Randomised health services studies.

The randomised controlled (or clinical) trial (RCT) is recognized as the most valid among the study designs. The use of RCT in research is widespread and well formalised. In contrast, implementations of new methods and policies in routine health care are commonly lacking a formalised design, impairing the ability to evaluate and improve health care. Use of experimental designs in health care is possible at the implementation phase of clinical or preventive action or more broad process-of-care. We propose the terminology randomised health services studies (RHS) to denote the use of a randomised design with observations in routine health care, regardless of whether randomisation is done at individual, population or process level. In contrast to RCT, the RHS should be based on the same regulative actions, funding mechanisms and ethical framework as routine health care itself. This commentary discusses the different basis, practicalities, and formalities that distinguish the RHS from the RCT. Development of a formalised framework for RHS, including distinct registration, could contribute to an increased use of valid methods in effectiveness research, thus gaining better and more direct evidence on routine medical practice.