Objective: To conduct a systematic review of studies for the validation of semiquantitative FFQ (SFFQ) that assess food intake in adults.
Design: The authors conducted a systematic search in PubMed for articles published as late as January 2020 in Spanish, English, French and Portuguese. Individual searches (twelve in total) paired three hyphenated and non-hyphenated variations of 'semiquantitative food frequency questionnaire' with both 'validity' and 'validation' using the 'all fields' and the 'title/abstract' retrieval categories. Independent extraction of articles was performed by four authors using predefined data fields.
Setting: We searched for original SFFQ validation studies that analysed general diet composition (nutrients with or without food groups or energy analysis) in healthy adults, in any setting, and that also reported correlation coefficients.
Participants: Healthy adults.
Results: Sixty articles were included. The preferred comparison standard for validation was food records (n 37). The main correlation coefficients used were Pearson's (n 41), and validity coefficients varied from -0·45 to 1. Most correlation coefficients were adjusted by energy (twelve studies presented only crude values). The elements mentioned most frequently were energy, macronutrients, cholesterol, SFA, PUFA, fibre, vitamin C, Ca and Fe.
Conclusions: Although all these SFFQ are reported as validated, coefficients may vary across groups of foods and nutrients. Based on our findings, we suggest researchers to consult our revision before choosing a SFFQ and to review important issues about them, such as their validation, number of items, number of participants, etc. Systematic Review Registration: PROSPERO number CRD42017064716. Available at: http://www.crd.york.ac.uk/PROSPERO/display_record.asp?ID=CRD42017064716.
Keywords: Reproducibility; Systematic review; Validation; Validity; semiquantitative FFQ.