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Psychometric Testing of a Polyphenol Screener

Katharine L Reutzel, University of Nebraska - Lincoln


Background A need exists to develop an assessment method for the evaluation of total polyphenol intake that is valid, reliable, and timely. Objective The study aimed to determine the usability, validity, and reliability of the self-administered 98-item Polyphenol Screener (PPS). Design We conducted a parallel-forms convergent design validation study, with 24-hour dietary recalls and 24-hour urine samples as the criterion standard. Participants/setting Two separate convenience samples were recruited to evaluate the usability, validity, and reliability of the PPS. Seven randomly assigned 24-hour dietary recalls were completed using ASA24® over a 1-month period and two subsequent administrations of the PPS. A subset of 8 participants also provided two randomly assigned 24-hour urine samples during the same month. Main outcome measures Total polyphenol intake reported by the PPS and 24-hour dietary recalls, and urinary polyphenol excretion, were compared. Statistical analyses performed Usability questionnaire scores were reported as median and frequency. Average daily polyphenol intake from the 24-hour dietary recalls and average total polyphenol intake from both administrations of the PPS were compared using a paired samples t-test, Pearson’s correlation, and a Bland-Altman plot, and were compared to urinary total polyphenols using Pearson’s correlation and the method of triads. Reliability was evaluated using Pearson’s correlation between repeat administrations of the PPS. Results Phase 1 (n=10) and Phase 2 (n=35) had median ages of 58.5 and 43.4, respectively, identified as white, and were highly educated. The overall usability of the PPS was 7.5 out of 10. The 24-hour dietary recalls and PPS were correlated (r=0.589; P<0.001), with the PPS overestimating polyphenol intake compared to the recalls (1,730 ± 988 mg/day (recall) vs 2,443 ± 1,597 mg/day (PPS); P=0.002). Mean total urinary polyphenol excretion was positively correlated with the PPS (r=0.629; P=0.095) and 24-hour dietary recalls (r=0.618; P=0.103). Total polyphenol intake was highly correlated between repeat administrations (r=0.936; P<0.01). The PPS took approximately 10-15 minutes for participants to complete. Conclusions The PPS was usable, valid for estimating total polyphenol intake, reliable, and an efficient use of time based on the study sample. Further research needs to take place with a larger, more diverse sample.

Subject Area

Quantitative psychology|Food Science|Nutrition

Recommended Citation

Reutzel, Katharine L, "Psychometric Testing of a Polyphenol Screener" (2021). ETD collection for University of Nebraska - Lincoln. AAI28418683.