Probabilities
To estimate the probabilities of the model (see Table 1 ) , we performed a systematic review of systematic reviews or RCTs published or observational studies up to January, 2020. In order to identify potentially relevant studies were made searches of computerized databases (MEDLINE, CENTRAL, LILACS, and CINAHL) ; using the following search strategy: (Magnesium Sulfate OR Sulfate, Magnesium OR Magnesium Sulfate, Heptahydrate OR Heptahydrate Magnesium Sulfate) AND ((asthma) AND (acute exacerbation) . No language restrictions were applied. To be included in the model, the studies had to be RCTs of parallel-group or cross-over design, systematic reviews or RCTs published or observational studies include children between 2 and 18 years of age. Also were included others observational clinical obtained during the review of references cited in published literature identified the potentially applicable studies . The computerized search yield 49 citations, and a total of 32 studies were examined in full text for possible inclusion. For inclusion of data in the model, participants in the studies needed to be under the age of 18 years with acute exacerbation asthma , studies needed to evaluated the use of MS and report at least one of the following outcomes: percentage of hospitalizacions or admission in pediatric intensive unit or acute complications during the period of observation. Studies were excluded if they included patients with no clear diagnosis of asthma and patients over 18 years. All probabilities were contrasted with probabilities extracted from local studies to derivate the ranges in the sensibility analisis (8-16).