Introduction: Chronic kidney disease patients undergoing hemodialysis are at high risk for malnutrition and electrolyte imbalances, making accurate dietary assessment essential. This study aimed to develop and validate a culturally-adapted food frequency questionnaire (FFQ) for Iranian hemodialysis patients, assessing its validity and reliability against food records and biochemical markers. Methods: A cross-sectional study was conducted among 145 adult hemodialysis patients at Imam Reza Hospital, Tabriz. A 113-item was developed and validated through expert review and pilot testing. The FFQ was administered twice, three months apart, to assess test-retest reliability. Six-day food records and biochemical markers (blood urea nitrogen, creatinine, calcium, phosphorus, sodium, and potassium) served as reference standards. Validity was evaluated using Pearson correlations, tertile classification agreement, and comparison with biochemical data. Test-retest reliability was assessed using intraclass correlation coefficients. Findings: The FFQ overestimated energy and most nutrient intakes compared to food records (mean energy: 2163 kcal vs. 2040 kcal). Validity correlations were highest for vegetable oil (r=0.99) and polyunsaturated fat (r=0.96), and lowest for nuts (r=0.382) and folate (r=0.581). Agreement in tertile classification was highest for vegetable oil (86.8%) and lowest for cholesterol and folate (22%). Significant positive correlations were observed between FFQ-derived protein intake and BUN/urea (r=0.224, P=0.007). Test-retest reliability was high, with no significant differences between FFQ administrations. Conclusion: The developed FFQ is a valid and reliable tool for assessing dietary intake in Iranian hemodialysis patients and can improve dietary management in this population.
Jozi et al. (Sun,) studied this question.