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. 2018 Apr 28;8(4):e019223. doi: 10.1136/bmjopen-2017-019223

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This displays the CHARMS risk of bias assessment on all included studies. Study participants: design of included study, sampling method and inclusion/exclusion criteria. Predictors: definition, timing and measurement. Outcome: definition, timing and measurement. Sample size and missing data: number of participants in study, events per variable and missing data. Statistical analysis: selection of predictors, internal validation and type of external validation.