How much searching is enough? Comprehensive versus optimal retrieval for technology assessments

Area of Science:

• Health Technology Assessment (HTA)
• Information Science
• Evidence Synthesis

Background:

• Effective literature searching is crucial for comprehensive Health Technology Assessment (HTA) reports.
• Deciding when to stop searching is a critical but often subjective aspect of evidence synthesis.

Purpose of the Study:

• To review and identify various methods for optimizing study retrieval in Health Technology Assessment (HTA).
• To highlight the current lack of formal evaluation regarding the efficacy of different retrieval optimization techniques.

Main Methods:

• Systematic review of methodology literature concerning literature searching strategies.
• Identification and categorization of techniques used to evaluate search yield and determine search cessation.

Main Results:

• Eight distinct methods for optimizing literature retrieval were identified.
• Methods include Capture-recapture, commissioner feedback, disconfirming cases, Gold standard comparison, Known items retrieval, diminishing returns, a priori stopping rules, and theoretical saturation.

Conclusions:

• A variety of methods exist for optimizing literature retrieval in HTA, but formal evaluation is scarce.
• An agenda for future research is proposed, focusing on evaluating method strengths/weaknesses and the impact of missing studies.