Background: Network meta-analyses (NMA) have become increasingly popular as innovative techniques to compare multiple interventions within a network of studies. Objective: To examine the epidemiology, reporting characteristics and adherence to Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA)-NMA extension of a representative sample of published systematic reviews (SRs) with NMAs.
Methods: Cross-sectional study (protocol at https://osf.io/pa6dz/). We searched Pubmed for NMAs indexed during January 2023. We extracted epidemiological (e.g., journal, country, authors, NMA focus) and reporting (e.g., number of studies, participants, nodes of interventions, outcomes, statistics, certainty of the evidence, PRISMA-NMA checklist, protocol registration) characteristics. Overall adherence to PRISMA-NMA was evaluated. Data were analyzed descriptively. Correlation analysis will be conducted to explore the characteristics that might affect quality of reporting by May 2023.
Results: A sample of 110 NMAs was included. Overall, 77.3% of NMAs were published on specialty journals with a median IF of 4.8 (IQR 2.9-6.4) and had a median number of 7 authors (IQR 2–11) often based in China (52.7%). The majority of NMAs focused on therapeutics (92.7%), primarily targeting cardiovascular diseases (21.8%) (Table 1). Types of interventions addressed were mainly pharmacological (59.0%). On average, each NMA included 21 studies (median, IQR 12–43) with 3695 participants (median, IQR 1525–12404). The majority (61.82%) prospectively registered a study protocol, reported four outcomes (median, IQR 2–7) including 7 nodes (median, IQR 4 – 12). Two-thirds (65.5%) reported having followed PRISMA-NMA, whereas one-third (35.5%) used GRADE to rate certainty of the evidence (Table 2). Preliminary results based on 10% of the sample (n=12) showed a median adherence to PRISMA-NMA items was 71.4% (35 out of 49 items, IQR 32.5-37.2). The less reported items were as follows: protocol registration, limitation and funding in abstracts, synthesis of results and geometry of network in methods, and results sections (Figure 1).
Conclusions: Most NMAs, focused on pharmacological interventions, are published in specialty journals with high impact factors but their quality of reporting can be easily improved. Patient, public, and/or healthcare consumer involvement: A more widely adherence to reporting guideline of NMA should be endorsed by authors and journals for letting stakeholders understand, assess, and trust this evidence.