Reliability and benefit of diagnostic procedure for asthma in young children ...(t strategy consisting of a test and an i...),Health

If information on diagnostic procedures and therapeutic measures is only available in separate studies (Phase 2 and 3 diagnostic studies, and therapy studies), it is possible to try to synthesize and link them to a certain extent. In this way, at least indirect findings on the clinical efficacy of diagnostic procedures can be obtained. However, this method of "linked evidence" involves certain methodological requirements. As IQWiG and its external experts established, the studies available to date on diagnosing asthma in children under 5 years of age do not contain these requirements. Thus, a reference standard was particularly lacking.

Even a modified procedure which, based on the linked evidence criteria, attempts to link the studies without a reference test is not possible. This is in part because the asthma-specific selection criteria are not precisely described in the therapy studies. Furthermore, none of the therapy studies used a selection method whose diagnostic accuracy had already been proven by studies.

IQWiG has therefore concluded that the results from the diagnostic and therapy studies cannot actually be synthesized in terms of "linked evidence". No robust conclusions can be drawn concerning the accuracy of individual tests used in therapy studies nor on the clinical efficacy of interventions tested in Phase 2 and 3 diagnosis studies.

IQWiG published the preliminary results in two separate preliminary reports in June (Part 1) and in September (Part 2) 2008 and interested parties were invited to submit comments. When the comments stage ended, the two preliminary reports were revised and then compiled into a final report, which was sent to the contracting agency at the beginning of June 2009. Documentation of the written comments for both preliminary reports an
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