Guevara 2005.

Methods	This was a non‐randomised comparative study. As part of a Cochrane Review comparing the effects of inhaled corticosteroids to cromolyn, authors of all included trials were contacted to clarify methods and/or to obtain missing outcome data. Authors listed as corresponding authors were contacted by e‐mail if available by post if e‐mail was unavailable or if there was no response to e‐mail, and by fax if e‐mail and post were both unavailable or there was no response to either Remaining authors were contacted if there was no response by the corresponding author
Data	Cochrane Review comparing the effects of inhaled corticosteroids to cromolyn; study authors of all 25 included trials were contacted to clarify methods and/or to obtain missing outcome data
Comparisons	E‐mail versus letter versus fax (total n = 25; sample size per study arm not reported)
Outcomes	Response rate Time to response
Notes	This study was published as an abstract
Risk of bias
Item	Authors' judgement	Description
Allocation concealment?	Unclear	Non‐randomised comparison therefore not applicable
Allocation sequence generation?	Unclear	Non‐randomised comparison therefore not applicable
How allocation occurred?	Unclear	Unclear
Attempts to balance groups?	Unclear	E‐mail was the preferred method of contact
Use of blinding?	No	No blinding