Non-evidence-based variables affecting physicians' test-ordering tendencies: a systematic review

Background: The concept of evidence-based medicine (EBM) was introduced in 1992. Incorporation of EBM into physicians' practices, however, has been slow. Test-ordering tendencies are still based on variables that are not necessarily evidence-based. Methods: The literature was reviewed to identify the non-EBM variables that affect physicians' practices of test ordering. Studies of interest were limited to original research on the determinants of physicians' test-ordering tendencies. The search strategy included queries in MEDLINE (1992-2006), Web of Science (1993-2006), EMBASE (1992-2006), and PsycINFO (1992-2006); checking of reference lists; hand searching relevant journals; and personal communication with experts. Two independent reviewers abstracted information on the design, quality, and limitations of the study. Review articles, letters, and editorials were excluded from analysis. Results: 104 original studies reporting on the variables affecting test ordering were identified. Of these, 53 studies assessing physician variables affecting test ordering were identified. Some of the recognisable physician factors included age, sex, degree of specialisation, geographic location and practice setting, individual belief systems, experience, knowledge, fear of malpractice litigation, physician regret, financial incentives, awareness of costs of tests ordered, and provision of written feedback by peers or employers. Conclusion: Despite considerable advances in our understanding of EBM and its application to patient care, several non-EBM physician variables influence physicians' test-ordering characteristics. Ongoing effort is needed to identify the modifiable non-EBM determinants of physicians' test ordering and to use appropriate tools and techniques to encourage evidence-based behaviours for test ordering.