Context. There has been surprisingly little attention to conceptual and methodological issues that influence the measurement of discretionary utilization at the end of life (DIAL), an indicator of quality care. Objective. The objectives of this study were to examine how DIALs have been operationally defined and identify areas where evidence is biased or inadequate to inform practice. Methods. We conducted a scoping review of the English language literature published from 1/1/04 to 6/30/17. Articles were eligible if they reported data on $2 DIALs within 100 days of the deaths of adults aged $18 years. We explored the influence of research design on how researchers measure DIALs and whether they examine demographic correlates of DIALs. Other potential biases and influences were explored. Results. We extracted data from 254 articles published in 79 journals covering research conducted in 29 countries, mostly focused on cancer care (69.1%). More than 100 DIALs have been examined. Relatively crude, simple variables (e.g., intensive care unit admissions [56.9% of studies], chemotherapy [50.8%], palliative care [40.0%]) have been studied more frequently than complex variables (e.g., burdensome transitions; 7.3%). We found considerable variation in the assessment of DIALs, illustrating the role of research design, professional norms and disciplinary habit. Variables are typically chosen with little input from the public (including patients or caregivers) and clinicians. Fewer than half of the studies examined age (44.6%), gender (37.3%), race (26.5%), or socioeconomic (18.5%) correlates of DIALs. Conclusion. Unwarranted variation in DIAL assessments raises difficult questions concerning how DIALs are defined, by whom, and why. We recommend several strategies for improving DIAL assessments. Improved metrics could be used by the public, patients, caregivers, clinicians, researchers, hospitals, health systems, payers, governments, and others to evaluate and improve end-of-life care.