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Table 3 The methodological quality of the trials

From: Withdrawal of inhaled corticosteroids in individuals with COPD - a systematic review and comment on trial methodology

Type of bias Criteria WISP O'Brien et al COPE COSMIC
Selection Method used to generate randomisation sequence? 'Patients were allocated with minimisation to intervention using the programme MINIM v1.3' 'Randomisation was performed by the clinical pharmacist who randomised an odd number dice roll to placebo and an even number dice roll to drug' 'Randomisation was performed in blocks of six by computer generated allocation' 'A randomisation schedule generated by the patient allocation for clinical trials (PACT) program'
  Method used to generate allocation concealment? 'Inhalers were given an alphanumeric code to conceal allocation' Inadequate Unclear Unclear
Performance Double-blinding? 'Study nurses and regular clinicians were blind to allocation throughout the study' 'The subject and pulmonary physician were blinded to the treatment regimen. Placebo and drug MDI canisters were identical, and the placebo mist was flavoured to make the treatments indistinguishable' 'This study was a randomised, double-blind parallel-group single centre study...' 'the study medication was packed in identical inhaler devices to ensure both the patient and investigator were unaware of the allocated treatment'
Attrition Loss of patients accounted for?   Steroid Placebo Unclear   Steroid Placebo   Steroid Placebo
   Number randomised 128 132   Number randomised 123 121 Number randomised 189 184
   Number analysed 128 132   Number analysed 122(1 died) 120(1 died) Number analysed unclear unclear
Detection Outcome assessor blind Unclear Unclear Unclear Unclear
Reporting Any evidence of reporting bias? No No No No