A combination of factors have contributed to an increased interest in patient-reported outcome (PRO) data. Increased chronic diseases and aging population, empowered patient group, a shift of treatment focus from curing diseases to ameliorating symptoms, as well as increasing budget constraint and competition among drugs developers are among the factors driving an increasing interest in assessing PROs. As the number and quantity of PROs increase, quality and criteria to assess these measures as well as sources of error and bias are increasingly being emphasized. A series of efforts were made in EU and the US to propose criteria for evaluating the scientific quality of PRO data in clinical practice. At the same time, major organizations sought to rationalize the field and improve the standing of PRO assessments through open communications with key regulatory agencies including the FDA and the EMEA. Accordingly, issues related to methodological standards for measuring and interpreting PROs in the drug evaluation process were debated and the research agenda on PROs were expedited. Current major trends in PRO research include computerized adaptive testing (CAT), ePROs, and an integrated data collection. The adoption of CAT supported by modern psychometrics such as Item Response Theory (IRT) have the potential to achieve far greater precision in measuring health outcomes without increasing the response burden. However, crucial theoretical and methodological concerns need to be addressed before widely applying this approach in patient outcome research. ePROs have prevailed in clinical trials and shown high patient acceptance. The advantages of ePRO are evident. However, practical issues may be another hurdle before the practice is widely accepted in clinical research. Finally, as PRO data collection becomes more common in clinical trials, the coordination of integrated data collection may be of benefit to all stakeholders.