ARTICLE. Demonstrated Use of Metered-Dose Inhalers and Peak Flow Meters by Children and Adolescents With Acute Asthma Exacerbations

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1 ARTICLE Demonstrated Use of Metered-Dose Inhalers and Peak Flow Meters by Children and Adolescents With Acute Asthma Exacerbations Richard J. Scarfone, MD; Geoffrey A. Capraro, MD; Joseph J. Zorc, MD; Huaqing Zhao, MA Objectives: To determine the ability of children and adolescents with acute asthma exacerbations to adhere to national guidelines for proper metered-dose inhaler (MDI) and peak flow meter (PFM) technique and to define characteristics associated with improper use. Design: A prospective study in which the patients were instructed to use a placebo MDI or a PFM in the emergency department exactly as at home. Technique was graded on the basis of performance of specific steps recommended by national guidelines. Setting and Participants: Children and adolescents (aged 2-18 years) with acute asthma exacerbations in the emergency department of an urban children s hospital with acute asthma. Results: Thirty-three (45.2%) of 73 patients using an MDI (MDI group) demonstrated multiple steps improperly compared with 60 (44.4%) of 135 using an MDI with a holding chamber (MDI-HC group; P=.92). In the MDI group, young ages of the patients (P.008) and the parents (P.003) were associated with improper use. In the MDI-HC group, factors independently and significantly associated with improper use were no hospitalizations within the past year, parent assistance of the patient with MDI-HC use, and nondaily use of the MDI-HC. Also, 165 (82.9%) of 199 children who, per national guidelines, should be using a PFM at home, did not. Eighty-two (73.9%) of 111 patients demonstrated perfect performance of all PFM steps. Conclusions: Among children with acute asthma, we found high rates of improper MDI use and PFM underuse. A greater emphasis must be placed on teaching methods to optimize drug delivery and to instruct patients about the importance of self-monitoring of disease severity. Arch Pediatr Adolesc Med. 2002;156: From the Departments of Pediatrics (Drs Scarfone and Zorc) and Biostatistics and Epidemiology (Mr Zhao), University of Pennsylvania School of Medicine, and the Division of Emergency Medicine, The Children s Hospital of Philadelphia, (Drs Scarfone and Zorc), Philadelphia; and the Department of Pediatrics, Boston University School of Medicine, and the Division of Pediatric Emergency Medicine, Boston Medical Center, Boston, Mass (Dr Capraro). IN 1997, the National Heart, Lung, and Blood Institute (NHLBI) of the National Institutes of Health published revised guidelines for the diagnosis and management of asthma. 1 Key recommendations of these guidelines are the administration of shortacting bronchodilators by means of a smallvolume nebulizer or a metered-dose inhaler (MDI) and monitoring of peak expiratory flow (PEF) using a peak flow meter (PFM) to help determine the degree of illness and to define appropriate treatment plans. The extent to which children with acute asthma exacerbations properly use MDIs and PFMs as recommended by these national guidelines has not been well studied, and predictors of poor technique have not been identified. We assessed a cohort of children with an asthma exacerbation of sufficient severity to necessitate emergency department (ED) care. We sought to determine the ability of children who routinely used MDIs to adhere to NHLBI guidelines for proper technique and to define characteristics associated with improper use. With respect to PFMs, we sought to determine primary care provider (PCP) prescribing patterns, overall utilization practices for PFM use, knowledge of score interpretation, and ability to adhere to NHLBI guidelines for proper technique. RESULTS MDI GROUPS As part of a larger and separate study in which children and adolescents with 378

2 PATIENTS AND METHODS SETTING AND PATIENTS The study took place in the ED of an urban tertiary care children s hospital. A convenience sample was enrolled prospectively from 8 AM to midnight, 7 days per week. Children and adolescents aged 2 to 18 years with an asthma exacerbation were included if they had a history of at least 2 episodes of wheezing that required bronchodilator therapy and presented with an English-speaking adult. Non English-speaking families constituted less than 1% of the total ED population and were excluded because of the concern that they may not fully understand study instructions. Children who received continuous nebulized albuterol sulfate, who had cystic fibrosis or congenital heart disease, or who had been enrolled previously were also excluded. The hospital s institutional review board approved the study. Emergency department physicians not involved with the study decided treatment for the study patients and prescribed medications at ED discharge. After treatment had been initiated, parents were approached by one of the investigators or a trained research assistant for study enrollment. Research assistants were taught the proper use of the MDI and the PFM before the start of the study. Fifty patients were enrolled during a prestudy pilot phase to allow investigators to develop their interviewing and observational skills, and meetings were held throughout the trial to reinforce proper MDI and PFM techniques. Some patients in the study demonstrated MDI and PFM use. Persistent asthma was defined by the following symptoms: coughing, wheezing, shortness of breath, chest tightness, and rapid or troubled breathing. One 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 persistent asthma. 1 All other symptoms were defined as mild, intermittent asthma. MDI GROUPS Patients who reported owning an MDI and using it daily or as needed to manage their asthma were identified. They were given an MDI placebo in the ED and asked to demonstrate it exactly as you would use it at home, even if they had not used it just before the ED visit. Similarly, patients reporting the regular use of an MDI with a holding chamber (MDI-HC) were provided the AeroChamber or AeroChamber With Mask MDI (Forest Pharmaceuticals, Inc, St Louis, Mo) and asked to demonstrate its use. Parents and patients were aware that the placebo MDI contained propellants but no active ingredients. The inhalation aerosol was identical in size and shape to that of widely available MDIs used to deliver 2 -agonists. The NHLBI recommends the following steps to optimize medication delivery via MDIs 1 : (1) shake the MDI before use; (2) exhale completely before actuation; (3) actuate once at the start of an inhalation; (4) inhale slowly; (5) hold your breath after inhalation; and (6) ensure a ratio of inhalation to actuation of 1:1. Investigators recorded their observations of the MDI demonstration, indicating which of the 6 steps the patients successfully completed. Parents were allowed to assist their children as needed. Patients who regularly used a holding chamber with a face mask underwent assessment for the proper completion of steps 1 to 5 above for the first inhalation and the following steps: (6) ensure a minimum ratio of inhalations to each actuation of 5:1 1 and (7) maintain a tight seal with the mask around the mouth and nose. We assessed a number of variables to determine whether any were significantly associated with improper MDI use. Morbidity factors included persistent disease as defined by the NHLBI, frequency of hospitalizations or ED visits for asthma in the past 12 months, severity of asthma exacerbation as assessed at ED triage, and frequency of restricted activity or missed days of school or work. Patient factors included age, sex, race, insurance status, and frequency of home MDI use. Parent factors included age, history of asthma, education, and supervision of the child s MDI use. Primary care provider factors included demonstration of MDI use or provision of written or verbal instructions for MDI use. PFM GROUP We identified a separate cohort of patients who, per the NHLBI criteria, should use PFMs to monitor asthma exacerbations. These included children 5 years or older with moderate to severe persistent asthma. They were asked about PFM prescribing patterns of their PCPs and their practices and knowledge regarding proper use of PFMs. Those who reported having a PFM at home to manage their asthma (even if they had not used it just before this ED visit) were identified. They were provided a Pocketpeak PFM (Ferraris Medical Inc, Holland, NY) in the ED and asked to demonstrate its use exactly as you would use it at home. Parents were allowed to assist their children as needed. The NHLBI recommends performing the following steps for proper recording of the PEF using a PFM 1 : (1) move the indicator to 0; (2) take the deepest inspiration possible; (3) close your lips around the mouthpiece; and (4) blow hard and fast. Investigators recorded their observations of PFM use, indicating which steps were successfully completed. STATISTICAL ANALYSIS We used univariate tests to assess the association between factors and improper MDI demonstration. Logistic regression was performed to determine independent associations with improper MDI use. We used 2 or Fisher exact tests to analyze categorical variables and the t test for continuous data. We analyzed data using Epi Info (Version 6.04b; Centers for Disease Control and Prevention, Atlanta, Ga) and STATA statistical software (Version 6.0; Stata Corp, College Station, Tex). asthma were asked questions about their adherence to asthma home-management guidelines, 433 patients were interviewed in the ED. Of these, 208 met inclusion criteria for the MDI demonstration and agreed to demonstrate its use in the ED. Seventy-three (35.1%) reported using an MDI without a holding chamber (MDI group) 379

3 % Using Improperly Shake Exhale Actuate Inhale Hold Ratio Figure 1. Steps performed improperly in the group using a metered-dose inhaler (MDI). Steps are described in the MDI Groups subsection of the Patients and Methods section. % Using Improperly Table 1. Patient Characteristics of the MDI Groups at Entry* MDI Group (n = 73) MDI-HC Group (n = 135) Mean age (SD), y 11 (3.9) 8 (3.8) Male 41 (56.2) 74 (54.8) African American 70 (95.9) 124 (91.9) Medicaid managed care or self-pay 43 (58.9) 89 (65.9) Triage acuity Mild 25 (35.2) 44 (34.4) Moderate 37 (52.1) 68 (53.1) Severe 9 (12.7) 16 (12.5) Disposition Admitted to ward 16 (22.9) 34 (25.8) Admitted to 23-h unit 9 (12.9) 12 (9.1) Home 45 (64.3) 86 (65.2) *Unless otherwise indicated, data are given as number (percentage). MDI indicates metered-dose inhaler; MDI-HC, MDI with a holding chamber. Shake Exhale Actuate Inhale Hold Ratio Seal Figure 2. Steps performed improperly in the group using a metered-dose inhaler (MDI) with a holding chamber. Steps are described in the MDI Groups subsection of the Patients and Methods section. at home. One hundred thirty-five (64.9%) used an MDI with a holding chamber (MDI-HC group), and of these, 61 (45.2%) regularly used a face mask. The 2 groups underwent separate analysis to determine what impact, if any, a holding chamber had on demonstrated use. Both groups were similar at entry except that patients in the MDI group were significantly older (P.001; Table 1). Also, within each group, no significant differences were found in patient disposition from the ED (Table 1). Eighteen patients (24.7%) in the MDI group performed all steps perfectly compared with 32 (23.7%) in the MDI-HC group (P=.88). Similarly, in the MDI group, 33 patients (45.2%) performed multiple ( 2) steps improperly, compared with 60 (44.4%) in the MDI-HC group (P=.92). Figure 1 and Figure 2 display the proportion of patients in each group who demonstrated improper performance of specific steps. In the MDI group, young age of the patients (P.008) and the parents (P.003) were associated with improper performance of multiple steps. Similarly, in the MDI-HC group, young age of the patients (P.001) and the parents (P.03) were associated with improper use. Table 2 displays improper use rates stratified by age. Among those in the MDI-HC group, we found an association between the parent assisting the patient with use of the MDI-HC and improper use (Table 3). On the other hand, hospitalizations and ED visits within the past year and daily MDI-HC use were inversely related to improper use (Table 3). Of the 6 factors having a significant association with technique, 3 remained significantly, positively, and independently associated with improper MDI-HC use when multivariate logistic regression analysis was performed. These included no hospitalizations within the past year, the parent assisting the patient with MDI-HC use, and nondaily MDI-HC use (Table 4). PFM GROUP We interviewed 305 patients 5 years or older as part of the larger, separate study. Of these, 199 met the NHLBI guidelines for regular PFM use. One hundred twentyfive (62.8%) had been prescribed a PFM by their PCP, and 34 (27.2%) of these had used it at home to monitor the asthma attack that prompted the ED visit. Thus, 165 (82.9%) of 199 children who (per the NHLBI guidelines) should be using a PFM to monitor degree of illness had failed to do so. Among the 125 children who had been prescribed a PFM, 38 (30.4%) tried to contact their PCP at the onset of this wheezing attack to receive management advice, 28 (22.4%) successfully reached the PCP, and 2 (1.6%) were advised to monitor their symptoms by using their PFM. Among the patients who reported regular use of a PFM during or between asthma exacerbations, 22 (28.9%) of 76 patients did not know that PFM measurement should be performed while standing; 28 (35.4%) of 79 did not know that 3 attempts should be made; 30 (39.5%) of 76 did not know that the highest value should be accepted; and 28 (35.9%) of 78 did not know the score that signified the need for more medication. A subset of 111 patients 5 years or older reported having a PFM at home and agreed to demonstrate its use in the ED. The mean age of this group was 11 years (SD, 3.2 years); 58% were male; 95% were African American; and 59% were uninsured or insured by Medicaid managed care. In the preceding 12 months, asthma had led to at least 1 hospitalization for 51 (45.9%). For the current exacerbation, 40 patients (36.0%) were ultimately hospitalized to the general ward or to a 23-hour observation unit. When asked to demonstrate their PFM technique, 82 (73.9%) did so perfectly. Figure 3 displays the proportion of children who demonstrated improper performance of specific PFM steps. 380

4 Table 2. Rates of Improper Use* Age Groups, y Comparison of Age Groups, y, RR (95% CI) vs vs 6-10 MDI group NA 15 (55) 9 (26) NA 1.66 ( ) MDI-HC group 23 (66) 25 (39) 10 (29) 2.06 ( ) 1.16 ( ) *RR indicates relative risk; CI, confidence interval; and NA, not applicable. Other abbreviations are given in the footnote to Table 1. Data are given as number (percentage) of patients. Table 3. Clinical Factors and Their Association With Improper Performance of Multiple Steps* Factor, No. (%) MDI Group (n = 73) Factor, No. (%) MDI-HC Group (n = 135) Factor Yes No RR (95% CI) Yes No RR (95% CI) Persistent disease 18/43 (42) 14/30 (47) 0.90 ( ) 45/95 (47) 14/38 (37) 1.29 ( ) Hospitalized in past year 8/19 (42) 24/54 (44) 0.95 ( ) 20/65 (31) 39/70 (56) 0.55 ( ) ED visit in past year 20/46 (43) 12/27 (44) 0.98 ( ) 42/108 (39) 17/27 (63) 0.62 ( ) Moderate or severe attack 23/46 (50) 8/25 (32) 1.56 ( ) 37/84 (44) 20/50 (40) 1.10 ( ) Restricted activity 14/28 (50) 17/44 (39) 1.29 ( ) 28/64 (44) 30/70 (43) 1.02 ( ) Missed school or work 16/38 (42) 14/32 (44) 0.96 ( ) 36/81 (44) 19/47 (40) 1.10 ( ) Male 19/41 (46) 13/31 (42) 1.11 ( ) 34/74 (46) 24/60 (40) 1.15 ( ) Nonwhite 32/70 (46) 0/ /126 (46) 1/7 (14) 3.72 ( ) Medical assistance or self-pay 21/43 (49) 8/25 (32) 1.53 ( ) 39/89 (44) 16/40 (40) 1.10 ( ) Daily MDI use 8/17 (47) 23/55 (42) 1.13 ( ) 6/34 (18) 53/101 (52) 0.34 ( ) Parent has asthma 10/22 (45) 21/48 (44) 1.04 ( ) 13/34 (38) 41/92 (45) 0.86 ( ) Parent education of high school or less 22/48 (46) 8/21 (38) 1.20 ( ) 38/88 (43) 17/38 (45) 0.97 ( ) Parent assists patient 15/29 (52) 15/41 (37) 1.41 ( ) 47/90 (52) 9/39 (23) 2.26 ( ) PCP demonstrated use 28/65 (43) 4/7 (57) 0.75 ( ) 50/120 (42) 7/10 (70) 0.66 ( ) PCP gave written instructions 20/45 (44) 12/27 (44) 1.00 ( ) 43/95 (45) 14/35 (40) 1.13 ( ) PCP gave verbal instructions 29/67 (43) 2/4 (50) 0.87 ( ) 51/120 (42) 6/10 (60) 0.71 ( ) *ED indicates emergency department; PCP, primary care provider. Other abbreviations are given in the first footnotes to Tables 1 and 2. Differences were statistically significant. Table 4. Multiple Logistic Regression Analysis of Risk Factors for Improper Use in the MDI-HC Group* Unadjusted Odds Ratio (95% CI) COMMENT MDI GROUPS Adjusted Odds Ratio (95% CI) Variable No hospitalization in the 2.8 ( ) 4.4 ( ) past 12 mo Parent assists 3.4 ( ) 3.5 ( ) No daily MDI-HC use 3.4 ( ) 2.4 ( ) *Abbreviations are given in the first footnotes to Tables 1 and 2. Among patients who used an MDI regularly, only about one quarter were judged to use perfect technique during an asthma exacerbation and almost half performed multiple steps improperly. Holding chambers were underused, and although they improve drug delivery to the distal airways, the use of a holding chamber with or without a face mask did not influence overall performance in this study. Improper use was most pronounced among the youngest children. % Using Improperly Move to Zero Inspire Seal Effort Figure 3. Steps performed improperly in the group using a peak flow meter (PFM). Steps are described in the PFM Group subsection of the Patients and Methods section. In the MDI group, too few factors were associated with improper use for further analysis. However, patients in the MDI-HC group were more likely to use MDIs improperly if they had not been hospitalized recently. Perhaps proper MDI technique was taught and reinforced by physicians, nurses, and respiratory therapists during hospitalizations. Patients requiring parental assistance were more likely to use the MDI-HC improperly. Assistance is undoubtedly required for younger children who are less able to adhere to the NHLBI guidelines for proper use. Also, these children may have behavioral or motor problems that cannot be overcome with parental assis- 381

5 What This Study Adds To our knowledge, this is the first study to critically assess the step-by-step technique in the use of MDIs or PFMs among children in the ED with acute asthma. We found a high rate of improper MDI use and identified factors associated with improper use. We found that PFMs were used properly by most children, but were underprescribed and underused. Thus, we have identified areas in which physicians, nurses, and respiratory therapists can focus their asthma educational efforts. tance. Finally, those who did not use an MDI-HC daily were more likely to demonstrate improper use. No attempts to quantify the delivery of aerosolized medication were made. However, aerosol deposition is critically dependent on a patient s inhalation technique. Numerous investigators have demonstrated that a slow inspiration maximizes the effect of the MDI 2-6 and that a breath hold is needed to permit time for aerosol particles to settle in the distal airways. 2,3,7 For example, in one trial, a 50% difference between efficient and nonefficient users was found in the mean improvement in forced expiratory volume in 1 second after 2 puffs of drug. 8 In the present study, since no one step was particularly troublesome for children, education efforts reinforcing proper performance of each step must be made. Many studies have demonstrated comparable outcomes for children in the ED who receive 2 -agonists by means of an MDI-HC or a small-volume nebulizer Studies based in the ED such as these represent ideal conditions in which children are instructed on the proper use of the MDI-HC just before enrollment and may not reflect conditions as they actually exist for children with acute asthma exacerbations at home or in most urban EDs. In addition, these studies may highlight the inefficiency of drug delivery by means of a small-volume nebulizer, rather than proving the advantages of delivery by means of an MDI-HC. Attempts were made to minimize the role that unfamiliar equipment might have played in influencing outcomes. The placebo MDI was of a standard size and shape, only patients who were experienced with MDI use were enrolled, and parents were allowed to assist. These factors should have increased the proportion of patients who demonstrated perfect use; thus, improper use may be more prevalent in the general population. On the other hand, the study population, by virtue of requiring ED care, might represent a group that is particularly unskilled with MDI use. Finally, the degree of illness may have affected the ability of children to use the MDI properly. However, MDIs are recommended as first line therapy to treat children with acute asthma exacerbations, and that is precisely the group we wished to study. Also, more than 80% of children were mildly or moderately ill, just one third required hospitalization, and severity of illness was not associated with improper use, making it unlikely that degree of illness played a major role the rate of improper use. However, these results may not be generalizable to children with milder exacerbations or with chronic stable asthma. PFM GROUP A few studies have questioned whether patients have better outcomes with PEF-based asthma management plans. 21,22 However, other investigators have found that PEF monitoring results in lower symptom scores and less use of maintenance therapy 23 or improved morbidity variables. 24 Lahdensuo et al 25 found a reduction in missed days of work, a better quality of life, and less use of oral corticosteroids. Furthermore, the NHLBI Expert Panel encourages patients to establish their personal best PEF and use it as the basis of their asthma action plan, as short-term daily peak flow monitoring is helpful for assessing the severity of a patient s asthma. 1 The PEF depends on effort and technique; therefore, patients need instructions, demonstrations, and frequent reviews of technique. 1 In a study assessing inner-city children aged 4 to 9 years with asthma, just 15% of parents reported that their child s physician had recommended a PFM. 26 Just 6% of patients actually obtained a PFM, and 1% reported measuring a PEF in response to an asthma attack. 26 These data and those reported in the present study show that although the PFM is a simple tool that is easy to use, the underprescription and underuse of PFMs and a lack of knowledge regarding score interpretation limit their potential impact on asthma selfmanagement. CONCLUSIONS One decade has passed since the publication of the first set of NHLBI asthma guidelines. This should have been ample time for the incorporation of these guidelines into asthma management programs, but we found a high degree of nonadherence to and lack of knowledge of the key components of the guidelines. These results point to a need for greater emphasis on teaching methods to optimize drug delivery, especially among young children, and instructing patients about the importance of self-monitoring of disease severity. Accepted for publication December 27, We thank Rosie Roundtree and Auria Rosa for their assistance with data entry and manuscript preparation. Reprints are not available from the authors. REFERENCES 1. Murphy S. Guidelines for the Diagnosis and Management of Asthma. Bethesda, Md: National Institutes of Health, National Heart, Lung, and Blood Institute; Report Newman SP, Pavia D, Clarke SW. Simple instructions for using pressurized aerosol bronchodilators. J R Soc Med. 1980;73: Dolovich M, Ruffin RE, Roberts R, Newhouse MT. Optimal delivery of aerosols from metered dose inhalers. Chest. 1981;80(suppl):911S-915S. 4. Lawford P, McKenzie D. Pressurised bronchodilator aerosol technique: influence of breath-holding time and relationship of inhaler to the mouth. BrJDis Chest. 1982;76:

6 5. Grainger JR. Correct use of aerosol inhalers. CMAJ. 1977;116: Woolf CR. Correct use of pressurized aerosol inhalers [letter]. CMAJ. 1979;121: 710, McFadden ER Jr. Improper patient techniques with metered dose inhalers: clinical consequences and solutions to misuse. J Allergy Clin Immunol. 1995;96: Lindgren S, Bake B, Larsson S. Clinical consequences of inadequate inhalation technique in asthma therapy. Eur J Respir Dis. 1987;70: Freelander M, Van Asperen PP. Nebuhaler versus nebulizer in children with acute asthma. BMJ. 1984;288: Fuglsang G, Pedersen S. Comparison of Nebuhaler and nebulizer treatment of acute severe asthma in children. Eur J Respir Dis. 1986;69: Pendergast J, Hopkins J, Timms B, Van Asperen P. Comparative efficacy of terbutaline administered by Nebuhaler and by nebulizer in young children with acute asthma. Med J Aust. 1989;151: Ba M, Spier S, Lapierre G, Lamarre A. Wet nebulizer versus spacer and metered dose inhaler via tidal breathing. J Asthma. 1989;26: 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: Kerem E, Levison H, Schuh S, et al. Efficacy of albuterol administered by nebulizer versus spacer device in children with acute asthma. J Pediatr. 1993;123: Lin YZ, Hsieh KH. Metered dose inhaler and nebulizer in acute asthma. Arch Dis Child. 1995;72: Parkin PC, Saunders NR, Diamond SA, Winders PM, Macarthure C. Randomized trial spacer vs nebulizer for acute asthma. Arch Dis Child. 1995;72: Chou KJ, Cunningham SJ, Crain EF. Metered-dose inhalers with spacers vs nebulizers for pediatric asthma. Arch Pediatr Adolesc Med. 1995;149: Williams JR, Bothner JP, Swanton RD. Delivery of albuterol in a pediatric emergency department. Pediatr Emerg Care. 1996;12: Butz AM, Eggleston P, Huss K, Kolodner K, Rand C. Nebulizer use in inner-city children with asthma: morbidity, medication use, and asthma management practices. Arch Pediatr Adolesc Med. 2000;154: Amirav I, Newhouse MT. Metered-dose inhaler accessory devices in acute asthma: efficacy and comparison with nebulizers: a literature review. Arch Pediatr Adolesc Med. 1997;151: Effectiveness of routine self monitoring of peak flow in patients with asthma: Grampian Asthma Study of Integrated Care (GRASSIC). BMJ. 1994;308: Jones KP, Mullee MA, Middleton M, Chapman E, Holgate ST, and the British Thoracic Society Research Committee. Peak flow based asthma self-management: a randomized controlled study in general practice. Thorax. 1995;50: Woolcock AJ, Yan K, Salome CM. Effect of therapy on bronchial hyperresponsiveness in the long-term management of asthma. Clin Allergy. 1988;18: Ignacio-Garcia JM, Gonzalez-Santos P. Asthma self-management education program by home monitoring of peak expiratory flow. Am J Respir Crit Care Med. 1995;151: 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: Leickly FE, Wade SL, Crain E, Kruszon-Moran D, Wright EC, Evans R III. Selfreported adherence, management behavior, and barriers to care after an emergency department visit by inner city children with asthma. Pediatrics [serial online]. 1998;101:doc e8. 383