Addi van Bergen

164 Supplementary file 3: CASP risk of bias tool for cohort studies 12 questions to help you make sense of cohort studies How to use this appraisal tool Three broad issues need to be considered when appraising a cohort study: • Are the results of the study valid? (Section A) • What are the results? (Section B) • Will the results help locally? (Section C) The 12questions on the followingpages are designed tohelpyou think about these issues systematically. The first two questions are screening questions and can be answered quickly. If the answer to both is “yes”, it is worth proceeding with the remaining questions.There is somedegreeof overlapbetween thequestions, youareasked to record a “yes”, “no” or “can’t tell” to most of the questions. A number of italicized prompts are given after each question. These are designed to remind you why the question is important. Record your reasons for your answers in the spaces provided. These checklists were designed to be used as educational tools as part of a workshop setting. @CASP This work is licensed under the Creative Commons Attribution-ShareAlike 3.0 Unported License. To view a copy of this license, visit http://creativecommons. org/licenses/by-nc-sa/3.0/ www.casp-uk.net. (A) Are the results of the study valid Screening Questions 1. Did the study address a clearly focused issue? Yes Can’t tell No HINT: A question can be focused in terms of: • the population studied • the risk factors studied • the outcomes considered • Is it clear whether the study tried to detect a beneficial or harmful effect? 2. Was the cohort recruited in an acceptable way? Yes Can’t tell No HINT: Look for selection bias which might compromise the generalisibility of the findings: • Was the cohort representative of a defined population? • Was there something special about the cohort? • Was everybody included who should have been included?