Background: To investigate whether equal access to
bortezomib has been achieved under the Dutch policy
regulations that guarantee equal access to expensive
inpatient drugs. Methods: We investigated accessibility to bortezomib treatment at national and regional levels by (i) conducting interviews with stakeholders in the Dutch healthcare system to explore prescription barriers and (ii) tabulating sales data from 2004-2009 and trial participation rates. Results: Interviews revealed awareness of the high treatment costs, although prescription barriers were not encountered. National use of bortezomib increased slowly (treating 2% of patients in 2004 to 17% in 2009), indicating a long adjustment period. Furthermore, use remains below the rate estimated by the professional association of haematologists (27%). Regional differences were found for both daily practice use (e.g. ranging from 13-27% in 2009) and clinical trial participation (e.g. ranging from 1-12% in 2006). Conclusion: Our results were somewhat conflicting: interviews did not reveal any prescription barriers, but quantitative methods showed regional differences, signs of underutilisation, and access inequality. Investigating use and accessibility, based on data triangulation, provides valuable feedback which can enhance evidence-based decision making for both physicians and policymakers. This could improve appropriate and efficient use and ensure equal access to expensive drugs.