The quality of evidence is downgraded by inconsistency (unexplained variability in results), and by imprecise results (wide confidence intervals).
A Cochrane review [Abstract] 1 included 30 studies with a total of 1 992 infants with bronchiolitis. Oxygen saturation did not improve with bronchodilators (MD -0.43, 95% CI -0.92 to 0.06; 25 studies, n = 1 242). Effect estimates for inpatients (MD -0.62, 95% CI -1.40 to 0.16; 12 studies, n=495) were slightly larger than for outpatients (MD -0.25, 95% CI -0.61 to 0.11; 13 studies, n=747) for oximetry. Oximetry outcomes showed significant heterogeneity (I2 = 81%). Including only studies with low risk of bias had little impact on the overall effect size of oximetry (MD -0.38, 95% CI -0.75 to 0.00; 15 studies, n=793) but results were close to statistical significance. Outpatient bronchodilator treatment did not reduce the rate of hospitalization (11.9% in bronchodilator group versus 15.9% in placebo group, OR 0.75, 95% CI 0.46 to 1.21; 11 studies, n = 710). Inpatient bronchodilator treatment did not reduce the duration of hospitalization (MD 0.06, 95% CI -0.27 to 0.39; 6 studies, n = 349). There was no change in average clinical score (SMD -0.14, 95% CI -0.41 to 0.12; 9 studies, n=416) with bronchodilators in inpatient studies. In outpatient studies, the average clinical score decreased slightly with bronchodilators (SMD -0.42, 95% CI -0.79 to -0.06; 12 studies, n=670), a statistically significant finding of questionable clinical importance. The clinical score outcome showed significant heterogeneity (I2 statistic = 73%). Including only studies with low risk of bias reduced the heterogeneity but had little impact on the overall effect size of average clinical score (SMD -0.22, 95% CI -0.41 to -0.03; 15 studies, n=734).Subgroup analysis limiting bronchodilators to albuterol or salbutamol among outpatients (9 studies) showed no effect on oxygen saturation, average clinical score, or hospital admission after treatment. Adverse effects included tachycardia, oxygen desaturation and tremors.
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