Compilation and meta-analysis of randomized placebo-controlled clinical trials on the prevention of respiratory tract infections in children using immunostimulants.

BACKGROUND: Several immunostimulants presume to prevent respiratory tract infections (RTIs) in children, but their efficacy is controversial. OBJECTIVES: To compile the findings of the randomized, placebo-controlled trials (RCTs) on the prevention of acute respiratory tract infections (ARTIs) in children using immunostimulants, and to perform a meta-analysis. DATA SOURCES: Medline, EMBASE databases, and register of Cochrane Acute Respiratory Infection Group. REVIEW METHODS: We searched all the references of immunostimulants and selected papers referring to RCTs on the prevention of ARTIs in children. Papers were rated according to Jadad's instrument. We abstracted the number of ARTIs, and a one-tailed probability value (p) was abstracted for each trial. Effect of medication was determined as weighted mean +/- SE of percent reduction of ARTIs regarding ARTIs of placebo groups as 100%. RESULTS: Four of five RCTs with Jadad's score > 3 showed significant reduction of ARTIs in immunostimulant groups. When only the trials reporting mean +/- SD and/or dispersion were considered (n = 16), the global weighted percent effect of immunostimulants showed a change of -42.64%, with 95% confidence intervals from -45.19% to -40.08%; i. e., the treated group presented about 60% of the mean number of ARTIs in the placebo group. CONCLUSIONS: According to this meta-analysis and RCTs with Jadad's score > 3, immunostimulants are an effective treatment for the prevention of ARTI. Further high-quality RCTs are required to demonstrate the effect and the size of the effect of each individual immunostimulant.