Doing palliative care research on hematologic cancer patients: A realist synthesis of literature and experts' opinion on what works, for whom and in what circumstances.

Background: Research in PC (Palliative Care) is frequently challenging for patient's frailty, study design, professional misconceptions, and so on. Little is known about specificity in PC research on Hematologic cancer patients, who have distinct characteristics that might influence the enrollment process. Aims: What works, how and for whom, in increasing enrollment in studies in PC on patients with hematologic malignancies? Methods: Realist review: a qualitative review whose goal is to identify and explain the interaction between Contexts, Mechanisms, and Outcomes (CMOs). The theory was informed by a narrative, theory-based literature research, including an initialsystematic research, and the addition of papers suggested by experts of the field. We also used 7 interviews with experts in PC about patients with hematologic malignancies research and our own experience from a PC pilot study on patients with hematologic malignancies to refine the initial theory. Results: In our initial theory we hypothesize that: - Access to palliative care could be beneficial to hematologic patients, even in early stages - Hematologists tend to under-use palliative care services in general, due to unpredictable disease trajectories and cultural barriers. - These factors may negatively impact the patients' enrollment in PC researchWe included secondary literature as narrative reviews, if they presented interesting propositions useful for our theoretical construction. 23 papers met our inclusion criteria.We also searched for relevant CMOs impacting referral in palliative care, and we selected a list of CMOs that could be relevant also in hematology. We accordingly theorized a group of interventions that could increase the enrollment in PC research and presented them using "social exchange theory" (SET) as a theoretical framework.Prominent researchers in PC in hematologic malignancies were interviewed on their opinion on our results, and additional CMOs. Conclusions: Before conducting research in PC on patients with hematologic malignancies, it's probably advisable to assess: - The perception of the different actors (physicians, nurses, other professionals involved), in particular the hematologists, in terms of pros and cons of referral to PC and enrollment in PC trials - The existing relationship between PC and the Hematology departmentAccordingly, it's possible to tailor different interventions on the various actors and choose a model of trial to increase the perception of benefits from PC and, consequently, enrollment.