| | Study identification | | Circle one option for each question |
| | (1.1) | The study sample represents the population of interest with regard to key characteristics, sufficient to limit potential bias to the results.
To minimize bias, the study population should be clearly defined and described and should represent the source population of interest.
Points to consider include the following.
Is the source population or the population of interest adequately described with respect to key characteristics?
Are the sampling frame and recruitment adequately described, possibly including methods to identify the sample (number and type used; e.g., referral patterns in healthcare), period of recruitment and place of recruitment (setting and geographical location)?
Are inclusion and exclusion criteria adequately described (e.g., including explicit diagnostic criteria or a description of participants at the start of the follow-up period)?
Is participation in the study by eligible individuals adequate?
Is the baseline study sample (i.e., individuals entering the study) adequately described with respect to key characteristics? | Yes | No | Unclear |
| | (1.2) | Loss of follow-up is unrelated to key characteristics (i.e., the study data adequately represent the sample), sufficient to limit potential bias.
To minimize bias, completeness of follow-up should be described and adequate. Points to consider include the following.
Is the response rate (i.e., proportion of study sample completing the study and providing outcome data) adequate?
Are attempts to collect information on participants who dropped out of the study described?
Are reasons for loss to follow-up provided?
Are the key characteristics of participants lost to follow-up adequately described?
Are there any important differences in key characteristics and outcomes between participants who completed the study and those who did not? | Yes | no | unclear |
| | (1.3) | The prognostic factor of interest is adequately measured in study participants, sufficient to limit potential bias.
To minimize bias, prognostic factors should have been defined and measured appropriately. Points to consider include the following.
Is a clear definition or description of the prognostic factor(s) measured provided (including dose, level, duration of exposure, and clear specification of the measurement)?
Are continuous variables reported, or appropriate cut-off points (i.e., not data-dependent) used?
Are the prognostic factor measured and the method of measurement valid and reliable enough to limit misclassification bias? (This may include relevant outside sources of information on measurement properties, as well as characteristics such as blind measurement and limited reliance on recall).
Are complete data for prognostic factors available for an adequate proportion of the study sample?
Are the method and setting of measurement the same for all study participants?
Are appropriate methods employed if amputation is used for missing data on prognostic factors? | Yes | No | Unclear |
| | (1.4) | The outcome of interest is adequately measured in study participants, sufficient to limit bias.
Is a clear definition of the outcome of interest provided, including duration of follow-up?
Are the outcome that was measured and the method of measurement valid and reliable enough to limit misclassification bias? (This may include relevant outside sources of information on measurement properties, as well as characteristics such as “blind” measurement and limited reliance on recall.)
Are the method and setting of measurement the same for all study participants? | Yes | No | Unclear |
| | (1.5) | Important potential confounders are appropriately accounted for, limiting potential bias with respect to the prognostic factor of interest.
To minimize bias, important confounders, should be defined and measured, and confounding should be accounted for in the design or analysis. Points to consider include the following.
Are all important confounders, including treatments (key variables in the conceptual model), measured? Are clear definitions of the important confounders measured (including dose, level and duration of exposures) provided?
Is measurement of all important confounders valid and reliable? (This may include relevant outside sources of information on measurement properties, as well as characteristics such as “blind” measurement and limited reliance on recall.)
Are the method and setting of measurement of confounders the same for all study participants?
Are appropriate methods employed if imputation is used for missing data on confounders?
Are important potential confounders accounted for in the study design (e.g., matching for key variables, stratification or initial assembly of complete groups)?
Are important potential confounders accounted for in the analysis (i.e., appropriate adjustment)? | Yes | No | Unclear |
| | (1.6) | The statistical analysis is appropriate for the design of the study, limiting potential for the presentation of invalid results.
To minimize bias, the statistical analysis undertaken should be clearly described and appropriate for the design of the study. Points to consider include the following.
Is the presentation of data sufficient to assess the adequacy of the analysis?
Where several prognostic factors are investigated? Is the strategy for model building (i.e., the inclusion of variables) appropriate and based on a conceptual framework or model?
Is the selected model adequate for the design of the study?
Is there any selective reporting of results?
Are only prespecified hypotheses investigated in the analyses? | Yes | No | Unclear |
| | It was used to perform the quality assessment and control of bias |
|
|
