Baseline study characteristics will be extracted
- Title, first author, year of publication, MR design (one-sample/two-sample), exposure(s) and outcome(s).
For the genetic instrument(s) used in each study, the following information will be extracted:
- Type of the genetic instrument(s)
- Proportion of variance explained by the genetic instruments
- P-value threshold for SNP selection
- Threshold for SNP linkage disequilibrium (r2)
- Statistical power of the genetic instruments and the corresponding effect estimate
For the exposure(s) and outcome(s) of each study, the following information will be extracted:
- Data source and ancestry
- Sample size (total participants, cases, controls)
- Covariates adjusted in the analysis
For the result(s) of each study, the following information will be extracted:
- Type of instrumental variable (IV) analysis (formal or reduced IV)
- Unit of estimated effect
- Analytical approach for main analysis
- Effect metric, effect size and the corresponding 95% CIs, as well as P-value
- Cochran’s Q-statistic and I-square statistic (I2) for heterogeneity
- Sensitivity analysis methods and results, if applicable