Quality of life of ovarian cancer patients treated with combined platinum taxane chemotherapy: protocol for a systematic review

Materials and methods The present systematic review will be designed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Patient consent and institutional review board approval will not be retrieved as they are not required in this type of study. Information sources and search methods We will use the Medline (1966–2021), Scopus (2004–2021), Clinicaltrials.gov (2008–2019), EMBASE (1980-2021), Cochrane Central Register of Controlled Trials CENTRAL (1999-2021) and Google Scholar (2004-2021) databases in our primary search along with the reference lists of electronically retrieved full-text papers. The date of our last search will be set at April 20th, 2021. Study selection We will not apply language, country or date restrictions during the electronic search to minimize the possibility of potential article losses. Articles that are written in non-Latin alphabet will be, however, excluded for translational reasons. The electronically retrieved studies will be screened in three consecutive stages. Firstly, deduplication of articles will be performed and following that the titles and abstracts of retrieved articles will be screened to assess their potential eligibility for inclusion in the present systematic review. Those that are presumed to meet the criteria for selection will be retrieved in full text. In the final stage, all observational (both prospective and retrospective) studies as well as randomized controlled trials (including quasi-randomized trials) that report the impact of combined platinum and taxane therapy on the QoL of ovarian cancer patients will be considered as eligible for inclusion. Conference proceedings and abstracts that are published in the databases that were used or included int the references of electronically retrieved articles will be also considered to be eligible, provided that the outcomes of interest are available within their context. Animal studies, case reports, case series and review articles will be excluded from the present meta-analysis. When discrepancies arise concerning article eligibility, assessment of risk of bias and selection of statistical analysis they will resolved by the consensus of all authors. Quality and risk of bias assessment The risk of bias and methodological quality of the included studies will be evaluated by two authors (F.L. and M.A.) using the Newcastle-Ottawa Scale (NOS), which evaluates the selection of the study groups, the comparability of the groups and the ascertainment of the exposure or outcome of interest. The quality of randomized trials will be assessed with the Risk of Bias 2 (RoB2) tool. Quality of evidence will be evaluated under the Grading of Recommendations Assessment, Development and Evaluation (GRADE) framework, ranging from very low to high. More specifically, credibility of evidence will be assessed by taking into account the following domains: study limitations, directness, consistency, precision and publication bias. In particular, study limitations will be evaluated based on risk of bias assessments (NOS score, RoB2 tool), while directness will be judged using the PICOS (population, intervention, comparison, outcome, study type) approach. To assess consistency and precision, clinically important effects will be defined as differences in QoL of ≥30%, indicating a range of equivalence from -15% to 15%. Study selection Types of studies and patients No language restrictions will be applied. We will include all observational studies as well as randomized trials that assess differences in the quality of life of ovarian cancer patients treated by combination therapy with a platinum-based agent and a taxane over the course of the chemotherapy treatment as well as following its completion. Studies will be selected irrespective of their follow-up duration and irrespective of the intervals that were used during patient assessment. To ensure homogeneity of reported results we will select only studies that evaluated the quality of life using the QLQ-C30 and QLQ-OV28 questionnaires. Data extraction and investigated outcomes Data extraction will be performed using a modified data form that will be based in Cochrane`s extraction form for intervention reviews for RCT`s and non-RCTs (Appendix 1). Anticipating significant differences in the timely intervals at follow-up of patients we chose to pre-define intervals of assessment that will include at least the following: i) start of chemotherapy – last cycle of chemotherapy, ii) last cycle of chemotherapy – 3 months post-chemotherapy, ii) 3 months post-chemotherapy – 6 months post-chemotherapy, iii) 6 months post-chemotherapy – 12 months post-chemotherapy iv) >12 months post-chemotherapy. However, the decision to exclude these predefined intervals in the absence of evidence, as well as the decision to include other potential intervals in the presence of sufficient data was also agreed during the design of this study. Statistical analysis Meta-analysis of selected indices will be performed in RStudio using the meta and metafor functions (RStudio Team (2015). We will calculate pooled risk ratios (RR), mean differences (MD) and 95% confidence intervals (CI) with the Hartung-Knapp-Sidik-Jonkman instead of the traditional Dersimonian-Laird random effects model analysis (REM). Publication bias, trial sequential analysis and metaregression analysis will be performed provided that at least 10 articles will be included in the quantitative analysis.

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