Background and Objectives. Children in the emergency department (ED) with acute asthma were enrolled to assess the impact of asthma on their activities of daily living and evaluate their access to care and preventive strategies, determine the proportion who adhered to the National Heart, Lung, and Blood Institute (NHLBI) guidelines for proper steps to take at home during an acute asthma exacerbation, and compare adherence rates for those with persistent and mild intermittent asthma.
Design and Methods. Children 2 to 18 years old who presented to the Children’s Hospital of Philadelphia’s ED with acute asthma exacerbations were enrolled prospectively. Parents and patients completed the 108-item Asthma Exacerbation Response Questionnaire with a focus on determining the home management steps they took both at the onset of the asthma exacerbation and just before coming to the ED.
Results. Among the 433 children studied, 76% had at least 1 doctor visit, 75% had at least 1 ED visit, and 43% had at least 1 hospitalization for asthma in the preceding 12 months. Overall, 64% had persistent asthma by NHLBI criteria, yet just 4% were cared for by an allergist or pulmonologist, 38% took daily anti-inflammatory therapy, and 18% received a daily inhaled corticosteroid. Also, 48% did not use a holding chamber with their metered-dose inhalers, and 66% did not use their peak flow meters. Regarding exacerbation response, 71% did not have a written action plan, and 89% did not maintain a symptom diary. Both at the onset of wheezing and just before coming to the ED, administration of a β2-agonist was the only step that the majority of children performed. One-third or fewer followed the other steps recommended by the NHLBI, including using a peak flow meter, beginning oral corticosteroids, calling or going to see the doctor, or going to the ED. Children with persistent asthma were not more adherent to the guidelines than those with mild intermittent disease.
Conclusions. Asthma has a significant adverse effect on the lives of these children. The NHLBI guidelines, first published a decade ago, were designed to reduce asthma’s increasing morbidity and mortality, but this study uncovered a high rate of nonadherence with many aspects of the guidelines, including preventive strategies and home management of an exacerbation.
Asthma is a significant public health problem, with alarming trends in prevalence, morbidity, and mortality. Overall, 6% of children in the United States under age 19 have asthma, the highest prevalence in any age group.1 From 1980 to 1994, there has been a 160% increase in asthma prevalence for children up to 4 years old.2 Among all children, asthma prevalence is greatest in urban areas, with some parts of inner cities reporting rates as high as 14%,3 and prevalence is highest among blacks and those living in households with lowest family income.1 Although emergency department (ED) visits and hospitalizations for asthma have remained stable in the past decade, rates are highest for children up to 4 years of age and 4.7 times higher for blacks than for whites.1 From 1978 to 1995, mortality rates for asthma have more than doubled, and blacks have had consistently higher death rates than whites.2
Not only do urban children experience the asthma burden disproportionately, but previous studies have suggested that they have a particularly high risk for receiving suboptimal care for asthma and being nonadherent to asthma programs.4,5,6 For example, in a recent survey, just 10% of inner-city children with persistent asthma were being treated with inhaled corticosteroids.4 Others have reported that inner-city asthmatic children have poor adherence to national guidelines in response to a mock asthma exacerbation.5,6
It has been a decade since the National Heart, Lung, and Blood Institute (NHLBI) published its asthma management guidelines.7 The guidelines recommend home management of asthma exacerbations to “avoid treatment delays, prevent exacerbations from becoming severe, and add to patients’ sense of control over their asthma.” There were no major changes to home management recommendations after the guidelines were revised in 1997, but mild intermittent and persistent severity classifications were defined.8 In the current study, children with acute asthma presenting to the ED of an urban tertiary care children’s hospital were enrolled. Study objectives were to assess the impact of asthma on activities of daily living and evaluate their access to care and preparedness for treatment, determine the proportion who adhered to the NHLBI guidelines for home management of an acute asthma exacerbation, and compare adherence rates for those with persistent and mild intermittent asthma.
Setting and Participants
The study took place in the ED of an urban tertiary care children’s hospital. Children 2 through 18 years of age who presented to the ED for an asthma exacerbation between 8:00 am and midnight were enrolled prospectively, 7 days per week. Children less than age 2 were excluded to avoid enrolling children who were wheezing because of bronchiolitis. Inclusion criteria included active asthma exacerbation, a history of at least 2 episodes of wheezing necessitating bronchodilator therapy, and presentation with an English-speaking adult. Non-English-speaking families make up <1% of the ED population and were excluded because of the concern that they would not fully understand study instructions. Adolescents ≥14 years of age presenting without a parent or primary caretaker were included if they were primarily responsible for their asthma management at home and could understand the questions. Excluded were children thought to be wheezing because of other conditions such as cystic fibrosis or congenital heart disease and any who had been previously enrolled in the study. Also excluded were those with a history of asthma who were in the ED for a reason other than an asthma exacerbation. The hospital’s institutional review board approved the study.
ED physicians not involved with the study directed the asthma care of the children. After treatment had been initiated, during the time used by ED physicians to judge response, parents were approached by an investigator or trained research assistant for study enrollment. Fifty patients were enrolled during a prestudy pilot phase to allow investigators to develop their interviewing and coding skills and to modify unclear questions, and meetings were held throughout the trial to reinforce proper coding of answers. Data for these 50 patients were not analyzed.
Study data were collected by completion of a questionnaire administered orally by a study investigator or trained research assistant. The data collection tool was the Asthma Exacerbation Response Questionnaire, developed for the study. The questionnaire contained 108 items within 5 domains: sociodemographic, morbidity and activities of living, access to care, prevention and preparedness, and exacerbation response. The following information was recorded within each domain.
Patient’s name, age, sex, race, and insurance type. In addition, the child’s ED triage classification and disposition were recorded. Inquiries regarding the parent included age, highest education completed, and asthma status.
Morbidity and Activities of Living
The impact of asthma on the children’s lives was ascertained by determining the frequency of doctor visits, ED visits, and hospitalizations for asthma exacerbations. In addition, parents reported the frequency with which asthma caused the child to miss day care, school, or work or restrict exercise or activity or resulted in the parent missing school or work. The frequency of the following daytime or nighttime symptoms was recorded: coughing, wheezing, shortness of breath, chest tightness, and fast breathing or trouble breathing. Based on symptom frequency, children were classified as having persistent or mild intermittent disease, as per NHLBI guidelines.8
Access to Care
Questions asked included “What type of physician manages the child’s asthma?” “If your child becomes ill in the evening or weekend, can he or she be seen in the primary care physician’s (PCP) office?” “Did you try to speak to the PCP before coming to the ED? If yes, did you successfully reach the PCP or an office nurse, and what advice were you given regarding acute management of your child’s asthma?” “How do you travel to the PCP office?” “How did you travel to the ED today?”
Prevention and Preparedness
The frequency of use of various asthma medications was determined. These medications included albuterol by small-volume nebulizer (SVN), metered-dose inhaler (MDI), or orally; salmeterol by MDI; corticosteroids by MDI; corticosteroids orally; cromolyn (Intal); nedocromil (Tilade); zafirlukast (Accolate); zileuton (Zyflo); montelukast (Singulair); and theophylline. The generic and brand names of drugs were provided, and commonly used inhaled and oral corticosteroids were named to assist parent recollection. For purposes of analysis, anti-inflammatories or long-term control medications included inhaled or oral corticosteroids, cromolyn, leukotriene modifiers, and theophylline.
Inquiries were made about methods of β2-agonist delivery and use of asthma equipment, including SVN, MDI, holding chambers, and peak flow meters (PFMs). Parents were also asked whether they or the child had specific written asthma instructions called an action plan or whether they maintained a daily symptom diary. They were also asked whether the child’s doctor taught them any of the following steps to take during an asthma attack: Use a PFM, begin or give extra albuterol, give oral corticosteroids (such as Prelone, Pediapred, or prednisone), call or come to the office, or go to the ED.
Among the steps recommended by the NHLBI to take in response to an asthma attack are 1) assess severity by measuring peak expiratory flow, 2) begin treatment with a short-acting β2-agonist, and for those with incomplete or poor responses, 3) start oral corticosteroids, 4) contact a clinician, and 5) proceed to the ED.7,8 Each of the 5 steps was read aloud to the parent and child, and they were asked whether they had followed them under 2 different sets of circumstances: at the onset of the exacerbation (onset) and, for those who did not go to the ED immediately at onset, in the hours just before the ED visit (pre-ED). Parents were asked whether they had been told by the PCP or an office nurse to follow each of the steps in response to the asthma attack prompting the ED visit. Finally, those with persistent and mild intermittent disease were compared for adherence rates, and adherence data were stratified by the patient’s degree of illness on arrival to the ED as assessed at triage, ED arrival time, and ED disposition.
Persistent asthma was defined by the following symptoms: coughing, wheezing, shortness of breath, chest tightness, and rapid breathing or trouble breathing. Parents were asked to assess daytime symptoms “in an average or typical week” and nighttime symptoms “in an average or typical month.” A child with either 1 or more daytime symptoms at least 3 days per week or 1 or more nighttime symptoms at least 3 nights per month was defined as having persistent asthma.8 All other children were determined to have mild intermittent asthma.
Work hours were defined as Monday through Friday from 8:00 am to 5:00 pm. After-hours were defined as Monday through Friday from 5:00 pm to midnight and on weekends. For the purposes of this study, PCP was defined as the generalist or specialist who was principally responsible for managing the child’s asthma and whom the parent would call to seek asthma management advice.
χ2 or Fisher exact tests were used to test the significance of the differences between categorical variables, and Student t test was used for continuous data. Significance was set at P < .05. Data were analyzed using Epi Info (Version 6.04b; Centers for Disease Control and Prevention, Atlanta, GA) statistical software.
Data were collected for 433 children, and patient characteristics at entry are shown in Table 1. Of these children, 305 (70%) were age ≥5. Among 422 children for whom a final disposition was known, 52.8% were discharged from the hospital, 35.5% were hospitalized, and 11.6% were admitted to a 23-hour observation unit.
The mean age of parents was 34 years, 69% had achieved no higher than a high school education, and 28% had asthma. For children with an SVN at home, 72% of parents reported assisting the children with using them.
Morbidity and Activities of Living
Table 1 lists the frequency of visits to the PCP or the ED and the number of hospitalizations for asthma exacerbations in the preceding 12 months. Twenty-six percent made 5 or more visits to the doctor’s office for asthma attacks in the past year, and 17% had 5 or more ED visits during that time. Overall, 74% of the children had been hospitalized for asthma at least once in their lives, and 31% had 5 or more hospitalizations.
In an average or typical month, 55% of children missed at least 1 day of day care or school or work, and 48% of parents missed at least 1 day of school or work because of the child’s asthma. In an average or typical week, asthma resulted in at least 1 day of activity or exercise restriction for 41% of the children.
Parents reported the frequencies of coughing, wheezing, shortness of breath, chest tightness, and rapid breathing or trouble breathing during the daytime in an average or typical week and during the nighttime in an average or typical month. Among the 433 children, 51% had 1 or more daytime symptom at least 3 days per week, and 57% had 1 or more nighttime symptom at least 3 nights per month, with much overlap between the 2 groups. Thus, as defined by the NHLBI, 64% had persistent asthma and 36% had mild intermittent disease.8
Access to Care
A pediatrician was identified as the doctor who managed the child’s asthma (the PCP) by 84%, 8% were cared for by a family practitioner, and 4% were seen by an allergist or pulmonologist. The PCP of 59% of the children did not have evening (after 5:00 pm) hours, and 51% did not have weekend hours. Forty-four percent of the children arrived for care in the ED during work hours, and 56% arrived after hours (P < .0004). Of those arriving during work hours, 43% attempted to contact their PCP before the ED visit, compared with 35% arriving after hours (P = .10). Of those attempting contact, 79% arriving during work hours were able to speak to either the PCP or an office nurse before the ED visit, compared with 67% arriving after hours (P = .08).
When traveling to the PCP’s office, 63% drive or are driven, and 33% walk or take public transportation. In contrast, 74% took a private vehicle to the ED for that day’s visit, 9% came by ambulance, and 12% walked or took public transportation.
Prevention and Preparedness
Table 2 reflects the medication use by the group. Overall, one-third used some form of short-acting β2-agonist on a daily basis, and the majority used them only during an asthma flare. Among the 277 with persistent disease, 23% used daily short-acting inhaled β2-agonists, and only 21% used daily inhaled corticosteroids.
Among all children, 38% took at least 1 daily anti-inflammatory medication, and 18% received a daily inhaled corticosteroid. A greater proportion of children with persistent disease took daily anti-inflammatory medication (113, 41%) than did those with mild intermittent disease (49, 32%), although this difference did not reach statistical significance (P = .07). In addition, just 17% reported that they had oral corticosteroids at home to administer in response to the asthma attack prompting the ED visit, with no significant differences between those with persistent (50, 18%) or mild intermittent (24, 16%) disease (P = .50). All other asthma medications, such as leukotriene antagonists or theophylline, were used by so few that these data were not included.
Among those delivering albuterol at home via an SVN, most were delivering an appropriate amount based on the child’s age and weight. Two thirds of parents delivered treatments every 4 hours when the child was ill with wheezing. The means by which albuterol was delivered by SVN was inappropriate for one fourth of the children, with the most common error being using a face mask for children old enough to use a mouthpiece.
Parents were questioned about asthma-related equipment that had been prescribed for their children. Most had been given an SVN (83%) or MDI (80%) for home use. However, just two-thirds given an MDI were also given a holding chamber to use with it, and of those using a MDI regularly, 194 (48%) did not routinely use a holding chamber with it. Forty-five percent had been given a PFM, but two thirds of these children did not use it.
Among all children, 71% did not have a specific written action plan to follow in the event of an asthma exacerbation, and 89% did not maintain a daily symptom diary. Regarding the exacerbation prompting the ED visit, just 7% consulted a written action plan at the first sign of wheezing (onset), and 4% did so just before coming to the ED (pre-ED).
Seventy-six percent of children did not come to the ED at onset but managed their asthma at home with a mean delay of 31 hours (median 18 hours) from onset to ED arrival. Assessments were made to determine how closely patients adhered to NHLBI guidelines with respect to the 5 appropriate steps to take in response to an asthma exacerbation. Table 3 lists the proportion of patients who report being taught each step at some time by their PCP. Also shown are the proportions advised to perform specific steps by the PCP among the 127 who successfully contacted their PCP pre-ED. Finally, the frequency with which the 433 children completed each step at onset is shown, as well as the adherence rates pre-ED for the 327 children who did not go to the ED at onset. Most children correctly began or increased short-acting β2-agonist therapy both at onset and pre-ED, but very few adhered to the other recommended steps (Table 3).
Table 4 compares adherence rates for those with persistent and mild intermittent disease at onset and pre-ED. A significantly greater proportion of children with persistent disease received oral corticosteroids at onset, but they were not more likely to adhere to any of the other 5 steps at onset or pre-ED.
Adherence rates were not influenced by illness severity as determined by triage classification for the 327 children who did not go to the ED at onset (Table 5). Also, compared with those discharged from the hospital from the ED, those needing hospitalization to the general ward or an observation unit were not more adherent in the use of PFM (P = .41), albuterol (P = .46), or oral corticosteroids (P = .86) or calling or going to the PCP’s office (P = .51). Similarly, compared with those arriving to the ED after hours, those arriving during working hours were not more adherent in the use of PFM (P = .31), albuterol (P = .06), or oral corticosteroids (P = .19) or calling or going to the PCP’s office (P = .57).
Among children presenting to an urban ED for acute asthma, asthma has a profound and detrimental impact on quality of life. About three fourths of children had at least 1 doctor visit, and a similar proportion had at least 1 ED visit for asthma in the past year. Approximately half had at least 1 hospitalization in the past year, with one-third having 5 or more hospitalizations in their lives, a large figure when one considers that the group’s mean age was just under 8 years. Also, the child’s asthma caused many days of activity restriction and many missed days of school or work for children and parents. This lost productivity is contributing to the annual US economic burden of asthma, which has been estimated at 6 billion dollars.9
Just 4% of patients were being cared for by an allergist or pulmonologist, yet 64% had persistent disease. Among the many criteria the NHLBI names as reasons to consider referring patients to an allergist or pulmonologist are moderate or severe persistent disease or failure to meet goals of therapy after 3 to 6 months of treatment.8 Clearly, the number of children in this study who would have benefited from referral to an asthma specialist was far greater than the number actually receiving such care. Also, the majority of physicians caring for these asthmatic children did not have evening or weekend hours. Fewer than half of parents attempted to contact the PCP to receive management advice, and when contact was made, more than twice as many were told to go to the ED rather than to administer β2-agonists. However, it should be noted that physician advice was no doubt influenced by what parents reported and by what steps the patient had already taken in response to the asthma exacerbation.
Analysis of the patient’s preventive strategies also revealed substantial problems. Although two thirds of children had persistent asthma, just 38% took daily anti-inflammatory medications, with only 18% receiving a daily inhaled corticosteroid. Conversely, many were using anti-inflammatories inappropriately by taking them only when ill. Similarly, in a previous study, 39% of children with persistent asthma took daily anti-inflammatory medications,5 and in a study of young inner-city children in the ED with asthma, just 24% used preventive medications.6 The proportion of children with persistent asthma in the present study may have been underrepresented, because children with persistent disease who were well-controlled with medication may have been misclassified.
Those with persistent asthma were not more likely than others to take daily anti-inflammatory medications or to have oral corticosteroids at home. This probably represents a combination of patient nonadherence and physician prescribing practices because just 20% had been taught by physicians to use oral corticosteroids during an asthma attack. Remarkably, among those with persistent disease, a greater proportion took short-acting β2-agonists daily than daily inhaled corticosteroids. Also, among all children, one-third used short-acting β2-agonists on a daily basis, a practice that is strongly discouraged by the NHLBI even for those with severe persistent disease.7,8 In one trial, among those with moderate asthma, regular use of fenoterol resulted in worsening pulmonary function,10 and others have noted no discernible benefits of regularly scheduled β2-agonist therapy.11,12,13 Therefore, short-acting β2-agonists should be reserved as quick-relief medications for use during an asthma flare.
Numerous studies have demonstrated the benefits of delivering β2-agonists using an MDI with a holding chamber compared with an MDI alone14,15,16,17 and favorable outcomes compared with delivery by SVN,18,19,20,21,22,23,24 yet one-half in the study population who reported regular MDI use did not use a holding chamber routinely. Also, the NHLBI recommends PFMs as an important component of patient self-monitoring of asthma, especially among those with moderate to severe persistent asthma.7,8 Several trials have demonstrated better outcomes for patients with PFM-based asthma management plans.25,26,27,28 In the study group, two-thirds who had been given a PFM did not use it. A previous trial also found that PFMs were underprescribed and underused among inner-city asthmatic children,6 and another study determined that just 30% of asthmatic children over age 5 had a PFM.5
Doctors had not consistently taught patients the appropriate steps to take in response to an asthma attack. Patients were likely to administer albuterol at the onset of the exacerbation or just before the ED visit but were nonadherent with all other NHLBI recommendations. Furthermore, children with persistent disease, although significantly more likely to administer oral corticosteroids at the first sign of wheezing, were not more likely to adhere to any of the other steps recommended by the NHLBI (Table 4).
When a child has an abrupt onset of a moderate-to- severe exacerbation, it may be appropriate to administer a short-acting β2-agonist, bypass most of the other recommended steps, and go directly to the ED as soon as possible. The goal of early home management according to the NHLBI is “to prevent deterioration and abort the exacerbation” rather than shift care away from the medical facility.7 Therefore, it is possible that in some cases being nonadherent to the guidelines was appropriate given the child’s degree of illness. However, there was no difference in adherence rates for those who were hospitalized and those who were not or among those with mild, moderate, or severe disease on ED arrival (Table 5). Thus, the severity of the exacerbation did not seem to influence a patient’s response to it.
The current study determined the response to an actual asthma exacerbation, both at its outset and just before the patient came to the ED. Others have recorded what actions parents report they would take in response to a mock asthma exacerbation.5,6 In one trial, 36% stated that they would administer a β2-agonist, but 57% would go to the ED without giving a β2-agonist first.5 Also, fewer then 5% would contact the clinician, use a PFM, or administer oral corticosteroids. In a separate trial, 82% of parents of young, inner-city asthmatic children reported that they would give an asthma medication in response to an attack, and 64% stated they would go to the ED or clinic.6 In that same sample, just 13% reported that they would call the physician, and 1% would use a PFM.6 In the present study, the assessment of actual behavior soon after ED arrival limits recall bias and more accurately reflects true patient conduct.
The NHLBI guidelines for asthma were first published in 1991 and revised in 1997. This should have been sufficient time for practitioners to educate themselves and their patients about the program and to improve adherence. Adherence to an asthma self-management program involves a partnership between physician and patient in which education and reinforcement play crucial roles. In a focus group, parents identified lack of knowledge about asthma, asthma medications, and environmental triggers as the most common barriers to asthma care for their children.29 Caretakers of young asthmatic children were found to be less likely to adhere to asthma medication regimens if they had doubts about the usefulness of the medication.6 Adherence among asthmatics may be particularly difficult given the episodic nature of the disease. For example, caretakers may be fearful of growth suppression with the daily use of inhaled corticosteroids and be less inclined to administer them to their asymptomatic children.
Problems inherent in the guidelines, either real or perceived, also may contribute to nonadherence by physicians. Barriers physicians face in implementing the guidelines have been described.30,31,32,33,34 In one study, pediatricians cited lack of awareness, agreement, self-efficacy, and outcome expectancy as reasons for not prescribing daily inhaled corticosteroids or recommending PFM use.30 Other barriers to implementing the guidelines include their length and complexity, time needed to teach them to families, and the need to tailor them to patients of various ages with a wide range of illness severity. In fact, a national survey discovered that the rates of maintenance medication use were the same for children in the 3 years before and after publication of the guidelines.35
One study limitation is the potential for response bias, with caretakers overstating their adherence to investigators for fear of embarrassment. Therefore, true adherence rates in the population are likely to be even lower than reported. Also, in fairness to physicians, their rates of adherence with NHLBI guidelines such as prescribing PFMs or teaching appropriate exacerbation responses are as reported by parents. These findings may be subject to recall bias and may underestimate the true adherence rates. Similarly, other information, such as the frequency of doctor visits and missed days of school or work, is subject to recall bias. Another potential limitation is that these data may not be generalizable to the total population of asthmatic children, many of whom do not need ED care. Other groups of asthmatics may be more aware of and more adherent to the national guidelines. However, we chose to study this cohort because others have found them to be at particularly high risk for asthma morbidity and mortality.1,2,3
Asthma has a profound impact on the lives of children in this study, resulting in frequent doctor and ED visits and hospitalizations and a substantial number of days of symptoms and restricted activity. The NHLBI guidelines were designed to reduce asthma’s increasing morbidity and mortality, but this study uncovered a high rate of nonadherence with many aspects of the guidelines 10 years after their publication. Numerous areas of concern were uncovered, including underuse of asthma specialists and anti-inflammatory medications and inappropriate exacerbation responses. The past decade has seen unprecedented development of new classes of drugs to treat asthma. However, during this same decade the message of prevention and home management has not reached the children at highest risk, and the asthma epidemic continues.
- Received April 4, 2001.
- Accepted June 9, 2001.
Reprint requests to (R.J.S.) Department of Pediatrics, University of Pennsylvania School of Medicine, Division of Emergency Medicine, The Children’s Hospital of Philadelphia, 34th Street and Civic Center Blvd, Philadelphia, PA 19104. E-mail:
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- ↵Crain EF, Weiss KB, Bijur PE, et al. An estimate of the prevalence of asthma and wheezing among inner-city children. Pediatrics.1994 ;94:356–362
- ↵Warman KL, Silver EJ, McCourt MP, Stein REK. How does home management of asthma exacerbations by parents of inner-city children differ from NHLBI guideline recommendations? Pediatrics.1999 ;103:422–427
- ↵Leickly FE, Wade SL, Crain E, et al. Self-reported adherence, management behavior, and barriers to care after an emergency department visit by inner-city children with asthma. Pediatrics.1998 ;101:1–8
- ↵National Asthma Education and Prevention Program. Expert Panel Report. Guidelines for the Diagnosis and Management of Asthma. Bethesda, MD: National Institutes of Health: National Heart, Lung, and Blood Institute; 1991. Report No. 91-3042
- ↵National Asthma Education and Prevention Program. Expert Panel Report 2. Guidelines for the Diagnosis and Management of Asthma. Bethesda, MD: National Institutes of Health: National Heart, Lung, and Blood Institute; 1997. Report No. 97-4051
- ↵Brown PH, Blundell G, Greening AP, Crompton GK. Do large volume spacer devices reduce the systemic effects of high dose inhaled corticosteroids? Thorax.1990 ;45:736–739
- ↵Lipworth BJ. New perspectives on inhaled drug delivery and systemic bioactivity. Thorax.1995 ;50:105–110
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- ↵Selroos O, Halme M. Effect of a volumatic spacer and mouth rinsing on systemic absorption of inhaled corticosteroids from a metered dose inhaler and dry powder inhaler. Thorax.1991 ;46:891–894
- ↵Lin YZ, Hsieh KH. Metered-dose inhaler and nebulizer in acute asthma. Arch Dis Child.1995 ;72:214–218
- ↵Lee N, Rachelefsky G, Kobayashi RH, et al. Comparison of efficacy and safety of albuterol administered by power-driven nebulizer (PDN) versus metered-dose inhaler (MDI) with Aerochamber and mask in young children with asthma [abstract]. J Allergy Clin Immunol.1991 ;87:307
- ↵Parkin PC, Saunders NR, Diamond SA, Winders PM, Macarthure C. Randomized trial spacer vs nebulizer for acute asthma. Arch Dis Child.1995 ;72:239–240
- ↵Grampian Asthma Study of Integrated Care. Effectiveness of routing self-monitoring of peak flow in patients with asthma. BMJ.1994 ;308:564–567
- ↵Jones KP, Mullee MA, Middleton M, Chapman E, Holgate ST. Peak flow based asthma self management: a randomized controlled study in general practice: British Thoracic Society Research Committee. Thorax.1995 ;50:851–857
- ↵Lahdensuo A, Haahtela T, Herrala J, et al. Randomized comparison of guided self-management and traditional treatment of asthma over 1 year. BMJ.1996 ;312:748–752
- ↵Mansour ME, Lanphear BP, DeWitt TG. Barriers to asthma care in urban children: parent perspectives. Pediatrics.2000 ;106:512–519
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- American Academy of Pediatrics