer dependent upon extrapolating from the cystic fibrosis experience. Nevertheless, substantial information gaps remain in determining the underlying disease mechanisms that initiate and sustain the pathophysiological pathways leading to bronchiectasis. National and international collaborations, standardizing definitions of clinical and research end points, and exploring novel primary prevention strategies are needed if further progress is to be made in understanding, treating and even preventing this often life-limiting disease.

Risk of current asthma among adult smokers with respiratory syncytial virus illnesses in early life

RATIONALE

Risk of subsequent asthma-like symptoms after early-life lower respiratory illness (LRI) caused by respiratory syncytial virus (RSV) is increased during the first decade of childhood and diminished thereafter by adolescence.

OBJECTIVES

To determine the relation of early-life RSV-LRI on adult asthma-like symptoms and its interactive role with adult smoking.

METHODS

A total of 1,246 nonselected infants were enrolled at birth and prospectively followed. Virologically confirmed RSV-LRIs were assessed during the first 3 years of life. At age 22, 24, 26, and 29 years, current asthma and smoking behavior were evaluated by questionnaire. Peak flow variability was assessed at age 26 and expressed as amplitude % mean. A longitudinal analysis was used to investigate the relation of RSV-LRI and active smoking to adult outcomes.

MEASUREMENTS AND MAIN RESULTS

Neither RSV-LRI nor active smoking were directly associated with increased current adult asthma or peak flow variability. However, there was a significant interaction between RSV-LRI and active smoking in relation to current asthma (P for interaction = 0.004) and peak flow variability (P for interaction = 0.04). Among subjects with early RSV-LRI, those who actively smoked were 1.7 times more likely to have current asthma (95% confidence interval, 1.2-2.3; P = 0.003) and had greater amplitude % mean (10.0% vs. 6.4%; P = 0.02) than nonsmokers. Among subjects without early RSV-LRI, there was no difference in asthma risk or peak flow variability between active smokers and nonsmokers.

CONCLUSIONS

Smoking is associated with increased risk of having asthma in young adults who had RSV-LRI in early life but not among subjects without these illnesses.

Prenatal development is linked to bronchial reactivity: epidemiological and animal model evidence

Chronic cardiorespiratory disease is associated with low birthweight suggesting the importance of the developmental environment. Prenatal factors affecting fetal growth are believed important, but the underlying mechanisms are unknown. The influence of developmental programming on bronchial hyperreactivity is investigated in an animal model and evidence for comparable associations is sought in humans. Pregnant Wistar rats were fed either control or protein-restricted diets throughout pregnancy. Bronchoconstrictor responses were recorded from offspring bronchial segments. Morphometric analysis of paraffin-embedded lung sections was conducted. In a human mother-child cohort ultrasound measurements of fetal growth were related to bronchial hyperreactivity, measured at age six years using methacholine. Protein-restricted rats' offspring demonstrated greater bronchoconstriction than controls. Airway structure was not altered. Children with lesser abdominal circumference growth during 11–19 weeks' gestation had greater bronchial hyperreactivity than those with more rapid abdominal growth. Imbalanced maternal nutrition during pregnancy results in offspring bronchial hyperreactivity. Prenatal environmental influences might play a comparable role in humans.

Long term respiratory consequences of intrauterine growth restriction

Epidemiological studies demonstrate that in-utero growth restriction and low birth weight are associated with impaired lung function and increased respiratory morbidity from infancy, throughout childhood and into adulthood. Chronic restriction of nutrients and/or oxygen during late pregnancy causes abnormalities in the airways and lungs of offspring, including smaller numbers of enlarged alveoli with thicker septal walls and basement membranes. The structural abnormalities and impaired lung function seen soon after birth persist or even progress with age. These changes are likely to cause lung symptomology through life and hasten lung aging.

Relation of early childhood growth and wheezing phenotypes to adult lung function

RATIONALE

Several studies have reported associations between indicators of birth size and postnatal growth rates with levels of pulmonary function achieved as adults. The objective of this study was to determine if levels and/or rates of weight gain, measured in early life (birth-6 years), are associated with FVC or FEV1 levels achieved in young adulthood and if these associations differ by early childhood wheezing phenotypes.

METHODS

We used data from participants in the Tucson Children's Respiratory Study (CRS), a prospective birth cohort study. Weight was measured quarterly up to age 3 years and again at age 6 years. Pulmonary function was assessed at ages 16 and 22. Mean weight and slope of weight growth between 3 and 6 years were estimated using standardized residuals. Longitudinal models were used to determine predictors of FVC and FEV1 at ages 16 and 22 years.

RESULTS

There were 127 non-Hispanic white subjects that had at least four weight measures and one or more pulmonary function measures as young adults. After adjusting for sex, height, and age, the standardized slope of weight growth (between 3 and 6 years) was positively associated with higher levels of FVC at age 16 and 22 years (P = 0.0001) among subjects who did not have preschool wheezing. However, this association was completely absent among subjects who had wheezing lower respiratory tract illnesses in the first 3 years of life. Similar trends were found for FEV1.

CONCLUSION

The rate of weight gain between 3 and 6 years is significantly positively related to adult FVC and FEV1 and this association is modified by early wheezy phenotypes.

Perinatal stress and early life programming of lung structure and function

Exposure to environmental toxins during critical periods of prenatal and/or postnatal development may alter the normal course of lung morphogenesis and maturation, potentially resulting in changes that affect both structure and function of the respiratory system. Moreover, these early effects may persist into adult life magnifying the potential public health impact. Aberrant or excessive pro-inflammatory immune responses, occurring both locally and systemically, that result in inflammatory damage to the airway are a central determinant of lung structure-function changes throughout life. Disruption of neuroendocrine function in early development, specifically the hypothalamic-pituitary-adrenal (HPA) axis, may alter functional status of the immune system. Autonomic nervous system (ANS) function (sympathovagal imbalance) is another integral component of airway function and immunity in childhood. This overview discusses the evidence linking psychological factors to alterations in these interrelated physiological processes that may, in turn, influence childhood lung function and identifies gaps in our understanding.

Association between lung function and cognition among children in a prospective birth cohort study

OBJECTIVES

To examine the relationship between lung function and cognition among children in the Maternal-Infant Smoking Study of East Boston, a prospective cohort of women and children enrolled before 20 weeks of gestation. A number of studies have demonstrated a relationship between lung function and cognition among adults, but this relationship has not been studied among children.

METHODS

At 6 years of age, children completed lung function tests. At 9 years of age, the Wide Range Assessment of Memory and Learning (WRAML) and Kaufman Brief Intelligence Test (K-BIT) were administered. Linear regression was used to assess the relationship between cognition and lung function.

RESULTS

The sample of 165 children included 53% girls and 52% Hispanic. Mean (+/- standard deviation) forced expiratory volume in 1 second (FEV (1)) was 1.26 +/- 0.2 L; mean forced vital capacity (FVC) was 1.37 +/- 0.2 L. In multivariate regression, a 1% increase from expected FEV(1) was associated with increases in the matrices and composite subscales of the K-BIT (p < .05), and in the verbal and learning subscales of the WRAML (p < .10). FVC was associated with increases in the composite and matrices subscale of the KBIT and in the visual and learning subscales of the WRAML (all p < .05).

CONCLUSION

Increased lung function was associated with increased cognitive development among children after adjusting for tobacco exposure, birthweight, and peak blood lead. Lung and cognitive function may operate under common regulatory processes and thus have shared vulnerabilities to a host of environmental factors during development.

Violence exposure, a chronic psychosocial stressor, and childhood lung function

OBJECTIVE

Chronic psychosocial stressors, including violence, and neuropsychological and behavioral development in children as well as physiologic alterations that may lead to broader health effects.

METHODS

We studied the relationship between violence and childhood lung function in a prospective birth cohort of 313 urban children (age range = 6-7 years). Mothers reported on their child's lifetime exposure to community violence (ETV) and interparental conflict in the home (Conflict Tactics Scale (CTS)) within 1 year of the lung function assessment.

RESULTS

In linear regression analyses, adjusting for maternal education, child's age, race, birthweight, tobacco smoke exposure, and medical history, girls in the highest CTS verbal aggression tertile had a 5.5% (95% confidence interval (CI) = -9.6, -1.5) decrease in percent predicted forced expiratory volume (FEV(1)) and a 5.4% (95% CI = -9.7, -1.1) decrease in forced vital capacity (FVC) compared with girls in the lowest tertile. The CTS verbal aggression subscale was associated with lung function among boys in the same direction, albeit this was not statistically significant. Boys in the highest ETV tertile had a 3.4% (95% CI = -8.0, 1.1) lower FEV(1) and 5.3% lower FVC (95% CI = -10.2, -0.4) compared with boys in the lowest tertile. The ETV score was not a significant predictor of girls' lung function.

CONCLUSIONS

Interparental conflict, specifically verbal aggression, and ETV were associated with decreased childhood lung function independent of socioeconomic status, tobacco smoke exposure, birthweight, and respiratory illness history. Gender differences were noted based on the type of violence exposure, which may warrant further exploration.

Maternal and child undernutrition: consequences for adult health and human capital

In this paper we review the associations between maternal and child undernutrition with human capital and risk of adult diseases in low-income and middle-income countries. We analysed data from five long-standing prospective cohort studies from Brazil, Guatemala, India, the Philippines, and South Africa and noted that indices of maternal and child undernutrition (maternal height, birthweight, intrauterine growth restriction, and weight, height, and body-mass index at 2 years according to the new WHO growth standards) were related to adult outcomes (height, schooling, income or assets, offspring birthweight, body-mass index, glucose concentrations, blood pressure). We undertook systematic reviews of studies from low-income and middle-income countries for these outcomes and for indicators related to blood lipids, cardiovascular disease, lung and immune function, cancers, osteoporosis, and mental illness. Undernutrition was strongly associated, both in the review of published work and in new analyses, with shorter adult height, less schooling, reduced economic productivity, and--for women--lower offspring birthweight. Associations with adult disease indicators were not so clear-cut. Increased size at birth and in childhood were positively associated with adult body-mass index and to a lesser extent with blood pressure values, but not with blood glucose concentrations. In our new analyses and in published work, lower birthweight and undernutrition in childhood were risk factors for high glucose concentrations, blood pressure, and harmful lipid profiles once adult body-mass index and height were adjusted for, suggesting that rapid postnatal weight gain--especially after infancy--is linked to these conditions. The review of published works indicates that there is insufficient information about long-term changes in immune function, blood lipids, or osteoporosis indicators. Birthweight is positively associated with lung function and with the incidence of some cancers, and undernutrition could be associated with mental illness. We noted that height-for-age at 2 years was the best predictor of human capital and that undernutrition is associated with lower human capital. We conclude that damage suffered in early life leads to permanent impairment, and might also affect future generations. Its prevention will probably bring about important health, educational, and economic benefits. Chronic diseases are especially common in undernourished children who experience rapid weight gain after infancy.

Candidate genes controlling pulmonary function in mice: transcript profiling and predicted protein structure

Impaired development and reduced lung capacity are risk factors of asthma and chronic obstructive pulmonary disease. Previously, our genomewide linkage analysis of C3H/HeJ (C3H) and JF1/Msf (JF1) mouse strains identified quantitative trait loci (QTLs) associated with the complex traits of dead space volume (Vd), total lung capacity (TLC), lung compliance (CL), and diffusing capacity for CO (D(CO)). We assessed positional candidate genes by comparing C3H with JF1 lung transcript levels by microarray and by comparing C3H, BALB/cByJ, C57BL/6J, A/J, PWD/PhJ, and JF1 strains, using exon sequencing to predict protein structure. Microarray identified >900 transcripts differing in C3H and JF1 lungs related to lung development, function, and remodeling. Of these, three genes localized to QTLs associated with differences in lung function. C3H and JF1 strains differed in transcript and protein levels of superoxide dismutase 3, extracellular [SOD3; mouse chromosome (mCh) 5: VD] and transcript of trefoil factor 2 (TFF2; mCh 17: TLC and D(CO)), and ectonucleotide pyrophosphatase/phosphodiesterase 2 (ENPP2; mCh 15: TLC and CL). Nucleotide sequencing of Sod3, Tff2, and previously identified Relaxin 1 (Rln1; mCh 19: CL) uncovered polymorphisms that could lead to nonsynonymous amino acid changes and altered predicted protein structure. Gene-targeted Sod3(-/-) mice had increased conducting airway volume (Vd/TLC) compared with strain-matched control Sod3(+/+) mice, consistent with the QTL on mCh 5. Two novel genes (Tff2 and Enpp2) have been identified and two suspected genes (Sod3 and Rln1) have been supported as determinants of lung function in mice. Findings with gene-targeted mice suggest that SOD3 is a contributing factor defining the complex trait of conducting airway volume.

Airflow obstruction in young adults in Canada

OBJECTIVE

Airflow obstruction is relatively uncommon in young adults, and may indicate potential for the development of progressive disease. The objective of the present study was to enumerate and characterize airflow obstruction in a random sample of Canadians aged 20 to 44 years.

SETTING

The sample (n=2962) was drawn from six Canadian sites.

DESIGN

A prevalence study using the European Community Respiratory Health Survey protocol was conducted. Airflow obstruction was assessed by spirometry. Bronchial responsiveness, skin reactivity to allergens and total serum immunoglobulin E were also measured. Logistic regression was used for analysis.

RESULTS

Airflow obstruction was observed in 6.4% of the sample, not associated with sex or age. The risk of airflow obstruction increased in patients who had smoked and in patients who had lung trouble during childhood. Adjusted for smoking, the risk of airflow obstruction was elevated for subjects with past and current asthma, skin reactivity to allergens, elevated levels of total immunoglobulin E and bronchial hyper-responsiveness. Of the subjects with airflow obstruction, 21% were smokers with a history of asthma, 50% were smokers without asthma, 12% were nonsmokers with asthma and 17% were nonsmokers with no history of asthma. Bronchial hyper-responsiveness increased the prevalence of airflow obstruction in each of these groups.

CONCLUSION

Smoking and asthma, jointly and individually, are major determinants of obstructive disorders in young adults. Bronchial hyper-responsiveness contributes to obstruction in both groups.

Chronic airway diseases in adult life and childhood infections

BACKGROUND

Respiratory disorders in childhood may predispose to pulmonary disease in late adult life.

OBJECTIVES

The aim of this study was to evaluate the relationship between their effects in adult life and the characteristics of the respiratory system in childhood.

METHODS

A total of 10,224 parents and grandparents of students from 14 randomly selected primary schools in the city center were asked to answer questionnaires given to their children. 9,853 of 10,224 persons (the overall response rate was 96.3%) were eligible for analysis. In the questionnaire subjects were asked about respiratory system-related symptoms and characteristics.

RESULTS

Chronic cough [14.3 vs. 4.7%, OR 3.4 (2.6-4.4), p < 0.001], chronic bronchitis [35.3 vs. 11.8%, OR 4.0 (3.4-4.8), p < 0.001] and asthma [34.2 vs. 5.1%, OR 9.6 (8.0-11.5), p < 0.001] in the childhood respiratory infection group were more common than in the control group. Childhood respiratory infections were associated with an increased risk of asthma (OR 5.6, p < 0.001), chronic bronchitis (OR 2.3, p < 0.001) and chronic cough (OR 1.5, p < 0.001), after adjusting for possible confounding factors. In addition, the presence of dampness or visible mould, wall-to-wall carpets, pets at home and parents' smoking during childhood were associated with an increased risk of frequent childhood respiratory infections.

CONCLUSION

These results indicated that frequent respiratory infections during childhood might play an important role in the occurrence of chronic airway diseases in adult life. The removing of risk factors for frequent childhood respiratory infections may reduce the subsequent risk of chronic airway disease in late adult life.

Altered airway responsiveness in adult sheep born prematurely: effects of allergen exposure

The aim of this study was to determine the effects of preterm birth per se on airway function in adult sheep. Preterm birth was induced at approximately 0.89 of term. At approximately 1 year of age the authors measured pulmonary resistance (RL) and airway responsiveness before and after house dust mite (HDM) challenge. Mature preterm sheep tended to have greater baseline RL than controls (P = .12): the smaller preterm sheep showed significantly greater RL than controls following bronchoconstrictor challenge. Preterm animals tended to have greater baseline total blood leukocyte count (P = .06). It was concluded that preterm sheep, especially with low postnatal growth, have greater airway responsiveness to bronchoconstrictor and higher baseline RL.

Cause-specific hospital admission and mortality among working men: association with socioeconomic circumstances in childhood and adult life, and the mediating role of daily stress

BACKGROUND

The aim of this study was to investigate the association of childhood and adulthood social class with the occurrence of specific diseases, including those not associated with a high mortality rate, and to investigate daily stress as the mechanism for that part of any association which cannot be accounted for by established risk factors.

METHODS

This was a prospective cohort study with 25 years of follow-up for cause-specific morbidity and mortality. A total of 5577 Scottish men were recruited from 27 workplaces in the West of Scotland. Childhood social class was determined from the occupation held by the individual's father, and adulthood social class from the individual's occupation at enrolment. Daily stress was measured at enrolment using the Reeder Stress Inventory.

RESULTS

Health differentials were found for cardiovascular diseases, lung cancer, peptic ulcer, asthma, accidents and violence, alcohol-related diseases, and perhaps psychiatric illness. Adulthood circumstances were associated with the incidence of most diseases in adulthood, the exception being stroke, which was strongly associated with less privileged circumstances in childhood. Both childhood and adulthood circumstances contributed to the incidence of coronary heart disease. Daily stress did not underlie any of these associations once the influence of established risk factors had been taken into account.

CONCLUSIONS

Socioeconomic circumstances in childhood and adulthood both contribute to health differentials in adulthood, the relative contributions depending upon the particular disease. Where known risk factors explained only part of the excess of a disease among individuals raised or living in less-privileged circumstances, there was no evidence to suggest that daily stress was the reason for the unexplained excess.

Cumulative deprivation and cause specific mortality. A census based study of life course influences over three decades

OBJECTIVE

To examine whether increasing cumulative deprivation has an incremental effect on total as well as cause specific mortality.

DESIGN

Census data on housing conditions as indicators of deprivation from 1960, 1970, and 1980 were linked to 1990-98 death registrations. Relative indices of inequalities were computed for housing conditions to measure the cumulative impact of differences in social conditions.

PARTICIPANTS

97 381 (71.1%) 30-49 year old and 70701 (80.0%) 50-69 year old inhabitants of Oslo, Norway, in 1990 with census information on housing conditions and recorded length of education.

MAIN RESULTS

Mortality risk was increased when all censuses' housing conditions were summed in both age groups and sex. The cause specific analysis indicated such an effect particularly for coronary heart disease, chronic obstructive lung disease, and smoking related cancers. Violent deaths were essentially associated with housing conditions closer to the time of death in men in both age groups and in young women.

CONCLUSIONS

To fully account for socially mediated risk of death, a full life course approach should be adopted. The relative importance of each stage seems to vary by cause of death.

[Socioeconomic circumstances and premature mortality from chronic diseases]

BACKGROUND AND OBJECTIVE

Our aim was to investigate the association between socioeconomic factors in childhood or adolescence and adulthood and premature mortality from various causes of death.

SUBJECTS AND METHOD

Men and women aged 25-74 years residing on May 1, 1996, in the Autonomous Community of Madrid. For the next 19 months, information on individuals who died and the cause of death were obtained from the Mortality Register. We estimated the mortality from 5 types of cancer and from 4 chronic diseases by the educational level--as an indicator of the socioeconomic circumstances in childhood or adolescence--and by income--as an indicator of the socioeconomic circumstances in adulthood.

RESULTS

When both variables were included in the analysis simultaneously, the relative mortality ratio for men with second grade first phase and lower educational level versus those with second grade, second phase and higher educational level and the relative mortality ratio for men belonging to income quartiles 3 and 4 (lowest) versus those belonging to quartiles 1 and 2 were, respectively: 1.15 (95% confidence interval 1.01-1.31) and 1.22 (1.09-1.36) for lung cancer; 1.46 (1.19-1,93) and 1.13 (0.90-1.41) for gastric cancer; 1.80 (1.32-2.44) and 1.46 (1.18-1.80) for chronic obstructive pulmonary disease; and 1.18 (0.77-1.81) and 0.68 (0.47-0.98) for diabetes mellitus. For women the relative mortality ratios were, respectively: 0.63 (0.43-0.92) and 0.72 (0.52-0.99) for lung cancer; 1.68 (0.99-2.83) and 1.17 (0.86-1.60) for gastric cancer; 0.76 (0.61-0.94) and 0.98 (0.82-1.16) for breast cancer; 1.36 (0.95-1.95) and 1.20 (0.97-1.48) for ischemic heart disease; 1.72 (1.19-2.50) and 0.93 (0.75-1.16) for stroke; and 2.23 (0.94-5.27) and 1.51 (1.02-2.25) for diabetes mellitus.

CONCLUSIONS

Premature mortality in adulthood is associated with several socioeconomic factors acting across the whole course of life. The contribution of these socioeconomic circumstances to mortality varies regarding the cause of death and gender.

Influence of intrauterine growth restriction on airway development in fetal and postnatal sheep

Epidemiologic studies suggest that intrauterine growth restriction (IUGR) can lead to impaired lung function, yet little information exists on the effects of IUGR on airway development. Our objectives were to characterize morphometrically effects of IUGR on airway structure in the fetus and to determine whether alterations persist into postnatal life. We used two groups of sheep, each with appropriate controls; a fetal group was subjected to IUGR by restriction of placental function from 120 to 140 d (term approximately 147 d), and a postnatal group, killed 8 wk after birth, was subjected to IUGR from 120 d to birth at term. In both fetuses and postnatal lambs, IUGR did not alter lung weight relative to body weight. In IUGR fetuses, the luminal areas and basement membrane perimeters of the trachea and larger bronchi (generations 0-8, trachea = 0) were smaller than in controls. Airway wall areas, relative to basement membrane perimeters, were reduced in IUGR fetuses compared with controls, largely due to reduced areas of cartilage and epithelium. At 8 wk after birth, there were no significant differences in airway dimensions between IUGR and control lambs. However, the number of profiles of bronchial submucosal glands, relative to basement membrane perimeters, was lower in IUGR lambs than in controls and the area of epithelial mucin was increased. We conclude that restriction of fetal growth during late gestation impairs the growth of bronchial walls that could affect airway compliance in the immediate postnatal period. Although airway growth deficits are reversed by 8 wk, alterations in mucus elements persist.

Temporal and spatial relations between age specific mortality and ambient air quality in the United States: regression results for counties, 1960-97

OBJECTIVE

To investigate longitudinal and spatial relations between air pollution and age specific mortality for United States counties (except Alaska) from 1960 to the end of 1997.

METHODS

Cross sectional regressions for five specific periods using published data on mortality, air quality, demography, climate, socioeconomic status, lifestyle, and diet. Outcome measures are statistical relations between air quality and county mortalities by age group for all causes of death, other than AIDS and trauma.

RESULTS

A specific regression model was developed for each period and age group, using variables that were significant (p<0.05), not substantially collinear (variance inflation factor <2), and had the expected algebraic sign. Models were initially developed without the air pollution variables, which varied in spatial coverage. Residuals were then regressed in turn against current and previous air quality, and dose-response plots were constructed. The validity of this two stage procedure was shown by comparing a subset of results with those obtained with single stage models that included air quality (correlation=0.88). On the basis of attributable risks computed for overall mean concentrations, the strongest associations were found in the earlier periods, with attributable risks usually less than 5%. Stronger relations were found when mortality and air quality were measured in the same period and when the locations considered were limited to those of previous cohort studies (for PM(2.5) and SO(4)(2-)). Thresholds were suggested at 100-130 microg/m(3) for mean total suspended particulate (TSP), 7-10 microg/m(3) for mean sulfate, 10-15 ppm for peak (95th percentile) CO, 20-40 ppb for mean SO(2.) Contrary to expectations, associations were often stronger for the younger age groups (<65 y). Responses to PM, CO, and SO(2) declined over time; responses in elderly people to peak O(3) increased over time as did responses to NO(2) for the younger age groups. These results generally agreed with previous prospective cohort and ecological studies for comparable periods, age groups, and pollutants, but they also suggest that the results of those previous studies may no longer be applicable.

CONCLUSIONS

Spatially derived relations between air quality and mortality vary significantly by age group and period and may be sensitive to the locations included in the analysis.

Body mass index and the risk of COPD

BACKGROUND

Previous studies have documented the prognostic value of low body weight in patients with COPD and also in general populations. However, it is not clear whether low body weight is a risk factor for COPD or a consequence of established disease.

STUDY OBJECTIVE

To determine whether asymptomatic subjects with low initial body mass were at a greater risk of having COPD develop during subsequent follow-up.

DESIGN AND SUBJECTS

Observational retrospective study of 458 male and 192 female participants (age range, 40 to 73 years) in the Baltimore Longitudinal Study of Aging. At baseline, the participants did not have COPD. After mean follow-up periods of 10.2 years for the men and 6.4 years for the women, 40 men and 7 women received a diagnosis of COPD.

METHODS

Cox proportional-hazards regression models were used to assess the relationship between COPD diagnosis and baseline body mass index (BMI) in men.

RESULTS

The risk of COPD developing in men varied inversely with baseline BMI, even after adjusting for other risk factors, including cigarette smoking, age, FEV(1) percent predicted, abdominal obesity, and educational status. In men, the relative risk of COPD developing for the lowest BMI tertile relative to the highest tertile was 2.76 (95% confidence interval, 1.15 to 6.59). The small number of women who had COPD did not allow us to draw conclusions regarding BMI as a risk factor for COPD.

CONCLUSION

After controlling for confounding variables, men with low BMI are at increased risk for getting COPD.

Compromised respiratory function in postnatal lambs after placental insufficiency and intrauterine growth restriction

Epidemiologic studies have shown persistent effects of low birth weight on respiratory function and lung health, but underlying mechanisms are not understood. Our aim was to determine the effects of intrauterine growth restriction (IUGR), a major cause of low birth weight, on postnatal respiratory function. IUGR was induced by umbilico-placental embolization during late gestation in chronically catheterized sheep. Umbilico-placental embolization was performed between 120 d of gestation and term ( approximately 146 d) during which fetuses were hypoxemic and hypoglycemic relative to controls. Umbilico-placental embolization led to a 48% reduction in birth weight compared with controls, and throughout the postnatal study period IUGR lambs (n = 8) remained lighter than controls (n = 8). Respiratory function was repeatedly studied in lambs for 8 wk after birth; during this period, IUGR lambs were mildly hypoxemic and tended to be hypercapnic compared with controls. In IUGR lambs, relative to controls, O(2) consumption (mL/min/kg) and minute ventilation (mL/kg) were increased and pulmonary diffusing capacity (adjusted for functional residual capacity) was decreased. Functional residual capacity, measured by helium dilution, and total lung capacity (measured at 30 cm H(2)O) were smaller in IUGR lambs than in controls. When adjusted for functional residual capacity, static lung compliance was reduced and chest wall compliance was increased in IUGR lambs. At 8 wk, pulmonary DNA and protein concentrations were decreased in IUGR lambs relative to controls. We conclude that restriction of fetal growth by placental insufficiency induces alterations in the lungs and chest wall that result in persistent impairments in respiratory function during early postnatal life.

Birth weight, body mass index and asthma in young adults

BACKGROUND

Impaired fetal growth may be a risk factor for asthma although evidence in children is conflicting and there are few data in adults. Little is known about risk factors which may influence asthma in late childhood or early adult life. Whilst there are clues that fatness may be important, this has been little studied in young adults. The relations between birth weight and childhood and adult anthropometry and asthma, wheeze, hayfever, and eczema were investigated in a nationally representative sample of young British adults.

METHODS

A total of 8960 individuals from the 1970 British Cohort Study (BCS70) were studied. They had recently responded to a questionnaire at 26 years of age in which they were asked whether they had suffered from asthma, wheeze, hayfever, and eczema in the previous 12 months. Adult body mass index (BMI) was calculated from reported height and weight.

RESULTS

The prevalence of asthma at 26 years fell with increasing birth weight. After controlling for potential confounding factors, the odds ratio comparing the lowest birth weight group (<2 kg) with the modal group (3-3.5 kg) was 1.99 (95% CI 0.96 to 4.12). The prevalence of asthma increased with increasing adult BMI. After controlling for birth weight and other confounders, the odds ratio comparing highest with lowest quintile was 1.72 (95% CI 1.29 to 2.29). The association between fatness and asthma was stronger in women; odds ratios comparing overweight women (BMI 25-29.99) and obese women (BMI >/=30) with those of normal weight (BMI <25) were 1.51 (95% CI 1.11 to 2.06) and 1.84 (95% CI 1. 19 to 2.84), respectively. The BMI at 10 years was not related to adult asthma. Similar associations with birth weight and adult BMI were present for wheeze but not for hayfever or eczema.

CONCLUSIONS

Impaired fetal growth and adult fatness are risk factors for adult asthma.