Meta analyses results.

RaR: Rate Ratio. CI: Confidence interval. CC: Case-control design. CS: cross-sectional. RCT: Randomized Clinical Trial. RCS: Retrospective Cross sectional. DIM: Difference in means.aACR criteria and ACR plus physician diagnosis included.bthe cohorts between 1976 and 1990 and between1976 and 2002 were overlapped between the two studies.cOnly ACR criteria included.dmeans change in SLEDAI.ethe means change in SLEDAI on max time of follow-up from both studies.fThere were included all subgroups from a study which is clustered by age (67).gThere were selected ever use in 25 years old and lower, data from one study (67).hThere were selected ever use in 26–35 years old data from one study (67).iThere were selected ever use in 36–45 years old data from one study (67).jThere were selected ever use in 46–55 years old data from one study (67).kthere were selected ever use in older 56 years old data from one study (67).‡Variance = 0.11.†Variance = 0.02.*1–11 months,**12 months or more.§Severe flares and major flares.ℓFlares combined by subtypes.¶Begg and Mazumdar p = 0.29. Trim and fill procedures showed a similar effect size. 25 articles with an effect size of zero would be needed to nullify the observed effect.