The economic aspects of drug delivery in asthma

The need for cost-effective asthma therapy is driven by the high prevalence of asthma as well as the high cost of both medical care and lost productivity through illness. Limited healthcare resources demand proven therapies that maintain sustained disease control. Optimal disease control is the essence of cost effectiveness, but this in turn is dependent on correct drug selection and appropriate drug delivery. Successful treatment depends on delivery of medication to the site of action in the airways. Although there is a substantial number of aerosol delivery systems available, there is considerable confusion as to the most suitable method in different clinical settings, and across different age groups. Optimal drug delivery can be achieved without adding substantially to the overall cost of therapy. Both drugs and delivery systems need to be individualised to the needs of the patients. The early introduction of oral corticosteroids for acute exacerbations has resulted in reduced hospitalisation and shortened illness, providing substantial cost savings. A reduction in the reliance on nebuliser therapy in both the acute and chronic setting will further optimise therapy and reduce costs. We have reviewed the current literature to determine the most cost-effective methods of drug delivery in asthma.

Accuracy of asthma treatment in schoolchildren in NSW, Australia

Insufficient use of anti-inflammatory drugs, such as inhaled corticosteroids and cromoglycate, may contribute to the disease burden associated with asthma. Conversely, aggressive treatment of mild disease may result in avoidable costs and/or adverse drug effects. The aim of this study was to determine the relationship between asthma severity and inhaled corticosteroid/cromoglycate use in a large (n=4,909) random sample of children, aged 8-11 yrs, in NSW, Australia. Asthma and its treatment were assessed by questionnaire responses. Asthma, defined as diagnosis plus current wheeze, was present in 901 children (18% of the sample), of whom 225 (5%) had moderate asthma, defined as asthma plus additional symptoms (sleep disturbance), utilization (hospital, casualty), or disability (reduced activity, school absence). Use of inhaled corticosteroid/cromoglycate was reported by 636 children (13% of the sample). Determinants of use included: asthma diagnosis, current wheeze, and troublesome dry nocturnal cough. There was also a strong relationship between anti-inflammatory treatment and a multicomponent asthma severity score constructed for each child. Inhaled corticosteroids and/or cromoglycate were used by 56% of the children with asthma (24% daily) and by 76% of children with moderate asthma (42% daily). Undertreatment, defined as less than daily inhaled corticosteroids/cromoglycate in moderate asthma, was identified in 130 children (14% of those with asthma or 3% of the sample). Conversely, apparently aggressive treatment, defined as inhaled corticosteroid/cromoglycate use in children with persistent minimal symptoms (asthma severity score of less than 3) was identified in 101 children (2% of the sample). Although there were significant differences between regions in the choice of anti-inflammatory drugs and in the prevalence both of undertreatment and apparently aggressive treatment, there was no clear relationship to regional utilization of emergency and hospital services for asthma. Nevertheless, the frequency of undertreatment suggests an opportunity to reduce asthma morbidity by more consistent application of current therapeutic guidelines.

Measuring health outcome in paediatrics: development of the RAHC measure of function

OBJECTIVE

To develop a genetic measure of health outcome (the RAHC Measure of Function) for paediatric health services.

METHODOLOGY

The RAHC Measure of Function (MOF) was modified from the Child Global Assessment Scale. The utility and reliability of the MOF was then tested by inter-clinician agreement on case scenarios, by inter-clinician agreement in outpatients, by parent-clinician agreement in outpatients and by responsiveness to change in acute admissions.

RESULTS

The inter-clinician agreement on MOF ratings for case scenarios was moderately good, with an overall kappa of 0.42; P < 0.0001. Clinicians at respiratory and child psychiatry clinics nominated the same or adjacent MOF category to describe 100% (95% CI: 71.5-100) and 90% (95% CI: 68.3-98.8%) of 11 and 20 cases assessed, respectively. Parents nominated the same or adjacent MOF category as the attending clinician for 89.7% (95% CI: 72.7-97.8) and 82.9% (95% CI: 67.9-92.9) of 29 and 41 children in the same two clinics. Twenty-eight inpatient children had an MOF assessed on admission and discharge, and the median MOF score improved from 50.5 to 79 points (z = 4.53; P < 0.0001).

CONCLUSIONS

The MOF is easy to use and provides a valuable description of health outcome that parents are able to understand. The MOF is moderately reliable, is likely to be sufficiently reliable to compare groups of paediatric patients and is responsive to change.

Prevalence and severity of childhood asthma and allergic sensitisation in seven climatic regions of New South Wales

OBJECTIVE

To compare the prevalence and severity of asthma and of allergic sensitisation in children in different regions. We hypothesised that regions with different standardised hospital admission rates would have different prevalences of childhood asthma and that diverse climates would result in a range of sensitisations to different allergens.

DESIGN AND SETTING

We studied large random population samples of children in seven regions in New South Wales (NSW) in 1991-1993. Hospitalisation rates were obtained from NSW Department of Health data.

PARTICIPANTS

6394 children aged 8-11 years.

OUTCOME MEASURES

History of respiratory symptoms by self-administered questionnaire; airway hyperresponsiveness by histamine inhalation test; and sensitisation to allergens by skin-prick tests.

RESULTS

Children in all regions had a high prevalence of recent wheeze (22%-27%), of diagnosed asthma (24%-38%) and of use of asthma medications (22%-30%), but no region was consistently higher or lower for all measurements. The prevalence of current asthma in children living in three coastal regions (where sensitisation to house-dust mites was high) and in the far west (where sensitisation to alternaria was high) was 12%-13%, which was significantly higher than the prevalence of 7%-10% in children living in three inland regions (where sensitisation to these allergens was lower) (P < 0.01).

CONCLUSIONS

We found significant variations in the prevalence and severity of childhood asthma in NSW. The prevalence of hospitalisations, diagnosed asthma, recent symptoms and medication use may relate to different regional diagnostic patterns, whereas current asthma prevalence may relate to different levels of allergic sensitisation.

The cost of childhood asthma to Australian families

There have been no estimates of the actual cost of asthma care to Australian families. Previous estimates have been of the total cost to the community and have relied upon data collected by government departments and agencies. It was the aim of this investigation to estimate the cost of childhood asthma from the parents perspective in Australian families. A total of 238 asthmatic children aged 8-12 years were identified through prevalence studies of asthma in Sydney and Belmont, N.S.W. Children were selected if they had wheezed in the previous 12 months, had used asthma medicines or had airway hyperresponsiveness when tested. The study sample had a wide range of asthma severity. Data were collected retrospectively and prospectively. Parents completed a questionnaire which asked about health insurance and special asthma equipment costs in the previous 12 months. Every 2 weeks for a total of 3 months between February and June parents completed further questionnaires which assessed costs incurred because of their child's asthma, together with time spent obtaining treatment. Items included doctor consultations and tests, alternative practitioner consultations and tests, medications and alternative therapies purchased, hospital and ambulance use, and the cost of childcare as a consequence of asthma. We collected two or more months of prospective data from a total of 193 children. The mean annual cost of asthma to the family was A$212.48 per asthmatic child and 13.4 hr were spent obtaining treatment. For the group of children who had not visited a doctor in the previous year, the mean annual cost was A$85.60 and 13.1 hr were spent obtaining treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

An exercise challenge for epidemiological studies of childhood asthma: validity and repeatability

We assessed the validity, repeatability and practicality of a standardized exercise challenge protocol for measuring airway responsiveness in epidemiological studies of asthma in children aged 8-11 yrs. The construct validity of the exercise challenge was assessed by comparing response to exercise with other measures of asthma, i.e. wheeze frequency, diagnosed asthma, asthma medication use, atopy and urgent doctor visits (n = 802), and by comparison with response to histamine challenge (n = 201). Repeatability was assessed by comparison of responsiveness to two exercise challenges within 3 days (n = 113), and practicality was assessed by measurement of consent, compliance and throughput rates (n = 802). There was a significant relationship between frequency of wheeze attacks and % fall in forced expiratory volume in one second (FEV1) to exercise. The correlation (r) between % fall in FEV1 to exercise challenge and dose-response ratio to histamine challenge was 0.59. The repeatability of the exercise challenge was +/- 12% fall in FEV1. Consent and compliance rates for exercise challenge were 78 and 99%, respectively, and the mean throughput rate was 45 children per school day for a team of seven researchers. In conclusion, this exercise challenge was found to have good validity and to be reliable and practical. Thus, this challenge could be used as a standardized epidemiological tool to investigate the prevalence, aetiology and mechanisms of asthma.

An exercise challenge for epidemiological studies of childhood asthma: validity and repeatability

We assessed the validity, repeatability and practicality of a standardized exercise challenge protocol for measuring airway responsiveness in epidemiological studies of asthma in children aged 8-11 yrs. The construct validity of the exercise challenge was assessed by comparing response to exercise with other measures of asthma, i.e. wheeze frequency, diagnosed asthma, asthma medication use, atopy and urgent doctor visits (n = 802), and by comparison with response to histamine challenge (n = 201). Repeatability was assessed by comparison of responsiveness to two exercise challenges within 3 days (n = 113), and practicality was assessed by measurement of consent, compliance and throughput rates (n = 802). There was a significant relationship between frequency of wheeze attacks and % fall in forced expiratory volume in one second (FEV1) to exercise. The correlation (r) between % fall in FEV1 to exercise challenge and dose-response ratio to histamine challenge was 0.59. The repeatability of the exercise challenge was +/- 12% fall in FEV1. Consent and compliance rates for exercise challenge were 78 and 99%, respectively, and the mean throughput rate was 45 children per school day for a team of seven researchers. In conclusion, this exercise challenge was found to have good validity and to be reliable and practical. Thus, this challenge could be used as a standardized epidemiological tool to investigate the prevalence, aetiology and mechanisms of asthma.

Better medication compliance is associated with improved control of childhood asthma

Our previous studies have shown that medication compliance in children prescribed continuous treatment for asthma is poor, and that an intervention can improve the level of compliance. The present study examined the effects of an intervention on the clinical course of moderately severe asthma. At each of six clinic visits, spirometry was performed, medication compliance was assessed by questionnaire, and the physicians made an overall assessment of asthma severity (Severity Score) and provided a score for asthma control (Control of Asthma Score). Peak expiratory flow rates were measured twice daily for one month prior to each clinic visit, and the coefficient of variation (% CV) was calculated. Subjects received the intervention after at least two visits, and 53 of the 78 recruits completed the study. Following the intervention, % CV, Control of Asthma Score, Severity Score and % compliance improved, showing that better medication compliance was associated with better control of moderately severe asthma.

Differences in airway responsiveness between children and adults living in the same environment: an epidemiological study in two regions of New South Wales

The aim of the present study was to compare the severity of asthma in children and adults living in the same home environments. In winter 1991 and 1992, we studied two large random samples of children living in two different regions; and, three months later, we conducted a study of adults who lived with enrolled children. A total of 805 children and 814 adults attended in Lismore, and 850 children and 711 adults in Wagga Wagga. Questionnaires were used to measure symptom history, histamine inhalation challenge to measure airway hyperresponsiveness (AHR) and skin-prick tests to measure allergy. There was a higher prevalence of asthma in children than in adults: recent wheeze was 1.5 times higher; asthma medication use was 1.5 times higher; diagnosed asthma was 1.6 times higher; and AHR was two times higher. Current asthma (AHR and recent wheeze) was 9.5-11.3% in children and 5.4-5.6% in adults. These differences were statistically significant. In both regions, airway responsiveness was more severe in children who were sensitized to common allergens than in similarly sensitized adults. These results suggests that airways can develop protective mechanisms with age, or that recent environmental changes in factors such as allergen levels, diet or treatment practices have led to immunological changes and to increased airway responsiveness in this generation of children.

Changing prevalence of asthma in Australian children

OBJECTIVE

To investigate whether prevalence of asthma in children increased in 10 years.

DESIGN

Serial cross sectional studies of two populations of children by means of standard protocol.

SETTING

Two towns in New South Wales: Belmont (coastal and humid) and Wagga Wagga (inland and dry).

SUBJECTS

Children aged 8-10 years: 718 in Belmont and 769 in Wagga Wagga in 1982; 873 in Belmont and 795 in Wagga Wagga in 1992.

MAIN OUTCOME MEASURES

History of respiratory illness recorded by parents in self administered questionnaire; airway hyperresponsiveness by histamine inhalation test; atopy by skin prick tests; counts of house dust mites in domestic dust.

RESULTS

Prevalence of wheeze in previous 12 months increased in Belmont, from 10.4% (75/718) in 1982 to 27.6% (240/873) in 1992 (P < 0.001), and in Wagga Wagga, from 15.5% (119/769) to 23.1% (183/795) (P < 0.001). The prevalence of airway hyperresponsiveness increased twofold in Belmont to 19.8% (173/873) (P < 0.001) and 1.4-fold in Wagga Wagga to 18.1% (P < 0.05). The prevalence of airway hyperresponsiveness increased mainly in atopic children only, but the prevalence of atopy was unchanged (about 28.5% in Belmont and about 32.5% in Wagga Wagga). Numbers of house dust mites increased 5.5-fold in Belmont and 4.5-fold in Wagga Wagga.

CONCLUSIONS

We suggest that exposure to higher allergen levels has increased airway abnormalities in atopic children or that mechanisms that protected airways of earlier generations of children have been altered by new environmental factors.

Asthma severity and morbidity in a population sample of Sydney schoolchildren: Part II--Importance of house dust mite allergens

BACKGROUND

Despite an increasing prevalence of childhood asthma, few studies have quantified the strength of associations between asthma and its aetiological factors.

AIMS

To quantify the risk factors associated with childhood asthma and to investigate the characteristics of children most at risk.

METHODS

We studied a population sample of 1339 schoolchildren aged eight-11 years living in Sydney, NSW. Questionnaires were used to measure respiratory illness, histamine inhalation test to measure airway hyperresponsiveness (AHR), skin prick tests to measure atopy and ELISA assay to measure house dust mite allergen (Der p I) levels. 'Current asthma' was defined as the presence of wheeze in the previous year and AHR.

RESULTS

The mean Der p I level in 72 homes was 22.5 micrograms/gm dust which is high compared to suggested thresholds of 2 microgram/gm for sensitisation and 10 micrograms/gm for exacerbation of symptoms. Sensitisation to house dust mites was the most important risk factor for current asthma (odds ratio 7.0, 95% CI 9.4, 22.2). Sensitisation to ryegrass was of minor importance (odds ratio 2.0, 95% CI 1.4, 3.1). The presence of AHR was strongly related to the degree of sensitisation to house dust mite allergen and children with skin wheals greater than 4 mm had frequent morbidity caused by asthma.

CONCLUSIONS

To reduce the high prevalence of childhood asthma in NSW, it is imperative that we design interventions which recognise that house dust mite allergens are a dominant risk factor and that children with large skin wheal reactions to this allergen are most at risk for severe illness including disturbed sleep, days missed from school and urgent medical attention.

Asthma severity and morbidity in a population sample of Sydney school children: Part I--Prevalence and effect of air pollutants in coastal regions

BACKGROUND

In two regions of Sydney where sewage treatment facilities with high temperature sludge burning incinerators are installed, there was concern that the resultant emissions were causing a local increase in symptoms of asthma and other allergic diseases.

AIM

To investigate whether living in a region with high temperature sludge burning incinerators was associated with an increased prevalence of childhood asthma or allergy.

METHODS

We studied 713 children aged eight-12 years in two regions close to incinerators and 626 children in a control region with no sludge burning incinerator. We measured respiratory illness in the previous year by questionnaire, airway hyper-responsiveness (AHR) by histamine inhalation test, and atopy by skin prick tests. 'Current asthma' was defined as AHR and recent wheeze.

RESULTS

Recordings of oxides of nitrogen and sulphur, hydrogen sulphide, ozone and particulates during the study period showed that the level of pollutants did not vary in any major way between the study regions and the control region. The prevalence of current asthma, atopy, symptom frequency or any category of severity of asthma illness was not significantly different between the control and study regions.

CONCLUSIONS

This suggests that factors other than intermittent or industrial air pollutants are responsible for the high prevalence of asthma symptoms, asthma medication use, asthma morbidity and AHR in the study of children.

A national policy on asthma management for schools. The Asthma Special Interest Group, Thoracic Society of Australia and New Zealand

Since asthma is the most common chronic illness in childhood, many of the problems associated with this condition will impact on the child's education. Because of widespread concerns regarding the management of asthma in schools, a subcommittee of the Thoracic Society of Australia and New Zealand, Asthma Special Interest Group, was convened to draw up national guidelines for school staff in order to provide optimal management of asthma in the school setting. We used current medial literature and the clinical experience of the authors who have dealt with children and adolescents suffering from asthma in the hospital, community and school environment. A number of issues had been identified, including: the availability of an asthma first aid kit; correct use of bronchodilator aerosols by puffer and spacer devices; and clear instructions as to when to notify parents and when to call an ambulance to the school.(ABSTRACT TRUNCATED AT 250 WORDS)

A profile of asthma and its management in a New South Wales provincial centre

OBJECTIVE

To describe aspects of the manifestations and management of asthma in a community setting.

DESIGN

Cross-sectional survey.

SETTING

A NSW provincial centre in October 1991.

PARTICIPANTS

Ninety-eight adults, identified from a population survey, with wheeze, shortness of breath, or cough, in the past year, and either airway hyperresponsiveness (AHR) or a reported doctor's diagnosis of asthma.

MAIN OUTCOME MEASURES

Histamine challenge test to measure AHR; asthma quality of life questionnaire (AQLQ) score (with the maximum score of 10 corresponding with lowest quality of life); need for medical attention or time off work; medical management and self-management of asthma; and the extent of beta 2-agonist use.

RESULTS

Of the 98 participants, 74 had had asthma diagnosed by their doctor, 34 had perennial asthma, and 30 had required medical attention or had missed work because of asthma in the preceding year. The median AQLQ score was 1.0 (interquartile range, 0.6-1.8). Inhaled steroids were used by 17 participants who accounted for 23% of those with medically diagnosed asthma, 32% of those with perennial asthma, 17% of those with moderate or severe AHR, 40% of those who had required medical attention or missed work because of asthma in the preceding year, and 31% of those with AQLQ scores in the top quartile. Only 18 participants owned a peak flow meter; seven had a written self-management plan; 18 stated they would respond to worsening asthma by starting or increasing treatment with inhaled steroids, and six would start therapy with orally administered steroids. Twelve had never used beta 2-agonists and only five had purchased more than 12 beta 2-agonist inhalers in the preceding year.

CONCLUSIONS

The spectrum of asthma in this community sample included many adults with mild disease and few with severe disease. Many were not managed in accordance with the recommendations of the Asthma Management Plan, but overuse of beta 2-agonists was not an important public health problem in this community.

An exercise challenge protocol for epidemiological studies of asthma in children: comparison with histamine challenge

We investigated whether an exercise challenge protocol is suitable for measuring bronchial responsiveness in epidemiological studies of asthma in children, and determined its comparability with histamine challenge. The exercise challenge was 6 minutes of outdoor, free-range running at 85-90% of maximum heart rate, measured by heart rate monitor. Nose clips were worn. Distance run was measured to estimate oxygen consumption. Water content of the inspired air was < 10 mg H2O.l-1. Histamine challenge was by the rapid method. We used questionnaires to measure respiratory symptoms and skin prick tests to measure atopy. A total of 96 children aged 8-11 years were studied. Bronchial hyperresponsiveness (BHR) to exercise challenge was defined as a fall in forced expiratory volume in one second (FEV1) of 13% of greater. Eleven children had a positive response to exercise challenge and 11 to histamine challenge but 12 responded to one challenge and not to the other. The correlation coefficient between the two tests was 0.65 (p = 0.0001). Exercise challenge thus proved to be a practical epidemiological tool for objective measurements of bronchial responsiveness in children. In this sample, some children responded to one challenge and not to the other which suggests that the two challenges identify different abnormalities of the airways.

Importance of house dust mite and Alternaria allergens in childhood asthma: an epidemiological study in two climatic regions of Australia

The relation of house dust mite allergen levels to asthma and allergy was examined in two population samples of children aged 8-11 years in northern New South Wales. We studied 805 children in Lismore (a hot, humid, coastal region) and 770 in Moree/Narrabri (a hot, dry inland region). Respiratory symptoms were measured by questionnaire, bronchial hyperresponsiveness (BHR) by histamine inhalation test, and allergy by skin-prick tests. Current asthma was defined as the presence of both wheeze in last 12 months and BHR. Der p I levels were measured in dust from the bed and floors in the homes of 57 randomly selected children in the coastal region and of 74 inland children. Der p I levels were significantly higher by the coast (83.0 vs 11.2 microg/g, P < 0.001). House dust mite sensitivity was of similar prevalence in both regions (28.6 vs 26.4%, n.s.) but Alternaria sensitivity was higher inland (4.0 vs 15.2% P<0.001). Bronchial responsiveness was more severe in coastal children sensitized to house dust mites and in inland children who were sensitized to Alternaria. The adjusted odds ratios for current asthma in children sensitized to house dust mites were 21.3 (95% CI 10.5, 43.2) by the coast and 2.7 (95% CI 1.3, 5.4) inland, and in children sensitized to Alternaria were 3.4 (95% CI 1.3, 9.1) in the coastal region and 5.6 (95% CI 3.1, 10.1 inland. These studies suggest that high house dust mite allergen levels in a humid, subtropical region act to significantly increase bronchial responsiveness in sensitized children, and that Alternaria allergens have a similar but less potent action in a dry, rural region.

Hospital admissions and attendances for asthma--a true increase?

OBJECTIVE

To compare the ratio of hospital admissions for asthma to total hospital admissions and to admissions for non-asthma respiratory conditions, over an 11-year period, to see if there has been a true increase in admissions for asthma or merely a change in diagnostic labelling. A similar comparison was made for presentations with asthma and non-asthma respiratory conditions to the accident and emergency department.

DESIGN AND SETTING

A case review of all patients with a confirmed diagnosis of respiratory disease admitted to hospital or attending the accident and emergency department at the Camperdown Children's Hospital between 1979 and 1989.

RESULTS

There was a 98% increase in the number of patients admitted with a confirmed diagnosis of asthma. While the ratio of admissions for asthma to total admissions increased from 0.053 in 1979 to 0.09 in 1989, the ratio of admissions for non-asthma respiratory conditions to total admissions remained relatively constant. The ratio of attendances for asthma to total accident and emergency attendances rose from 0.017 in 1979 to 0.072 in 1989, whereas the ratio of attendances for non-asthma respiratory conditions to total accident and emergency attendances had a maximum variation of 0.065 to 0.09.

CONCLUSIONS

These results suggest that there has been a major increase in the number of cases of asthma being treated at this hospital and that this is a true increase, perhaps representing increased severity, rather than a change in diagnostic labelling.

Evaluation of a community-based asthma management program in a population sample of schoolchildren

OBJECTIVE

To assess the effect of a community-based management program, incorporating both education and treatment directed at children, parents, doctors, pharmacists, community nurses and school teachers.

DESIGN

The effect of this intervention in a population sample of 65 children with a wide range of morbidity due to asthma was compared with a control group of 55 children living in a different area. Both groups were re-evaluated concurrently after three and six months.

MAIN OUTCOME MEASURES

Forced expiratory volume in one second (FEV1); bronchial responsiveness to histamine measured as the provoking dose causing a 20% fall in FEV1 (PD20FEV1) and as dose-response ratio (DRR); Airflometer variability; symptom frequency; and knowledge of asthma. Morbidity was measured by parents using a self-administered questionnaire and included days absent from school and unscheduled doctor or emergency room visits.

RESULTS

At three months, the intervention group had a significant improvement in knowledge of asthma compared with both their baseline and the control group's change in knowledge. Also, FEV1 improved in this group and symptoms which limit activity decreased significantly. However, the largest improvements were recorded at the six-month follow up. In the intervention group, bronchial responsiveness and night cough were reduced significantly and FEV1 was improved, compared with both baseline measurements and the control group. Knowledge of asthma also improved significantly from baseline, and unscheduled doctor or emergency room visits were reduced.

CONCLUSION

These improvements in this group of children, many of whom had mild asthma, verify that community-based management programs can be effective in treating childhood asthma.

A comparison of a bodyweight dose versus a fixed dose of nebulised salbutamol in acute asthma in children

OBJECTIVE

To compare the efficacy of salbutamol as a fixed dose Ventolin Nebule (2.5 mg) and as variable dose respirator solution (0.1 mg/kg bodyweight).

DESIGN

Multicentre, randomised, double-blind, parallel group comparison.

SETTING

The Emergency Departments of the Royal Children's Hospital, Melbourne, Victoria; Princess Margaret Hospital for Children, Perth, Western Australia; and The Children's Hospital, Sydney, New South Wales.

PATIENTS

Ninety-nine children between four and 12 years of age who presented to the Emergency Departments with mild to moderate acute asthma from May to December 1990.

INTERVENTIONS

Children enrolled in the study were randomly allocated to one of two groups. Group 1 received one Nebule (2.5 mg salbutamol in 2.5 mL aqueous solution) delivered by wet nebulisation. Group 2 received salbutamol (approximately 0.1 mg/kg bodyweight) diluted with saline to 2.5 mL, delivered by identical wet nebulisation.

MAIN OUTCOME MEASURES

(i) Clinical score; (ii) pulse oximetry; and (iii) peak expiratory flow rate (PEFR) where possible--measured before, and at 15 and 30 minutes after treatment with salbutamol.

RESULTS

The clinical score significantly improved in both treatment groups after 15 minutes (P < 0.001), but the difference between the two treatments (adjusted for covariates) was not significant (P = 0.97). Both preparations of salbutamol produced a significant increase in oxygen saturation after 15 minutes (P < 0.05), while the difference between the two treatments (adjusted means) was not significant (P = 0.46). Peak flow measurements were available for 65 of the 99 patients. Both preparations of salbutamol produced highly significant (P < 0.001) improvements in PEFR at 15 minutes after treatment. The difference in peak flow rates between the two treatment groups (adjusted means) was not significant (P = 0.89). The study had a power of 0.8 to detect differences between treatments of 9% PEFR (percentage predicted), 0.8% oxygen saturation and 0.77 units of clinical score.

CONCLUSIONS

A fixed dose of nebulised salbutamol is as efficacious as a salbutamol dose calculated for bodyweight in children with mild to moderate acute asthma.

The cost of asthma: can it be reduced?

Asthma is a major public health problem in developed countries, where it consumes a large and increasing share of scarce health resources. Ideally, medical management should be both optimal in terms of improving the patient's quality of life, and cost-effective for society. At present, there is very little information relating to costs and economic efficiency of current asthma management. Although the true total cost of asthma is unknown, current estimates suggest it is high. The main value of recent total cost estimates is that they identify the most expensive areas of asthma costs, and ideally, formal cost-effectiveness analyses should be concentrated on these areas. Asthma is still under- or inappropriately diagnosed, and undertreated. Several national and international consensus plans for the optimal management of asthma in children and adults have been published. If these inadequacies in asthma management were corrected, using current treatment recommendations, the overall cost of asthma from both the community and patient perspective should fall. The situation requires increased use of preventative medications {sodium cromoglycate (cromolyn sodium) or inhaled corticosteroids}, more widespread use of written crisis plans, more proactive medical consultations (rather than reactive or urgent consultations), further expansion of asthma education programmes, and further education of medical practitioners about the optimum management of both long term asthma and the acute exacerbation of asthma in the patient's home, the doctor's office, the hospital emergency room and the hospital inpatient setting. The increased costs associated with these measures would be more than offset by reduced expenditure on bronchodilator drugs, less widespread use of nebulisers at home and in hospitals, reduced antibiotic usage, reduced need for expensive emergency medical care and particularly reduced utilisation of hospital resources. To ensure that resources are being directed into the most cost-effective areas of asthma care, clinical trials of asthma should include utilisation of healthcare resources as an outcome measure, and estimates of the costs of the treatment under study. In addition, since the intangible cost (quality of life) is one of the most important effects of treatment from the patient's perspective, this should be more widely used as an outcome measure in clinical trials. Ultimately, prevention of asthma is the long term goal. If the hypothesis that sensitisation to house dust mite in early infancy is a major contributor to the subsequent development of asthma, then prevention may require drastic and expensive changes to current housing.

A multicentre randomized placebo-controlled double-blind study on the efficacy of Ketotifen in infants with chronic cough or wheeze

The efficacy of Ketotifen was examined in the treatment of 113 infants between 6 and 36 months of age presenting with a history of cough and/or wheeze in a multicentre randomized placebo-controlled double-blind study. A 4 week no-medication baseline phase preceded the 16 week treatment phase in which infants took 2.5 mL twice daily of either placebo or Ketotifen (0.5 mg) syrup; this was followed by a 4 week wash-out phase. Diary card evaluation was performed by the parent or guardian for the duration of the study and recorded wheeze and cough twice daily as well as medication used. The percentage of symptom-free days decreased significantly in both groups (P < 0.005) with placebo-treated infants experiencing significantly more symptom-free days compared with the Ketotifen group (P < 0.01), although this difference was never more than 10% in any 4 week treatment period. Symptom severity scores and use of beta-agonist medication were also less in the placebo-treated infants but did not reach statistical significance. This study was unable to show a therapeutic advantage of Ketotifen over placebo in this group of infants with chronic cough and/or wheeze and the apparent statistical advantage of placebo is not a clinically relevant finding.

Toward a definition of asthma for epidemiology

Because there is no "gold standard" for defining asthma for epidemiology, we have defined current asthma as bronchial hyperresponsiveness (BHR) plus recent wheeze (in the 12 months prior to study). To describe the characteristics of groups categorized by these measurements, we studied two samples of children aged 7 to 12 yr: 210 from a population sample and 142 self-identified asthmatics. Bronchial responsiveness to histamine was measured by the rapid method, respiratory symptom history, and asthma medication use by self-administered questionnaire to parents and atopy by skin prick tests to 14 allergens. Children recorded daily Airflometer readings and symptom scores for 2 wk. Children with current asthma had more severe bronchial responsiveness, greater Airflometer variability, more symptoms, more atopy (particularly to house dust mites), and used more asthma medication than children with BHR or recent wheeze alone. Children with BHR, but not with recent wheeze, were intermediate between the current asthma and normal groups in terms of bronchial responsiveness, Airflometer variability, and atopy. Children with recent wheeze and normal responsiveness differed from the normal group only in symptoms and medication use. Our definition of current asthma discriminates a group of children that is clearly different in terms of both clinical features and physiologic measures. As such, it is the most useful definition to date for measuring the prevalence of clinically important asthma in populations.