Table 2

Primary and subgroup analyses for the PBI

PBI analysesNumber of trialsNumber of meta-analysesPBI (95% CI*)
Primary analysis118310.57 (0.50 to 0.63)
Subgroup analyses
Availability of a systematic review protocol
 With a protocol27120.55 (0.39 to 0.72)
 Without a protocol91190.57 (0.49 to 0.65)
 Subgroup difference†=−0.02 (95% CI −0.19 to 0.18; two-tailed p value of test of interaction 0.87)
Availability of a core outcome measurement set for the clinical condition of the review
 Available core set (RA/OA systematic reviews)55150.62 (0.53 to 0.71)
 No core set (depressive/anxiety disorder systematic reviews)63160.51 (0.41 to 0.62)
 Subgroup difference†=0.11 (95% CI −0.04 to 0.24; two-tailed p value of test of interaction 0.15)
  • *Percentile-based CIs for the PBI were constructed using bootstrap methods by resampling individual trials 2000 times.12

  • †The confidence limits and p value for the difference in PBI between subgroups was constructed using bootstrap methods from 2000 replicates.

  • OA, osteoarthritis; PBI, Potential Bias Index; RA, rheumatoid arthritis.