Systematic reviews and meta-analysis in nutrition research

There exists an ever-increasing number of systematic reviews, with or without meta-analysis, in the field of nutrition. Concomitant with this increase is the increased use of such to guide future research as well as both practice and policy-based decisions. Given this increased production and consumption, a need exists to educate both producers and consumers of systematic reviews, with or without meta-analysis, on how to conduct and evaluate high-quality reviews of this nature in nutrition. The purpose of this paper is to try and address this gap. In the present manuscript, the different types of systematic reviews, with or without meta-analyses, are described as well as the description of the major elements, including methodology and interpretation, with a focus on nutrition. It is hoped that this non-technical information will be helpful to producers, reviewers and consumers of systematic reviews, with or without meta-analysis, in the field of nutrition.

First-line treatment in the management of advanced renal cell carcinoma: systematic review and network meta-analysis

OBJECTIVES

To conduct a systematic review and network meta-analysis (NMA) to assess effectiveness of first-line treatments for advanced renal cell carcinoma (RCC).

METHODS

Database searches were conducted to identify randomized controlled trials (RCTs) reporting results for eligible treatments. A fixed-effect Bayesian NMA was conducted to assess the relative effectiveness of treatments, with progression-free survival (PFS) reported as hazard ratios (HRs) and 95% credible intervals (CrIs).

RESULTS

Eleven unique RCTs were suitable for inclusion in the NMA. In the base case, in terms of PFS, sunitinib was superior compared with bevacizumab + IFN-α (HR = 0.79, 95% CrI: 0.64 - 0.96), everolimus (HR = 0.70, 95% CrI: 0.56 - 0.87), sorafenib (HR = 0.56, 95% CrI: 0.40 - 0.77) and temsirolimus + bevacizumab (HR = 0.74, 95% CrI: 0.56 - 0.96). Although, the point values for the mean and median HRs were < 1.0, there was no significant difference in PFS between sunitinib and axitinib, pazopanib or tivozanib. Although sensitivity analyses impacted the results of the NMA, no treatment was significantly more efficacious than sunitinib.

CONCLUSION

Results from this analysis suggest that there is no treatment superior to the current benchmark treatment, sunitinib, in the management of advanced RCC in the first-line setting.

Comparing vaccines: a systematic review of the use of the non-inferiority margin in vaccine trials

BACKGROUND

Non-inferiority (NI) randomized controlled trials (RCTs) aim to demonstrate that a new treatment is no worse than a comparator that has already shown its efficacy over placebo within a pre-specified margin. However, clear guidelines on how the NI margin should be determined are lacking for vaccine trials. A difference (seroprevalence/risk) of 10% or a geometric mean titre/concentration (GMT) ratio of 1.5 or 2.0 in antibody levels is implicitly recommended for vaccine trials. We aimed to explore which NI margins were used in vaccine RCTs and how they were determined.

METHODS

A systematic search for NI vaccine RCTs yielded 177 eligible articles. Data were extracted from these articles using a standardized form and included general characteristics and characteristics specific for NI trials. Relations between the study characteristics and the NI margin used were explored.

RESULTS

Among the 143 studies using an NI margin based on difference (n=136 on immunogenicity, n=2 on efficacy and n=5 on safety), 66% used a margin of 10%, 23% used margins lower than 10% (range 1-7.5%) and 11% used margins larger than 10% (range 11.5-25%). Of the 103 studies using a NI margin based on the GMT ratio, 50% used a margin of 0.67/1.5 and 49% used 0.5/2.0. As observed, 85% of the studies did not discuss the method of margin determination; and 19% of the studies lacked a confidence interval or p-value for non-inferiority.

CONCLUSION

Most NI vaccine RCTs used an NI margin of 10% for difference or a GMT ratio of 1.5 or 2.0 without a clear rationale. Most articles presented enough information for the reader to make a judgement about the NI margin used and the conclusions. The reporting on the design, margins used and results of NI vaccine trials could be improved; more explicit guidelines may help to achieve this end.