# Executive Summary Patient-based outcome measures are tools used to assess health-related quality of life, functional status, and other health-related concerns from the patient's perspective. These measures are increasingly used as primary or secondary endpoints in clinical trials. This review aims to describe the diversity of available patient-based outcome measures and to identify the criteria investigators should consider when selecting such measures for use in clinical trials. The review identifies eight key criteria for selecting patient-based outcome measures: appropriateness, reliability, validity, responsiveness, precision, interpretability, acceptability, and feasibility. These criteria are not consistently defined, and the literature associated with them is not clearly summarized. It is not possible to rank the relative importance of these criteria in relation to decisions about selecting measures for inclusion in a trial. The review also discusses the different types of patient-based outcome measures, including disease-specific, site-specific, dimension-specific, generic, summary item, individualized, and utility measures. Each type has its own advantages and disadvantages, and the choice of measure depends on the specific needs of the trial. The review concludes that investigators need to consider these criteria when selecting patient-based outcome measures for trials. Developers of instruments should provide evidence under the same headings. Further research and consensus processes should be used to evaluate leading instruments in different fields of healthcare to improve the use of patient-based outcome measures in research. Primary research is needed either in the form of methodological additions to substantive clinical trials or studies of leading measures with methodology as the primary rationale.# Executive Summary Patient-based outcome measures are tools used to assess health-related quality of life, functional status, and other health-related concerns from the patient's perspective. These measures are increasingly used as primary or secondary endpoints in clinical trials. This review aims to describe the diversity of available patient-based outcome measures and to identify the criteria investigators should consider when selecting such measures for use in clinical trials. The review identifies eight key criteria for selecting patient-based outcome measures: appropriateness, reliability, validity, responsiveness, precision, interpretability, acceptability, and feasibility. These criteria are not consistently defined, and the literature associated with them is not clearly summarized. It is not possible to rank the relative importance of these criteria in relation to decisions about selecting measures for inclusion in a trial. The review also discusses the different types of patient-based outcome measures, including disease-specific, site-specific, dimension-specific, generic, summary item, individualized, and utility measures. Each type has its own advantages and disadvantages, and the choice of measure depends on the specific needs of the trial. The review concludes that investigators need to consider these criteria when selecting patient-based outcome measures for trials. Developers of instruments should provide evidence under the same headings. Further research and consensus processes should be used to evaluate leading instruments in different fields of healthcare to improve the use of patient-based outcome measures in research. Primary research is needed either in the form of methodological additions to substantive clinical trials or studies of leading measures with methodology as the primary rationale.