Evaluation of ‘implications for research’ statements in systematic reviews of interventions in advanced cancer patients – a meta-research study

Abstract

Background: Implications for research (IfR) sections are an important part of systematic reviews (SRs) to inform health care researchers and policy makers. PRISMA 2020 recommends reporting IfR, while Cochrane Reviews require a separate chapter on IfR. However, it is unclear to what extent SRs discuss IfR. We aimed i) to assess whether SRs include an IfR statement and ii) to evaluate which elements informed IfR statements. Methods: We conducted a meta-research study based on SRs of interventions in advanced cancer patients from a previous project (CRD42019134904). As suggested in the Cochrane Handbook, we assessed if the following predefined variables were referred to in IfR statements: patient, intervention, control, outcome (PICO) and study design; concepts underlying Grading of Recommendations, Assessment, Development and Evaluation (GRADE) domains: risk of bias, inconsistency, indirectness, imprecision, publication bias. Data were independently extracted by three reviewers after piloting the data extraction form. Discrepancies were resolved in weekly in-depth discussions. Results: We included 261 SRs. The majority evaluated a pharmacological intervention (n = 244, 93.5%); twenty-nine were Cochrane Reviews (11.1%). Four out of five SRs included an IfR statement (n = 210, 80.5%). IfR statements commonly addressed ‘intervention’ (n = 121, 57.6%), ‘patient ‘ (n = 113, 53.8%), and ‘study design’ (n = 107, 51.0%). The most frequent PICO and study design combinations were ‘patient and intervention ‘ (n = 71, 33.8%) and ‘patient, intervention and study design ‘ (n = 34, 16.2%). Concepts underlying GRADE domains were rarely used for informing IfR recommendations: ‘risk of bias ‘ (n = 2, 1.0%), and ‘imprecision ‘ (n = 1, 0.5%), ‘inconsistency ‘ (n = 1, 0.5%). Additional elements informing IfR were considerations on cost effectiveness (n = 9, 4.3%), reporting standards (n = 4, 1.9%), and individual patient data meta-analysis (n = 4, 1.9%). Conclusion: Although about 80% of SRs included an IfR statement, the reporting of PICO elements varied across SRs. Concepts underlying GRADE domains were rarely used to derive IfR. Further work needs to assess the generalizability beyond SRs in advanced cancer patients. We suggest that more specific guidance on which and how IfR elements to report in SRs of interventions needs to be developed. Utilizing PICO elements and concepts underlying GRADE according to the Cochrane Handbook to state IfR seems to be a reasonable approach in the interim. Registration: CRD42019134904.