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Effects of ambient air pollution on symptoms of asthma in Seattle-area children enrolled in the CAMP study.

We observed a panel of 133 children (5-13 years of age) with asthma residing in the greater Seattle, Washington, area for an average of 58 days (range 28-112 days) during screening for enrollment in the Childhood Asthma Management Program (CAMP) study. Daily self-reports of asthma symptoms were obtained from study diaries and compared with ambient air pollution levels in marginal repeated measures logistic regression models. We defined days with asthma symptoms as any day a child reported at least one mild asthma episode. All analyses were controlled for subject-specific variables [age, race, sex, baseline height, and FEV(1) PC(20) concentration (methacholine provocative concentration required to produce a 20% decrease in forced expiratory volume in 1 sec)] and potential time-dependent confounders (day of week, season, and temperature). Because of variable observation periods for participants, we estimated both between- and within-subject air pollutant effects. Our primary interest was in the within-subject effects: the effect of air pollutant excursions from typical levels in each child's observation period on the odds of asthma symptoms. In single-pollutant models, the population average estimates indicated a 30% [95% confidence interval (CI), 11-52%] increase for a 1-ppm increment in carbon monoxide lagged 1 day, an 18% (95% CI, 5-33%) increase for a 10-microg/m(3) increment in same-day particulate matter < 1.0 microm (PM(1.0)), and an 11% (95% CI, 3-20%) increase for a 10-microg/m(3) increment in particulate matter < 10 microm (PM(10)) lagged 1 day. Conditional on the previous day's asthma symptoms, we estimated 25% (95% CI, 10-42%), 14% (95% CI, 4-26%), and 10% (95% CI, 3-16%) increases in the odds of asthma symptoms associated with increases in CO, PM(1.0), and PM(10), respectively. We did not find any association between sulfur dioxide (SO(2)) and the odds of asthma symptoms. In multipollutant models, the separate pollutant effects were smaller. The overall effect of an increase in both CO and PM(1. 0) was a 31% (95% CI, 11-55%) increase in the odds of symptoms of asthma. We conclude that there is an association between change in short-term air pollution levels, as indexed by PM and CO, and the occurrence of asthma symptoms among children in Seattle. Although PM effects on asthma have been found in other studies, it is likely that CO is a marker for vehicle exhaust and other combustion by-products that aggravate asthma.

Adolescent↗

Asthma in the United States: burden and current theories.

Asthma has emerged as a major public health problem in the United States over the past 20 years. Currently, nearly 15 million Americans have asthma, including almost 5 million children. The number of asthma cases has more than doubled since 1980. Approximately 5,500 persons die from asthma each year, and rates have increased over the past 20 years. Rates of death, hospitalization, and emergency department visits are 2-3 times higher among African Americans than among white Americans. The costs of asthma have also increased to 12.7 billion dollars in 1998. Both lifestyle and environmental hypotheses have been invoked to explain the increase in asthma prevalence. Several studies have examined the relationship of obesity and asthma and found associations suggesting that obesity predisposes to the development of asthma. Some studies have found that day care attendance and having older siblings protect against the development of asthma. This observation has led investigators to hypothesize that increased exposure to microbial agents might protect against asthma (the hygiene hypothesis). Environmental exposures found to predispose to asthma include house dust mite allergen and environmental tobacco smoke. Although current knowledge does not permit definitive conclusions about the causes of asthma onset, better adherence to current recommendations for medical therapy and environmental management of asthma would reduce the burden of this disease.

Adult↗

Assessment of practical knowledge of self-management of acute asthma.

AIMS: To develop an instrument for the measurement of, and to determine the level of, practical knowledge of self-management of acute asthma. METHODS: Eighty patients with moderate/severe asthma attending a hospital-based asthma clinic responded to an interviewer-administered questionnaire. Subjects were asked to describe the action they would take in response to each of two hypothetical evolving attacks: (1) one of gradually increasing severity and (2) the other developing rapidly. Responses were scored according to the appropriateness of actions taken relevant to the stage of the attack. Transcripts of the responses were scored independently by three of the investigators according to a system based on Thoracic Society of Australia and New Zealand (TSANZ) and British Thoracic Society (BTS) consensus statements on asthma management. A 25-point scale was used on which 0 represented a total lack of appropriate responses and a score of 25 was an optimal response. RESULTS: Interrater and intrarater reliability were excellent. Mean (+/- SD) scores for the slow and rapid onset attacks were 12.8 +/- 4.0 and 13.9 +/- 4.8, respectively. The scores for the two scenarios were predicted by each other (p = 0.002) and by the interviewer's rating of asthma management knowledge (p = 0.0004, p = 0.0001), but not by age, sex, race, previous asthma morbidity, depression, or anxiety. In both scenarios, most patients indicated that they would increase inhaled beta-agonist (85% for slow-onset scenarios and 94% for rapid-onset scenarios, respectively) and use their action plan and/or seek urgent medical advice at an appropriate time (74% and 70%). Although some would measure peak expiratory flow (PEF) initially (54% and 30%), only a minority would continue to monitor PEF in the context of worsening acute asthma (30% and 24%). When a severe life-threatening situation was described, only 50% and 64%, respectively, indicated that they would call emergency services. CONCLUSIONS: Scenarios describing hypothetical asthma attacks are a useful and reproducible method of assessing practical knowledge of self-management of acute asthma. Patients presented with scenarios frequently made errors in their hypothetical responses. The errors made with scenarios, which parallel errors reported in real clinical situations, occurred despite the fact that this patient population had received considerable education and training about how to manage asthma. Most indicated they would not monitor PEF even in an exacerbation of asthma and would not call emergency services despite life-threatening asthma. These scenarios may allow us to explore the gap between knowledge about treatment and actual practice, and perhaps to help close that gap and thus reduce asthma morbidity and mortality.

Acute Disease↗

Exhaled pentane levels in acute asthma.

BACKGROUND: Exhaled pentane, a product of lipid peroxidation, has been proposed as an objective, nonspecific, and noninvasive marker of active inflammation. Reactive oxygen species, which elicit lipid peroxidation, are increased in asthma and contribute to airway dysfunction. OBJECTIVE: To determine whether exhaled pentane levels are increased in acute asthma, and whether they decrease once acute asthma subsides. METHODS: Expired air was collected through a mouthpiece into a pentane-impermeable collection bag from 12 patients (40+/-5 years; mean+/-SEM) presenting to the emergency department of the University of Illinois Hospital in Chicago with acute asthma. Exhaled air was also collected after discharge from the hospital once acute asthma subsided. Eleven patients with stable asthma (40+/-5 years) and 17 healthy volunteers (31+/-5 years) served as control subjects. Exhaled air and ambient room air were analyzed for pentane content by gas chromatography. Peak expiratory flow rates were determined in each subject. RESULTS: Peak expiratory flow rates were 202+/-29 L/min during acute asthma and 327+/-26 L/min once acute asthma subsided (p<0.05). Exhaled pentane levels were 8.4+/-2.9 nmol/L during acute asthma and decreased significantly to 3.5+/-0.5 nmol/L once acute asthma subsided (p<0.05). Exhaled pentane levels were similar in patients with stable asthma and normal control subjects (3.6+/-0.4 nmol/L and 2.6+/-0.2 nmol/L, respectively; p>0.05). No pentane was detected in ambient air. CONCLUSION: Exhaled pentane levels are increased in patients with acute asthma and decrease significantly once acute asthma subsides.

Acute Disease↗

Prevalence of physician-diagnosed asthma in Saskatchewan, 1981 to 1990.

STUDY OBJECTIVE: To examine trends in asthma prevalence in the Province of Saskatchewan using the Medical Claim Insurance Branch (MCIB) database. DESIGN: For each calendar year from 1981 to 1990, first visits to physicians for asthma were identified from the MCIB database. Age- and sex-specific prevalence rates were obtained for each calendar year by dividing the number of first asthma visits by the number of subjects in the age- and sex-specific group insured by the Provincial Government of Saskatchewan in that calendar year. RESULTS: Asthma prevalence increased in children and adults from 1981 to 1990. In the calendar year 1990, the prevalence of asthma was 5.1% in children < or = 4 years old, 4.4% in children 5 to 14 years old, 2.2% in young adults 15 to 34 years old, and 1.9% in adults 35 to 64 years old. Boys had higher asthma prevalence than girls in the age groups 0 to 4 years and 5 to 14 years, but it was reversed in older age groups, with women having greater asthma prevalence than men. Asthma diagnoses were verified by checking for asthma-related drug purchase in the Prescription Drug Plan database. Among the 0- to 4-year-old children with physician-diagnosed asthma, 57.3% purchased at least one asthma-related drug in 1981 and 72.3% purchased that in 1990. Among adults, asthma-related drug purchase was >73% in 1990. CONCLUSIONS: Asthma prevalence increased in children and adults in the province of Saskatchewan. Reasons for the increase are not clear and further studies are required to determine factors related to the increase.

Adolescent↗

The association between occupation and asthma in general medical practice.

BACKGROUND: In general practice settings, the proportion of adult asthma attributable to occupational factors is not known. OBJECTIVE: The goal of this study was to estimate the proportion of adult asthma cases that can be attributed to occupational factors initiating new disease onset and exacerbating preexisting disease. METHODS: We performed a cross-sectional analysis of interview data for 150 adults with asthma recruited from a random sample of family practice specialists. We ascertained the asthma and work histories of the subjects and estimated the proportion with likely work-initiated asthma and work-related asthma recrudescence. RESULTS: Seventy-four subjects (49%) reported adult-onset asthma while employed; an additional 25 (17%) reported recrudescence of previously quiescent childhood-onset asthma during employment. Of those with new-onset asthma while employed, 15 (10% of the study group; 95% confidence interval, 5 to 15%) were employed in occupations at increased risk of occupational asthma initiation on the basis of an independent job scoring matrix. Of those with asthma recrudescence in adulthood, seven (5% of the study group; 95% confidence interval, 2 to 8%) were employed in occupations at increased risk of exposures aggravating asthma. CONCLUSIONS: Among adults with asthma treated in general practice settings, > 1 in 10 patients has a work history strongly suggestive of a potential relationship between exposure and disease.

Adolescent↗

Underdiagnosis and undertreatment of asthma in the elderly. Cardiovascular Health Study Research Group.

OBJECTIVE: To describe the clinical correlates of asthma in a community-based sample of elderly persons. PARTICIPANTS: A community sample of 4,581 persons > or = 65 years old from the Cardiovascular Health Study. MEASUREMENTS: Standardized respiratory, sleep, and quality-of-life (QOL) questions, a medication inventory, spirometry, and ambulatory peak flow. RESULTS: Four percent of the participants reported a current diagnosis of asthma (definite asthma), while another 4% reported at least one attack of wheezing accompanied by chest tightness or dyspnea during the previous 12 months (probable asthma). Smokers and those with congestive heart failure were excluded from the subsequent analyses, leaving 2,527 participants. Of those who had definite asthma, 40% were taking a sympathomimetic bronchodilator, 30% inhaled corticosteroids, 21% theophylline, and 18% oral corticosteroids; 39% were taking no asthma medications. The participants with definite or probable asthma were much more likely than the others to have a family history of asthma, childhood respiratory problems, a history of workplace exposures, dyspnea on exertion, hay fever, chronic bronchitis, nocturnal symptoms, and daytime sleepiness. They were also more likely to report poor general health, symptoms of depression, and limitation of activities of daily living. There was little difference in the morbidity and QOL of participants with recent asthma-like symptoms who had received the diagnosis of asthma versus those who had not. CONCLUSIONS: Asthma in elderly persons is associated with a lower QOL and considerable morbidity when compared with those who do not have asthma symptoms. Asthma is underdiagnosed in this group and is often associated with allergic triggers; inhaled corticosteroids are underutilized.

Age Factors↗

Aerobic conditioning in mild asthma decreases the hyperpnea of exercise and improves exercise and ventilatory capacity.

STUDY OBJECTIVE: To determine the effect of an aerobic conditioning program on fitness, respiratory physiology, and resting lung function in patients with mild asthma. DESIGN: Prospective cohort study. SETTING: Outpatient rehabilitation facility. METHODS: Five patients with mild intermittent asthma and five normal control subjects completed a 10-week aerobic conditioning program. Pulmonary function studies and noninvasive cardiopulmonary exercise tests were performed before and after the conditioning program. RESULTS: After aerobic conditioning, there were significant gains in maximum oxygen consumption (VO(2)max; 22.73 mL/kg/min vs 25.29 mL/kg/min, p = 0.01, asthma; 22.94 mL/kg/min vs 27.85 mL/kg/min, p = 0.03, control) and anaerobic threshold (0.99 L/min vs 1.09 L/min, p = 0.03, asthma; 0.89 L/min vs 1.13 L/min, p = 0.01, control) in both groups. Although FEV(1) was unchanged, the maximum voluntary ventilation (MVV) improved in the asthma group (96.0 L/min vs 108.2 L/min, p = 0.08, asthma; 134.0 L/min vs 131.2 L/min, p = 0.35, control). During exercise, minute ventilation (VE) for each level of work was decreased in the asthma group after conditioning, while little change occurred in the control group (68. 48 L/min vs 51.70 L/min at initial VO(2)max, p = 0. 02, asthma; 65.82 L/min vs 63.12 L/min at initial VO(2)max, p = 0.60, control). A significant decrease in the ventilatory equivalent (VE/oxygen consumption, 40.8 vs 30.4 at VO(2)max, p = 0.02, asthma; 37.2 vs 35.8 4 at VO(2)max, p = 0.02, control) and the dyspnea index (VE/MVV) at submaximal (0.44 vs 0.38, p = 0.05, asthma; 0.32 vs 0.38, p < 0.01, control) and maximal exercise (0.72 vs 0.63, p = 0.03, asthma; 0.49 vs 0.62, p = 0.02, control) occurred in the asthma group. CONCLUSIONS: Exercise rehabilitation improves aerobic fitness in both asthmatic and nonasthmatic participants of a 10-week aerobic fitness program. Additional benefits of improved ventilatory capacity and decreased hyperpnea of exercise occurred in patients with mild asthma.

Adult↗

Childhood asthma in an urban community: prevalence, care system, and treatment.

OBJECTIVES: We describe the system of asthma care in Hartford, CT, an urban, minority community. METHODS: The health field concept was used to organize factors influencing asthma prevalence and severity. Data were obtained from national, state, and municipal reports, and from surveys of children in Hartford seeking medical care in an asthma program called Easy Breathing. RESULTS: Between June 1, 1998, and May 1, 2000, 21% of children receiving Medicaid in Hartford did not file a medical claim. Between 1998 and 2000, the number of providers in Hartford decreased by 37% while the number of outpatient visits increased by 8%. Using claims data, we found the following: 19.0% of Hartford children had asthma (data from the International Classification of Disease, ninth revision, and the National Drug Code); and 12% of children with asthma filled a prescription for inhaled corticosteroid therapy, 83% for a bronchodilator, and 36% for an oral corticosteroid. Children with asthma were more likely to be hospitalized (10% vs 5%, respectively) and to visit an emergency department (45% vs 29%, respectively), and, on average, they had more hospital days (0.603 vs 0.415 days per child, respectively) and more outpatient visits per year (4.7 vs 2.5 visits, respectively) compared to children without asthma. Asthma prevalence in the 6,643 children surveyed in the Easy Breathing program was 41%. Persistent asthma was diagnosed in 50% of the children with asthma. Asthma prevalence varied by ethnic origin, age, and gender, and was highest in Hispanic/Puerto Rican children, in children 5 to 10 years of age, in boys up to 10 years of age, and in girls after 15 years of age. CONCLUSION: Improved personal behaviors and medical care will have a limited sustained impact on childhood asthma until basic environmental issues are modified. The health field concept provides a mechanism with which to address the issues surrounding asthma in urban communities.

Adolescent↗

A comparison of the clinical characteristics of children and adults with severe asthma.

OBJECTIVES: This study sought to better define the clinical characteristics of severe asthma in both children and adults, and to evaluate the effect of asthma duration on multiple parameters of disease severity. DESIGN: Retrospective analysis of prospectively collected data on 275 patients (125 children) with severe asthma who were admitted to a tertiary asthma referral center. METHODS: Demographics, lung function (ie, spirometry and body box plethysmography), glucocorticoid (GC) pharmacokinetic studies, and lymphocyte stimulation assays were performed on all patients. RESULTS: Children were as likely to require therapy with high-dose inhaled GCs and long-term therapy with oral GCs, and to have had a prior intubation, yet they had significantly less airflow limitation (mean [+/- SEM] FEV(1), 74.0 +/- 2.1% predicted vs 57.1 +/- 1.8% predicted, respectively; p < 0.0001), less resistance to airflow (mean airway resistance, 140.3 +/- 8.5% predicted vs 311 +/- 18% predicted, respectively; p < 0.0001), and larger lung volumes (mean total lung capacity, 116.4 +/- 1.6% predicted vs 105.3 +/- 1.8% predicted, respectively; p < 0.0001) compared to adults. Children were more likely to be male and to display greater responsiveness to GCs in vitro. Lung function impairment was associated with asthma duration in children and in adults with onset of asthma in childhood, while there was no relationship between disease severity and asthma duration among those with adult-onset asthma. Despite significant differences in disease duration, patients with adult-onset asthma had equally compromised lung function compared to adults with long-standing asthma. CONCLUSIONS: Children with severe asthma tended to be male, to have less severe airflow obstruction, and to display greater responsiveness to GCs in vitro compared to adults. Symptoms and episodic acute declines in lung function may precede chronic airflow limitation in this group of children. As such, it may be more relevant to follow the deterioration in lung function over time in children. Finally, disease severity in children and adults whose onset of asthma occurred in childhood was related to disease duration, but not in patients with onset of asthma in adulthood.

Adolescent↗

Gastroesophageal reflux disease and asthma: a longitudinal study in UK general practice.

STUDY OBJECTIVES: Gastroesophageal reflux disease (GERD) and asthma are common causes for consultation in primary care, but the relationship between the two remains unclear. The aim of our study was to investigate the temporal relationship between first diagnoses of GERD and asthma in general practice. METHODS: We used the UK General Practice Research Database to identify a cohort of patients with a first diagnosis of GERD (n = 5,653) and another cohort of patients with a first diagnosis of asthma (n = 9,712) during 1996, which we compared with age-matched and sex-matched control cohorts drawn from the general population without either diagnosis. We investigated the incidence of a GERD diagnosis among the asthma patients and control subjects, and the incidence of an asthma diagnosis among the GERD patients and control subjects during a mean follow-up period of 3 years. We calculated the relative risk (RR) of these diagnoses using Cox regression analysis and examined the risk associated with medication use using nested case-control analysis. RESULTS: The incidence rates of GERD and asthma among the control cohorts were 4.4 and 3.8 per 1,000 person-years, respectively. During the follow-up period, the RR of an incident asthma diagnosis in patients with a new diagnosis of GERD was 1.2 (95% confidence interval [CI], 0.9 to 1.6), while the RR of an incident GERD diagnosis among patients with a new diagnosis of asthma was 1.5 (95% CI, 1.2 to 1.8) after adjustment for age, sex, smoking, prior comorbidity, and number of health-care contacts. This increased risk was mainly seen during the first year of follow-up. The prior use of prescription medications for asthma and GERD had no significant effects on the risk of GERD and asthma diagnosis, respectively. CONCLUSIONS: Patients with asthma are at a significantly increased risk of developing GERD, mainly during the first year following diagnosis. A nonsignificant increase in the risk of developing asthma was evident among GERD patients. The relationship between GERD and asthma warrants further investigation.

Adolescent↗

An interdisciplinary intervention for undertreated pediatric asthma.

STUDY OBJECTIVES: To examine the effectiveness of an interdisciplinary intervention for pediatric asthma. DESIGN: Randomized, controlled study. SETTING: Urban tertiary-referral pediatric hospital. PARTICIPANTS: One hundred seventy-five patients with asthma lacking written treatment plans and presenting with asthma-related emergency department visits (two or more) and/or hospitalizations (one or more) in the past year were randomized to a comparison group receiving medical care alone (n = 86) or to an interdisciplinary intervention group receiving medical care, asthma education, and problem-solving therapy (n = 89) INTERVENTION: All participants received written asthma management plans, peak flow meters, and spacer devices. The intervention group also received asthma education, an asthma risk profile assessment, brief problem-solving therapy, and access to a 24-h nurse advice line. The primary outcome measure was change in asthma symptoms, and secondary outcomes included health-care utilization and asthma-related quality of life. RESULTS: Both groups demonstrated significant reductions in asthma symptoms and improvements in quality of life without any between-group differences identified over the course of follow-up. In contrast, the intervention group demonstrated less frequent health-care utilization than the comparison group, with 28% of the intervention group requiring emergency department or inpatient services for asthma compared to 41% of the comparison group (adjusted odds ratio, 1.92; 95% confidence interval, 1.00 to 3.69) over the 12-month follow-up period. CONCLUSIONS: This study examined the effectiveness of an interdisciplinary intervention for undertreated asthma. The intervention did not result in improvements in asthma symptoms, but accomplished modest reductions in the utilization of acute medical care.

Anti-Asthmatic Agents↗

Risk factors for onset of asthma: a 12-year prospective follow-up study.

BACKGROUND: Asthma development and prognosis have been studied extensively in at-risk populations, but knowledge of the natural history of asthma in the general population is limited. OBJECTIVE: To describe the incidence and remission of asthma and its predictors, data from a 12-year follow-up study of a random population sample (n = 291; age range, 7 to 17 years) at enrollment, were analyzed. METHODS: The sample was examined in 1986 and in 1998. A case history, including data on asthma, allergic diseases, and lifestyle factors, was obtained by questionnaire and interview. Airway hyperresponsiveness (AHR) to histamine, lung function, and skin-prick test reactivity to a standard panel of 10 aeroallergens were measured. RESULTS: The point prevalence of asthma increased from 4.1% at the first survey to 11.7% at follow-up, at which point 19.6% of the sample had ever experienced asthma symptoms. Of the subjects with ever-asthma, 40% had remitted at follow-up. Asthma developed in 45 subjects (16.1%) during the follow-up period, which was predicted by the following factors: wheezing in childhood (odds ratio [OR], 3.61; 95% confidence interval [CI], 1.34 to 9.75), AHR (OR, 4.94; 95% CI, 2.42 to 10.08), allergic sensitization to house dust mites (OR, 3.23; 95% CI, 1.00 to 10.40), and dermatitis (OR, 2.94; 95% CI, 1.22 to 7.11). The simultaneous presence of more than one of these risk factors was associated with a high probability of developing asthma at follow-up (61.5%). In subjects without any risk factors, such as AHR, allergic sensitization, rhinitis, dermatitis or wheezing in childhood; paternal/maternal allergy, or asthma, asthma developed in only 4% during follow-up. CONCLUSION: The presence of AHR and concomitant atopic manifestations in childhood increase the risk of developing asthma in adulthood, and should be recognized as markers of prognostic significance, whereas the absence of these manifestations predicts a very low risk of future asthma.

Adolescent↗

Health-care use among Puerto Rican and African-American children with asthma.

STUDY OBJECTIVES: To compare the rates of emergency department (ED) visits, hospitalizations, hospital days, and outpatient clinic visits for asthma among children in two ethnic minority groups that are disproportionately affected by asthma (Puerto Ricans and African Americans). STUDY DESIGN: This cross-sectional study was part of an asthma intervention program in Hartford, CT, in which 6,554 children were screened for asthma by primary care providers using a parental survey. Medicaid and the supplementary State Children's Health Insurance Plan data about health-care utilization for asthma were obtained for each child for the 12 months preceding completion of the screening survey. RESULTS: Among 2,304 children in whom asthma had been diagnosed, Puerto Ricans had more severe asthma than African Americans. In analyses adjusted for asthma severity and other potential confounders, Puerto Rican children had more clinic visits for asthma (rate ratio [RR], 1.31; 95% confidence interval [CI], 1.12 to 1.53) but spent fewer days in the hospital for asthma (RR, 0.36; 95% CI, 0.24 to 0.53) than African-American children. There were no differences in the rates of ED visits or hospitalizations between the two groups. CONCLUSIONS: Puerto Rican children had more severe asthma but were less likely than African-American children to have prolonged hospitalizations for asthma. This finding may be due to the frequent clinic visits for asthma made by Puerto Rican children. Further research is needed to understand the cultural factors that contribute to different approaches to health-care utilization among ethnic minorities.

Adolescent↗

The influence of perceived control of asthma on health outcomes.

BACKGROUND: Psychosocial factors play an important role in outcomes of asthma. Perceived control, a measure of patients' beliefs about their ability to control their disease, has not been studied in association with asthma health outcomes METHODS: We used data from a prospective cohort study of patients who were hospitalized for asthma (n = 865). After hospital discharge, we conducted structured telephone interviews to obtain demographic characteristics, asthma history, and psychological variables. Interviews included administration of the Perceived Control of Asthma Questionnaire (PCAQ). We then prospectively measured emergency department (ED) visits and hospitalizations for asthma over time, with a median follow-up time of 1.9 years RESULTS: Greater perceived control was associated with better physical health status (mean score increment per 2-point change in PCAQ score, 1.13; 95% confidence interval [CI], 0.79 to 1.47), better asthma-related quality of life (mean score increment, -2.24; 95% CI, -2.6 to -1.83), fewer days of restricted activity due to asthma (mean increment, -1.23; 95% CI, -1.62 to -0.83), and lower asthma severity scores (mean score increment, -0.40; 95% CI, -0.53 to -0.27). In a multivariate model, greater perceived control was associated with a significantly decreased prospective risk of ED visits (hazard ratio [HR], 0.92; 95% CI, 0.86 to 0.98; p = 0.008) and hospitalizations for asthma (HR, 0.84; 95% CI, 0.78 to 0.90; p < 0.0001). There was no association found between perceived control and most aspects of preventive care or self-management CONCLUSIONS: Greater perceived control is associated with improved asthma-related health status as well as with a decreased prospective risk of severe asthma attacks resulting in emergency health-care utilization. This difference does not appear to be mediated by changes in preventive care or asthma self-management practices.

Adult↗

Childhood asthma management and control. Analysis of the Student Lung Health Survey (SLHS) database, Canada 1996.

UNLABELLED: The objective of this study was to estimate the severity of childhood asthma in Canada, identify the effects of asthma interventions in different target groups, and to profile asthma management and control practices by geographic area, sex, age, and severity groups. METHODS: The SLHS was conducted as a stratified and multi-staged cluster survey across Canada in 1996. It included a total of 136 public, private and separate schools in nine health units (Prince Edward Island, Halifax, Sherbrooke, Kingston, Guelph, Winnipeg, Saskatoon, Edmonton, and Kelowna). The target study population was schoolchildren aged 5 to 19 years. Descriptive analyses were used to calculate the severity of childhood asthma for the different groups. Logistic regression was then employed to measure the quality of asthma intervention and control. Multivariate logistic regression was also used to compare the severity and treatment of asthma with age, sex and lifestyle, living and housing conditions. Using existing Clinical Practice Guidelines as a reference, the study also evaluated the effectiveness of interventions such as treatment, and asthmatic education. RESULTS: Based on the Canadian Consensus Recommendations of definition of asthma control, among all 5-19 years old students, 39.9% were well controlled, 33.8% were acceptably controlled and 26.3% were poor controlled. The rates of intermittent and mild asthma were 44.8% and 11.6% compared with moderate (15.3%) and severe (0.9%). Students with asthma reported receiving more advantaged information from a demonstration of inhaler users (OR = 7.51, 95% CI = 5.65-8.94), during a medical visits (OR = 6.33, 95% CI = 5.11-7.83), from the pamphlet/brochures (OR = 6.22, 95% CI = 5.05-7.76) or from a demonstration of the correct use of medicine (OR = 5.62, 95% CI = 4.62-6.82). More students visited a family doctor (40.3%, OR = 5.52, 95% CI = 4.95-6.64) and medical specialists (31.0%, OR = 3.69, 95% CI = 2.58-4.78) than other specialist when they had respiratory problems. CONCLUSIONS: The results of the SLHS study demonstrated variations in the management and control of childhood asthma across Canada. The interventions and the practice guidelines for asthma control are useful for preventing and controlling asthma. These findings provide indications of interventions that are being used for the control of asthma in Canada.

Adolescent↗

Socioeconomic variation in asthma hospitalization: excess utilization or greater need?

OBJECTIVE: To assess the hypothesis that higher incidence of severe acute asthma exacerbation, not lower severity threshold for admission, explains the difference between the asthma hospitalization rates of inner-city and suburban children. METHODS: All 2028 asthma hospitalizations between 1991 and 1995 for children (aged >1 month and <19 years) dwelling in Rochester, New York, were analyzed. ZIP codes defined residences as inner-city, other urban, or suburban. Based principally on the worst oxygen saturation (SaO2) during the first 24 hours of hospitalization, severity was examined by hospital record review (n = 443) of random samples of inner-city, other urban, and suburban asthma admissions. RESULTS: Large inner-city/suburban differences were noted in many sociodemographic attributes, and there was also a distinct, stepwise gradient in risk factors in moving from the suburbs to other urban areas and to the inner city. Racial and economic segregation was particularly striking. Black individuals accounted for 62% of inner-city births versus <3% in the suburbs. Medicaid covered 65% of inner-city births, whereas Medicaid covered only 6% of suburban births. The overall asthma hospitalization rate was 2.04 admissions/1000 child-years. Children <24 months old, those most commonly hospitalized for asthma, were fourfold more likely to be hospitalized (OR: 3.97, 95% CI: 3. 44-4.57) than children between the ages of 13 and 18 years. The hospitalization rate of asthma in boys was almost twice the rate of asthma in girls. The greatest gender difference was observed among children who were <24 months old. For these children, the rate for boys was 6.10/1000 child-years compared with 2.65/1000 child-years for girls (OR: 2.31, 95% CI: 1.95-3.03). This gender difference diminished gradually in older age groups to the extent that there was no difference among girls and boys between the ages of 13 and 18 years (males, 1.12/1000 child-years vs females, 1.09/1000 child-years). Based on worst SaO2 values, mild (worst SaO2 >/=95%), moderate (90%-94%), and severe (<90%) admissions constituted 10.3%, 41.9%, and 47.7% of all hospitalizations, respectively. Although rates within the community followed a distinct geographic pattern of suburban (1.05/1000 child-years) < other urban (2.99/1000 child-years) < inner-city (5.21/1000 child-years), the proportions of admissions with low severity did not vary among areas. Likewise, the proportions of admissions that were severe (SaO2 <90%) were not significantly different (44.8, 45.7, and 52.1% for suburban, other urban, and inner-city areas, respectively). The distributions of asthma severity, measured by the duration of frequent nebulized bronchodilator treatments and the length of hospital stay, were also similar among children from different socioeconomic areas. CONCLUSION: The marked socioeconomic and racial disparity in Rochester's asthma hospitalization rates is largely attributable to higher incidence of severe acute asthma exacerbations among inner-city children; it signals greater need, not excess utilization. Both adverse environmental conditions and lower quality primary care might explain the higher incidence. Interventions directed at the environment offer the possibility of primary prevention, whereas primary care directed at asthma is focused on secondary prevention, principally on improved medication use. Higher hospitalization rates cannot be assumed to identify opportunities for cost reduction. The extent to which our observations about asthma hold true under other conditions and in other communities warrants systematic attention. Knowledge of when higher rates signal excess utilization and when, instead, they signify greater needs should guide equitable national health policy.

Adolescent↗

Increase in admission threshold explains stable asthma hospitalization rates.

BACKGROUND: Asthma morbidity and mortality has increased substantially in recent years, but asthma hospitalization rates among many geographic and sociodemographic groups have remained stable. Observations on asthma hospitalization rates and severity of acute episodes might provide valuable insight into the functioning of the health care system during this period of health care reform. OBJECTIVE: To analyze changes between 1991 and 1995 in childhood asthma hospitalization rates and severity of acute episodes. DESIGN AND METHODS: All 29 329 hospitalizations, including 2028 for asthma, for the 198 893 children (<19 years of age) in Monroe County (Rochester), New York, were studied during this 5-year period. Severity was determined by hospital record review on a 22% random sample. Using the worst oxygen saturation (SaO(2)) during the first 24 hours of hospitalization as the primary index of severity, episodes were categorized as mild (0 to >/=95), moderate (90 to 94), or severe (<90). RESULTS: Hospitalization rates are expressed as hospitalizations per 1000 child-years. The overall asthma hospitalization rate was 2.04 (95% confidence interval, 1.95-2.13). The overall annual asthma hospitalization rate remained relatively stable from 1991 (1.90) to 1995 (2.31), whereas the hospitalization rates for severe asthma rose 270%-from 0.57 to 1.55-during this period. Simultaneously, the hospitalization rates for mild asthma decreased from 0.26 to 0.12. As a proportion of all asthma hospitalizations between 1991 and 1995, severe episodes increased from 31.5% to 60.4%; conversely, mild episodes decreased from 14.1% to 4.7%. CONCLUSIONS: Severity increased significantly among children hospitalized for asthma while the overall asthma hospitalization rate remained stable. It seems that the health care system in this community has responded to an increase in severity of asthma by raising the severity threshold for admission.

Adolescent↗