Accuracy and reliability of college athletes’ scoring of artificial urine color samples to determine hydration status

There is potential for error when athletes self-assess urine color when attempting to distinguish between high and low urine concentration. This study investigates student athletes’ ability to score artificial urine color samples (Uc) using an 8-color Uc chart. A total of 35 student-athletes (n = 30 women) scored 51 samples on two days 2–5 days apart. Artificial urine color samples were designed to match urine colors 4–7 from an 8-color Uc chart. The color rating took place using a scoring box with LED lights providing an illuminance of 1660 lux. The data were used to design random effect models to test the contrast between the athletes' color ratings and the actual color of the reference, with significance set at P ≤ 0.05. Results showed that as a group, participants scored samples similarly between days (4.4 ± 1.2 vs. 4.5 ± 1.2, P = 0.52), but on an individual level, samples were rated inconsistently (intraclass correlation coefficient: 0.30, 95% CI: 0.13–0.56), with correlations between reported scores and the reference colors ranging from r = −0.74 to + 0.64. Samples were scored significantly lighter than their actual color shade (odds ratio: 2.64, 95% CI 1.55–4.52, P < 0.001). In conclusion, athletes scored the color of artificial urine color samples inconsistently between days. Further, the odds are 2.6 to 1 that athletes report urine samples one shade lighter than their actual color, which in practice may affect the correct classification of urine samples with a color close to the selected Uc cut-off value to detect a high versus low urine concentration.