Adherence to Protocol Registration Among Systematic Reviews on Photobiomodulation: A Meta-Research Study.

Area of Science:

• Biomedical research
• Evidence-based medicine
• Photobiomodulation therapy

Background:

• Photobiomodulation (PBM), including low-level laser therapy (LLLT) and light-emitting diode (LED) therapies, is widely studied.
• Systematic reviews are critical for synthesizing evidence but require rigorous methodology.
• Assessing the quality of systematic reviews on PBM is essential for reliable clinical application.

Purpose of the Study:

• To map systematic reviews on PBM, evaluating protocol registration, adherence to registry updates, and topic redundancy.
• To identify gaps and areas for improvement in the conduct and reporting of PBM systematic reviews.
• To inform best practices for future systematic reviews in PBM research.

Main Methods:

• Searched MEDLINE (PubMed) and Epistemonikos for systematic reviews on PBM up to June 2, 2025.
• Extracted data on protocol registration (PROSPERO, INPLASY, OSF), registry updates, protocol deviations, and evidence certainty assessment (GRADE).
• Analyzed 285 systematic reviews, with a focus on dentistry and orofacial dysfunctions.

Main Results:

• Only 45% of PBM systematic reviews had registered protocols, with most on PROSPERO.
• 72% of PROSPERO records remained "ongoing" post-publication, indicating poor status updates.
• 22.4% showed deviations between protocols and published reviews; topic redundancy was high (e.g., 20 reviews on orthodontics).
• Only 18.5% used the GRADE approach for certainty of evidence, primarily in reviews with meta-analysis.

Conclusions:

• Low adherence to protocol registration and limited registry updates were observed in PBM systematic reviews.
• High topic redundancy and infrequent certainty of evidence assessments were noted.
• Strengthening prospective registration and transparent reporting is vital for trustworthy PBM evidence to guide clinical decisions and policy.