Background: The objective of this report is to explore methodologic issues on the basis of a systematic review of the literature of effectiveness research on palliative cancer care with regard to selection and characteristics of a study population, interventions, and outcome assessment.
Methods: A systematic review was performed of randomized clinical trials on comprehensive palliative care with quality assessment of the studies by three independent observers, using predefined quality criteria.
Results: In the literature search, 11 relevant studies were identified. Without exception, methodologic problems were experienced. In two studies, the problems were so severe that no results were reported. Problems were associated with the recruitment of a study population in 10 studies, its homogeneity in six, patient attrition in four, defining and maintaining the contrast between the strategies in six, and selection of the outcome variables in four.
Conclusion: Effectiveness research in palliative care is complex and has many pitfalls. To enhance the quality of future palliative care trials and the validity of their results, we particularly stress the importance of careful case finding, strict eligibility criteria, precise documentation of the process of care, and comprehensive outcome measurement. The relation of structure, process, and outcome variables in comprehensive palliative care should be further explored. It is a challenge for future research to link patient outcomes to the quality of care, independent from the autonomous course of the disease and from personal characteristics.