Can Google Scholar Serve as a Sufficient Source for Systematic Reviews? Reconsidering the Need for Multiple Database Searches

Abstract Systematic reviews derive their credibility from the comprehensive identification of relevant evidence. In medical science research, systematic reviews have traditionally been pursued through searches of multiple curated bibliographic databases, a practice reinforced by methodological convention and consensus reporting frameworks. However, this approach developed in an earlier era of scientific communication, when dissemination was slower, more journal-centered, and more tightly bounded by selective indexing systems. The contemporary scientific literature has evolved substantially, with research now disseminated rapidly across preprint servers, institutional repositories, open-access platforms, and multilingual digital venues that are variably represented in subscription-based databases. Google Scholar reflects a different model of evidence retrieval. Rather than relying on journal-level selection, it aggregates scholarly content across disciplines, languages, and publication formats with greater immediacy and broader accessibility than traditional databases. This Opinion article re-examines the assumption that multiple curated databases are methodologically necessary for systematic reviews and advances a specific proposition: that, under transparent, systematic, and rigorous search and screening practices, Google Scholar may be sufficient solely to support evidence identification for systematic and related reviews. This proposition is examined across four domains: comprehensiveness, timeliness, accessibility, and methodological adaptability. Google Scholar may reduce structural omission of non-English studies, gray literature, preprints, and regionally disseminated research; improve capture of rapidly emerging evidence; and remove access barriers associated with subscription-based tools. Its limitations—including reduced search transparency, increased screening burden, and the absence of controlled vocabularies—are acknowledged. However, these limitations can be mitigated through transparent reporting, structured keyword selection strategies, citation tracking, and the use of complementary tools such as Publish or Perish software and emerging artificial intelligence-assisted screening approaches. The central question, therefore, is not whether Google Scholar has limitations, but whether those limitations outweigh its advantages in approximating the primary objective of systematic reviews, namely the broad and timely identification of relevant evidence. Reconsidering this balance is warranted to ensure that evidence retrieval practices remain aligned with the contemporary landscape of scientific communication while upholding methodological rigor.