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.


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


METHODS
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.


METHODS
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.


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


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.


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.
van der Wouden
Johannes C
JC
Department of General Practice, Erasmus MC, University Medical Center , Room Ff304, PO Box 2040, Rotterdam, Netherlands, 3000 CA. j.vanderwouden@erasmusmc.nl
Uijen
Johannes H J M
JH
Bernsen
Roos M D
RM
Tasche
Marjolein J A
MJ
de Jongste
Johan C
JC
Ducharme
Francine
F
D018927:Anti-Asthmatic Agents / Q000627:therapeutic use*; D001249:Asthma / Q000188:drug therapy*; D002648:Child; D004205:Cromolyn Sodium / Q000627:therapeutic use*; D006801:Humans; D016032:Randomized Controlled Trials as Topic
D018927:Anti-Asthmatic Agents; D004205:Cromolyn Sodium