Asthma: from childhood to adulthood

Role of infections in the induction and development of asthma: genetic and inflammatory drivers

Genetic and environmental factors interact to initiate and even maintain the course of asthma. As one of the highly risky environmental factors, infections in predisposed individuals can promote asthma development and exacerbations and/or prolong symptoms. This review will describe our current understanding of the genetic markers of innate immunity in the induction and development of asthma, the diverse roles of infections in modulating allergic inflammation, host susceptibility to infections and subsequent acute exacerbations in an allergic setting, and the therapeutic or preventive implications of existing knowledge. Current challenges and future directions in basic and clinical research of asthma are also discussed.

Inconclusive Evidence for Allergic Rhinitis to Predict a Prolonged or Chronic Course of Acute Rhinosinusitis

Objective

To systematically review the evidence on allergic rhinitis as a predictor for a prolonged or chronic course in adult patients with acute rhinosinusitis.

Data Sources

Pubmed, EMBASE, and the Cochrane library.

Review Methods

A systematic literature search was performed on March 15, 2013. During screening of title and abstract, 3 authors independently selected studies on allergic rhinitis as a predictor for the course of acute rhinosinusitis in adults. The reported study design was assessed for directness of evidence and risk of bias. We aimed to extract prior and posterior probabilities for a prolonged or chronic course of acute rhinosinusitis.

Results

Of 13,202 retrieved articles, 2 articles were eligible for study assessment. They provided a high directness of evidence but carried a high risk of bias. The studies showed an incidence of a prolonged and chronic course of, respectively, .19 (95% confidence interval [CI] .16-.23) and .05 (95% CI, .02-.13). In patients with allergic rhinitis, the incidence was .25 (95% CI, .18-.35) and .14 (95% CI, .04-.34), so the added value of allergic rhinitis to predict a prolonged course is 6% and to predict a chronic course 8%.

Conclusion and Recommendation

While the 2 included studies suggest that allergic rhinitis adds little to the prediction of a prolonged or chronic course in patients with acute rhinosinusitis, they carry a high risk of bias. As the available evidence does not provide grounds for different management of patients with and without allergic rhinitis, namely, according to clinical practice guidelines, both can be managed with expectant observation and symptomatic treatment.

Asthma and lung structure on computed tomography: the Multi-Ethnic Study of Atherosclerosis Lung Study

BACKGROUND

The potential consequences of asthma in childhood and young adulthood on lung structure in older adults have not been studied in a large, population-based cohort.

OBJECTIVE

The authors hypothesized that a history of asthma onset in childhood (age 18 years or before) or young adulthood (age 19-45 years) was associated with altered lung structure on computed tomography in later life.

METHODS

The Multi-Ethnic Study of Atherosclerosis Lung Study recruited 3965 participants and assessed asthma history by using standardized questionnaires, guideline-based spirometry, and segmental airway dimensions and percentage of low attenuation area (%LAA) on computed tomographic scans.

RESULTS

Asthma with onset in childhood and young adulthood was associated with large decrements in FEV(1) among participants with a mean age of 66 years (-365 mL and -343 mL, respectively; P < .001). Asthma with onset in childhood and young adulthood was associated with increased mean airway wall thickness standardized to an internal perimeter of 10 mm (0.1 mm, P < .001 for both), predominantly from narrower segmental airway lumens (-0.39 mm and -0.34 mm, respectively; P < .001). Asthma with onset in childhood and young adulthood also was associated with a greater %LAA (1.69% and 4.30%, respectively; P < .001). Findings were similar among never smokers, except that differential %LAA in childhood-onset asthma were not seen in them.

CONCLUSION

Asthma with onset in childhood or young adulthood was associated with reduced lung function, narrower airways, and among asthmatic patients who smoked, greater %LAA in later life.

The natural history of asthma from childhood to adulthood

Medical Practitioners are often questioned regarding the prognosis of a child with asthma. We have performed a literature review of the natural history of childhood asthmatics. Factors which affect the natural history and prognosis of childhood asthma are discussed. Current evidence suggests that evolution of asthma severity is fairly predictable. Features of childhood asthma such as severity, duration, atopy, bronchial hyperresponsiveness and exposure to smoking can predict the course of asthma into adulthood. Most children with mild intermittent asthma will outgrow their asthma, or have mild episodic asthma. Early commencement of anti-inflammatory therapy, such as inhaled corticosteroids may prevent the progression of the disease. Most patients with mild asthma have good functional outcome and low healthcare utilisation.

Intensity of bronchial hyperresponsiveness and asthma relapse risk in the young adult

BACKGROUND

The evolution of asthma starting in childhood varies and depends on a series of factors (atopy, allergens, and environmental irritants, etc). Treatment may influence the evolution of the disease and even cause the symptoms to disappear. However, there remains a risk of relapse years later.

OBJECTIVES

To assess the role of bronchial hyperresponsiveness in asthma relapse in young adulthood in patients with symptoms that disappeared after treatment prescribed in childhood.

MATERIAL AND METHODS

To determine the evolution of asthma and patients' personal opinions, 78 patients were sent a questionnaire several years after having been discharged without symptoms in the previous 2 years, and without the need for medication. The methacholine test was used to evaluate bronchial hyperresponsiveness at discharge. The 40 patients who correctly completed the questionnaire were divided into three groups according to the methacholine dose required to obtain a 20 % decrease in forced expiratory volume in 1 second (PD20): group 1 (15 patients), < 1000microg; group 2 (10 patients) between 1001 and 2000 microg; and group 3 (15 patients) > 2100 microg. The mean age at discharge was 16 years (range 13-25 years) versus 26 years at the time of response (range 18-33 years), with a similar distribution in all three groups. Age at disease onset, with estimation of severity, age at the first visit and at the start of treatment, and respiratory function were evaluated.

RESULTS

Thirty of the interviewed patients considered themselves to be cured. Seven of the patients (three in group 1, one in group 2, and three in group 3) did not consider themselves to be cured, although their symptoms were minimal and they rarely used medication. Health status was described as "regular" with sporadic symptoms by one patient in each group. No correlation with methacholine response was observed.

CONCLUSION

No relationship was found between the degree of bronchial hyperresponsiveness and the risk of relapse in young adults who suffered asthma in childhood.

Relationship among pulmonary function, bronchial hyperresponsiveness, and atopy in children with clinically stable asthma

Pulmonary function testing plays a key role in the diagnosis and management of asthma in children. However, the literature does not clearly show whether children with clinically stable asthma have significantly reduced lung function when compared with normal children. We compared the lung function of 242 clinically stable asthmatic children who were initially diagnosed with mild intermittent or mild persistent asthma with the lung function of 100 nonasthmatic controls. The lung function was assessed using FEV1, FEV1/FVC, FEF25-75 and PEF. In addition, we measured bronchial hyperresponsiveness (BHR) using the provocation concentration of methacholine needed to produce a 20% fall in FEV1. All measures of pulmonary function were significantly decreased in the children with asthma. Pulmonary function was not influenced by atopy, serum IgE, or total eosinophil count (TEC). However, the likelihood ratio for trends revealed a significant association between our pulmonary parameters and the degree of BHR. Children with mild-to-severe BHR had greatly decreased lung function compared with those with normal BHR, the control group. In addition, a direct correlation was found between PC20 and our pulmonary parameters in asthmatic children. However, only atopic children with asthma had a significant correlation between PC20 and TEC. We found children with clinically stable asthma to have pulmonary obstruction, which associated strongly with their degree of BHR.

Sex differences in factors associated with childhood- and adolescent-onset wheeze

RATIONALE

Factors predicting the development of wheeze may differ between sexes and between childhood and adolescence.

METHODS

A New Zealand birth cohort of 1,037 children was followed to age 26. For this analysis, those reporting recurrent wheezing at two or more assessments were classified as "wheezers." We examined risk factors for development of wheeze before age 10 (childhood) and subsequently (adolescent-onset) for males and for females separately using Cox regression modeling.

RESULTS

Males more often developed childhood wheeze (p = 0.002) and females adolescent-onset wheeze (p < 0.001). Maternal atopy (asthma or hay fever) was a risk factor for childhood wheeze in both sexes (hazard ratio [HR], 1.48, p < 0.05 for males; HR, 2.37, p < 0.001 for females). Paternal atopy also influenced childhood wheeze, significantly for males (HR, 1.72; p = 0.01), and similarly but not significantly for females (HR, 1.70; p = 0.08). For adolescent-onset wheeze, neither maternal (HR, 1.41; p = 0.19) nor paternal history (HR, 0.73; p = 0.42) was a risk factor in males, but maternal history (HR, 2.08; p < 0.01) was a significant risk factor for females. When both age ranges were combined, providing greater power for analysis, paternal history was a stronger risk factor for wheeze in females (HR, 1.62; p = 0.02) than in males (HR, 1.35; p = 0.12).

CONCLUSION

The influence of parental atopy on the development for wheeze differs between males and females and between childhood- and adolescent-onset wheeze.

Rationale for the Dutch hypothesis. Allergy and airway hyperresponsiveness as genetic factors and their interaction with environment in the development of asthma and COPD

The Dutch hypothesis, formulated in the 1960s, holds that the various forms of airway obstruction are different expressions of a single disease entity. It suggests that genetic factors (eg, airway hyperresponsiveness [AHR] and atopy), endogenous factors (eg, sex and age), and exogenous factors (eg, allergens, infections, and smoking) all play a role in the pathogenesis of chronic nonspecific lung disease. This review finds evidence that AHR and smoking are common risk factors for asthma and COPD. To prove the Dutch hypothesis definitively, however, genetic studies, preferably longitudinal, must be performed. Such studies must include subjects who have airway obstruction that does not necessarily meet the current strict definitions of asthma or COPD (ie, the extremes of these conditions) that are used in clinical studies.

Usefulness of monitoring lung function in asthma

There is no firm evidence from randomised controlled trials that routine monitoring of lung function improves asthma control in children. Guidelines for management of asthma consistently recommend routine home monitoring of peak expiratory flow (PEF) in each patient. However, changes in PEF poorly reflect changes in asthma activity, PEF diaries are kept very unreliably, and self management programmes including PEF monitoring are no more effective than programmes solely based on education and symptom monitoring. PEF diaries may still be useful in isolated cases of diagnostic uncertainty, in the identification of exacerbating factors, and in the rare case of children perceiving airways obstruction poorly and exacerbating frequently and severely. If a reliable assessment of airways obstruction in asthma is needed, forced expiratory flow-volume curves are the preferred method. Monitoring of hyperresponsiveness and nitric oxide cannot be recommended for routine use at present. Clinical judgement and expiratory flow-volume loops remain the cornerstone of monitoring asthma in secondary care.

A longitudinal, population-based, cohort study of childhood asthma followed to adulthood

BACKGROUND

The outcome of childhood asthma in adults has been described in high-risk cohorts, but few population-based studies have reported the risk factors for persistence and relapse.

METHODS

We assessed children born from April 1972 through March 1973 in Dunedin, New Zealand, repeatedly from 9 to 26 years of age with questionnaires, pulmonary-function tests, bronchial-challenge testing, and allergy testing.

RESULTS

By the age of 26 years, 51.4 percent of 613 study members with complete respiratory data had reported wheezing at more than one assessment. Eighty-nine study members (14.5 percent) had wheezing that persisted from childhood to 26 years of age, whereas 168 (27.4 percent) had remission, but 76 (12.4 percent) subsequently relapsed by the age of 26. Sensitization to house dust mites predicted the persistence of wheezing (odds ratio, 2.41; P=0.001) and relapse (odds ratio, 2.18; P=0.01), as did airway hyperresponsiveness (odds ratio for persistence, 3.00; P<0.001; odds ratio for relapse, 3.03; P<0.001). Female sex predicted the persistence of wheezing (odds ratio, 1.71; P=0.03), as did smoking at the age of 21 years (odds ratio, 1.84; P=0.01). The earlier the age at onset, the greater the risk of relapse (odds ratio, 0.89 per year of increase in the age at onset; P<0.001). Pulmonary function was consistently lower in those with persistent wheezing than in those without persistent wheezing.

CONCLUSIONS

In an unselected birth cohort, more than one in four children had wheezing that persisted from childhood to adulthood or that relapsed after remission. The factors predicting persistence or relapse were sensitization to house dust mites, airway hyperresponsiveness, female sex, smoking, and early age at onset. These findings, together with persistently low lung function, suggest that outcomes in adult asthma may be determined primarily in early childhood.

Characterization of wheezing phenotypes in the first 10 years of life

BACKGROUND

Childhood wheezing illnesses are characterized into different phenotypes. However, severity of the disease associated with these phenotypes has not been extensively studied.

OBJECTIVES

To determine characteristics of childhood wheezing phenotypes in the first decade of life using health outcomes plus measurements of atopy, lung function and bronchial hyper-responsiveness.

METHODS

A whole population birth cohort (n = 1456) was prospectively studied to examine the natural history of childhood wheezing. Children were seen at 1, 2, 4 and 10 years for questionnaire completion and prospectively collected data used to define wheezing phenotypes. Assessment was made of adverse health outcomes plus spirometry, bronchial hyper-responsiveness, serum IgE measurement at 10 years and skin test sensitization at both 4 and 10 years for wheezing phenotypes.

RESULTS

Phenotypic analysis identified that 37% early life wheezers (symptom onset by age 4 years) still wheezed at 10 years. These persistent wheezers showed significantly more physician-diagnosed asthma in early life (P < 0.005 at 2 years) than early transient wheezers (wheezing transiently with onset by age 4 years). Overall they experienced greater multiple hospital admissions (P = 0.024), specialist referral (P = 0.009) and use of inhaled (P < 0.001) and oral steroids (P < 0.001) than early transient wheezers. They also demonstrated enhanced bronchial hyper-responsiveness compared with early transient wheezers (P < 0.001). However, both groups of early life wheezers showed impairment of baseline lung function at 10 years in comparison with non-wheezers: FEV1 (P < 0.029) and FEV1/FVC ratio (P < 0.001) with persistent wheeze and PEF (P = 0.036) with early transient wheeze. Late-onset wheezers (onset from 5 years onwards) had similar BHR to persistent wheezers but maintained normal lung function at age 10 and had lower cumulative prevalence of adverse health outcomes than persistent wheezers.

CONCLUSIONS

Persistent wheezing with early childhood onset is associated with substantial morbidity in the first decade of life in association with high levels of atopy, bronchial hyper-responsiveness and impaired lung function at 10 years of age. Late-onset wheezing in the first decade of life could harbour potential for similarly significant disease subsequently.

Geographical variations of asthma and asthma symptoms among schoolchildren aged 5 to 8 years and 12 to 15 years in Palestine: the International Study of Asthma and Allergies in Childhood (ISAAC)

BACKGROUND

Many studies demonstrated the existence of geographic differences, within and between countries, in the prevalence of asthma, rhinitis, and eczema. However, in Palestine, there are no comprehensive Palestinian data to compare with those from other regional and international centers.

OBJECTIVE

To describe the prevalence of asthma and asthma symptoms in schoolchildren in two districts (Ramallah and North Gaza) in Palestine.

METHODS

After a two-stage stratified systematic sampling, approximately 14,500 schoolchildren, from the first and second grades of elementary school (ages 5 to 8 years) and eighth and ninth school grades (ages 12 to 15 years), were invited to participate in a survey using International Study of Asthma and Allergies in Childhood phase III questionnaires and protocols.

RESULTS

In general, younger children were reported to have a higher 12-month wheezing prevalence rate than older children (9.6 and 7.2%, respectively), and more physician-diagnosed asthma (8.4 and 5.9%, respectively). However, nocturnal cough and exercise-related wheezing were higher in the older age group compared with younger children. Younger children living in North Gaza district showed slightly higher prevalence rates for asthma and asthma symptoms, but older children had higher rates in Ramallah district. After adjustment using logistic regression analysis, male sex, living in inland areas, and younger age were shown to predict 12-month wheezing and physician-diagnosed asthma.

CONCLUSIONS

Palestinian children have asthma symptoms rates that are similar to several countries in the Mediterranean region such as Spain and Turkey, but still lower than other Middle East countries such as Saudi Arabia and Israel.

Inhaled salmeterol/fluticasone propionate combination: a pharmacoeconomic review of its use in the management of asthma

Asthma guidelines recommend an inhaled corticosteroid plus a long-acting inhaled beta(2)-agonist (beta(2)-adrenoceptor agonist) as the preferred maintenance therapy for moderate and severe persistent asthma. Advair/Seretide Diskus also registered as Accuhaler is fixed-dose salmeterol (a long-acting inhaled beta(2)-agonist) and fluticasone propionate (a corticosteroid) administered via a single powder inhalation device. The clinical effectiveness of salmeterol/fluticasone propionate in patients with persistent asthma symptoms has been established in comparative clinical trials. Pharmacoeconomic analyses, based on data from these clinical trials, have been conducted from a healthcare payer perspective in various countries. In patients with asthma not controlled with inhaled corticosteroids, salmeterol/fluticasone propionate was associated with more favourable (lower) cost-effectiveness ratios than fluticasone propionate monotherapy, oral montelukast plus inhaled fluticasone propionate, inhaled budesonide, and inhaled formoterol plus budesonide. As the initial maintenance therapy in patients with persistent asthma symptoms while receiving short-acting beta(2)-agonists alone, salmeterol/fluticasone propionate was cost effective relative to montelukast monotherapy. Although the total cost of asthma management tended to be slightly higher with salmeterol/fluticasone propionate than with fluticasone propionate or montelukast monotherapy, salmeterol/fluticasone propionate consistently had a more favourable cost-effectiveness ratio in terms of per successfully treated week or symptom-free day and/or was associated with small incremental costs to achieve significant additional clinical benefits. In clinical practice, salmeterol plus fluticasone propionate was associated with lower asthma-related costs than treatment with other maintenance therapies.In patients with asthma symptoms despite treatment with inhaled corticosteroids, salmeterol/fluticasone propionate produced clinically meaningful improvements in overall Asthma Quality of Life Questionnaire (AQLQ) scores relative to salmeterol or placebo monotherapy, in emotional function domain scores relative to fluticasone propionate or budesonide, and in asthma symptoms domain scores relative to budesonide. In patients with persistent asthma symptoms while receiving short-acting beta(2)-agonists alone, salmeterol/fluticasone propionate produced clinically meaningful improvements in overall AQLQ scores compared with fluticasone propionate or montelukast.

CONCLUSIONS

Pharmacoeconomic analyses indicate that salmeterol/fluticasone propionate administered via a single inhaler represents a cost-effective treatment option (relative to fluticasone propionate at the same nominal dosage, budesonide, formoterol plus budesonide and montelukast plus fluticasone propionate) in patients with asthma not controlled with inhaled corticosteroid therapy. In patients with asthma not controlled with short-acting beta(2)-agonists alone, salmeterol/fluticasone propionate is a cost effective treatment relative to monotherapy with montelukast. Importantly, salmeterol/fluticasone propionate is also associated with improvements in health-related quality of life.

Lung function and symptom perception in children with asthma and their parents

A large proportion of children with asthma are managed without recourse to specialized care, and treatment decisions are based solely on symptoms as reported by the children and their parents. We investigated 90 school-age children with the diagnosis of asthma and their accompanying parent to evaluate whether we can obtain better information by using three different means of asking for asthma symptoms: a questionnaire for children (QSR(children)), "smilies," and a visual analogue scale for children (VAS(children)). Furthermore, we analyzed the relationship between these symptom reports and lung function results. Finally, we attempted to determine whether performing a lung function test contributes relevant information toward improving asthma management. Multiple linear regression adjusted for age and gender showed a significant relationship between VAS for children and forced expiratory volume in 1 sec (FEV(1)) (P = 0.047) and maximal expiratory flow at 50% of forced vital capacity (MEF(50)) (P = 0.037). Neither age, gender, QSR for children, "smilies for children" nor all the parents' scores showed a significant association with lung function measurement in the regression model. Subgroup analysis with Spearman's rank correlation coefficients by age group revealed significant correlation in children <10 years between VAS for children, QSR for parents, smilies for parents, and the lung function parameters FEV(1), and MEF(50). Above age 10 years there was no correlation at all, with the accuracy correlation ranging from -0.04 to +0.21. Our data demonstrate that reported symptoms do not reliably correlate with lung function results in asthmatic children and the childrens' parents, and correlation is dependent on the instrument used for symptom evaluation. In children, the VAS, and in parents, the QSR were the most valuable means of obtaining best information on asthma symptoms. This underlines the importance of supplementing information on asthma symptoms with lung function measurements to more reliably assess the severity of asthma.

Asthma severity, allergy and lung function during young middle life in subjects with asthma in childhood

The further course of asthma severity lung function, bronchial hyperresponsiveness (BHR) to cold air challenge (CACh), clinical allergies and allergic sensitization in young middle adulthood was studied in a cohort of 55 subjects with childhood asthma. All subjects (27 females) have attended all five previous and the current follow-up visit, undertaken at a mean age of 35 years. Twelve subjects (22%) reported no current asthma, 28 (51%) mild/intermittent, and 15 (27%) moderate/severe asthma. Asthma severity changed little in the individual subjects over the last 5-year period. Females continued to have higher asthma severity scores than the males, but the previously noted lower resting and post-bronchodilator % predicted FEV1 in females was not confirmed now. Pathological BHR to CACh tended to be more common among the males. Forty-four subjects were still allergic to animal danders and 35 to pollens. Sensitization rates (skin prick test or RAST) were similar to those recorded 5 years earlier and there was no clear evidence of tolerance developing. Five subjects have never shown evidence of allergy or sensitization. The extent of sensitization to animal danders showed statistically significant relationships to asthma severity and BHR to CACh. Social development and professional careers continued to be good.

Long-term outcome of childhood asthma

What we know: The outcome of childhood asthma is dependent on the pattern of asthma through childhood. Episodic asthma in childhood tends to resolve in adolescence and through mid-adult years, with no impairment of lung function. Persistent asthma in childhood is more likely to persist into adult years, with modest impairment of lung function. The impairment of lung function occurs early in the disease process and is not progressive, despite continuing symptoms. What we need to know: Are there clearly identifiable phenotypes of childhood asthma that have different aetiologies, response to treatment, genotypes and natural history? Does early treatment with anti-inflammatory agents prevent impairment of lung function? Can an algorithm be developed to predict the likelihood of persistent asthma on first presentation?

Follow-up studies of asthma from childhood to adulthood

One of the main questions from parents of children with asthma is whether the child will outgrow the disease and what is the role of treatment. All outcome studies show that in the transition period from childhood to adulthood asthma symptoms decrease and thereby asthma seems to be cured. However, the reality is that more than 50% of children with asthma suffer from asthma in adult life. The role of treatment is uncertain, since all studies began in a period when inhaled corticosteroids and other novel medications were not available. The recent findings from a study of bronchial biopsies in subjects in remission from asthma for more than 3 years suggests that asthma might persist throughout life.

Incidence and remission of asthma: a retrospective study on the natural history of asthma in Italy

BACKGROUND

The knowledge of the natural history of asthma from birth to adulthood could provide important clues for its cause and for the understanding of epidemiologic findings.

OBJECTIVE

This study is aimed at assessing the incidence and remission of asthma from birth to the age of 44 years by using data from 18,873 subjects involved in a large, nationally representative, cross-sectional study carried out in Italy from 1998 through 2000.

METHODS

The onset of asthma was defined as the age at the first attack, and remission was considered present when a subject was neither under treatment nor had experienced an asthma attack in the last 24 months. Person-years and survival techniques were used for the analysis.

RESULTS

The average annual incidence rate for the 1953 to 2000 period was 2.56/1000 persons per year. Incidence peaked in boys less than 10 years of age (4.38/1000 persons per year) and in women 30 years of age or older (3.1/1000 persons per year) and showed a generational increase (incident rate ratio = 2.63 and 95% CI = 2.20-3.12 for 1974-1979 vs 1953-1958 birth cohort). The overall remission rate was 45.8% (41.6% in women and 49.5% in men, P <.001). Asthmatic patients in remission had an earlier age at onset (7.8 vs 15.9 years, P <.001) and a shorter duration of the disease (5.6 vs 16.1 years, P <.001) than patients with current asthma. The probability of remission was strongly (P <.001) and inversely related to the age at onset (62.8% and 15.0% in the <10- and > or =20-years age-at-onset groups, respectively).

CONCLUSION

With respect to its natural history, asthma presents 2 different forms: early-onset asthma, which occurs early in childhood, affects mainly boys, and has a good prognosis, and late-onset asthma, which generally occurs during or after puberty, mainly affects women, and has a poor prognosis. The minority of patients with early-onset asthma who do not remit represents more than 35% of patients with current asthma in the general young adult population.

Critical evaluation of prognostic factors in childhood asthma

Current knowledge of the natural history of asthma is improving through the establishment of a more precise definition of asthma linked with information from a number of large-scale longitudinal studies. Risk factors for the development of childhood asthma are now more clearly understood. They include gender, atopic status, genetic and familial factors, respiratory infections, and outdoor and indoor pollution (1). In the present review two types of asthma and their prognosis will be discussed: (1) Asthma in preschool children and its risk factors for evolution towards persistent childhood asthma. (2) Asthma in older children and its risk factors for evolution towards adult asthma.

The early course of newly diagnosed asthma

PURPOSE

We describe the intensity of therapy for patients with newly diagnosed asthma and how it changed during subsequent years in relation to age, sex, and initial level of therapy.

METHODS

We examined a cohort of 13,671 patients in Saskatchewan, Canada, who were initially between the ages of 5 and 44 years. Patients were followed prospectively, and the intensity of asthma therapy was measured during successive 12-month periods.

RESULTS

Based on the intensity of asthma drug therapy during the first year after entry into the cohort, 6661 patients (48.7%) were initially prescribed therapy judged to be appropriate for mild asthma, and 977 (7.1%) were dispensed medications in a manner suggesting their asthma was severe; the remaining 6033 (44.1%) were classified as receiving treatment of intermediate intensity. Among patients initially classified as receiving treatment appropriate for mild disease, only about 3% were dispensed medications that suggested that their asthma had become severe during up to 5 years of follow-up. Intensity of therapy waned in a substantial proportion of patients who were initially classified as having severe asthma, especially if they were initially younger than 15 years of age. Thirty-four per 100 patients initially younger than 15 years old were receiving medications appropriate for mild asthma, and 23 per 100 such patients received no medication for asthma during a 12-month period when followed up to 5 years.

CONCLUSION

Patients with asthma who are initially treated with therapy appropriate for mild asthma are rarely treated later with therapy suggesting the advent of severe disease. Patients initially dispensed medications suggesting the presence of severe asthma often see the intensity of treatment wane over time.

Inhaled salmeterol/fluticasone propionate combination. A pharmacoeconomic review of its use in the management of asthma

Cost estimates from developed countries indicate that asthma accounts for up to 2% of the economic cost of all diseases. A large proportion of asthma-related costs are attributable to poor asthma control. Treatment strategies which improve clinical outcomes in patients with asthma, therefore, have the potential for significant economic benefits, and it is important to evaluate new asthma therapies for cost effectiveness. Several studies have established that salmeterol and fluticasone propionate combined in a single dry powder inhalation device are at least as effective as a combination of the 2 drugs administered via separate dry powder inhalers and more effective than monotherapy with fluticasone propionate or budesonide. Importantly, pharmacoeconomic analysis of several of these studies show that the salmeterol/fluticasone propionate combination is cost effective relative to monotherapy with fluticasone propionate or budesonide. Although the total cost of asthma management tended to be slightly higher with salmeterol/fluticasone propionate than with inhaled corticosteroid monotherapy, in most cases mean cost-effectiveness ratios were lower (i.e. more favourable) for salmeterol/fluticasone propionate than either fluticasone propionate or budesonide. Cost effectiveness was assessed according to 3 end-points: successfully treated weeks, symptom-free days and episode-free days. Mean cost-effectiveness ratios consistently favoured salmeterol/fluticasone propionate over the comparator drug for the end-point successfully treated weeks, and in most cases the other 2 end-points also favoured the combination product over the comparator. In a further study, salmeterol/fluticasone was also less costly than therapy with formoterol and budesonide administered via 2 separate inhalers. Studies of health-related quality of life (HR-QOL) using the Asthma Quality of Life Questionnaire indicate that salmeterol/fluticasone propionate produces clinically meaningful improvements in overall HR-QOL relative to salmeterol monotherapy or placebo. Improvements in overall HR-QOL were statistically significantly greater for salmeterol/fluticasone propionate than with fluticasone propionate or budesonide alone, although the differences between treatments did not exceed the threshold for clinical significance. In conclusion, short term cost-effectiveness data show that salmeterol/fluticasone propionate is more cost effective than the inhaled corticosteroids budesonide and fluticasone propionate alone. The combination product also appears to improve HR-QOL relative to placebo or salmeterol alone.

Association between allergy and asthma from childhood to middle adulthood in an Australian cohort study

A cohort of 378 asthmatic children was studied from 7 to 35 yr of age at 7-yr intervals. On selection for inclusion in the study sample, the children had a wide range of severity of wheezing. At each 7-yr review, asthma severity, the presence of eczema or hay fever, and skin test reactivity to house dust mite or rye grass were recorded by questionnaire or clinical interview. We report on the course of asthma and these atopic conditions over the study period and discuss associations between the two phenomena. The presence of an atopic condition in childhood was found to increase the odds of more severe asthma in later life (odds ratio [OR] = 1.66, 95% confidence interval [CI]: 1.17 to 2.36 in the case of eczema; OR = 1. 39, 95% CI: 1.00 to 1.92 for hay fever; and OR = 2.25, 95% CI: 1.49 to 3.39 for skin test reactivity). Additionally, the odds of eczema and hay fever in later life increased with severity of asthma in childhood. The findings of this study provide substantially new quantitative information on the extent of association between asthma and atopic conditions from childhood into middle adulthood.

Inhaled fluticasone propionate. A pharmacoeconomic review of its use in the management of asthma

Contemporary asthma management guidelines list inhaled corticosteroids as the preferred controller medication for patients with persistent asthma. Despite the availability of explicit guidelines, there is evidence that these agents are underused and that guidelines are not always adhered to. Fluticasone propionate is one of several inhaled corticosteroids used for the treatment of asthma. Like other agents of its class, its efficacy is backed by extensive clinical data. More recently, the quality of life of recipients of fluticasone propionate and its relative cost effectiveness have been investigated. A series of comparative analyses show that inhaled fluticasone propionate is more cost effective than oral zafirlukast and triamcinolone acetonide and slightly more cost effective than flunisolide in adult patients with asthma. Analyses used cost per symptom-free day and/or cost per successfully treated patient as outcome measures and were generally conducted from the perspective of the third-party payer. When administered at a microgram dose of half or less than budesonide (as is therapeutically appropriate), the cost effectiveness of fluticasone propionate was similar to or better than that of budesonide. In children, fluticasone propionate was more cost effective per treatment success compared with inhaled sodium cromoglycate. Quality-of-life assessments in patients with mild to moderate disease show that inhaled fluticasone propionate achieved improvements which were deemed to be clinically meaningful in patients with mild to moderate asthma; these changes were significantly greater than those achieved with oral zafirlukast, inhaled triamcinolone acetonide or placebo. Greater improvements were evident with inhaled fluticasone propionate in patients with severe disease.

CONCLUSIONS

In addition to the considerable body of clinical evidence supporting the use of inhaled fluticasone propionate in patients with asthma, accumulating short term cost-effectiveness data also suggest that this agent can be administered for a similar or lower cost per outcome than other inhaled corticosteroids or oral zafirlukast. Importantly, the clinical benefits offered by fluticasone propionate in patients with persistent asthma are accompanied by clinically significant improvements in quality of life.

Asthma in adults: comparison of adult-onset asthma with childhood-onset asthma relapsing in adulthood

The prevalence of asthma in children and young adults is rising. Although the general features of asthma are similar in children and adults, there are several differences. Studies of the differences between childhood- and adult-onset asthma may provide new insight into the phenotypic heterogeneity of asthma. The aim of this cross-sectional study was to compare the characteristics of asthmatic adults who reported having (n = 84) or not having (n = 235) asthma in childhood. The participating patients were recruited by chest specialists throughout France and were examined from March to November 1995. The specialists completed a standardized questionnaire, and carried out a clinical examination and spirometric tests. Male sex; greater severity, particularly lower spirometry values related to small airways; greater severity and earlier onset of allergy; and maternal history of atopic dermatitis and perennial rhinitis were found to be associated with reported childhood asthma. This study exhibits highly internally consistent results and indicates that subjects who did have childhood asthma and relapse in adulthood appeared to have a potentially more severe form of asthma.

Consequences of long-term inflammation. The natural history of asthma

Although asthma is classically defined as reversible airflow obstruction, and often remits in younger subjects with milder disease, the natural history of asthma is that various degrees of airflow obstruction may persist and, in the long-term, asthma may become moderately to fully irreversible. Severe, irreversible airflow obstruction may develop despite apparently appropriate therapy and in the absence of other risk factors, such as smoking and environmental insults. All studies of subjects with persisting asthma show increased decline in lung function compared with normal subjects. Persistent abnormal physiology is reflected both in reduced airflow rates and in increased airway responsiveness. The cellular and molecular mechanisms of airway remodeling are described elsewhere in this issue. Questions not yet clearly answered are the reasons for these persistent abnormalities in some asthmatics, and which subjects are most at risk. Factors that adversely impact the outcome as adults identified relatively consistently among many longitudinal studies of the natural history of asthma include: Female gender. Environmental tobacco smoke exposure in childhood. Personal tobacco smoking in adolescence and adulthood. Age of onset of symptoms. Severity of childhood asthma. Duration of asthma. Severity of lung function abnormality in childhood. Bronchodilator reversibility. Degree of airway hyperresponsiveness. Delay in initiating anti-inflammatory therapy. Remission among adult asthmatics is uncommon, but is associated with better initial lung function, young age, male gender, and lesser degrees of airway responsiveness. The role of atopy remains controversial. Conversely, risk factors for death from asthma include older age, smoking, atopy, impaired lung function, and moderate to high reversibility. Treatment can improve lung function, reduce airway responsiveness, and improve quality of life. The overall effect of treatment on the natural history of the disease is not yet clear, despite significant short-term improvements from effective anti-inflammatory therapy.

Asthma from childhood to adulthood: course and outcome of lung function

Lung function (FEV1 before and after bronchodilatation) was studied prospectively over five visits in 55 asthmatic children (28 boys) from childhood to adulthood (age 30). At the last follow-up recordings were made at rest, after cold air challenge (CACh), and after bronchodilatation. Results were related to clinical asthma scoring and to sensitization to furred animals, as described in a companion paper. Lung function outcome was shown to be influenced by initial FEV1 (% predicted) and gender, but not by initial asthma severity or sensitization. FEV1 (% predicted) was higher in females than in males over the first two follow-ups, but the reverse was found over the subsequent visits. It deteriorated from childhood to adulthood in the females but improved in the males. In adulthood the females (for height 170 cm) had a steeper normalized annual fall in post-bronchodilator FEV1 than the males (55 +/- 38 vs. 25 +/- 36 ml; P = 0.006). The degree of bronchial hyperresponsiveness was associated significantly with asthma severity and the extent of sensitization to furred animals, but not with gender. The results indicate a better lung function outcome for asthmatic boys than for girls, confirming trends seen in clinical asthma severity. In adulthood the extent of sensitization to relevant perennial inhaled allergens significantly influences airway responsiveness and asthma severity, but not lung function.

Natural history of asthma: a 23-year followup of college students

OBJECTIVE

A 23-year followup study of 1,601 college students who were initially evaluated for evidence of asthma and allergic rhinitis by direct interviews, physical examination, laboratory tests, and repeated questionnaires was conducted.

METHODS AND RESULTS

The individuals were located through addresses from the alumnae office. Of these, 1,021 (64%) returned their completed questionnaires and these included 738 (72%) who had allergy skin tests as freshmen. A similar proportion of our total population of 1,021 were skin tested as freshmen compared with the original study population of 1,836 in the freshmen year (72% versus 68%). This difference was not statistically significant. Among these 738 alumnae, with a mean age of 40 years, there were a total of 84 with a history of asthma. At the time of the 23-year followup, 44 (52%) were considered to have active asthma and 40 (48%) were symptom free. A majority (85%) of those with inactive asthma were symptom free for 5 years or longer. Of those with active asthma, 50% felt they were improved, 39% unchanged, 9% felt worse, and 2% were unknown. Atopy was a non-prognostic indicator of asthma outcome as determined by scratch skin testing as college freshmen. New asthma occurred in 36 (5.2%) of those at risk to develop new asthma in this 23-year period for a rate of 0.23% per year.

CONCLUSION

This 23-year followup study demonstrates that the cumulative prevalence of asthma continues to increase as the individuals become older. The asthma symptoms were no longer present or were improved in about three-fourths of the asthma subjects in this 40-year-old age group. Of the remainder, most symptoms were unchanged and a small number felt worse.

Asthma from childhood to adulthood: asthma severity, allergies, sensitization, living conditions, gender influence and social consequences

The course of asthma severity, clinical allergies, allergic sensitization, changes in living conditions and social outcome were studied prospectively over five follow-up visits from the mean age of 9 to 30 years in a cohort of 28 boys and 27 girls, selected randomly among asthmatic children attending a paediatric outpatient unit. Asthma severity improved from childhood to adulthood, judged by symptom and medication scores and by the number of hospital admissions, but only nine subjects (16%) had been free from symptoms and medication over the last year of follow-up. After adolescence, asthma continued to improve among the males but not among the females. This difference could not be explained by gender differences in the course of clinical allergies or sensitization (skin-prick-tests and RAST) to common inhaled allergens, or by differences in environmental or social conditions. Sensitization to relevant perennial inhaled allergens correlated with asthma severity during adulthood. In general, clinical allergies and sensitization to inhaled allergens adopted during childhood persisted into adulthood. Approximately 10% of the subjects never adopted a clinical allergy or a positive allergy test. The social outcome was good.

Incidence and prevalence of asthma among adult Finnish men and women of the Finnish Twin Cohort from 1975 to 1990, and their relation to hay fever and chronic bronchitis

STUDY OBJECTIVES

To examine the prevalence of asthma and hay fever, and the incidence and temporal relationships of asthma, hay fever, and chronic bronchitis among adult twins during a 15-year period.

DESIGN

Prospective cohort study.

PARTICIPANTS

A population of 11,540 Finnish adult men and women, initially 18 to 45 years of age, who returned a health questionnaire in 1975, 1981, and 1990 as part of the Finnish Twin Cohort study.

METHODS

Age-standardized prevalences and cumulative incidences among individuals were calculated for asthma, hay fever, and chronic bronchitis. The incidence of asthma among subjects with and without hay fever or chronic bronchitis was analyzed in the entire cohort as well as in twin pairs discordant for incident asthma.

RESULTS

The prevalence of asthma increased slightly from 1975 (2.0% in men and 2.2% in women) to 1990 (2.9% in men and 3.1% in women). The prevalence of hay fever showed a larger increase in men and women (from 6.8% and 9.8% to 11.8% and 15.3%, respectively). Compared with figures for 1976 to 1981, no significant increase in asthma incidence occurred from 1982 to 1990, whereas the incidence of hay fever was lower during the latter period among men (incidence rate ratio, 0.7; 95% confidence interval, 0.6 to 0.9) as was the incidence of chronic bronchitis among women (incidence rate ratio, 0.7; 95% confidence interval, 0.6 to 0.9). Hay fever and chronic bronchitis were usually diagnosed before asthma. Both diseases increased the risk of asthma significantly on the basis of analyses of all individuals and of discordant twin pairs.

CONCLUSIONS

The pattern of increase in asthma and hay fever prevalence with time was similar, and hay fever was a strong predictor of asthma. These diseases showed no significant increase in incidence.

Evolution of asthma through childhood

The greatest incidence of childhood asthma is among males under 5 years, with decreasing numbers of new cases with age. Many young children wheeze, but remission is common especially in non-atopic children without a family history of allergy or asthma, whose wheezing relates more to infections and environmental tobacco smoke exposure. The prognosis of childhood asthma is best established from population studies, in which some two-thirds of wheezy children become symptom-free as adults, whereas follow-up studies of wheezing children seen in office or specialty clinic practice, who generally have more severe asthma, show a much greater likelihood (60-80%) of persistence of asthma into adulthood. Factors predisposing to persistence of childhood asthma include a positive family history, development of atopy, environmental exposures to allergens and cigarette smoke, markers of severity of childhood asthma, and female gender.