Development and introduction of new diagnostic techniques have greatly accelerated over the past decades. The evaluation of diagnostic techniques, however, is less advanced than that of treatments. Unlike with drugs, there are generally no formal requirements for adoption of diagnostic tests in routine care. In spite of important contributions, 1 2 the methodology of diagnostic research is poorly defined compared with study designs on treatment effectiveness, or on aetiology, so it is not surprising that methodological flaws are common in diagnostic studies.3-5 Furthermore, research funds rarely cover diagnostic research starting from symptoms or tests.
Since quality of the diagnostic process largely determines quality of care, overcoming deficiencies in standards, methodology, and funding deserves high priority. This article summarises objectives of diagnostic testing and research, methodological challenges, and options for design of studies.