68 Chapter 2 Supplemental Table 2. Continued Biases Issues to consider for judging overall rating of “Risk of bias” Outcome and prognostic factor information on those lost to follow-up Participants lost to follow-up are adequately described for key characteristics. There are no important differences between key characteristics and outcomes in participants who completed the study and those who did not. Study Attrition Summary Loss to follow-up (from baseline sample to study population analyzed) is not associated with key characteristics (i.e., the study data adequately represent the sample) sufficient to limit potential bias to the observed relationship between PF and outcome. 3. Prognostic Factor Measurement Goal: To judge the risk of measurement bias related to how PF was measured (differential measurement of PF related to the level of outcome). Definition of the PF A clear definition or description of ‘PF’ is provided (e.g., including dose, level, duration of exposure, and clear specification of the method of measurement). Valid and Reliable Measurement of PF Method of PF measurement is adequately valid and reliable to limit misclassification bias (e.g., may include relevant outside sources of information on measurement properties, also characteristics, such as blind measurement and limited reliance on recall). Continuous variables are reported or appropriate cut-points (i.e., not datadependent) are used. Method and Setting of PF Measurement The method and setting of measurement of PF is the same for all study participants. Proportion of data on PF available for analysis Adequate proportion of the study sample has complete data for PF variable. Method used for missing data Appropriate methods of imputation are used for missing ‘PF’ data. PF Measurement Summary PF is adequately measured in study participants to sufficiently limit potential bias. 4. Outcome Measurement Goal: To judge the risk of bias related to the measurement of outcome (differential measurement of outcome related to the baseline level of PF). Definition of the Outcome A clear definition of outcome is provided, including duration of follow-up and level and extent of the outcome construct.
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