Chất lượng, khi đề cập đến các thử nghiệm ngẫu nhiên (RCT), là một khái niệm đa chiều bao gồm phù hợp của thiết kế, thực hiện, phân tích, báo cáo và nhận thức của nó Hiệu lực lâm sàng đề cập đến mức độ mà các kết quả nghiên cứu | 9 How to critically appraise a study reporting effectiveness of an intervention Hywel Williams Definitions of quality validity and bias Quality when referring to randomised controlled trials RCTs is a multidimensional concept that includes appropriateness of design conduct analysis reporting and its perceived clinical Validity refers to the extent to which the study results relate to the truth . Validity may be internal . are the results of this trial true or external to what extent do the results of this trial apply to my patients . Factors affecting external validity are discussed further in Chapter 12. Internal validity is a prerequisite for external validity. In addition to assessing the role of chance a crucial component in appraising the internal validity of a trial is assessment of its potential for bias. Bias denotes a systematic error resulting in an incorrect estimation of the true effect. With respect to clinical trials bias may be best understood in terms of selection bias - resulting in an imbalance in treatment groups performance bias - treating one group of people differently from the other detection bias - biased assessment of outcome resulting from lack of blinding attrition bias - biased handling of deviations from the study protocol and those lost to follow up. This chapter guides the reader on applying the various forms of bias to appraising the internal validity of an RCT. How does one tell a good RCT from a bad one Quality criteria derived from research Three main factors related to study reporting have been associated with altering the estimation of the risk estimate usually by inflating the claimed These are shown in Box . Generation and concealment of treatment allocation Generation and concealment of treatment allocation are two interrelated steps in the crucial process of randomisation. The first refers to the method used to generate the randomisation sequence. The second refers to the subsequent steps taken
