Background: Asthma is the most prevalent chronic disease in childhood and has been growing globally over the last three decades. Studies in this regard indicate different and irrelevant results in Iran. Different prevalence of asthma has been reported in industrialized countries, prevalence of 25.9% in the United Kingdom, 12.8% in Spain and 31% in Australia. This study aimed to evaluate asthma ...

Appropriate methods for meta-regression applied to a set of clinical trials, and the limitations and pitfalls in interpretation, are insufficiently recognized. Here we summarize recent research focusing on these issues, and consider three published examples of meta-regression in the light of this work. One principal methodological issue is that meta-regression should be weighted to take account...