To develop and to validate a food frequency questionnaire (FFQ) to assess potassium
intake of patients on hemodialysis (HD).
This is a cross-sectional study that included 41 patients in the FFQ development step
and 53 patients in the FFQ validation step. In the FFQ development step, the patients
completed a three-day food record (used as a reference method). Total potassium intake
and potassium from each food item were calculated. Food items that contributed up
to 90% of the total potassium intake were considered to be included in the FFQ food
list. Then the FFQ was applied in person through the google-forms platform. The result
of potassium intake obtained by the FFQ was compared with that obtained by the three-day
A total of 94 patients were included, 53.2% women; age 55.7±15.0 years; 47.9% had
diabetes; body mass index 25.0±4.5 kg/m2 and dialysis vintage 34.5 (17.0-68.2) months. Demographic, clinical and laboratory
parameters did not differ between the development and validation groups. From the
255 registered food items, 85 comprised the FFQ. The standardized Cronbach’s alpha
obtained was 0.71. No difference was found between the potassium intake obtained by
the FFQ and by the three-day food record (1,438.5±659.4 mg/d vs. 1,464.8±529.4mg/d;
p=0.753 respectively) with an intraclass correlation coefficient of 0.66 (p=0.001).
No systematic bias or proportionality bias between the methods was observed in the
Bland-Altman graphical analysis.
The quantitative FFQ presented strong relative validity and may constitute a practical
tool in the analysis of potassium intake of patients on hemodialysis.
Received in revised form:
Publication stageIn Press Journal Pre-Proof
This work was supported in part by the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq; #302765/2017-4).
The author GASM receives a scholarship from Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq; #133958/2019-1). The authors GC and CIR receive a scholarship from Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES; #88882.430671/2019-01; #88887.352924/2009-00).
Financial conflicts of interest:
The authors declare no conflict of interest.
Credit author statement:
Gisselma Alny Santos Muniz: Conceptualization, Methodology, Formal analysis, Investigation, Writing-original draft. Christiane Ishikawa Ramos: Conceptualization, Methodology, Formal analysis, Writing-review & editing. Gabriele Claudino: Methodology, Investigation, Writing-original draft. Lilian Cuppari: Conceptualization, Methodology, Resources, Supervision, Writing- review & editing.
© 2022 Published by Elsevier Inc. on behalf of the National Kidney Foundation, Inc.