Background: Prognostic studies aim to assess the ability of diagnostic tests or clinical observations to predict future events, or to evaluate associations of risk factors and health outcomes in populations of patients [1]. Prognostic research has to date received much less attention than research into therapeutic or diagnostic areas [2]. As more and more of these studies become available, the demand for summarising prognostic studies in systematic reviews, health technology assessments, and guidelines is increasing. Consistent, reproducible assessment of the methodological quality of primary studies is key to the interpretation of secondary research. Where studies of prognostic tests use a test accuracy type design (health outcome being treated as the reference standard) it may be reasonable to assess their methodological quality using a modified version of the QUADAS tool [3]. However, many observational prognostic studies appropriately assess the association of possible prognostic factors, or of having tests done or not done, or of certain test results, with health outcomes using a multivariate regression modelling approach. Tools are needed to standardise the assessment of the risk of bias in observational prognostic studies. Objectives: We are currently preparing five reports for the German Institute for Quality and Efficiency in Health Care (IQWiG) on the clinical effects and the diagnostic and prognostic accuracy of positron emission tomography (PET) in various oncological indications. These reports also include primary studies of prognostic tests, which are of a multivariate regression model design, i.e. not test accuracy studies. Methods: Based on the methods described by Altman [1] and Hayden [4], we developed a tool for the assessment of risk of bias and variation of effects of this type of prognostic studies consisting of 17 items in 5 domains. Results/ Conclusions: We would like to present and discuss results and experiences with this tool.
References
1. Altman DG. Systematic reviews of evaluations of prognostic variables. BMJ 2001;323:224–8.
2. Centre for Reviews and Dissemination. Systematic reviews: CRD’s guidance for undertaking reviews in health care. York: University of York. 2009. Chapter 2.3, Prognostic tests; p. 135–147.
3. Whiting P, Rutjes AWS, Reitsma JB, Bossuyt PMM, Kleijnen J. The development of QUADAS: a tool for the quality assessment of studies of diagnostic accuracy included in systematic reviews. BMC Medical Research Methodology 2003, 3:25.
4. Hayden JA, C ôté P, Bombardier C. Evaluation of the Quality of Prognosis Studies in Systematic Reviews. Ann Intern Med 2006;144: 427–437.