CLINICAL REVIEW
Elaine Lau, BScPhm, PharmD, MSc
Pediatric considerations in asthma
A
sthma is the most common chronic childhood disease, affecting about 500,000 Canadians under age 18.1 Approximately 10% to 15% of children develop asthma.2 High rates of emergency department visits, hospitalization, and school absences3 are a considerable burden for the whole family.4 Despite guidelines and available effective treatments, childhood asthma control is suboptimal and improved care is needed. Diagnosing asthma is difficult in children 6 years of age and younger. Symptoms can be similar to other childhood illnesses (e.g., episodic coughing and wheezing are commonly due to viral respiratory tract infections), wheeze is sometimes absent, and pulmonary function tests (PFT) are unreliable. Children between 4 and 5 years old can be taught to use a peak expiratory flow (PEF) meter, but parental supervision is required to ensure accurate results.5 Diagnosis should be based on clinical judgment, symptoms, and physical findings. Consider any child who has had 3 or more episodes of wheezing and/or dyspnea to have asthma until proven otherwise.6 Most who develop wheezing after age 5 have asthma. Use a treatment trial with short-acting bronchodilators and inhaled corticosteroids (ICS) to help confirm diagnosis. Objective asthma control measures used for adults (e.g., PFT) are difficult to ascertain in children. Both parents and physicians tend to overestimate control and underestimate severity.7,8 Use validated pediatric asthma screening and monitoring tools such as the Asthma Therapy Assessment Questionnaire (ATAQ)9 and Asthma Control Test (ACT) questionnaires to identify those with uncontrolled asthma who need additional asthma management support.10 (See Resources, page S39.) Short-acting inhaled b2-agonists (SABA) are the most effective bronchodilators and are the preferred treatment for acute asthma in all children. ICS are the preferred treatment for maintenance therapy. In children older than 5, ICS can: • Control asthma symptoms • Reduce the frequency of acute exacerbations and the number of hospital admissions • Improve quality of life, lung function, and bronchial hyperresponsiveness • Reduce exercise-induced bronchoconstriction11 Dose-response studies demonstrate marked and rapid symptom and PFT improvements at low ICS doses (e.g., 100 to Elaine Lau is coordinator of Drug Information Services, Department of Pharmacy, at the Hospital for Sick Children in Toronto. Contact:
[email protected].
200 mcg of beclomethasone or equivalent daily) and mild disease is well controlled. With a spacer device, daily doses of 400 mcg of beclomethasone or equivalent result in near-maximum benefits.12 Long-acting inhaled b2-agonists (LABA) have been studied mainly in children older than 5 as add-on therapy for patients whose asthma is not controlled with ICS. Most studies found significant PFT improvements, but the effects are not consistent with symptoms, reliever medication need, and exacerbation frequency.13,14 As monotherapy, leukotriene receptor antagonists (LTRA) provide clinical benefit in children older than 5, but less than low-dose ICS. They also partially protect against exerciseinduced bronchoconstriction within hours and reduce viralinduced asthma exacerbations in children ages 2 to 5 with a history of intermittent asthma. As add-on treatment in children whose asthma is insufficiently controlled Knowledge into practice by low ICS doses, leukotriene modi• Assess children for the fiers provide moderrespiratory effort required ate clinical improveto use a spacer device, and ments, including a switch to wet nebulization if significant exacerbanecessary.26 tion reduction.15 • Use distraction techniques if Most guidelines children are uncooperative now recommend ICS (e.g., sing a song, make it over sodium cromogame, administer medication glycate (SCG) for perwhile patient is sleeping).27 sistent asthma con• Work with teens directly trol. Recent reviews and address their concerns have shown that SCG about discretion, in order to is not as effective as improve medication adherICS, and no more efence. fective than placebo. SCG is also inconvenient, as it is now only available as nebules. Consider a SCG trial if asthma is moderate and corticosteroid adverse effects are a major concern, but quickly replace with ICS if control is not achieved.16,17 Theophylline has a less favourable side effect profile, potential for drug interactions, and need for serum concentration monitoring compared to other treatments. It has only been assessed as an add-on therapy in a small number of trials, with
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conflicting results.18 The clinical benefits of intermittent systemic or ICS for children with intermittent, viral-induced wheeze remain controversial. Because such children are asymptomatic between exacerbations, intermittent ICS treatment is attractive to both physicians and families, and this management strategy is prevalent in Canada even though evidence is lacking. While some studies in older children found small benefits, a study in young children found no effects on wheezing symptoms.19 Carefully monitor children on this form of therapy to verify the treatment is successful and switch to continuous ICS if necessary. Early intervention with ICS reduces morbidity during therapy, but does not alter the course of asthma.20,21 A common concern is long-term ICS effect on growth. Study results stated “while low to medium doses of ICS may have the potential to decrease growth velocity, the effect is not sustained in subsequent years of treatment, is not progressive, and may be reversible.”22 Most children treated with moderate ICS doses attain their predicted adult height.23,24
Since growth suppression is dose-dependent, use the minimum doses required to maintain control. Periodically measure height in children who regularly require high daily doses of ICS (e.g., >400 mcg daily of inhaled beclomethasone). Reassess if growth rate changes. Metered-dose inhalers (MDI) with a spacer are the best devices for young children. Although nebulizers are considered easier to use in acute asthma exacerbations with insufficient inspiratory flow to use a spacer, they have imprecise dosing, are expensive, are time-consuming to use, and require maintenance. An MDI is at least as effective as a nebulizer in severe acute asthma exacerbations, reduces hospitalizations, and improves pulmonary function.25 Reserve nebulizers for children who cannot use other inhaler devices. Despite advances in pediatric asthma management, poor control continues to affect children’s quality of life. There are challenges adults do not typically encounter that need to be addressed to ensure pediatric asthma patients derive the most benefit from their treatment. n
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