Comparative effectiveness research: a view from the other side of the pond

CER seeks answers to the first three of these questions but the antagonism to CER, by some US politicians [101], astounds those of us who are mere observers of American healthcare politics. Nevertheless, the establishment of the PatientCentered Outcomes Research Institute (PCORI) promises to enhance healthcare both in the USA and globally. Indeed, it is encouraging that PCORI, as part of its agenda, will be examining the methodological challenges facing CER. The publication, in this issue of the journal, of a quartet of articles focusing on study designs for CER is therefore timely. The theme, running throughout these articles, emphasizes the importance of observational – as well as experimental – designs to provide robust evidence about the comparative effectiveness of competing interventions. The only surprising omission is the absence of a discussion about the role and importance of ‘effect size’ in the evaluation of the effectiveness of health technologies. It has been accepted, by even the most rigorous methodologists [1], that observational studies in the form of historical controlled trials can provide reliable evidence of effectiveness when there is a ‘dramatic’ response. Indeed, under such circumstances, the use of historical controls may make randomized controlled trials unnecessary [2]. The adoption, for example, of imatinib (Gleevec, Glivec) for the treatment of chronic myeloid leukemia was initially based on comparisons with historical controls [3]. However, there are other issues relating to comparative effectiveness that will need to be resolved as the techniques of CER mature. They include: ■ The comparator(s)