We present descriptive statistics on study characteristics (including quality, in terms of concealment of allocation, reporting of intention to treat analysis, and attrition rates of <20%).
*Number of quality criteria on which studies were judged as adequate (criteria were adequate concealment of allocation, reporting of intention to treat analysis, and <20% attrition).
In order to assess the methodological quality of each trial the authors recorded the allocation concealment and randomisation technique used, the blinding procedure, reporting of an intention-to-treat analysis, completeness of follow up, reasons for patient exclusion, and whether a protocol was published and supplied with the trial.
aStudy quality was judged on the following criteria: randomization, allocation, blinding, similarity of groups, loss to follow-up, imbalance between groups, reporting of data from intention-to-treat group and whether the study was free of selective reporting.
The ELIVS scoring system used in this study was developed from initial work by Jadad et al 23 and Linde et al. 24 It measures the following quality domains: treatment allocation, randomisation method, allocation concealment, postrandomisation baseline comparison, blinding, handling and reporting of withdrawals and intention to treat analysis.
Adequate allocation concealment and the reporting of intention to treat analysis were the only two quality criteria that improved over time.
To evaluate the methodological quality of the RCTs, the risk of bias was determined using the Cochrane classification for eight criteria: random sequence generation, allocation concealment, patient blinding, assessor blinding, reporting of dropout or withdrawal, intention-to-treat analysis, selective outcome reporting and other potential biases [ 8].
The majority of included studies that assessed the impact of design based strategies reduced the risk of bias by randomisation, reporting of predetermined primary outcomes and intention to treat analysis.
6 Following revision of the CONSORT (consolidated standards of reporting trials) statement, 9 a study 10 of 403 randomised controlled trials published during 2002 in 10 medical journals found a higher proportion of trials reporting use of intention to treat than before the statement was revised.
Since excluding patients from the analysis often results in biased estimates of treatment effects, trialists should ensure low dropout rates and high compliance rates and minimise missing outcome data Trialists should always report results of intention to treat analyses, including all randomised patients in the analysis in the group to which they were originally allocated.
