Semi-structured Interview for Safety Studies of Probiotics and Dietary Supplements
Keywords:
Delphi method; content validation; semi-structured interview; safety; probiotics; food supplements; side effects.Abstract
ABSTRACT
Introduction: Evaluating the safety and tolerability of dietary supplements and probiotics requires validated instruments that capture the user's subjective experience in real-world contexts.
Objective: To develop a semi-structured interview, validated using the Delphi method, to collect clinical information on the effects perceived by probiotic consumers.
Methods: An adaptation of the Delphi method was used to validate the interview content. As a first step, an initial draft was developed, structured around thematic domains: general health, digestive health, appetite control, emotional well-being, systemic symptoms/inflammation, side effects/safety, and weight loss/metabolism. Subsequently, nine experts evaluated each item (question) on three dimensions: clinical relevance, clarity of wording, and representativeness of the domain, using an implicit Likert scale with four levels: not relevant, somewhat relevant, relevant, and very relevant.
Results: The analysis showed high consensus among the experts, with most items rated as relevant or highly relevant across all dimensions. For example, the items “Easy to incorporate into the routine” and “Post-capsule pain” received high clinical relevance ratings from eight and nine experts, respectively. The instrument's internal consistency was excellent, evidenced by the high agreement rate.
Conclusions: The validated semi-structured interview proves to be a highly relevant tool which is clear, and representative content for the critical domains in assessing the safety of supplements. Its content validation makes it a reliable instrument for use in future clinical and pharmacovigilance studies.
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