title: Prediction of unsuccessful treatment in patients with severe acute asthma.
abstract: BACKGROUND
  Clinical assessment can be used to identify which patients with acute asthma are at risk of unsuccessful initial treatment.
  
  
  OBJECTIVE
  To determine which elements of clinical assessment predict unsuccessful treatment, defined as needing critical care or any unplanned additional treatment.
  
  
  METHODS
  We analysed data from a large multicentre trial (the 3Mg trial). Adults with severe acute asthma underwent standardised clinical assessment, including peak expiratory flow rate (PEFR), up to 2 h after initiation of treatment. Standard care was provided other than blinded random allocation to trial treatment or placebo. Patients were followed up by record review up to 30 days. Unsuccessful treatment was defined as needing (1) critical care or (2) critical care or any unplanned additional treatment within 7 days of presentation. Logistic regression was used to identify predictors and derive a prediction model for each outcome.
  
  
  RESULTS
  Out of 1084 patients analysed, 81 (7%) received critical care and 157 (14%) received critical care or unplanned additional treatment. Baseline PEFR (p=0.017), baseline heart rate (p<0.001), other serious illness (p=0.019), PEFR change (p=0.015) and heart rate change (p<0.001) predicted need for critical care. Baseline PEFR (p=0.010), baseline heart rate (p<0.001), baseline respiratory rate (p=0.017), other serious illness (p=0.023), PEFR change (p=0.003) and heart rate change (p=0.001) predicted critical care or additional treatment. Models based on these characteristics had c-statistics of 0.77 and 0.69, respectively.
  
  
  CONCLUSIONS
  PEFR, heart rate and other serious illnesses are the best predictors of unsuccessful treatment, but models based on these variables provide modest predictive value.
authors.affiliation: School of Health and Related Research (ScHARR), University of Sheffield, Sheffield, UK.
authors.forename: Steve
authors.initials: S
authors.lastname: Goodacre
authors.affiliation: School of Health and Related Research (ScHARR), University of Sheffield, Sheffield, UK.
authors.forename: Mike
authors.initials: M
authors.lastname: Bradburn
authors.affiliation: School of Health and Related Research (ScHARR), University of Sheffield, Sheffield, UK.
authors.forename: Judith
authors.initials: J
authors.lastname: Cohen
authors.affiliation: Emergency Department, Royal Infirmary of Edinburgh, Edinburgh, UK.
authors.forename: Alasdair
authors.initials: A
authors.lastname: Gray
authors.affiliation: Faculty of Health and Life Sciences, University of the West of England, Bristol, UK.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Benger
authors.affiliation: Emergency Department, Leicester Royal Infirmary, Leicester, UK.
authors.forename: Tim
authors.initials: T
authors.lastname: Coats
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D000368:Aged; D001249:Asthma / Q000150:complications / Q000503:physiopathology / Q000628:therapy*; D002121:Calcium Channel Blockers / Q000627:therapeutic use; D003422:Critical Care; D004636:Emergency Service, Hospital; D005260:Female; D005500:Follow-Up Studies; D006339:Heart Rate; D006760:Hospitalization; D006801:Humans; D008278:Magnesium Sulfate / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D020380:Needs Assessment; D010366:Peak Expiratory Flow Rate; D011237:Predictive Value of Tests; D056152:Respiratory Rate; D017211:Treatment Failure; D055815:Young Adult
chemical_list: D002121:Calcium Channel Blockers; D008278:Magnesium Sulfate
keywords: Asthma; Clinical Assessment; Respiratory