Patient Reported Outcomes: Why are we still using percentage change from baseline as an outcome?

Patient-reported outcome (PRO) measures are generally used to examine the effect of medical interventions on how patients feel or functional status. When analyzing PRO endpoints, interpreting the change in scores between two-time points or the difference in change scores between treatment groups can be challenging. There is a lack of consensus in the research community regarding a frequently used endpoint 'change from baseline percentage.' This research discusses the advantages and disadvantages of using the anchor-based method in PRO studies. A case example is provided to illustrate concepts. Appropriate search parameters were identified to examine the topic, and PubMed was selected as the most relevant database. Published studies were retrieved between January 2000 and December 2021. Search terms included keywords: "anchor-based," "patient-reported outcome", "SF-36" and "change from baseline,". Articles were excluded if they did not include 'anchor-based' as a method. The information from the resulting articles was grouped into four categories: advantages, disadvantages, validity of the PRO method, and the PRO method's ability to detect change. The mismatch between the PRO instrument and the intended outcome is an important consideration in using percentage change from baseline as an outcome. This study provides an overview of key issues in assessing and documenting how patients feel or function.