BACKGROUND: The use of systematic review methods are widely recognized to be essential in the development of recommendations in clinical practice guidelines to prove their trustworthiness. The objective of this study was to assess the use of systematic search methods by authors of guidelines published in the oncology field.
METHODS: We analyzed 590 guidance documents identified in PubMed, NGC, GIN and web sites for guidelines in 2009-2015 in oncology. The main outcome measure used was incidence of guidance documents supported by a systematic search of the literature. In addition to descriptive analyses, logistic regression was used to evaluate if adequate search methods were explained by guideline characteristics.
RESULTS: Of 590 guidance documents included in the study, 305 (51.7%) declared the use of systematic search methods but only 168 (28.5%) applied methods meeting minimum standards for quality and provided sufficient details to allow classification. 164 (27.8%) guidance documents did not report any use of literature evaluation. Guidance documents produced by a Government Agency in North America (OR 2.16, 95% CI 1.16-4.17) and those with a focused scope (OR 2.35, 95% CI 0.97-5.56) were positively associated with the use of systematic search methods. We found no association between the year of publication and use of systematic search methods.
CONCLUSIONS: A relatively small number of guidance documents was informed by scientific evidence identified through adequate systematic search methods. We observed substantial room for improvement of applied methods and reporting, especially in documents with a broad focus, or those produced by professional societies or independent expert panels in other continents than North America.