The highest level of evidence — with no primary data collection. Evidens runs the entire methodology, from the research question to GRADE, and hands back the complete, documented statistical synthesis for your committee and your article. The writing and the authorship stay 100% yours.
They are related but distinct. The systematic review is the method of searching and synthesizing the literature; the meta-analysis is the statistical step that combines the results numerically — and not every systematic review ends in a meta-analysis.
Identifies, selects and appraises all the relevant literature for a well-defined question, following an explicit and reproducible protocol. It reduces reviewer bias through pre-registered inclusion criteria, a comprehensive search and dual screening. When studies are too heterogeneous to combine, the synthesis can be qualitative (a structured narrative, for example SWiM).
It is the quantitative synthesis within the systematic review: it combines the results of multiple studies into a single pooled estimate, with a confidence interval. By bringing the samples together, it gains the statistical power and precision that individual studies lack, and lets you explore why results diverge from one another.
Well conducted, a systematic review with meta-analysis sits at the top of the evidence pyramid: it generates no new data, but critically synthesizes what has already been published.
It is one of the most efficient paths to publishing with impact — especially for those who don't yet have the infrastructure for a primary study.
It sits at the top of the pyramid and tends to be highly cited, because it synthesizes an entire field into a single reference work — with strong potential impact on your CV and in your area.
It works on already published data. Because it uses secondary, aggregate sources, it often does not require contact with patients or IRB/ethics committee approval — always confirm the rules of your institution and target journal.
With no recruitment, follow-up or fieldwork, the timeline is shorter and more predictable than that of a cohort study or a clinical trial.
Accessible to students, residents and graduate students with no infrastructure: what it demands is rigorous methodology and access to bibliographic databases — not a lab bench or field funding.
It produces a substantial publication with first-line authorship, adds weight to your academic record and opens doors to selection processes, grants and academic advancement.
By pooling several samples, it resolves disagreements in the literature, estimates the effect more precisely and maps the gaps that justify future research.
You bring the question and the topic; Evidens executes every methodological step with reporting rigor (PRISMA 2020) and delivers the complete, documented statistical synthesis. We walk you through each stage, transparently, so you can understand, write up and defend every decision.
We frame the question in PICO/PECO and define the inclusion and exclusion criteria, the primary and secondary outcomes and the study designs to include.
We structure the protocol with you and register it on PROSPERO (or an equivalent platform), following PRISMA-P, ensuring transparency and priority for your project before the search begins.
We build the search syntax (MeSH/Emtree and free-text terms, Boolean operators) and run it across multiple databases — PubMed, Embase, Cochrane CENTRAL, Scopus and Web of Science, with hand-searching of references.
Screening by two independent reviewers, with conflict resolution, documented in the PRISMA 2020 flow diagram (identification, screening, eligibility and inclusion).
Standardized extraction on a pre-defined form: study characteristics, population, intervention/exposure, outcomes and effect measures with their variances.
Assessment with the right tool for the design: RoB 2 for randomized trials, ROBINS-I for observational studies and QUADAS-2 for diagnostic accuracy.
Pooling of effects with the appropriate model — fixed effect vs. random effects — on the right scale: OR, RR, HR, MD, SMD or proportion, depending on the outcome.
We quantify between-study heterogeneity with I², Cochran's Q and tau², and interpret what it means for confidence in the pooled estimate.
Subgroup analyses and meta-regression to investigate sources of heterogeneity, plus sensitivity analyses (e.g., leave-one-out) to test robustness.
Assessment via funnel plot, Egger's test and trim-and-fill when the number of studies allows, to estimate the impact of unpublished studies.
Rating of confidence in the body of evidence with GRADE, with the Summary of Findings table by outcome.
We deliver the figures, the tables and the documentation of every methodological decision, organized by the PRISMA 2020 checklist — the complete foundation for you to write Methods and Results.
Each study's effect and the pooled estimate, with weights and confidence intervals.
Funnel plot for inspecting publication bias, with Egger's test reported.
Summary of Findings table by outcome, with the GRADE certainty rating.
Diagram of study identification, screening, eligibility and inclusion.
Summary by domain (RoB 2 / ROBINS-I / QUADAS-2) and by study.
Every decision documented per PRISMA 2020, ready to support your write-up of Methods and Results.
From a first publication to a thesis — a meta-analysis fits almost every stage of a career.
Tell us the topic and the research question. We reply by email with the scope, the timeline and the quote — and stay with you from the protocol to submission.