Evidence that self-affirmation improves phosphate control in hemodialysis patients: a pilot cluster randomized controlled trial.

Background: Hemodialysis patients are at risk of serious health complications, yet treatment non-adherence remains high.
Purpose: Warnings about health risks associated with non-adherence may trigger defensive reactions. We studied whether an intervention based on self-affirmation theory (Steele 1988) reduced patients' resistance to health-risk information and improved adherence.
Methods: One hundred twelve patients either self-affirmed or completed a matched control task before reading about the risks associated with a lack of phosphate control. Serum phosphate was collected from baseline up to 12 months.
Results: Self-affirmed patients had significantly reduced serum phosphate levels at 1 and 12 months. However, contrary to the predictions derived from self-affirmation theory, self-affirmed participants and controls did not differ in their evaluation of the health-risk information, behavioural intention or self-efficacy.
Conclusions: A low-cost, high-reach health intervention based on self-affirmation theory was shown to reduce serum phosphate over a 12 month period. Further work is required to identify mediators of the observed effects.