Psychometric Properties of the Turkish Version of the Dietary Sodium Restriction Questionnaire

Background Sodium restriction is the primary nonpharmacological treatment in heart failure (HF) to prevent rehospitalization and reduce HF symptom burden. Despite the importance of restricting sodium in the diet, the prevalence of nonadherence to a low-sodium diet has been known to be high. To reduce the high prevalence of nonadherence, we have to know the facilitating and challenging factors. The planned behavior theory shows those factors, including attitudes, social norms, and perceived behavioral control. The Dietary Sodium Restriction Questionnaire (DSRQ) was developed based on the planned behavior theory. However, in Turkey, the psychometric properties of this instrument have not been studied yet. Therefore, the aim of this study was to conduct a psychometric testing of the Turkish version of the DSRQ among patients with HF. Methods Data were collected from 300 patients who were recommended a sodium-restricted diet because of a diagnosis of HF. Validity was tested using content validity index, Kendall W, and exploratory and confirmatory factor analyses. Reliability was tested using item-total and interitem correlations, Cronbach's alpha coefficient of reliability, independent-sample t test, and test-retest analysis. Results The exploratory factor analysis revealed that 3 factors accounted for 78.2% of the explained variance. The factor loads ranged between 0.67 and 0.96. The results of the confirmatory factor analysis showed goodness-of-fit indices greater than 0.90, with a root-mean-square error of approximation less than 0.10 and a root-mean-square residual of 0.05. The Cronbach's alpha coefficient for DSRQ was 0.92 and for each subscale was as follows: attitude and subjective norm, 0.97; perceived external behavior control, 0.89; and perceived internal behavior control, 0.83. Conclusions The DSRQ is a valid and reliable instrument in assessing the attitudes, beliefs, and perceived behavioral control related to following a low-sodium diet of patients with HF in the Turkish population.