For example, for treatment evaluation, clinical trials are the best, but if there are secondary studies (systematic reviews or meta-analyses) that synthesize information from several studies, the results will be more important and the scientific conclusions will be more relevant.
We searched for relevant primary and secondary publications (systematic reviews and health technology assessment reports) in Medline, Embase, PsycINFO, BIOSIS, and the Cochrane Library published up until February 2009.
We excluded protocols of randomised trials, secondary analyses, systematic reviews, methodological studies, pilot studies, and early phase trials (for example, phase 1).
We searched MEDLINE, Embase, the Cochrane Library, and Centre for Reviews and Dissemination (CRD) to identify secondary studies (systematic reviews and meta-analyses) that can be used to estimate the relative rates (see search strategy in Additional file 1).
Seventy-eight percent (N = 94) of the critical appraisal tools were developed for use on primary research [ 1- 5, 7, 9, 18, 19, 25- 27, 34, 37- 41], while the remainder (N = 26) were for secondary research (systematic reviews and meta-analyses) [ 2- 5, 15- 36, 116].
However, systematic secondary metabolites biosynthesis genes relationship might give insight into the molecular level, seem to be absent.
Adherence to primary and secondary safety recommendations, systematic monitoring of laboratory personnel, and the design of proactive plans to prevent accidents help to minimize the risk of infection and provide adequate protection for the community.
Omitting lymphadenectomy carries a risk of inadequate staging, leading to secondary lymphadenectomy or systematic adjuvant radiotherapy.
In order to answer this question we conducted a systematic secondary analysis of published trial data.
