In a review of stroke rehabilitation studies, concealed allocation was under reported

The objective of this two-phase study was to assess the adequacy of the reporting of concealed allocation (CA) in randomized controlled trials (RCTs) evaluating interventions associated with stroke rehabilitation.

In phase I of the study, 50 RCTs included in a systematic review were selected to establish agreement between two raters. Two investigators determined if the method described to conceal the randomization schedule was adequate, inadequate, or not reported. In phase II, using a larger sample size (n=165), the differences in the proportion of studies with and without adequate CA are reported for two comparisons: (1) pharmacological vs. nonpharmacological trials and (2) multicentered vs. single-site studies.

In both phases I and II, CA was described adequately in one-third of all studies sampled. The agreement between raters was 88% (small ka, Cyrillic=0.79; 95% confidence interval: 0.65, 0.94). No significant differences in the adequacy of reporting for CA were found with respect to study type (pharmacological vs. nonpharmacological), whereas multicentered trials reported adequacy of CA more frequently.

Although concealment of group allocation is an important feature of trial design, it was frequently not reported in many RCTs associated with stroke rehabilitation.