Data were analysed using Stata 12 (StataCorp, College Station, TX, US). Internal consistency of the nutrition knowledge score was mea- sured using the Cronbach's alpha statistic. Univariate analyses were performed to assess the relationship between nutrition knowledge, the DASH score and blood pressure. Baron and Kenny's approach to mediation analyses was used to assess the DASH score (diet quality) as a mediator (Baron and Kenny, 1986). For the multivariate logistic regression, the DASH score variable was collapsed to an ordinal variable based on the DASH score quintiles. Participants in quintile 5 had the highst DASH score and best diet quality and quintiles 4–1 had lower DASH scores and progressively poorer quality diets. The high DASH score and hypertension variables were entered into the models as dichotomous, dependent variables. The nutrition knowledge score variable was recoded as an ordinal variable based on the quintiles and entered into all models as an independent variable. Results were adjusted for potential confounding variables including socio-demographic, lifestyle and health characteristics.
Ethics
Ethical approval was granted by the Clinical Research Ethics Committee of the Cork Teaching Hospitals in Ireland, March 2013. All participants provided written informed consent.