# Dairy intake screener as web‐based application is reliable and valid

## TL;DR

A web-based tool called 'Dairy Diary' was found to reliably and moderately accurately assess dairy intake among nutrition-literate users.

## Contribution

The study demonstrates the test-retest reliability and moderate validity of a new web-based dairy intake screener.

## Key findings

- The screener showed strong test-retest reliability with high correlations for individual dairy products.
- The screener had moderate validity when compared to weighed food records, with acceptable agreement for total dairy intake.
- The tool had high sensitivity but low specificity, indicating it can detect dairy intake but may overestimate.

## Abstract

The “Dairy Diary” is a user‐friendly web‐based dairy intake screener. The reliability and validity are unknown. We aimed to evaluate the screener in terms of test–retest reliability and comparative validity. In a diagnostic accuracy study, a purposefully recruited sample of 79 (age: 21.6 ± 3.8 years) undergraduate dietetics/nutrition students from three South African universities completed 3 non‐consecutive days of weighed food records (reference standard) within a seven‐day period (comparative validity), followed by two administrations, 2 weeks apart, of the screener (index test) (reliability). For the four dairy product serving scores (PSSs) and the summative dairy serving scores (DSSs) of the screener and the food records, t‐tests, correlations, Bland–Altman, Kappa, McNemar's, and diagnostic accuracy were determined. For reliability, mean PSSs and DSSs did not differ significantly (p > .05) between the screener administrations. The mean PSSs were strongly correlated: milk (r = .69; p < .001), maas (fermented milk) (r = .72; p < .001), yoghurt (r = .71; p < .001), cheese (r = .74; p < .001). For DSSs, Kappa was moderate (k = 0.45; p < .001). Non‐agreeing responses suggest symmetry (p = .334). For validity, the PSSs of the screener and food records were moderately correlated [milk (r = .30; p = .0129), yoghurt (r = .38; p < .001), cheese (r = .38; p < .001)], with k = 0.31 (p = .006) for DSS. Bland–Altman analyses showed acceptable agreement for DSSs (bias: −0.49; 95% CI: −0.7 to −0.3). Categorized DSSs had high sensitivity (81.4%) and positive predictive value (93.4%), yet low specificity (55.6%) and negative predictive value (27.8%). The area under the receiver operating characteristic curve (0.7) was acceptable. The “Dairy Diary” is test–retest reliable with moderate comparative validity to screen for dairy intake of nutrition‐literate consumers.

The “Dairy Diary” is a user‐friendly web‐based dairy intake screener. The reliability and validity are unknown. We aimed to evaluate the screener in terms of test–retest reliability and comparative validity. The “Dairy Diary” is test–retest reliable and has moderate comparative validity to screen for dairy intake in groups.