Results Although highlighting a general lack of high- quality real-life effectiveness observational research on these clinical ly important topics , the analysis provided insights into how identified observational studies might inform asthma guidelines developers and clinicians .
Overall , RELEVANT appeared reliable and easy to use by expert review ers .
Conclusions Using such quality appraisal tools is m and atory to assess whether specific observational real-life effectiveness studies can be used to inform guideline development and /or decision-making in clinical practice
Abstract Introduction A Task Force was commissioned jointly by the European Academy of Allergy and Clinical Immunology ( EAACI ) and the Respiratory Effectiveness Group ( REG ) to develop a  quality assessment tool for real-life observational research to identify high- quality real-life asthma studies that could be considered within future guideline development .
Good research practices for comparative effectiveness research: approaches to mitigate bias and confounding in the design of nonrandomized studies of treatment effects using secondary data sources: the International Society for Pharmacoeconomics and Outcomes Research Good Research Practices for Retr
OBJECTIVES The goal of comparative effectiveness analysis is to examine the relationship between two variables , treatment , or exposure and effectiveness or outcome . Unlike data obtained through r and omized controlled trials , research ers face greater challenges with causal inference with observational studies . Recognizing these challenges , a task force was formed to develop a guidance document on method ological approaches to addresses these biases . METHODS The task force was commissioned and a Chair was selected by the International Society for Pharmacoeconomics and Outcomes Research Board of Directors in October 2007 . This report , the second of three reported in this issue of the Journal , discusses the inherent biases when using secondary data sources for comparative effectiveness analysis and provides method ological recommendations to help mitigate these biases . RESULTS The task force report provides recommendations and tools for research ers to mitigate threats to validity from bias and confounding in measurement of exposure and outcome . Recommendations on design of study included : the need for data analysis plan with causal diagrams ; detailed attention to classification bias in definition of exposure and clinical outcome ; careful and appropriate use of restriction ; extreme care to identify and control for confounding factors , including time-dependent confounding . CONCLUSIONS Design of nonr and omized studies of comparative effectiveness face several daunting issues , including measurement of exposure and outcome challenged by misclassification and confounding . Use of causal diagrams and restriction are two techniques that can improve the theoretical basis for analyzing treatment effects in study population s of more homogeneity , with reduced loss of generalizability
Results Although highlighting a general lack of high- quality real-life effectiveness observational research on these clinical ly important topics , the analysis provided insights into how identified observational studies might inform asthma guidelines developers and clinicians .
Overall , RELEVANT appeared reliable and easy to use by expert review ers .
Conclusions Using such quality appraisal tools is m and atory to assess whether specific observational real-life effectiveness studies can be used to inform guideline development and /or decision-making in clinical practice
Abstract Introduction A Task Force was commissioned jointly by the European Academy of Allergy and Clinical Immunology ( EAACI ) and the Respiratory Effectiveness Group ( REG ) to develop a  quality assessment tool for real-life observational research to identify high- quality real-life asthma studies that could be considered within future guideline development .