Childhood disadvantage and adolescent socioemotional wellbeing as predictors of future parenting behaviour

INTRODUCTION

In extending work on early life antecedents of parenting, we investigate associations between childhood family history of disadvantage, adolescent socioemotional wellbeing, and age at first parenthood and subsequent parenting behaviour.

METHODS

Parent-child interactions were recorded when participants in the longitudinal Dunedin Multidisciplinary Health and Development Study (New Zealand) had a three-year-old child. Data were available for 358 mothers and 321 fathers, aged between 17.7 and 41.5 at the time of their child's birth. Associations between parenting and antecedent data on socioeconomic disadvantage, adolescent wellbeing and mental health, as well as current adult mental health and age at parenting, were tested for using structural equation modelling.

RESULTS

Family disadvantage in childhood and lower adolescent wellbeing was associated with less positive future parenting, but only adult (not adolescent) anxiety/depression symptoms were directly associated with parenting behaviour. Childhood family disadvantage was associated with further disadvantage across the life course that included less positive parenting of the next generation. In contrast, socioemotional wellbeing during adolescence and later age of onset of parenting were associated with more positive parenting.

CONCLUSIONS

Reducing childhood disadvantage and improving socioemotional wellbeing during childhood and adolescence is likely to have intergenerational benefits through better parenting of the next generation.

Obesity, underweight and BMI distribution characteristics of children by gross national income and income inequality: results from an international survey

BACKGROUND

Economic wealth and income inequality may impact on childhood BMI distribution by affecting overconsumption of food and sedentary forms of transportation and entertainment across the whole or some of the population.

OBJECTIVES

To determine whether BMI distribution of children differs by gross national income (GNI) per capita and Gini index derived from World Bank data.

METHODS

Secondary analysis of largely self-reported height and weight data from a multi-country, cross-sectional study (ISAAC), of 77,963 children aged 6-7 (from 19 countries) and 205,388 adolescents aged 13-14 (from 36 countries), were used to examine underweight vs obesity prevalence and BMI distribution skewness, median and dispersion.

RESULTS

Children and adolescents from 'lower' GNI countries had higher prevalence of underweight than those from 'higher' GNI countries (6% vs 3%, p = 0.03; 2% vs 1%, p = 0.05 respectively), but the prevalence of obesity was not different (2% vs 5%, p = 0.29; 2% vs 2%, p = 0.66). BMI distribution of participants from 'higher' GNI countries had higher median, without significant difference in skewness or dispersion compared to 'lower' GNI countries (higher medians +1.1 kg/m2 for 6-7 year olds, and + 0.7 kg/m2, +1.2 kg/m2 for 13-14 year old girls and boys respectively). Gini index was not associated with underweight or obesity prevalence in either children or adolescents, nor with any BMI distribution characteristics with one exception. Adolescent girls from higher income inequality countries had a greater median BMI (+0.7 kg/m2) and a less skewed BMI distribution.

CONCLUSIONS

It appears that the obesogenic impact of economic prosperity affects all children similarly. Income inequality may have a gender specific effect affecting BMI distribution in adolescent girls.

Birth weight and subsequent body mass index in children: an international cross-sectional study

BACKGROUND

The reported association between birth weight and subsequent body mass index (BMI) is conflicting.

OBJECTIVES

To examine the relationship between birth weight and BMI in children aged 6-7 years.

METHODS

Secondary analysis of data from a multi-centre, multi-country, cross-sectional study (International Study of Asthma and Allergies in Childhood (ISAAC) Phase Three). Parents/guardians of children aged 6-7 years completed questionnaires about their children's birth weight, current height and weight and whether their mother smoked in the first year of the child's life. A general linear mixed model was used to determine the association between BMI and birth weight.

RESULTS

A total of 72 111 children (17 countries) were included in the analysis. There was a positive association of birth weight with BMI (for each kg increase in birth weight the BMI at 6-7 increased by 0.47 (SE 0.02) kg/m² ; p < 0.0001) with a clear gradient by birth weight category. There was no statistically significant interaction between birth weight and Gross National Income (GNI).

CONCLUSIONS

There is a positive linear relationship between birth weight and BMI in 6-7 year old children, which is present in both high and low income countries.

Association between breastfeeding and body mass index at age 6-7 years in an international survey

BACKGROUND

Breastfeeding is believed to reduce children's risk for obesity but data are conflicting. It is also uncertain if breastfeeding has different effects on obesity in high- and low-income countries.

OBJECTIVES

This study aimed to investigate the association between having been breastfed and body mass index (BMI) in 6- to 7-year-old children in a large international survey.

METHODS

Parents/guardians reported whether their child had been breastfed and their current height and weight. Some centres measured height and weight directly. Analyses adjusted for whether height and weight were reported or measured, child's age, sex, country gross national income and centre.

RESULTS

Data were available for 76,635 participants from 31 centres in 18 countries. Reported breastfeeding rates varied from 27 to 98%. After adjusting for potential confounders, the estimated BMI difference was 0.04 kg m(-2) lower among those who had been breastfed (P = 0.07). The risk for being overweight or obese was slightly lower among breastfed children (odds ratio = 0.95, P = 0.012). There was no evidence that the association between breastfeeding and BMI was different in lower income countries compared with higher income countries.

CONCLUSIONS

The findings suggest that breastfeeding has little impact on children's BMI. Increasing breastfeeding is unlikely to reduce the global epidemic of childhood obesity.

Cardiac dysfunction and N-terminal pro-B-type natriuretic peptide in exacerbations of chronic obstructive pulmonary disease

Elevated levels of B-type natriuretic peptides among patients with exacerbations of chronic obstructive pulmonary disease (COPD) are associated with higher mortality. The pathophysiology is unclear. To establish if elevated levels of N-terminal pro-B-type natriuretic peptide (NT-proBNP) are due to right or left heart dysfunction, we performed echocardiograms in 18 patients admitted to hospital with COPD. Elevated levels of NT-proBNP were associated with both right and left heart dysfunction and indicate that these patients have biventricular dysfunction rather than isolated right ventricular compromise.

Antibiotic treatment during infancy and increased body mass index in boys: an international cross-sectional study

OBJECTIVE

To investigate whether antibiotic exposure during the first year of life is associated with increased childhood body mass index (BMI).

DESIGN

Secondary analysis from a multi-centre, multi-country, cross-sectional study (The International Study of Asthma and Allergies in Childhood Phase Three).

SUBJECTS

A total of 74 946 children from 31 centres in 18 countries contributed data on antibiotic use in the first 12 months of life and current BMI.

METHODS

Parents/guardians of children aged 5-8 years completed questionnaires that included questions about their children's current height and weight, and whether in the child's first 12 months of life, they had received any antibiotics, paracetamol, were breastfed or the mother/female guardian smoked cigarettes, and whether the child had wheezed in the past 12 months. A general linear mixed model was used to determine the association of antibiotic exposure with BMI, adjusting for age, sex, centre, BMI measurement type (self-reported or measured), maternal smoking, breastfeeding, paracetamol use, gross national income and current wheeze.

RESULTS

There was a significant interaction between sex and early-life antibiotic exposure. Early-life antibiotic exposure was associated with increased childhood BMI in boys (+0.107 kg m(-2), P<0.0001), but not in girls (-0.008 kg m(-2), P=0.75) after controlling for age, centre and BMI measurement type. The association remained in boys (+0.104 kg m(-2), P<0.0007), after adjustment for maternal smoking, breastfeeding, paracetamol use and current wheeze. There was no interaction between age, maternal smoking, breastfeeding, paracetamol use, gross national income and current wheeze in the association between early antibiotic exposure and BMI.

CONCLUSIONS

Exposure to antibiotics during the first 12 months of life is associated with a small increase in BMI in boys aged 5-8 years in this large international cross-sectional survey. By inference this provides additional support for the importance of gut microbiota in modulating the risk of obesity, with a sex-specific effect.

Forceps birth delivery, allergic sensitisation and asthma: a population-based cohort study

BACKGROUND

Studies indicate an increased risk of allergies among children born by caesarean section, possibly because immune development is altered by avoiding exposure to maternal vaginal flora. It is unknown if other obstetric interventions are associated with allergies.

OBJECTIVE

To assess associations between delivery with forceps assistance and development of atopy and asthma.

METHODS

In a population-based cohort of 1037 individuals born in 1972/73, atopy was assessed by skin-prick tests for common allergens at ages 13 and 32 years. A history of asthma was obtained at the same ages. Associations between birth with forceps assistance, atopy and asthma were assessed with adjustments for sex, head circumference at birth, parental atopy disease, birth order and socio-economic status.

RESULTS

Children born using forceps were more likely to have atopy at ages 13 (53% vs. 44%) and 32 (68% vs 59%). They were also more likely to have asthma (21% vs. 11% and 23% vs. 16% at ages 13 and 32 respectively). Except for asthma at age 13, these associations were not statistically significant after adjustment for multiple confounding factors.

CONCLUSIONS & CLINICAL RELEVANCE

Delivery with forceps assistance is associated with an increased risk of atopy and asthma, but the associations were weaker after adjustment for confounding factors. The previously reported association between caesarean birth and atopic disease may be due to confounding rather than altered exposure to maternal flora, although other factors associated with a difficult labour cannot be ruled out.

Effects of cannabis on lung function: a population-based cohort study

The effects of cannabis on lung function remain unclear and may be different from those of tobacco. We compared the associations between use of these substances and lung function in a population-based cohort (n = 1,037). Cannabis and tobacco use were reported at ages 18, 21, 26 and 32 yrs. Spirometry, plethysmography and carbon monoxide transfer factor were measured at 32 yrs. Associations between lung function and exposure to each substance were adjusted for exposure to the other substance. Cumulative cannabis use was associated with higher forced vital capacity, total lung capacity, functional residual capacity and residual volume. Cannabis was also associated with higher airway resistance but not with forced expiratory volume in 1 s, forced expiratory ratio or transfer factor. These findings were similar among those who did not smoke tobacco. In contrast, tobacco use was associated with lower forced expiratory volume in 1 s, lower forced expiratory ratio, lower transfer factor and higher static lung volumes, but not with airway resistance. Cannabis appears to have different effects on lung function from those of tobacco. Cannabis use was associated with higher lung volumes, suggesting hyperinflation and increased large-airways resistance, but there was little evidence for airflow obstruction or impairment of gas transfer.

Cardio-selective and non-selective beta-blockers in chronic obstructive pulmonary disease: effects on bronchodilator response and exercise

BACKGROUND

Patients with chronic obstructive pulmonary disease (COPD) often have co-existing cardiovascular disease and may require beta-blocker treatment. There are limited data on the effects of beta-blockers on the response to inhaled beta2-agonists and exercise capacity in patients with COPD.

OBJECTIVE

To determine the effects of different doses of cardio-selective and non-selective beta-blockers on the acute bronchodilator response to beta-agonists in COPD, and to assess their effects on exercise capacity.

METHODS

A double-blind, randomized, three-way cross-over (metoprolol 95 mg, propranolol 80 mg, placebo) study with a final open-label high-dose arm (metoprolol 190 mg). After 1 week of each treatment, the bronchodilator response to salbutamol was measured after first inducing bronchoconstriction using methacholine. Exercise capacity was assessed using the incremental shuttle walk test.

RESULTS

Eleven patients with moderate COPD were recruited. Treatments were well-tolerated although two did not participate in the high-dose metoprolol phase. The area under the salbutamol-response curve was lower after propranolol compared with placebo (P=0.0006). The area under the curve also tended to be lower after high-dose metoprolol (P=0.076). The per cent recovery of the methacholine-induced fall was also lower after high-dose metoprolol (P=0.0018). Low-dose metoprolol did not alter the bronchodilator response. Oxygen saturation at peak exercise was lower with all beta-blocker treatments (P=0.046).

CONCLUSION

Non-selective beta-blockers and high doses of cardio-selective beta-blockers may inhibit the bronchodilator response to beta2-agonists in patients with COPD. Beta-blockers were also associated with lower oxygen saturation during exercise. The clinical significance of these adverse effects is uncertain in view of the benefits of beta-blocker treatment for cardiovascular disease.

Associations between birth weight, early childhood weight gain and adult lung function

BACKGROUND

Low birth weight is associated with lower values for spirometry in adults but it is not known if birth weight influences other measures of pulmonary function. It is also unclear whether postnatal growth affects adult lung function. The associations between birth weight, postnatal growth and adult lung function were assessed in an unselected birth cohort of 1037 children.

METHODS

Birth weight, weight gain between birth and age 3 years, and lung function at age 32 years were measured. Analyses were adjusted for adult height and sex and further adjusted for multiple other potential confounding factors.

RESULTS

Birth weight was positively correlated with spirometric (forced expiratory volume in 1 s and forced vital capacity) and plethysmographic (total lung capacity and functional residual capacity) lung function and with lung diffusing capacity. These associations persisted after adjustment for confounding factors including adult weight, exposure to cigarette smoke in utero and during childhood, personal smoking, socioeconomic status, asthma and gestational age. Weight gain between birth and age 3 years was also positively associated with lung diffusing capacity, and with higher values of lung volumes in men after adjustment for covariates. Neither birth weight nor postnatal weight gain was associated with airflow obstruction.

CONCLUSIONS

Low birth weight and lower weight gain in early childhood are associated with modest reductions in adult lung function across a broad range of measures of lung volumes and with lower diffusing capacity. These findings are independent of a number of potential confounding factors and support the hypothesis that fetal and infant growth is a determinant of adult lung function.

High-sensitive C-reactive protein is associated with reduced lung function in young adults

Systemic inflammation has been associated with reduced lung function. However, data on the interrelationships between lung function and inflammation are sparse, and it is not clear if low-grade inflammation leads to reduced lung function. Associations between high-sensitive C-reactive protein (CRP) and spirometric lung function were assessed in a population-based cohort of approximately 1,000 Danes aged 20 yrs. In males, the average decline in forced expiratory volume in one second (FEV(1)) in the highest CRP quintile was 23 mL.yr(-1) versus 1.6 mL.yr(-1) in the lowest quintile. In females, the average decline was 6.2 mL.yr(-1) in the highest CRP quintile versus an increase of 1.8 mL.yr(-1) in the lowest CRP quintile. In a multiple regression analysis adjusted for sex, body mass index, cardiorespiratory fitness, smoking, asthma, airway hyperresponsiveness and serum eosinophil cationic protein, higher levels of CRP at age 20 yrs were associated with a greater reduction in both FEV(1) and forced vital capacity between ages 20 and 29 yrs. The findings show that higher levels of C-reactive protein in young adults are associated with subsequent decline in lung function, suggesting that low-grade systemic inflammation in young adulthood may lead to impaired lung function independently of the effects of smoking, obesity, cardiorespiratory fitness, asthma and eosinophilic inflammation.

Psychosocial correlates of 6-n-propylthiouracil (PROP) ratings in a birth cohort

This study investigated the relation between ratings of 6-n-propylthiouracil (PROP) and two psychosocial constructs, socioeconomic status and IQ, which are related to health outcomes. A 3.2mM solution of PROP was rated by 922 32-year-old members of a birth cohort (450 women) relative to the strongest imaginable sensation of any kind using the generalised Labelled Magnitude Scale. Women had higher PROP ratings than men. Following normalisation of PROP ratings, multiple linear regression showed that higher ratings were independently associated with lower childhood socioeconomic status, lower childhood IQ scores and ratings of an imagined stimulus made on the same scale (r(2)=0.12). Results suggest that psychosocial variables, sex and scale use, in addition to established genetic determinants, may help explain variability in ratings of supra-threshold concentrations of PROP.

Changes in medication use from age 26 to 32 in a representative birth cohort

BACKGROUND

To date, longitudinal studies of medications have been confined to older adults or clinical samples, with no data from prospective studies of younger adults. The aim of the study was to examine changes in medication usage between ages 26 and 32 in a prospective study of a representative birth cohort.

METHODS

Medication use during the previous 2 weeks was investigated among 960 individuals at ages 26 and 32.

RESULTS

Nearly two-thirds took at least one medication at each age, with medication prevalence higher among women than among men. Three-quarters of those taking at least one at age 26 were doing so at 32. Over-the-counter medication prevalence increased from 35 to 43% between 26 and 32 years of age. Although the prevalence of prescribed medications decreased (from just under half to just over one-third, and from two-thirds to below half among women), there was no significant difference between the ages once hormonal contraceptives were accounted for. By 32, reduced usage of hormonal contraceptives was apparent, with one-third of age-26 users still taking these at 32. Other categories showing major changes were analgesics (increased), anti-asthma drugs (decreased), antidepressants (increased) and antiulcer drugs (increased). At 32, 82% of those taking analgesics, 85% of those taking nutrient supplements, 71% of those taking antihistamines and 33% of those taking antiulcer drugs had self-prescribed them.

CONCLUSION

A considerable proportion of the sample used medications by age 32, and there was considerable change between 26 and 32. The changes are likely to have been due to a mix of ageing and period effects.

Audit of acute admissions of chronic obstructive pulmonary disease: inpatient management and outcome

BACKGROUND

Despite the publication of several management guidelines for exacerbations of chronic obstructive pulmonary disease (COPD), there is little information on standards of care in clinical practice. The aim of this audit was to examine the assessment, management and outcome of COPD admissions to a secondary and tertiary referring New Zealand hospital during two different seasons. Compliance to current recommendations was examined and compared with the available international published work.

METHODS

All COPD-related admissions to Waikato Hospital during the months of May and October 2004 were reviewed. Ninety-four cases (from 84 patients) were audited.

RESULTS

General characteristics, clinical features and lung function tests were similar to that of other cohorts. Twenty-three per cent of the admissions were Maori and the mean age of Maori admissions were significantly less than that of the non-Maori admissions (57 and 72 years, respectively; P = 0.0001). The geometric mean length of stay was 3.4 days, which is significantly less than most other reported hospital lengths of stays related to exacerbations of COPD. Fifty-five per cent of the cohort was admitted more than once to the hospital for COPD in the 12 months before the index admission. Thirteen per cent of all admissions received assisted ventilation. Overall 30-day mortality was 8% and the 12-month mortality was 31%. Decreased body mass index was a risk factor for death as was an increased CURB-65 (confusion, urea, respiratory rate, blood pressure age) score--a simple bedside assessment score, which has previously been used to predict mortality in patients with community-acquired pneumonia.

CONCLUSION

This audit documented the general characteristics, assessment, management and outcome of the COPD admissions to a secondary New Zealand hospital. Further investigations into factors contributing to shorter length of stay and predictors of mortality are needed.

Watching television is associated with childhood obesity: but is it clinically important?

OBJECTIVE

To assess the impact of television viewing during childhood and adolescence on body mass index (BMI) in children up to the age of 15 years.

DESIGN

Unselected birth cohort, assessed at birth and every 2 years from age 3 to 15 years.

SUBJECTS

In all, 1037 individuals were assessed at age 3 years. At age 15 years, 976 (95% of living cohort) continued to participate.

MEASUREMENTS

Parental estimates of weekday television viewing between age 5 and 11 years. Self-reports of television viewing at age 13 and 15 years. Weight and height were measured at each age to calculate BMI.

RESULTS

BMI and prevalence of overweight at all ages were significantly associated with mean hours of television viewing reported in the assessments up to that age. These associations were stronger in girls than boys. The associations remained significant after adjusting for parental body mass indices and socio-economic status.

CONCLUSION

Time spent watching television is a significant predictor of BMI and overweight in childhood. Although the effect size appears small, it is larger than the effect sizes commonly reported for nutritional intake and physical activity. Television viewing should be regarded as an important contributing factor to childhood obesity.

Association between C-reactive protein, metabolic cardiovascular risk factors, obesity and oral contraceptive use in young adults

OBJECTIVE

This study sought to determine the relationship between levels of the inflammatory marker, C-reactive protein (CRP), cardiovascular risk factors and oral contraceptive use in young adults.

DESIGN

Cross-sectional study of a community cohort.

SUBJECTS

A total of 822 men and women aged 26 y.

MEASUREMENTS

CRP, body mass index (BMI), blood pressure, lipid and lipoprotein levels, smoking status, socioeconomic status, health status, and hormonal contraceptive use in women.

RESULTS

Multiple regression analysis showed that obesity was independently related to CRP with an increase in ratio CRP of 1.03 (95% CI 1.01, 1.05) for men and 1.07 (1.05, 1.09) for women associated with a 1 kg/m(2) increase in BMI. In women, combined oral contraceptive use was associated with a ratio change in CRP of 1.52 (1.27, 1.82) compared with nonusers. Other independent determinants of CRP in men and women were apolipoprotein B level, systolic blood pressure and apolipoprotein A1 in men. Univariate analysis showed that the relationship between CRP and BMI, systolic blood pressure and apolipoprotein B was significantly stronger in women than men.

CONCLUSION

These findings suggest that obesity is associated with inflammation independent of other cardiovascular risk factors that may contribute to an increased risk for cardiovascular disease in men and women. Elevated CRP related to combined oral contraceptive use may influence the rate of cardiovascular events in young women.

Relationship between socioeconomic status and asthma: a longitudinal cohort study

BACKGROUND

There is conflicting information about the relationship between asthma and socioeconomic status, with different studies reporting no, positive, or inverse associations. Most of these studies have been cross sectional in design and have relied on subjective markers of asthma such as symptoms of wheeze. Many have been unable to control adequately for potential confounding factors.

METHODS

We report a prospective cohort study of approximately 1000 individuals born in Dunedin, New Zealand in 1972-3. This sample has been assessed regularly throughout childhood and into adulthood, with detailed information collected on asthma symptoms, lung function, airway responsiveness, and atopy. The prevalence of these in relation to measures of socioeconomic status were analysed with and without controls for potential confounding influences including parental history of asthma, smoking, breast feeding, and birth order using cross sectional time series models.

RESULTS

No consistent association was found between childhood or adult socioeconomic status and asthma prevalence, lung function, or airway responsiveness at any age. Having asthma made no difference to educational attainment or socioeconomic status by age 26. There were trends to increased atopy in children from higher socioeconomic status families consistent with previous reports.

CONCLUSIONS

Socioeconomic status in childhood had no significant impact on the prevalence of asthma in this New Zealand born cohort. Generalisation of these results to other societies should be done with caution, but our results suggest that the previously reported associations may be due to confounding.

Bronchodilator tolerance: the impact of increasing bronchoconstriction

Chronic exposure to beta-agonists causes tolerance to their bronchodilator effects, which is best demonstrated during acute bronchoconstriction. The aim of the present study was to assess whether tolerance becomes more evident with increasing bronchoconstriction, as might occur in acute asthma. In a randomised, double-blind, placebo-controlled, crossover study comprising 15 patients, the treatments were salbutamol 400 microg q.i.d. or placebo given via Diskhaler for 28 days with a 2-week washout between treatments. Patients attended on days 14, 21 and 28. Bronchoconstriction was induced on two of these three occasions to achieve a reduction in the forced expiratory volume in one second (FEV1) of 0 (no methacholine), 15 and 30% (using methacholine) in a randomised order. Immediately after this, salbutamol 100 microg, 100 microg and 200 microg was inhaled at 0, 5, and 10 min. FEV1 was measured over 40 min. Dose/response curves were plotted and values for the area under the curve (AUC)0-40 FEV1 were compared between treatments and by degree of bronchoconstriction. Regular salbutamol resulted in attenuation of the acute response to beta-agonist, which was increasingly evident with greater bronchoconstriction. With a reduction in FEV1 of 0, 15 and 30%, the AUC0-40 FEV1 with salbutamol were 11.2, -14.6 and -35.7% respectively, compared to placebo. There was a linear relationship between the magnitude of bronchoconstriction and the between-treatment differences in AUC0-40 FEV1. Increasing bronchoconstriction conferred greater susceptibility to the effects of bronchodilator tolerance.

Exhaled NO and assessment of anti-inflammatory effects of inhaled steroid: dose-response relationship

Exhaled nitric oxide (eNO) is an easily measured marker of airway inflammation. This study was undertaken to evaluate the usefulness of serial eNO in investigating the dose-response relationship for inhaled beclomethasone (BDP), and to compare eNO with other markers of airway inflammation. Following withdrawal of inhaled corticosteroid (ICS) therapy, 65 patients entered a double-blind, parallel-group, placebo-controlled trial of 50, 100, 200 or 500 microg x BDP x day(-1) for eight weeks. eNO and spirometry were performed weekly and a hypertonic saline challenge with sputum induction was performed at the beginning and end of treatment. The relationship between the dose of ICS and changes in eNO and forced expiratory volume in one second (FEV1) was linear at 1 week and at the end of treatment. A linear dose-response relationship was also seen for sputum eosinophils. Changes in eNO correlated significantly with changes in sputum eosinophils. Changes in the provocative dose of saline causing a 15% fall in FEV1 saline did not differ across the treatment groups nor did they correlate with changes in other measurements. Exhaled nitric oxide may be used to assess the dose-response relationship for the anti-inflammatory effects of inhaled beclomethasone. The relationship found in this study was linear over the dose range 0-500 microg x day(-1) soon after commencing therapy and continued over time.

Long-acting beta-agonist treatment in patients with persistent asthma already receiving inhaled corticosteroids

International guidelines recommend that long-acting beta-agonists should be considered in patients who are symptomatic despite moderate doses of inhaled corticosteroids. When combined with inhaled corticosteroids they improve asthma symptoms and lung function and reduce exacerbations. The evidence suggests that they are well tolerated. However, they are less effective than inhaled corticosteroids as monotherapy and should not be used alone, although the addition of a long-acting beta-agonist may permit a small reduction in the corticosteroid dose. Both salmeterol and formoterol appear equally effective in improving asthma control. Formoterol, however, has a rapid onset of action and is now being promoted for the relief of acute asthma symptoms. Both drugs provide prolonged protection against exercise-induced bronchospasm. However, this effect rapidly diminishes with continuous therapy and if this is the main aim of treatment, intermittent use may be preferable. When compared with alternative treatments, inhaled long-acting beta-agonists are more effective in controlling asthma symptoms than either theophylline or antileukotriene agents. Bambuterol, an oral prodrug of terbutaline, appears to be as effective as the inhaled long-acting beta-agonists and has the advantage of once daily oral administration. However, the inhaled long-acting beta-agonists are less likely to have systemic adverse effects. There are theoretical concerns that regular beta-agonist treatment may lead to tolerance and a failure to respond to emergency asthma treatment. While there is no doubt that tolerance occurs, there is currently little evidence that this is a clinical problem. Insights into pharmacological as well as therapeutic interactions between inhaled corticosteroids and beta-agonists are providing justification for their use in combination. Guidelines for the management of patients with chronic persistent asthma are likely to require modification to reflect these developments.

The predictive value of exhaled nitric oxide measurements in assessing changes in asthma control

Exhaled nitric oxide (eNO) levels are increased in untreated or unstable asthma and measurements can be made easily. Our aim was to assess the usefulness of eNO for diagnosing and predicting loss of control (LOC) in asthma following steroid withdrawal. Comparisons were made against sputum eosinophils and airway hyperresponsiveness (AHR) to hypertonic saline (4.5%). Seventy-eight patients with mild/moderate asthma had their inhaled steroid therapy withdrawn until LOC occurred or for a maximum of 6 wk. Sixty (77.9%) developed LOC. There were highly significant correlations between the changes in eNO and symptoms (p < 0.0001), FEV(1) (p < 0.002), sputum eosinophils (p < 0.0002), and saline PD(15) (p < 0.0002), and there were significant differences between LOC and no LOC groups. Both single measurements and changes of eNO (10 ppb, 15 ppb, or an increase of > 60% over baseline) had positive predictive values that ranged from 80 to 90% for predicting and diagnosing LOC. These values were similar to those obtained using sputum eosinophils and saline PD(15) measurements. We conclude that eNO measurements are as useful as induced sputum analysis and AHR in assessing airway inflammation, with the advantage that they are easy to perform.

Reversing acute bronchoconstriction in asthma: the effect of bronchodilator tolerance after treatment with formoterol

Continuous treatment with a short-acting beta2-agonist can lead to reduced bronchodilator responsiveness during acute bronchoconstriction. This study evaluated bronchodilator tolerance to salbutamol following regular treatment with a long-acting beta2-agonist, formoterol. The modifying effect of intravenous corticosteroid was also studied. Ten asthmatic subjects (using inhaled steroids) participated in a randomised, double-blind, placebo-controlled, cross-over study. Formoterol 12 microg b.i.d. or matching placebo was given for 10-14 days with >2 weeks washout. Following each treatment, patients underwent a methacholine challenge to induce a fall in forced expired volume in one second (FEV1) of at least 20%, then salbutamol 100 microg, 100 microg, and 200 microg was inhaled via a spacer at 5 min intervals, with a further 400 microg at 45 min. After a third single-blind formoterol treatment period, hydrocortisone 200 mg was given intravenously prior to salbutamol. Dose-response curves for change in FEV1 with salbutamol were compared using analysis of covariance to take account of methacholine-induced changes in spirometry. Regular formoterol resulted in a significantly lower FEV1 after salbutamol at each time point compared to placebo (p<0.01). The area under the curves (AUCs) for 15 (AUC0-15) and 45 (AUC0-45) min were 28.8% and 29.5% lower following formoterol treatment (p<0.001). Pretreatment with hydrocortisone had no significant modifying effect within 2 h of administration. It is concluded that significant tolerance to the bronchodilator effects of inhaled salbutamol occurs 36 h after stopping the regular administration of formoterol. This bronchodilator tolerance is evident in circumstances of acute bronchconstriction.

The influence of polymorphism at position 16 of the beta2-adrenoceptor on the development of tolerance to beta-agonist

Polymorphism at position 16 of the beta2-adrenoceptor alters receptor down-regulation in vitro. Our aim was to compare the development of tolerance to beta-agonist in homozygous Gly-16 patients with patients harboring the "wild" genotype (homozygous Arg-16) during regular treatment with salmeterol. In a prospective, randomized, double-blind, placebo-controlled, cross-over study, 20 subjects with mild to moderate asthma (10 Gly-16, 10 Arg-16) received 2 weeks of treatment with inhaled salmeterol 100 microg b.i.d. Thereafter, dose responses to inhaled salbutamol were constructed for forced expiratory volume in 1 sec (FEV1), heart rate, QTc interval, serum potassium and glucose, and finger tremor. The protective effect of salbutamol against adenosine monophosphate (AMP) challenge was also measured. Salmeterol resulted in a significant reduction in the area under curve (AUC) for FEV1 (p = 0.01), heart rate (p = 0.01), QTc interval (p = 0.01), and tremor (p = 0.05), and in the maximum responses for FEV1 (p = 0.05), heart rate (p = 0.02), and glucose (p = 0.02). The protective effect of salbutamol against AMP was reduced by 3.61 doubling doses (p < 0.001). However, differences between Gly-16 and Arg-16 patients were small and nonsignificant. Thus, although tolerance is influenced in vitro by polymorphism of the beta2-adrenoceptor, the magnitude of between-genotype differences in vivo is unlikely to be significant.

Home ventilation: the Green Lane Hospital experience

AIMS

To describe the characteristics and outcomes of patients treated with domiciliary nocturnal support ventilation (NSV).

METHODS

Case-note review of all patients treated with home NSV by Green Lane Hospital.

RESULTS

111 patients received home NSV between 1990 and 1999. 59 had respiratory failure due to obesity-hypoventilation syndrome (OHS), most of whom were Maori or Pacific Island people. Their mean BMI was 53 kg/m2. They frequently presented acutely, and often in extremis. After a median duration of 22 months treatment, 37 patients continued treatment. Four have died, but none from respiratory failure. Other causes of respiratory failure included: neuromuscular disease (26), kyphoscoliosis (19) and obstructive sleep apnoea (8). Patients who did not have OHS were mostly of New Zealand European ethnicity, required lower ventilation pressures than patients with OHS, and had better arterial blood gases on treatment. After a median follow-up of 35 months, however, fourteen have died. 33 continued on treatment. Both OHS and non-OHS patients had high deprivation scores according to NZdep96. This was most apparent for patients with OHS.

CONCLUSIONS

OHS is an important cause of respiratory failure in New Zealand, particularly affecting Maori and Pacific people. The prognosis of OHS treated with NSV appears to be good despite significant co-morbidity.

Asthma exacerbations during long term beta agonist use: influence of beta(2) adrenoceptor polymorphism

BACKGROUND

Polymorphisms of the beta(2) adrenoceptor influence receptor function in vitro and asthma phenotypes in vivo. However, their importance in determining responses to inhaled beta agonist treatment has not been clearly defined.

METHODS

In a retrospective analysis of previously published data we have examined relationships between polymorphisms at codons 16 and 27 of the beta(2) adrenoceptor and clinical outcomes in a randomised, placebo controlled, crossover trial of regularly scheduled salbutamol and salmeterol in 115 patients with mild to moderate asthma. Genotyping was obtained for positions 16 and 27 in 108 and 107 patients, respectively. For position 16, 17 patients (16%) were homozygous Arg-Arg, 40 (37%) were heterozygous Arg-Gly, and 51 (47%) were homozygous Gly-Gly.

RESULTS

Within the homozygous Arg-16 group major exacerbations were more frequent during salbutamol treatment than with placebo (1.91 (95% CI 1.07 to 3.12) per year versus 0.81 (95% CI 0.28 to 1.66) per year; p = 0.005). No significant treatment related differences occurred for heterozygous Arg-Gly patients (salbutamol 0.11 (95% CI 0.01 to 0.40), placebo 0.54 (95% CI 0.26 to 1.00) exacerbations per year) or homozygous Gly-16 patients (salbutamol 0.38 (95% CI 0.17 to 0.73), placebo 0.30 (95% CI 0.12 to 0.61) exacerbations per year). No adverse changes occurred for any position 16 subgroup with salmeterol. There was no significant relationship between position 27 genotypes and treatment related outcomes.

CONCLUSION

Homozygous Arg-16 patients are susceptible to clinically important increases in asthma exacerbations during chronic dosing with the short acting beta(2) agonist salbutamol.

Bronchodilator tolerance and rebound bronchoconstriction during regular inhaled beta-agonist treatment

There is uncertainty about the development of airway tolerance to beta-agonists and the phenomenon of rebound bronchoconstriction on beta-agonist withdrawal. We have recently completed a study of the regular terbutaline and budesonide treatment in asthma. We report our observations on the effect of starting and stopping terbutaline treatment on morning and evening peak flows. The study was a randomized four-way, double-dummy, cross-over comparison of regular inhaled terbutaline (500-1000 microg four times daily), budesonide, combined treatment and matching placebo. Each treatment was given for 6 weeks following a 4 week single-blind placebo washout. Ipratropium was used for symptom relief. No other asthma medication was permitted during either the treatment or wash-out periods. Evaluable data were obtained from 52 subjects for both placebo and terbutaline treatment. Changes in mean morning and evening peak flows during terbutaline treatment were compared to the baseline peak flows during the last 2 weeks of the preceding washout. The peak flow changes on stopping terbutaline were also analysed. Mean morning peak flow was not significantly different during terbutaline treatment when compared to either baseline or placebo treatment. Evening peak flows were significantly higher during terbutaline treatment [mean increase 23.1 l min(-1) (95% CI = 18.8, 27.4)]. Analysis of the peak flow changes on a day-by-day basis revealed an initial increase in morning peak flows for the first 2 days of treatment of 19.2 and 13.41 min(-1) [increases of 25.0 and 17.31 min(-1) in comparison with the corresponding values during placebo (P<0.01)] followed by a return to baseline. The increase in evening peak flows was also greater for the first 2 days of treatment than for the remainder of the treatment period (P<0.01). On ceasing terbutaline treatment there was a fall in mean morning peak flow below the baseline on the following morning of 21.6 l min(-1) (P<0.05 compared to placebo). The temporary increase in morning peak flows and greater than expected rise in evening peak flows for the first 2 days of treatment suggest the development of tolerance to the bronchodilator effect of terbutaline. Similarly, the fall in morning peak flows on treatment withdrawal suggests rebound bronchoconstriction. These effects are likely to be mediated by downregulation of the beta-receptor during treatment. The clinical significance of these changes is uncertain in view of the stability of overall asthma control during terbutaline treatment, but sudden withdrawal of beta-agonist treatment could conceivably lead to a deterioration in asthma control.

Effects of terbutaline and budesonide on sputum cells and bronchial hyperresponsiveness in asthma

Previous studies have shown that the regular administration of short acting beta-agonists can be associated with adverse effects on airway caliber and bronchial hyperresponsiveness (BHR) and that this may occur through a proinflammatory mechanism. The aim was to explore possible adverse effects of high-dose beta-agonist therapy and to assess any adverse interaction with corticosteroids. We undertook a randomized, crossover study to investigate the effects of 6 wk of treatment with regular terbutaline (1 mg four times a day), regular budesonide (400 microg twice a day), combined treatment, and placebo in subjects with mild to moderate asthma. Major endpoints were PD(15) saline, PD(20) methacholine, and induced sputum differential cell counts. Thirty-four subjects were randomized and 28 completed the study. PD(15) saline decreased on terbutaline alone compared with placebo treatment and on combined treatment compared with budesonide alone (mean fold decrease of 0.57 [95% CI = 0.36, 0.90] and 0.65 [95% CI = 0.43, 0.97], respectively). PD(20) methacholine was not affected by the use of terbutaline either alone or in combination with budesonide. The percentage of eosinophils in induced sputum increased during terbutaline treatment alone compared with placebo (median 8.3% versus 4.4%, p = 0.049). The addition of terbutaline to budesonide did not affect the percentage of eosinophils compared with budesonide treatment alone. These findings support the hypothesis that short-acting beta-agonists have a permissive effect on airway inflammation and that when used in high dose there may be an unfavorable interaction with inhaled corticosteroids.

Tolerance to beta-agonists during acute bronchoconstriction

Previous reports suggest that regular use of beta-agonists does not lead to tolerance to their bronchodilator effects. However, most studies have been conducted in stable asthma. This study investigates whether bronchodilator tolerance can be demonstrated during acute bronchoconstriction. Thirty-four asthmatic subjects were treated with 6 weeks inhaled terbutaline (1 mg q.i.d.), budesonide (400 microg, b.i.d.), both drugs or placebo in a randomized, double-blind, cross-over study. After each treatment methacholine was administered to induce a 20% fall in the forced expiratory volume in one second (FEV1). The response to inhaled salbutamol 100, 100, 200 microg at 5 min intervals) was then measured. Dose-response curves were compared using an analysis of covariance. Pre-methacholine FEV1, the highest pre-methacholine FEV1, the fall in FEV1 induced by methacholine and the logarithm of the provocative dose of methacholine required to induce the 20% fall in FEV1 (PD20) were used as covariates. There was a significantly reduced response to salbutamol after 6 weeks terbutaline treatment: the mean (95% confidence intervals (CI)) area under the dose-response curve was reduced by 36% (24, 47) compared to placebo (p<0.0001). The reduction in bronchodilator response was not affected by concomitant treatment with budesonide. Significant tolerance to the bronchodilator effect of inhaled beta-agonists may be demonstrated when tested during acute bronchoconstriction. Continuous treatment with inhaled beta-agonists may lead to a reduced response to emergency beta-agonist treatment during asthma exacerbations.

Randomised trial of an inhaled beta2 agonist, inhaled corticosteroid and their combination in the treatment of asthma

BACKGROUND

Although many asthmatic patients are treated with a combination of beta2 agonist and corticosteroid inhalers, the clinical effects of combining the drugs are unknown. Studies on the early asthmatic response to allergen suggest that beta2 agonists may reduce the benefit of inhaled corticosteroids. A study of the effects of combining the drugs on asthma control was undertaken.

METHODS

Sixty one subjects with mild to moderate asthma were randomised to a double blind crossover comparison of inhaled budesonide (200-400 microg twice daily), terbutaline (500-1000 microg four times daily), combined treatment, and placebo. Each treatment was given for six weeks following a four week washout period. Ipratropium was used for symptom relief. Treatments were ranked from worst (1) to best (4) based on need for oral steroid, mean morning peak flow, nocturnal awakening, ipratropium use, and asthma symptoms. Lung function and bronchial hyperresponsiveness were measured before and after each treatment.

RESULTS

Evaluable data for all four treatments were obtained from 47 subjects. The mean rank of each treatment was: placebo = 2.05; terbutaline = 2.13; budesonide = 2.48; combined treatment = 3.34. Combined treatment was ranked significantly better than any other treatment (p<0.01). Mean (95% CI) morning and evening peak flows were 14 (5 to 23) and 24 (15 to 34) l/min higher, respectively, during combined treatment than during budesonide, and 27 (17 to 37) and 15 (7 to 23) l/min higher than during terbutaline. Asthma symptoms tended to be least frequent during combined treatment but were not significantly different from budesonide alone. There was no significant difference between combined treatment and budesonide alone for lung function and bronchial hyperresponsiveness.

CONCLUSIONS

In this group of mild to moderate asthmatic subjects the combination of beta2 agonist and corticosteroid gave better asthma control than either treatment alone. There was no evidence that regular beta2 agonist treatment impaired the beneficial effect of inhaled corticosteroid.

Effects of inhaled beta agonist and corticosteroid treatment on nuclear transcription factors in bronchial mucosa in asthma

BACKGROUND

Inhaled corticosteroids and beta agonists are the most commonly used treatments in asthma and are often used together. Recent evidence suggests that many of the anti-inflammatory actions of corticosteroids are mediated by cross-talk between the activated glucocorticoid receptor (GR) and other transcription factors such as the pro-inflammatory nuclear factor kappa B (NFkappaB). Beta agonists can activate the transcription factor cAMP response element binding protein (CREB). A mutual inhibition between GR and CREB occurs in vitro which raises the possibility of a negative interaction between corticosteroid and beta agonist drugs. A study was undertaken to determine whether these interactions occur during treatment with beta2 agonists and corticosteroids in asthma.

METHODS

Seven subjects who were participating in a randomised, placebo controlled, crossover study of six weeks treatment with inhaled budesonide (400 microg twice daily), terbutaline (1 mg four times daily), and combined treatment were recruited. Biopsy samples of the bronchial mucosa were obtained after each treatment and analysed for the DNA binding activity of GR, CREB, and NFkappaB.

RESULTS

Budesonide increased GR activity (p<0.05) and decreased NFkappaB activity (p<0.05). No treatment combination altered CREB activity and terbutaline had no significant effects on any transcription factor.

CONCLUSIONS

Inhaled corticosteroids have significant effects on GR and NFkappaB activity in bronchial mucosa. A negative interaction between inhaled corticosteroids and beta agonists was not found.

Polymorphism of the beta2-adrenoceptor and the response to long-term beta2-agonist therapy in asthma

Polymorphisms affecting amino acids 16 and 27 of the beta2-adrenoceptor alter receptor regulation in vitro. Whether these polymorphisms alter the response to beta2-agonist therapy in asthma is unknown. In a previous study of 64 asthmatics, most experienced a deterioration in asthma control during regular inhaled beta2-agonist (fenoterol) treatment, while a minority improved. We have determined the beta2-adrenoceptor genotypes in these subjects, to establish whether changes in asthma control during the earlier study were influenced by beta2-adrenoceptor polymorphism. The genotypes coding for amino acids 16 and 27 were identified in 60 subjects using allele-specific polymerase chain reaction. The effects of regular beta2-agonist treatment on asthma control were compared between genotypes. There was no association between genotype and change in overall asthma control during regular beta2-agonist treatment. Only two of 10 markers of asthma control showed changes that were significantly associated with genotype: subjects homozygous for glycine at position 16 had no increase in bronchial responsiveness to methacholine during regular treatment; subjects homozygous for glutamic acid at position 27 had no increase in evening peak expiratory flow rates during regular treatment. These differences are the opposite of those that would have been predicted by the results of in vitro studies. In these subjects, the deleterious response to regular inhaled beta2-agonist treatment was not related to beta2-receptor polymorphism.

Polymorphism of the beta2-adrenoceptor and the response to long-term beta2-agonist therapy in asthma

Polymorphisms affecting amino acids 16 and 27 of the beta2-adrenoceptor alter receptor regulation in vitro. Whether these polymorphisms alter the response to beta2-agonist therapy in asthma is unknown. In a previous study of 64 asthmatics, most experienced a deterioration in asthma control during regular inhaled beta2-agonist (fenoterol) treatment, while a minority improved. We have determined the beta2-adrenoceptor genotypes in these subjects, to establish whether changes in asthma control during the earlier study were influenced by beta2-adrenoceptor polymorphism. The genotypes coding for amino acids 16 and 27 were identified in 60 subjects using allele-specific polymerase chain reaction. The effects of regular beta2-agonist treatment on asthma control were compared between genotypes. There was no association between genotype and change in overall asthma control during regular beta2-agonist treatment. Only two of 10 markers of asthma control showed changes that were significantly associated with genotype: subjects homozygous for glycine at position 16 had no increase in bronchial responsiveness to methacholine during regular treatment; subjects homozygous for glutamic acid at position 27 had no increase in evening peak expiratory flow rates during regular treatment. These differences are the opposite of those that would have been predicted by the results of in vitro studies. In these subjects, the deleterious response to regular inhaled beta2-agonist treatment was not related to beta2-receptor polymorphism.

The efficacy of inhaled corticosteroids in the management of non asthmatic chronic airflow obstruction

AIMS

The aims of this investigation were to evaluate the efficacy of regular inhaled beclomethasone in the control of symptoms and lung function with non-asthmatic smoking related obstructive pulmonary disease and to evaluate the relationship between clinical responses to a short course of oral prednisone and longer term outcomes using inhaled steroid.

METHODS

The study was a randomised, double blind, placebo controlled, crossover investigation in 18 patients. The active treatment was inhaled beclomethasone 1000 micrograms given twice daily for three months by metered dose inhaler. At the end of each treatment period, patients received oral prednisone 30 mg/day for ten days. The two treatment phases were separated by a one month washout interval. Peak flow rates, symptom scores and "rescue" bronchodilator use were recorded twice daily. Lung function (FEV1, FVC and lung volumes) and bronchial hyperresponsiveness (PC20 methacholine) were measured at monthly visits. The number of exacerbations requiring intervention therapy were also recorded.

RESULTS

There were no consistent benefits attributable to beclomethasone. Lung function was not significantly better as a result of active treatment. Sputum production improved but other symptom scores were similar during active and placebo therapy. Three patients exhibited an increase in FEV1 of 15% or more during active treatment but did not do so when oral prednisone was administered immediately after the period of placebo treatment. A further three patients showed an improvement in FEV1 of 15% or more with oral prednisone but failed to improve during treatment with inhaled beclomethasone. The predictive value of the "trial of steroid" was 0% and 81.3% for positive and negative outcomes respectively.

CONCLUSIONS

Our results indicate that in non-asthmatic chronic obstructive pulmonary disease inhaled corticosteroid fails to achieve significant improvements in either lung function or symptoms. The response to a "trial of steroid" using oral prednisone is not clinically helpful in selecting the small number of patients who may subsequently benefit from this form of therapy.

Cortical generators of the CI component of the pattern-onset visual evoked potential

Thirteen-channel visual evoked potentials (VEPs) to pattern-onset were recorded with stimuli restricted to individual octants of the peripheral field, to halves and to quadrants of the fovea. The voltage of the CI component was measured in each channel to define its topography for each stimulated sector. The potential fields so obtained were then analysed to find the orientation and location of a dipole that would produce a corresponding pattern of voltages at the scalp. The locations of the computed dipoles are consistent with the hypothesis that CI is generated in striate cortex. The computed locations and orientations are not compatible with alternative arrangements of sources in extrastriate cortex. A significant problem remains. If CI is indeed generated by the striate cortex then the orientation of the dipoles excited by stimulation of the peripheral field indicates that the cortex is surface negative. This leads to the prediction that foveal stimuli will elicit a CI which is negative at posterior electrodes. The experiments reported here confirm that CI is positive with such stimuli, and its source is calculated as a horizontal dipole with its positive pole oriented posterolaterally. Two possible explanations are considered for the reversed polarity of foveal CI: (a) that macropotentials associated with stimulation of the fovea are opposite in polarity from those associated with stimulation of the peripheral field; (b) that the foveal area of the retinotopic map extends into the lateral calcarine fissure with the effect that much of it faces in the reverse direction from the cortex at the pole.