Are b2-agonists Effective Treatment for Acute Bronchitis or Acute Cough in Patients Without Underlying Pulmonary Disease? A Systematic Review

The studies were also all of a short duration. There is no information as to whether treatment with b2-agonists would alter outcomes beyond 3 to 7 days. This is an important omission, because many patients in these studies were still bothered by symptoms at the end of the trials.

Only 2 studies evaluated inhaled b2-agonists, which would currently be the most likely formulation used in adults and older children. Neither of these studies used spacing devices. The delivery of the medicine may have been suboptimal and resulted in less benefit than might have been seen had spacers been used.

Overall, the quality of the trials was fair to good . There may have been additional biases, however, because most of the trials had unequal distribution of co-interventions and did not record compliance with study medications. Also, even though the studies were all double-blinded, the fact that the majority of the patients in one trial knew which study medication they had been given indicates that the blinding may not have been adequate in these studies because of the taste or side effects of the study medications.

Conclusions

Our review highlights the gaps in evidence regarding the utility of b2-agonists in the treatment of acute cough and acute bronchitis in patients without underlying pulmonary disease. Although there is a possibility that these agents may be useful, additional data demonstrating benefit is required before they can be routinely recommended. There is a particular need for identifying clinical characteristics that can predict which patients might benefit. For example, there is a complete lack of data in children older than 2 years who have signs of airway obstruction. More evidence on the risk-benefit ratio of b2-agonists in adults with clinical signs of airflow limitation is also necessary. Additional areas of useful research would be in evaluating long-acting b2-agonists (because of ease of adherence), in evaluating the benefits of inhaled b2-agonists with spacing devices, and in comparing b2-agonists with other symptomatic treatments.

Acknowledgments

We thank Bill Hueston, Ben Littenberg, Hasse Melbye, and Peter Rowe for providing unpublished information; Bill Grant for assistance with statistics; and Ron D’Souza and Steve MacDonald of the Cochrane Collaboration and Bette Jean Ingui for assistance with database searches.