Understanding the associations between modifying factors, individual health beliefs, and hemodialysis patients' adherence to a low-phosphorus diet.

Objective: Hyperphosphatemia in end-stage renal disease is associated with significant morbidity and mortality. Because phosphorus is not effectively dialyzed, dietary adherence remains a significant problem. Previous studies have examined the health belief model, but none have looked at stages of change and dietary adherence in patients undergoing hemodialysis (HD).

Design: Cross-sectional survey.

Setting: Three dialysis centers in Columbus, Ohio, between August 2012 and March 2013.

Subjects: English-speaking patients age 18 or older on HD without dementia or developmental delay.

Intervention: None.

Main Outcome Measure: Associations between dietary adherence based on the Precaution Adoption Process Model (stages of change) and serum phosphorus levels via a conceptual model incorporating modifying factors and individual health beliefs.

Results: Ninety-five patients completed the survey; 59 (62%) endorsed adherence to a low-phosphorus diet and 32 (34%) had phosphorus values ≤5.5 mg/dL. Modifying factors associated with diet adherence included nonminority status odds ratio (OR), 95%CI 8.99 (1.08-74.60), greater level of education OR 18.23 (1.62-205.00), better quality of life OR 9.28 (1.35-63.71), and time on dialysis OR 1.04 (1.01-1.07). Individual health beliefs associated with diet adherence included perceived benefits OR 3.18 (1.47-6.88) and self-efficacy OR 1.22 (1.09-1.38). Modifying factors associated with phosphorus control included: age OR 0.94 (0.90-0.99), minority status OR 0.11 (0.02-0.68), greater level of education OR 6.60 (1.41-31.04), knowledge about chronic kidney disease OR 1.48 (1.03-2.13), and time on dialysis OR 0.98 (0.96-0.99). Individual health beliefs associated with phosphorus control included self-efficacy OR 1.08 (1.01-1.16).

Conclusion: HD clinicians and educators may obtain better results with dietary adherence and phosphorus control if they focus not only toward disease and dietary education but also on understanding modifying factors and individual health beliefs. Assessing where the patient is with regard to stages of change may assist health care providers in better matching interventions that build patients' self-efficacy.