Aims: To validate the questionnaire designed by OConnor et al. (2018) and investigate the association between vitamin D knowledge and serum 25-OH-D.
Methods: Face and content validity were assessed by a panel of experts and public (n=8). The final questionnaire comprised of four sections; demographics (12 questions), knowledge (13 questions), attitudes toward sun exposure and vitamin D (11 questions) and perceptions of supplementation and fortification (four questions). Construct validity was assessed by employing known-groups approach. Internal consistency was examined via Cronbach alpha (α ≥0.70) and factor analysis. Approximately two-weeks after the first questionnaire administration, the questionnaire was re-distributed for testretest reliability. A sub-population was recruited and serum 25(OH)D was measured via blood-spot and LCMS analysis. Further descriptive statistic, t-test analysis, Chi-square and Kendalls tau-b correlation were performed (significance taken at P<0.05).
Results: 190 individuals completed the first-round questionnaire, and n=62 completed the second-round online (Online Surveys). Content and face validity resulted in nine items reformulation. Factor analysis revealed the knowledge construct contained three components that had eigenvalues values >1, explaining 29.1%, 34%, 37.5%, of the total variance. Internal consistency was adequate (Cronbach α=0.786). Construct validity was adequate (68.32% (±15.24) vs. 38.06% knowledge score (±14.19), P<0.001). Testretest identified one knowledge question answer ((χ2(1) =1.032, P =0.040) and two answer options (χ2(1) =8.267, P=0.040 and χ2(1)=5.905 P=0.015)) to have statistical significant answer distributions. A non-significant, moderate, positive association between knowledge score and serum 25-OH-D was identified (n=10, τb=.333, P=.180).
Conclusion: The questionnaire can be used as a validated instrument to assess vitamin D knowledge, attitudes and perceptions within research. Moreover, the pilot study demonstrates vitamin D knowledge is associated with vitamin D status, however, requires further research to verify this relationship.