Herbal interventions for chronic asthma in adults and children

Impact of non-drug therapies on asthma control: A systematic review of the literature

Background: Despite growing access to effective therapies, asthma control still needs improvement. Many non-drug factors, such as allergens, air pollutants and stress also affect asthma control and patient quality of life, but an overview of the effectiveness of non-drug interventions on asthma control was lacking.

Objectives: To identify non-drug interventions likely to improve asthma control.

Methods: A systematic review of the available literature in Medline and the Cochrane Library was conducted in March 2017, without any time limit. Initial searching identified 884 potentially relevant clinical trial reports, literature reviews and meta-analyses, which were screened for inclusion using criteria of quality, relevance, and reporting outcomes based on asthma control.

Results: Eighty-two publications met the inclusion criteria. In general, the quality of the studies was low. Patient education programmes (22 studies) significantly improved asthma control. Multifaceted interventions (10 studies), which combined patient education programmes with decreasing exposure to indoor allergens and pollutants, significantly improved asthma control based on clinically relevant outcomes. Renovating homes to reduce exposure to allergens and indoor pollutants improved control (two studies). Air filtration systems (five studies) were effective, especially in children exposed to second-hand smoke. Most measures attempting to reduce exposure to dust mites were ineffective (five studies). Dietary interventions (eight studies) were ineffective. Promoting physical activity (five studies) tended to yield positive results, but the results did not attain significance.

Conclusion: Twenty-six interventions were effective in asthma control. Simultaneously combining several action plans, each focusing on different aspects of asthma management, seems most likely to be effective.

Therapeutic Effects of Kangzhi Syrup in a Guinea Pig Model of Ovalbumin-Induced Cough Variant Asthma

Purpose

This study aimed to investigate the possible effects and underlying mechanisms of Kangzhi syrup on ovalbumin- (OVA-) induced cough variant asthma (CVA) in guinea pigs.

Methods

All 48 guinea pigs were randomly assigned to four experimental groups: normal, OVA model with or without Kangzhi syrup (OVA and OVA + KZ), and OVA with Dexamethasone (OVA + DM). After sensitizing the guinea pigs, a cough challenge was performed by the inhalation of capsaicin. The antitussive effect, inflammatory cells, cytokines in bronchoalveolar lavage fluid (BALF) and lung tissue, and morphological changes were examined.

Results

Compared with model group, Kangzhi syrup effectively exerted an antitussive effect (p < 0.0001) and reduced the pneumonic anaphylacticitis by inhibiting the infiltration of total inflammatory cells (p < 0.0001) and reducing the percentage of eosinophil in BALF (p < 0.0001). Moreover, evidence from morphological studies also demonstrated that Kangzhi syrup inhibited the infiltration of inflammatory cells and ameliorated the structure changes. NF-κB and TGF-β1 expression were attenuated in the OVA + KZ group versus the OVA group (p < 0.0001). Additionally, a semiquantitative analysis of TGF-β1 expression also demonstrated that the Kangzhi syrup attenuated this profibrogenic growth factor (p < 0.001).

Conclusions

The results demonstrated that Kangzhi syrup exerted a considerable antitussive effect in CVA animal model, which depended on its marked impact on the anti-anaphylactic inflammation. Additionally, it could ameliorate the airway remodeling by inhibiting NF-κB and TGF-β1 signal pathway.

Herbal Medicines for Asthmatic Inflammation: From Basic Researches to Clinical Applications

Asthma is one of the most common chronic inflammatory disorders, associated with reversible airflow obstruction, airway hyperresponsiveness, and airway remodeling. This disease has a significant impact on individuals, their families, and society. Standardized therapeutics such as inhaled corticosteroid in combination with long acting β2 agonist have been applied for asthma control; however, complementary and alternative medicines, especially herbal medicines, are still widely used all over the world. A growing body of literature suggests that various herbals or related products might be effective in inhibiting asthmatic inflammation. In this review, we summarize recent advances about the mechanistic studies of herbal medicines on allergic airway inflammation in animal models and their potential application into clinic for asthma control.

Interventions for managing asthma in pregnancy

BACKGROUND

Asthma is the most common respiratory disorder complicating pregnancy, and is associated with a range of adverse maternal and perinatal outcomes. There is strong evidence however, that the adequate control of asthma can improve health outcomes for mothers and their babies. Despite known risks of poorly controlled asthma during pregnancy, a large proportion of women have sub-optimal asthma control, due to concerns surrounding risks of pharmacological agents, and uncertainties regarding the effectiveness and safety of different management strategies.

OBJECTIVES

To assess the effects of interventions (pharmacologic and non-pharmacologic) for managing women's asthma in pregnancy on maternal and fetal/infant outcomes.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (2 June 2014) and the Cochrane Airways Group's Trials Register (4 June 2014).

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials comparing any intervention used to manage asthma in pregnancy, with placebo, no intervention, or an alternative intervention. We included pharmacological and non-pharmacological interventions (including combined interventions). Cluster-randomised trials were eligible for inclusion (but none were identified). Cross-over trials were not eligible for inclusion.We included multi-armed trials along with two-armed trials. We also included studies published as abstracts only.

DATA COLLECTION AND ANALYSIS

At least two review authors independently assessed trial eligibility and quality and extracted data. Data were checked for accuracy.

MAIN RESULTS

We included eight trials in this review, involving 1181 women and their babies. Overall we judged two trials to be at low risk of bias, two to be of unclear risk of bias, and four to be at moderate risk of bias.Five trials assessed pharmacological agents, including inhaled corticosteroids (beclomethasone or budesonide), inhaled magnesium sulphate, intravenous theophylline, and inhaled beclomethasone verus oral theophylline. Three trials assessed non-pharmacological interventions, including a fractional exhaled nitric oxide (FENO)-based algorithm versus a clinical guideline-based algorithm to adjust inhaled corticosteroid therapy, a pharmacist-led multi-disciplinary approach to management versus standard care, and progressive muscle relaxation (PMR) versus sham training.The eight included trials were assessed under seven separate comparisons. Pharmacological interventionsPrimary outcomes: one trial suggested that inhaled magnesium sulphate in addition to usual treatment could reduce exacerbation frequency in acute asthma (mean difference (MD) -2.80; 95% confidence interval (CI) -3.21 to -2.39; 60 women). One trial assessing the addition of intravenous theophylline to standard care in acute asthma did not report on exacerbations (65 women). No clear difference was shown in the risk of exacerbations with the use of inhaled beclomethasone in addition to usual treatment for maintenance therapy in one trial (risk ratio (RR) 0.36; 95% CI 0.13 to 1.05; 60 women); a second trial also showed no difference, however data were not clearly reported to allow inclusion in a meta-analysis. No difference was shown when inhaled beclomethasone was compared with oral theophylline for maintenance therapy (RR 0.88; 95% CI 0.59 to 1.33; one trial, 385 women). None of these trials reported on neonatal intensive care admissions.

SECONDARY OUTCOMES

inhaled magnesium sulphate in acute asthma was shown to improve lung function measures (one trial, 60 women); intravenous theophylline in acute asthma was not associated with benefits (one trial, 65 women). No clear differences were seen with the addition of inhaled corticosteroids to routine treatment in three trials (374 women). While inhaled beclomethasone, compared with oral theophylline, significantly reduced treatment discontinuation due to adverse effects in one trial (384 women), no other differences were observed, except for higher treatment adherence with theophylline. Four of the five trials did not report on adverse effects. Non-pharmacological interventionsPrimary outcomes: in one trial, the use of a FENO-based algorithm was shown to significantly reduce asthma exacerbations (RR 0.61; 95% CI 0.41 to 0.90; 220 women); and a trend towards fewer neonatal hospitalisations was observed (RR 0.46; 95% CI 0.21 to 1.02; 214 infants). No exacerbations occurred in one trial assessing pharmacist-led management; this approach did not reduce neonatal intensive care admissions (RR 1.50; 95% CI 0.27 to 8.32; 58 infants). One trial (64 women) assessing PMR did not report on exacerbations or neonatal intensive care admissions.

SECONDARY OUTCOMES

the use of a FENO-based algorithm to adjust therapy led to some improvements in quality of life scores, as well as more frequent use of inhaled corticosteroids and long-acting β-agonists, and less frequent use of short-acting β-agonists (one trial, 220 women). The FENO-based algorithm was associated with fewer infants with recurrent episodes of bronchiolitis in their first year of life, and a trend towards fewer episodes of croup for infants. Pharmacist-led management improved asthma control scores at six months (one trial, 60 women); PMR improved lung function and quality of life measures (one trial, 64 women). No other differences between comparisons were observed.

AUTHORS' CONCLUSIONS

Based on eight included trials, of moderate quality overall, no firm conclusions about optimal interventions for managing asthma in pregnancy can be made. Five trials assessing pharmacological interventions did not provide clear evidence of benefits or harms to support or refute current practice. While inhaled magnesium sulphate for acute asthma was shown to reduce exacerbations, this was in one small trial of unclear quality, and thus this finding should be interpreted with caution. Three trials assessing non-pharmacological interventions provided some support for the use of such strategies, however were not powered to detect differences in important maternal and infant outcomes. While a FENO-based algorithm reduced exacerbations, the effects on perinatal outcomes were less certain, and thus widespread implementation is not yet appropriate. Similarly, though positive effects on asthma control were shown with PMR and pharmacist-led management, the evidence to date is insufficient to draw definitive conclusions.In view of the limited evidence base, further randomised trials are required to determine the most effective and safe interventions for asthma in pregnancy. Future trials must be sufficiently powered, and well-designed, to allow differences in important outcomes for mothers and babies to be detected. The impact on health services requires evaluation. Any further trials assessing pharmacological interventions should assess novel agents or those used in current practice. Encouragingly, at least five trials have been identified as planned or underway.

An overview of integrative therapies in asthma treatment

Treatment of asthma lends itself to an integrative medicine approach due to the multifactorial nature of the disease. It is well established that asthma has a neuromuscular component (bronchospasm), an immunological component (inflammation), and a psychological component. This encourages the use of diverse approaches to address all avenues of pathophysiology, aiming for the most effective blend of treatment approaches possible. Integrative medicine is defined by NIH NCCAM ( http://nccam.nih.gov ) as medicine that blends the use of evidence-based complementary therapies with conventional medicine. Statistics from the 2007 National Health Interview Survey (NHIS), conducted by the Centers for Disease Control and Prevention's (CDC) National Center for Health Statistics (NCHS), showed that approximately four out of 10 adults and approximately one in nine children and more than 50 % of children living with chronic illness, including asthma, used complementary therapies in the USA in 2007. Asthma and allergies rank among the top 15 most common medical conditions in which integrative therapies are used in both children and adults. To date, integrative treatment approaches with some evidence for benefit in asthma treatment include the following: nutrition modification, mind-body medicine, physical activity, and certain dietary supplement interventions.

Integrated traditional Chinese medicine for childhood asthma in Taiwan: a Nationwide cohort study

Background

Traditional Chinese medicine (TCM) is the most commonly used alternative therapy in children with asthma, especially in the Chinese community. This study aimed to investigate the effects of the government-sponsored Outpatient’s Healthcare Quality Improvement (OHQI) project with integrated TCM treatment on childhood asthma.

Methods

This study used the Longitudinal Health Insurance Database 2000, which is a part of the Taiwan National Health Insurance Research Database (NHIRD). Children with diagnosed asthma and aged under 15 years from 2006–2010 were enrolled. They were collated into 3 groups: (1) subjects treated with non-TCM; (2) subjects treated with single TCM; and (3) subjects treated with integrative OHQI TCM. The medical visits and the cost of treatment paid by the Bureau of National Health Insurance (BNHI) to the outpatient, emergency room, and inpatient departments were evaluated for the study subjects within 1 year of the first asthma diagnosis during the study period.

Results

Fifteen multi-hospitals, including 7 medical centers, and 35 TCM physicians participated in OHQI during the study period. A total of 12850 children from the NHIRD database were enrolled in this study, and divided as follows: 12435 children in non-TCM group, 406 children in single TCM group, and 9 children in integrative OHQI TCM group. Although the total medical cost paid by the BNHI per patient in the integrative OHQI TCM group was greater than that in the non-OHQI groups, the patients in the integrative OHQI TCM group exhibited greater therapeutic effects, and did not require ER visits or hospitalization. In addition, ER visits and hospitalization among patients who received a combination of conventional therapy with integrated TCM were lower than those among patients who underwent conventional therapy alone or single TCM treatment.

Conclusions

Asthmatic children at partly controlled level under conventional therapy may benefit from adjuvant treatment with integrated TCM.

The use of a collaborative structured methodology for the development of a multifaceted intervention programme for the management of asthma (the MIA project), tailored to the needs of children and families of South Asian origin: a community-based, participatory study

Background

Asthma is one of the most common chronic childhood illnesses in the UK. South Asian children are more likely to suffer from their asthma and be admitted to hospital. While this inequality needs to be addressed, standard behaviour-change interventions are known to be less successful in minority ethnic groups. Evidence suggests a need to enhance services provided to ethnic minority communities by developing culturally sensitive tailored interventions.

Objectives

The Management and Interventions for Asthma (MIA) project aimed to test an iterative multiphase participatory approach to intervention development underpinned by the socioecological model of health, producing an intervention-planning framework and enhancing an evidence-based understanding of asthma management in South Asian and White British children.

Design

Interviews and focus groups facilitated by community facilitators (CFs) were used to explore knowledge and perceptions of asthma among South Asian communities, children, families and healthcare professionals (HCPs). A smaller comparison group of White British families was recruited to identify aspects of asthma management that could be addressed either by generic interventions or by a tailored approach. Collaborative workshops were held to develop an intervention planning framework and to prioritise an aspect of asthma management that would be used as an exemplar for the development of the tailored, multifaceted asthma intervention programme.

Setting

The community study was based in a largely urban environment in Leicester, UK.

Participants

Participants were recruited directly from the South Asian (Indian, Pakistani and Bangladeshi) and White British communities, and through the NHS. Children were aged between 4 and 12 years, with a range of asthma severity.

Intervention development

The study had four phases. Phase 1 consisted of an evidence review of barriers and facilitators to asthma management in South Asian children. Phase 2 explored lay understandings of childhood asthma and its management among South Asian community members (n = 63). Phase 3 explored perceptions and experiences of asthma management among South Asian (n = 82) and White British families (n = 31) and HCP perspectives (n = 37). Using a modified intervention mapping approach incorporating psychological theory, phase 4 developed an intervention planning framework addressing the whole asthma pathway leading to the development of an exemplar multifaceted, integrated intervention programme called ‘ACT [Awareness, Context (cultural and organisational) and Training] on Asthma’.

Results

Data on the social patterning of perceptions of asthma and a lack of alignment between the organisation of health services, and the priorities and competencies of British South Asian communities and families were produced. Eleven key problem areas along the asthma pathway were identified. A four-arm multifaceted tailored programme, ‘ACT on Asthma’, was developed, focusing on the theme ‘getting a diagnosis’. This theme was chosen following prioritisation by families during the collaborative workshops, demonstrating the participatory, iterative, phased approach used for the intervention design.

Conclusions

The MIA study demonstrated barriers to optimal asthma management in children at the family, provider and healthcare system levels and across the whole asthma pathway. Interventions need to address each of these levels to be effective. Minority ethnic communities can be successfully engaged in collaborative intervention development with a community-focused and culturally sensitive methodology.

Future work

Further research is required to (1) assess the feasibility and effectiveness of the proposed ‘ACT on Asthma’ programme, (2) develop methods to increase active participation of children in research and service development, (3) develop and test strategies to enhance public understanding of asthma in South Asian communities and (4) identify effective means of engaging the wider family in optimising asthma management.

Funding

The National Institute for Health Research Health Services and Delivery Research programme.

Alternative treatment for asthma: case study of success of traditional chinese medicine treatment of children from urban areas with different levels of environmental pollution

The present study examined efficacy of traditional Chinese medicine (TCM) treatment in Dutch children with asthma in areas with differing air pollution. The study results indicate that TCM treatment of children living in more polluted urban area is less successful then that of children living in cleaner air area.

Cochrane systematic reviews of Chinese herbal medicines: an overview

OBJECTIVES

our study had two objectives: a) to systematically identify all existing systematic reviews of Chinese herbal medicines (CHM) published in Cochrane Library; b) to assess the methodological quality of included reviews.

METHODOLOGY/PRINCIPAL FINDINGS

We performed a systematic search of the Cochrane Database of Systematic Reviews (CDSR, Issue 5, 2010) to identify all reviews of CHM. A total of fifty-eight reviews were eligible for our study. Twenty-one of the included reviews had at least one Traditional Chinese Medicine (TCM) practitioner as its co-author. 7 reviews didn't include any primary study, the remaining reviews (n = 51) included a median of 9 studies and 936 participants. 50% of reviews were last assessed as up-to-date prior to 2008. The questions addressed by 39 reviews were broad in scope, in which 9 reviews combined studies with different herbal medicines. For OQAQ, the mean of overall quality score (item 10) was 5.05 (95% CI; 4.58-5.52). All reviews assessed the methodological quality of primary studies, 16% of included primary studies used adequate sequence generation and 7% used adequate allocation concealment. Of the 51 nonempty reviews, 23 reviews were reported as being inconclusive, while 27 concluded that there might be benefit of CHM, which was limited by the poor quality or inadequate quantity of included studies. 58 reviews reported searching a median of seven electronic databases, while 10 reviews did not search any Chinese database.

CONCLUSIONS

Now CDSR has included large numbers of CHM reviews, our study identified some areas which could be improved, such as almost half of included reviews did not have the participation of TCM practitioners and were not up-to-date according to Cochrane criteria, some reviews pooled the results of different herbal medicines and ignored the searching of Chinese databases.

Patient-centered care and its effect on outcomes in the treatment of asthma

Patient-centered care may be pivotal in improving health outcomes for patients with asthma. In addition to increased attention in both research and clinical forums, recent legislation also highlights the importance of patient-centered outcomes research in the Patient Protection and Affordable Care Act. However, whether patient-centered care has been shown to improve outcomes for this population is unclear. To answer this question, we performed a systematic review of the literature that aimed to define current patient-focused management issues, characterize important patient-defined outcomes in asthma control, and identify current and emerging treatments related to patient outcomes and perspectives. We used a parallel search strategy via Medline(®), Cochrane Central Register of Controlled Trials, CINAHL(®) (Cumulative Index to Nursing and Allied Health Literature), and PsycINFO(®), complemented with a reference review of key articles that resulted in a total of 133 articles; 58 were interventions that evaluated the effect on patient-centered outcomes, and 75 were descriptive studies. The majority of intervention studies demonstrated improved patient outcomes (44; "positive" results); none showed true harm (0; "negative"); and the remainder were equivocal (14; "neutral"). Key themes emerged relating to patients' desires for asthma knowledge, preferences for tailored management plans, and simplification of treatment regimens. We also found discordance between physicians and patients regarding patients' needs, beliefs, and expectations about asthma. Although some studies show promise regarding the benefits of patient-focused care, these methods require additional study on feasibility and strategies for implementation in real world settings. Further, it is imperative that future studies must be, themselves, patient-centered (eg, pragmatic comparative effectiveness studies) and applicable to a variety of patient populations and settings. Despite the need for further research, enough evidence exists that supports incorporating a patient-centered approach to asthma management, in order to achieve improved outcomes and patient health.

Systematic review of clinical trials assessing the effectiveness of ivy leaf (hedera helix) for acute upper respiratory tract infections

Introduction. Among nonantibiotic cough remedies, herbal preparations containing extracts from leaves of ivy (Hedera helix) enjoy great popularity. Objective. A systematic review to assess the effectiveness and tolerability of ivy for acute upper respiratory tract infections (URTIs). Methods. We searched for randomized controlled trials (RCTs), nonrandomized controlled clinical trials and observational studies evaluating the efficacy of ivy preparations for acute URTIs. Study quality was assessed by the Jadad score or the EPHPP tool. Results. 10 eligible studies were identified reporting on 17463 subjects. Studies were heterogeneous in design and conduct; 2 were RCTs. Three studies evaluated a combination of ivy and thyme, 7 studies investigated monopreparations of ivy. Only one RCT (n = 360) investigating an ivy/thyme combination used a placebo control and showed statistically significant superiority in reducing the frequency and duration of cough. All other studies lack a placebo control and show serious methodological flaws. They all conclude that ivy extracts are effective for reducing symptoms of URTI. Conclusion. Although all studies report that ivy extracts are effective to reduce symptoms of URTI, there is no convincing evidence due to serious methodological flaws and lack of placebo controls. The combination of ivy and thyme might be more effective but needs confirmation.

Necessary alternatives: patients' views of asthma treatment

This article is based on semistructured interviews and focus groups conducted with 27 asthma patients in The Netherlands who chose complementary and alternative medicine (CAM) for treatment of their condition. All subjects were contacted through an online forum for asthma patients hosted by the Dutch Asthma Foundation. Nineteen subjects (12 women and seven men) between the ages of 29 and 65 years participated in the interviews, held between June 2009 and January 2010. All of the participating subjects had experience with conventional medications, including anti-inflammatory corticosteroids and bronchodilators. For the focus group meeting, held in February 2010, the sample included seven subjects (four women and three men) between the ages of 31 and 46 years, none of whom had ever used conventional medication and all of whom were using CAM. All subjects in the sample had been diagnosed with asthma by their physician or lung specialist. The study examined the causes of patient noncompliance with the prescribed medical regime. It is argued that evidence-based rationality on the part of subjects is an overlooked dimension of their experience of asthma. This study demonstrates the role that the patients' social network, including medical practitioners, friends, and family, and other asthmatics, plays in the process of decision-making and choices about treating asthma. It also demonstrates the role of patients' information-searching strategies. The author concludes that patient noncompliance with commonly prescribed medication and selection of alternative medical treatment is less a matter of denial of their diagnosis or the severity of their illness, but more a matter of choice informed by evidence-based rationality.

Common respiratory diseases

The self-medication phenomenon in upper respiratory tract infections, rhinosinusitis, asthma, and chronic obstructive pulmonary disease are significant and will continue to increase. Current level of evidence is poor because of the small number of good quality studies, small sample size, short duration, and variation in the composition of the herbal interventions or therapies. The current review points to several potential therapies that could be effective either alone, or as adjuncts to conventional therapies.

Anti-allergic effects of PG102, a water-soluble extract prepared from Actinidia arguta, in a murine ovalbumin-induced asthma model

BACKGROUND

Asthma is a chronic inflammatory disease of the lung and its incidence has been increasing around the world. We previously reported that oral administration of a water-soluble extract prepared from Actinidia arguta, code-named PG102, could modulate the level of Th1 and Th2 cytokines and suppress the production of immunoglobulin E (IgE) in the ovalbumin (OVA)-immunized murine model as well as in the in vitro cell culture system, and furthermore could significantly improve dermatitis conditions in the NC/Nga murine model. These data suggested that PG102 might have therapeutic effects in a broad range of allergic diseases.

OBJECTIVE

To assess the possible anti-allergic effects of PG102 in the OVA-induced murine asthma model.

METHODS

The quality of PG102 was standardized, using its effects on the production of IgE, IL-5, and IL-13, in in vitro cell culture systems. To test effects on asthma, BALB/c mice were orally administrated with PG102, followed by OVA sensitization and challenge to induce asthmatic symptoms. Airway hyperresponsiveness (AHR), bronchoalveolar lavage fluid, serum, and lung tissue were analysed by using various methods.

RESULTS

PG102 could decrease the level of IgE, IL-5, and IL-13 in in vitro cell culture systems with IC(50) being 1.12-1.43 mg/mL. PG102 could ameliorate asthmatic symptoms, including AHR and eosinophilia in the lungs. Such improvement of asthmatic symptoms by PG102 was accompanied by the down-regulation of IL-5 and IgE. In PG102-treated mice, high level expression of heme oxygenase-1, a potent anti-inflammatory enzyme, was observed in alveolar inflammatory cells, while the mRNA levels of foxp3, TGF-beta1, and IL-10, important markers for regulatory T cells, were also up-regulated in the lung tissue.

CONCLUSIONS

PG102 may have potential as a safe and effective reagent for the prevention or treatment of asthma.

Inhaled sodium cromoglycate for asthma in children

BACKGROUND

Sodium cromoglycate has been recommended as maintenance treatment for childhood asthma for many years. Its use has decreased since 1990, when inhaled corticosteroids became popular, but it is still used in many countries.

OBJECTIVES

To determine the efficacy of sodium cromoglycate compared to placebo in the prophylactic treatment of children with asthma.

SEARCH STRATEGY

We searched the Cochrane Airways Group Trials Register (October 2007), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 3, 2007), MEDLINE (January 1966 to November 2007), EMBASE (January 1985 to November 2007) and reference lists of articles. We also contacted the pharmaceutical company manufacturing sodium cromoglycate. In 2007 we updated the review.

SELECTION CRITERIA

All double-blind, placebo-controlled randomised trials, which addressed the effectiveness of inhaled sodium cromoglycate as maintenance therapy, studying children aged 0 up to 18 years with asthma.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted data. We pooled study results.

MAIN RESULTS

Of 3500 titles retrieved from the literature, 24 papers reporting on 23 studies could be included in the review. The studies were published between 1970 and 1997 and together included 1026 participants. Most were cross-over studies. Few studies provided sufficient information to judge the concealment of allocation. Four studies provided results for the percentage of symptom-free days. Pooling the results did not reveal a statistically significant difference between sodium cromoglycate and placebo. For the other pooled outcomes, most of the symptom-related outcomes and bronchodilator use showed statistically significant results, but treatment effects were small. Considering the confidence intervals of the outcome measures, a clinically relevant effect of sodium cromoglycate cannot be excluded. The funnel plot showed an under-representation of small studies with negative results, suggesting publication bias.

AUTHORS' CONCLUSIONS

There is insufficient evidence to be sure about the efficacy of sodium cromoglycate over placebo. Publication bias is likely to have overestimated the beneficial effects of sodium cromoglycate as maintenance therapy in childhood asthma.